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Integrated control of insect pests in the Netherlands

Editors:A.K . Minks and P. Gruys

(~x-^S- gtltuut voor onderzoek niTr^iiiùiiiiiii nTîiiii ii ii MarjJ 67Q9^PG Wageninge ? Tfirt^08370-11821/11752

Wageningen Centre for Agricultural Publishing and Documentation 1980

!c-, Il _ i- 'l ) rJ - i i Coverdrawing . Adoxophyes orana (F.v.R.)draw nb yH .Beeke ,Researc hStatio nfo rFrui t Growing,Wilhelminador p (Zeeland).

ISBN9 022 071 62

(c)Centr efo rAgricultura lPublishin gan dDocumentation ,Wageningen ,198 0

Nopar to fthi sboo kma yb ereproduce dan dpublishe d inan yform ,b yprint ,photoprint , microfilmo ran yothe rmean swithou twritte npermissio nfro mth epublishers . Contents

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Introduction 1

1 Fruit crops 3 1.1 Developmento fa nintegrate dcontro lprogra mfo rorchard s (P. Gruys) 5 1.2 Implementation ofintegrate d control inorchard s (P. Gruys, D.J. de Jong & H.J. Mandersloot) 11 1.3 Tortricidsi nintegrate dcontro li norchard s (D.J. de Jong) 19 1.4 Populationregulatio no fth efruit-tre ere dspide rmit ePanonychu sulm i bypredator s (M. van de Vrie) 23 1.5 Biologyan dcontro lo fsecondar y insectpest si nfrui tcrop s (D.J. de Jong) 29 1.6 Relationbetwee ninsec tpest so fapple ,an dthei rparasite san dpredator s (H.H. Evenhuis) 33 1.7 Natural control of the leaf-miner Stigmella malella in apple orchards (P. Gruys) 37 1.8 The sterile-male technique in control of Adoxophyes orana (Lepidoptera: Tortricidae) (G.W. Ankersmit) 43 1.9 Threshold of economic injury for apple powdery mildew and scab (H.A.Th, van der Scheer) 49 1.10 Fungi from phyllosphere and carposphere in relation to integrated control in an apple orchard (G. van den Ende) 53

2 Field crops 57 2.1 Integrated control of aphid-borne viruses of potatoes (D. Hille Ris Larribers) 59 2.2 Transmission of potato leafroll virus (M.B. Ponsen) 67 2.3 Aphids in sugar-beet (J. Gut) 71 2.4 Aphids on wheat (P.H. Vereijken & W.P. Mantel) 75 2.5 Significance of predators on the development of insect pests in crops (W. Nijveldt) 79 2.6 Approachest ointegrate dcontro lo fsoi larthropod si nsugar-bee t (W. Heijhroek, C.F. van de Bund, P.W.Th. Maas, C.A.A.A. Maenhout, V.R. Simons & G.M. Tichelaar) 83 2.7 Mesofauna ofarabl e soil (C.F. van de Bund) 87 2.8 Sterile-insect techniquefo rcontro lo fth e onionmaggot ,Deli a antiqua {J. Ticheler, M. Loosj'es & J. Noorlander) 93 2.9 Genetic controlo fth eonio n fly,Deli aantiqua ,wit h chromosomalre ­ arrangements {A.S. Robinson & C. van Heemert) 99 2.10 Integrated controlo fpest si noutdoo r vegetable crops {H. den Ouden S J. Theunissen) 103

3 Greenhouse crops 107 3.1 Integrated controlo fvegetabl e pestsi ngreenhouse s {J.C. van Lenteren, P.M.J. Ramakers &J. Woets) 109 3.2 Astrai no fPhytoseiulu s persimilis (Acari:Phytoseiidae ) resistantt o organophosphoruscompound s {G.G.M. Schulten) 119 3.3 Evaluationo fth epredaciou s miteAmblyseiu sbiben s {L.H.M. Blommers & W. Helle) 121 3.4 Geneticso fresistanc ei nspide rmite s fromros ehouse s {W.P.J. Overmeer & W. Helle) 125 3.5 Inductionan dterminatio no fdiapaus ei nth e spidermit e Tetranychus urticae {A. Veerman) 129 3.6 Isolationmechanism si npopulation so fspide rmit ei nros ehouse s {W.P.J. Overmeer, A.Q. van Zon & W. Helle) 133 3.7 Genetic controlo fth egreenhous e spidermit eTetranychu s urticae {A.M. Feldmann) 137

4 Insect-host plant relations 141 4.1 Host-plant selectioni nth eColorad opotat obeetl e {J.H. Visser &J. de Wilde) 143 S 4.2 Roleo fchemoreceptor si nhost-plan t recognitionb yinsect s {L.M. Schoonhoven) 147 4.3 Physiological conditiono fth epotat oplan tan dpopulatio n developmento f Myzuspersica e (P. Harrewijn) 151 4.4 Nutritional relationshipbetwee nhos tplant s andphytophagou smite s {J.J.H. Storms) 155 4.5 Elementsi nth epopulatio n dynamicso fEuprocti s chrysorrhoeao nroadsid e trees {F.J. van der Linde) 159

5 Host-plant resistance 163 5.1 Resistancet oaphid si nbarle y andwhea t {G.A.M. van Marrewijk & F.L. Dieleman) 165 5.2 Breedingo fcarro t (Daucus carota)fo rresistanc et ocarro tfl y(Psil a rosae) {O.M.B. de Ponti & J.C. Freriks) 169 5.3 Breedingonio n (Alliumcepa )fo rresistanc et oonio nfl y(Deli aantiqua ) {O.M.B. de Ponti) 173 5.4. Resistancei nlettuc e (Lactucasativa )t oth egree npeac h aphid (Myzus persicae) {A.E. Eenink & F.L. Dieleman) 177 5.5 Breeding lettuce (Lactuca sativa)fo rresistanc et oth eaphi d Nasonovia ribisnigri {F.L. Dieleman &A.H. Eenink) 183 5.6 Breeding tomato (Lycopersicon esculentum)fo rresistanc et oth egreenhous e whitefly (Trialeurodesvaporariorum ) {O.M.B. de Ponti S N.G. Hogenboom) 187 5.7 Breeding cucumber (Cucumis sativus)fo rresistanc et oth etwo-spotte d spidermit e (Tetranychus urticae) {O.M.B. de Ponti) 191 5.8 Breeding glabrous cucumber (Cucumis sativus)varietie st oimprov eth e biological controlo fth e greenhousewhitefl y (Trialeurodes vaporariorum) {O.M.B. de Ponti) 197

6 Pheromones and attraetants 201 6.1 Isolationan didentificatio no fpheromone s {F.J. Ritter S C.J. Persoons) 203 6.2 Synthesisan dinvestigatio no fpotentia l sexpheromone so finsect s {S. Voerman) 207 6.3 Useo fse xpheromone sfo rth econtro lo fleaf-roller si norchard s (C. van der Kraan, P. van Deventer & A.K. Minks) 211

7 Selective insecticides 215 7.1 Processesi nselectiv e toxicityo finsecticide st oinsect s {F.J. Oppenoorth & W. Welling) 217 7.2 Fungitoxicmechanis mo forganophosphoru s compounds {M.A. de Waard) 221 7.3 Modeo factio no fdiflubenzuro n {W.H. van Eck &F.J. Oppenoorth) 223 7.4 Impacto fth e insecticide diflubenzurono ninsectivorou s birds {R.H. de Reede) 225 7.5 Effect of pesticides on predacious mites {A.Q. van Zon S L.P.S. van der Geest) 111

8 Insect hormones 231 8.1 Endocrine regulationo fseasona l statesi nth eColorad opotat obeetle , Leptinotarsadecemlineat a {C.A.D. de Kort, H. Schooneveld & J. de Wilde) 233 8.2 Effectso fjuvenil e hormonean dsom e analogueso ncast e differentiationan d behaviouri nth ehone ybee ,Api smellifer a {J. Beetsma) 241 8.3 Useo finsec tgrowt h regulatorswit h juvenile hormone activityt ocontro l Adoxophyes orana: laboratory studies {H. Schooneveld) 245 8.4 Useo fth e insectgrowt h regulator,epofenonane ,i nintegrate d controli n orchards {J.P. van der Molen &P. Gruys) 251

9 Micro-organisms, viruses and nematodes 255 9.1 Trialswit hBacillu s thuringiensis against lepidopterous pests {L.P.S. van der Geest &H.J.M. Wassink) 257 9.2 Baculovirusesa sagent si nbiologica l control {D. Peters) 261 9.3 Restriction endonucleases:a ne wtoo li nbaculoviru s identification {J.M. Vlak) 265 9.4 Control of aphids with insect pathogens (L.P.S. van der Geest, H.A. Samson & H.J.M. Wassink) 271 9.5 Controlo finsect swit hnematode s [U.R. Simons) 275

10 Supporting techniques 279 10.1 Systemsanalysi san dsimulatio na sa nai dt oth eunderstandin go facarin e predator-preysystem s (R. Rabbinge &M.U. Sabelis) 281 10.2 Epidemiologyo fth ecerea laphid ,Sitobio navena e (G.W. Ankersmit & R. Rabbinge) 291 10.3 Msteorologyan dintegrate dpes tcontro l (W.N. Lablans) 297 10.4 Radionuclides andionizin gradiatio ni nresearc ho nintegrate dcontro l y.Ph.W. Noordink) 301 Introduction

Thirtyfiv eyear sago ,th efirs tsyntheti cinsecticide sastounde dal lthos eengage di n thecontro lo fpest swit hthei runprecedente deffectiveness .No tver ylon gafte rthei r introductioni nagriculture ,however ,scientist sbega nt oquestio nth eunqualifie dbenefi t thatman yexpecte dfro mpesticides .I nth eNetherlands ,Voût e (1946),Kuene n (1948)an d Briejèr (1949)expresse dthei rdoubt sabou tth ecours eplan tprotectio nwa staking .Th e needt oresum eresearc ho nnon-chemica lmethod so fpes tcontro lwa sincreasingl yrecognize d and,i n1956 ,Professo rD eWild eo fth eAgricultura lUniversity' sDepartmen to fEntomolog y established acommitte et ocoordinat ean dstimulat eresearc ho nsuc hmethods .O n2 0Septem ­ ber 1958,thi scommitte ereceive dofficia lstatu swithi nth eauspice so fth eTN ONationa l Councilfo rAgricultura lResearc ha sth eWorkin gPart yo nIntegrate dContro lan dobtaine d additionalfund st oinitiat eresearc ho nintegrate dcontro l furthert owha tcooperatin g researchinstitute swer ealread ydoing .D eWild ean dD eFluite ro fth eResearc hInstitut e forPlan tProtectio ninitiate da wid evariet yo factivities .Unti lhi suntimel ydeat hi n 1970,D eFluite rwa sals oactiv ei nth einternationa lscene . Duringit searl yyears ,th eWorkin gPart yconcentrate do nbasi cstudie si ninsec tphys ­ iology,biochemistr yan dpopulatio ndynamic sa sa backgroun d tointegrate dcontrol .Late r theemphasi sgraduall yshifte dt opractica lapplication .Th eacquisitio nb yth eWorkin g Partyo fit sow nexperimenta lfrui tfar mi n196 5contribute dt othi sshift ;th eapproac h advocatedcoul dther efreel ypu tt oth etest . TheWorkin gPart yha sno wcom eo fag ean dthi sboo ksum su pwha tha sbee nachieve dfo r readersi nothe rcountries ,describin gsom esixt yproject so nth etheor yan dpractic eo f integratedcontrol .I tbring stogethe ran dupdate sinformatio nfro mscattere dpublication s andprovide ske yreference sfo rthos eintereste d inth edetails . Duringth eWorkin gParty' sexistence ,considerabl eprogres sha sbee nachieve di nback ­ groundknowledg ean dpractica lapplicatio no fintegrate dcontro lo fpests .Supervise dcon ­ troli sno wgenerall yaccepte di nth epolic yo fplan tprotection .W emus ttak ecar ean d indeedhav ereaso nt ofea rtha tthos econcerne dwit hpes tcontro lwil l lookfo rth eeas y wayou tan dcompromis eth emethod so fsupervise dcontrol .Biologica lcontro l issuccessfull y appliedi nsom esituations ;an da numbe ro fselectiv epesticide shav ereache dth emarket . Therear epromisin gnove ltechnique sawaitin gimplementation .Pesticide sknow nt ob einjuri ­ oust oth eenvironmen thav ebee nlargel ywithdrawn . Overth esam eperio do ftime ,however ,th eus eo fchemica lpesticide sha sgreatl yincreas -

1 ed.Fungicide san daphicide sar euse da sa routin ei ncerea lcrops ,th eus eo fherbicide s hasexpanded ,an di nprotecte dcultivatio na swel la scertai ncrop si nth eopen ,soi ldis ­ infectantsar elavishl yused .Agricultur eha sbecom eincreasingl ydependen to nth equick - -and-easypus ho nth echemica lbutton .I ti seas yfo ral lengage di nplan tprotectio nt o continuewit hth eestablishe dmean so fchemica lcontrol .S ow ecanno ttak emuc hsatisfactio n withth eprogres sachieved .Bu ti ti sperhap sunrealisti ct othin ktha ta fundamenta lchang e inth eapproac ht oplan tprotectio ncoul dhav ebee nachieve dwithi ntwent yyears .Wha tha s beendon ei nthi sperio di st osho wtha tintegrate dcontro li sfeasibl ean di nsom ecase s is economic.I ti sou rtas ki nth enex tdecade st oimplemen tthi smetho do fplan tprotec ­ tiont oth efull ,n oeas ymatter .Th egrowin gawarenes so fth econsume ro fproduct sgrow n witha minimu mus eo fpesticide swil lperhap shelp . Onlya comprehensiv epla no faction ,carefull ydesigne dan dresolutel yexecute di na n international framework,offer san ychanc eo fshiftin gth ehabit so fdecades .Thi stas k awaitsconcerte dactio nb yth eInternationa lOrganizatio no fBiologica lContro lan dth e EuropeanCommunities .Thi sboo ktrie st osummariz ewha tw ei nth eNetherland shav et ooffer .

EditorialCommitte e A.K.Mink s P.Gruy s W.Hell e H.Hoestr a O.M.B,d ePont i

REFERENCES

Briejèr,C.J. , 1949.Zij nwi jo pd egoed eweg ? (inDutch )Maandbl .Landb.Voorl.Diens t 6:93-95 . Kuenen,D.J. , 1948.Chemisch einsectenbestrijdin g enhaa rbeperkingen , (inDutch )Vakbl . Biol.28 :82-89 . Voûte,A.D. ,1946 .Toegepast e entomologiee nverrijkin go fverarmin gde rfauna , (inDutch ) Tijdschr.PIZiek t52 :150-157 .

Acknowledgments

Wegratefull yacknowledg e thecooperatio nwit hPudo ci npublishin gthi sbook .Severa l projectswer esupporte db ygrant sfro mth eNationa lCounci lo fAgricultura lResearc hTNO . 1 Fruit crops

Sinceth eearl yday so fth eWorkin gParty ,a larg epar to fth eeffor ti nputtin gth e principleso fintegrate dcontro lt opractic eha sconcentrate do norchards .Muc hwor kha s beendevote dt oanalysi so fth erelationship so fphytophagou s arthropodsi norchard swit h theirparasite san dpredator s (1.6).Fruit-tre ere dspide rmite , Panonychus ulmi, andappl e pygmymoth , Sttgmella malella, couldb econtrolle dt oa satisfactor ydegre eb ynativ ebene ­ ficialarthropod s (1.4,1.1 ,1.7) .Fo rothe rmajo rpests ,suc ha saphid san dleaf-rollers , controlb ynaturall yoccurrin go rmass-reare dan drelease dbénéficiai sprove dinsufficien t (1.5, 1.6).Leaf-roller sstil lpos ea difficul tproblem ,becaus eth emai nspecie si nDutc h orchards, Adoxophyes orana, resistsselectiv econtro lan dbecaus eothe rtortricid sris et o peststatu sunde ra selectiv eprogramm a (1.3).Th elatte rhold sfo rothe rmino rpest sa s well (1.5, 1.1).Althoug hth esterile-mal etechniqu egav esatisfactor yresult sagains t Adoxophyes orana, itprove duneconomica l (1.8).Fortunately ,othe rselectiv emethod sagains t leaf-rollerssho wpromis e (6.3,8.4 ,9.2) .Sinc ewor kbegan ,th enumbe ro fselectiv epesti ­ cidespu to nth emarke tb ychemica lindustr yha sgraduall yincreased ,wit hth eresul ttha t asatisfactor yprogra mintegratin gbiologica lan dchemica lcontro li sno wrunnin go na n experimentalscal ei ncommercia lorchard s (1.1,1.2) .Supervise dchemica lcontro lha sbee n adoptedb yabou t20° so fth efrui tgrower si nth eNetherland s (1.2).Wor ko nth eantagonisti c relationsbetwee nmicro-organism s onappl etree san dothe rapproache saime da treducin gth e profuseapplicatio no ffungicide sno wcommo ni na mois tclimat estarte dsom eyear sag o (1.9, 1.10). Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 1.1 Development of an integrated control program for orchards

P.Gruys 1

DeSchuilenbur gexperimenta lorchard ,TNO ,Lienden ,th eNetherlands .

INTRODUCTION

Orchardsar esubjec tt osevera lfunga ldisease san dman yarthropo dpests .I nth e1960s , routinespra yprogram so fabou t6-- 8insecticid ean d 14fungicid espray swer ehabitual ,re ­ sultingi nimprove dharves tbu ti nth ewell-know ncomplications ,includin gresistanc eo f Panonychus ulmi topesticide s (Section1.4) . Initiallymodifie dspra yprograms ,designe dt opermi tnatura lcontro lfactor st ooperate , wereteste di nplot so nprivat eholdings .Sinc eth ecommercia linterest so fth eowner san d theneed so fresearc hwer edifficul tt oreconcile ,a norchar dwa sse tasid efo rth epurpos e in1965 .Th ewor kther eaime da tdevelopin ga neconomicall yacceptabl esyste mo fcontro l withminimu mus eo fchemica lpesticides .I tbega ni n1967 .

METHODS

Theare ao fthi sorchard ,calle dD eSchuilenburg ,a tLiende nnea rWageninge ni s1 2ha . Itconsist spredominantl yo fspindlebus happle-tree so ndwarfin grootstocks .I nlong-ter m comparativetrial so nplot so fabou t 1ha ,th eeffec to fthre eexperimenta l factors,spra y program,nitroge nfertilize ran dpresenc eo fflowerin gweeds ,wa steste db ypes tincidence , effectivenesso fnatura lenemie so fpests ,an damoun tan dqualit yo fharvest .Initiall yth e factorinterferin gmos tdrasticall ywit hth ebeneficia lfauna ,spra yprogram ,wa sse ta t fourlevels :(1 )n oinsecticide ;(2 )a conventiona lspra yprogram ; (3)a moderat eprogra m composedo fcertai ncommerciall yavailabl epesticide schose nbecaus eo fthei rpresume d relativemildnes stoward snon-targe torganisms ;(4 )pesticide sconsidere dstrictl yselec ­ tive.Later ,whe nsupervise dchemica lcontro lbecam eaccepte di npractice ,Spra yProgra m3 wasstoppe dan dvariant so fSelectiv eProgra m4 wer eadded . Besidesthes elong-ter mtrials ,th eorchar di sbein guse dfo rfiel dtest so na smal l scaleo fne wcontro ltechniques ,suc ha sselectiv echemical s includinginsec tgrowt hregu ­ lators (Section 8.4),pheromone s (Section6.3) ,viruse s (Section9.2) ,an dnematode s (Section9.5) ,an dfo rstudie so nrelationship sbetwee nmicroorganism sinhabitin gth e surfaceo fth eappl eplan t (Section 1.10).

1.Presen taddress :Researc hInstitut efo rNatur eManagement ,Arnhem ,th eNetherlands . RESULTS

Monitoringtechnique swer edevise dan dpreliminar yeconomi cthreshold slai ddow nan d tested (VanFrankenhuyze n& Gruys ,1971) ,a sa basi sfo rsupervise dchemica lcontrol ,th e procedureo fwhic hwa ssubsequentl ydevelope di ndetai l ina serie so fplot selsewher e (Section1.2) . Inth emoderatel yan dth eselectivel yspraye dplots ,som especie sbecam esever epest s inth efirs tyear s (Panonychus ulmi, Stigmella malella), contraryt oth esituatio ni nth e plotreceivin gn oinsecticides .Thi sdifferenc ewa sdu et oth eabsenc eo fcertai nbénéfi ­ ciais (typhlodromids; Chrysooharis pvodioe) . Theydi dno treadil ymigrat eint oth emoderat e andselectiv eplot sand ,particularl y inth eformer ,wer esuppresse db yinsufficientl yse ­ lectivepesticides .Afte rthe yha dbee nrelease di nth eselectiv eplots ,biologica lcontro l ofthes epest sbecam esuccessfu lwithi n2- 3year s (Fig.1 ;Sectio n1.7) . Highnitrogen ,contrar yt oearlie rfinding sdi dno tpreclud esuccessfu lbiologica lcon ­ trolo f P. ulmi. Agroun dflor ao fsowe dflowerin gweed sdi dno treduc epes tnumbers ,a s mightb eexpecte do nth eassumptio ntha ti tstimulate sentomophagou s arthropods.O nth e contrary,i tincrease dth enumber so fth enoxiou sbug , Lygus pabulinus. Adoxophyes orana, amajo rpes ti norchard si nth eNetherlands ,decline dfirs ti nth e selectivelytreate dplot sbu tha sincrease dagai ni nrecen tyears .Althoug hmortalit yo f thecaterpillar sb yparasite si sheav yi nsummer ,i ti sno tsufficien to rno tsufficien t inever yyear .Wor ki sno wgoin go nwit hth echalcid , Colpoclypeus florus, toincreas eit s parasiticimpac to n Adoxophyes.

Density ofPanonychu s ulmi

W WW W- W W WW W w A 4

Economic threshold

tu tk Tl r£L ni B 4 Ft

LQ. ru-, r-i-.? r-rV' 1971 1972 1973 1974 1975 1976 1977 1978 Fig. 1.Densitie so f Panonychus ulmi inwinter ,June ,an dAugust ,1971-1978 . A:a plo tunde rconventiona l chemicalcontrol ,i nwhic hpredator ymite sar elacking . B:a plo tunde r integrated control,i nwhic hpredator ymite shav ebee nintroduce d andar e presentsince . Densityo f P. ulmi isi nscal e0-6 ,wher e6 correspond st oove r 100pe rleaf .Arrow sindi ­ cateapplication so fspecifi cacaricides ;broke narro windicate sapplicatio n topar to f Naturalcontro lo fsevera lothe rcommo nharmfu linsect sha sbee ninsufficien ti nth e selectivelyspraye dplot sa swel la si nth eplo treceivin gn oinsecticides .Thes einclude d Operophtera brumata, aphidsan d Lygus pabulinus. Inth eselectivel ytreate dplots ,certai nothe rinsect sgraduall ydevelope dint opests , becausether ewer en obroad-spectru mspray srestrainin gthe mo rbecaus e theorchar dbecam e amor efavourabl ehabita tt othe ma si tgre wolder ,o rboth .Thes einclude dsevera ltortri - cids (sucha s Pandemis heparana, Spilonota ooellana, Archips podanus and Laspeyresia pomo- nella), Hoplooampa testudinea; Eriosoma lanigerum, Lepidosaphes ulmi, Anthonomus pomorum and Phyllobius oblongus. Someothe rpotentia lpest sdi dno tincreas et oinjuriou snumber s inthes etrials ,bu tdi ds oi nother selsewher e (Orthosia spp.; Arahips rosanus; Argyresthia conjugella; Dasineura mali; (Section1.2) . Someo fthes epest sar eprobabl ysusceptibl et oon efor mo ranothe ro fecologica lcontrol . Although leadsar eavailable ,w ehav eno tye tworke dou twhic hfactor sshoul db emanipulate d toachiev ethis .Th ebes tdefenc efo rth etim ebein gi sselectiv epesticides .Comparativ e testswer estarted ,a svariant swithi nth eselectiv espra yprogram ,o nth eeffectivenes s ofsom eo fthes ecompound san dthei rcompatibilit ywit hbiologica lcontrol . Diflubenzuronha sbee nfoun dindispensabl et oapproac hth eproportio no fblemish-fre e fruitrequire da tpresent .It sus ei scompatibl ewit hbiologica lcontro lo f P. ulmi, and iti seffectiv eagains ta broa drang eo fpest sincludin gLepidoptera , H. testudinea toa -probabl ysufficien t- degree , P. oblongus and A. pomorum. Controlo fColeopter ai sachiev ­ edb yreduce dfertilit yo fth eadults .Diflubenzuro nis ,however ,no teffectiv eagains tcer ­ taintortricid s (A. orana, P. heparana, and A. rosanus), althoughi ti sa poten tinsecti ­ cideagains tother smember so fth efamil y (L. pomonella, S. ooellana, and A. podanus). How canthi sga pb efilled ? Bacillus thuringiensis hasno tprove dsatisfactor y (Section9.1) .Th eexperimenta l juvenilehormon emimic ,epofenonane ,gav egoo dcontro lo f A. orana ifapplie di nsufficientl y isolatedorchard so rlarg eareas ;i tprove dhelpfu li nsuppressin gothe rpest s (sucha sothe r specieso ftortricids ,aphids ,includin g Eriosoma lanigerum; and Lepidosaphes ulmi) andcompat ­ iblewit hbiologica lcontro lo f Panonychus ulmi. Iti sdisheartenin gtha tcommercia lcondi ­ tionsar erestrainin gth edevelopmen tan dmarketin go fthi susefu linsecticide .Th eexperi ­ mentalpyrazolin einsecticid ePH60-4 1 (Muldere tal. ,1975 )als omeet sth erequirement sfo r A. orana controli na nintegrate dprogram ,bu ti tseem ssubjec tt osimila rcommercia ldelay . Viruseso f A. orana, andconfusio no fmale sb ypheromones ,hav eshow npromis ei npreliminar y tests (Section9. 2 and6.3) . Thechoic eo ffungicide s isessentia lfo rth esucces so fbiologica lcontro lo f P. ulmi. Captan,on eo fth efungicide sapplie dagains t Venturia inaequalis, provedharmles sfo r predatorymites .Neithe rdi di tupse tbiologica lcontro lo f P. ulmi byphysiologica lstimu ­ lationo fth espide rmites ,a negativ eeffec tsometime sreporte do fcaptan .Dodin ean d thiophanate-methyl,use dincidentally ,als oprove dapplicable .However ,th efungicid e mancozebwa sfoun dt okil ltyphlodromid san dpreclud ebiologica lspide rmit econtrol , thoughsometime srecommende d inintegrate dprogram selsewher ebecaus eo fit ssuppressiv e effecto nspide rmites .Th esam ewa sfoun dfo rothe rmanganese-containin gbisdithio - carbamates (Section7.5) .Th econventiona l fungicidesuse dagains t Podosphaera leucotricha, sucha ssulphur ,dinocap ,an dbinapacryl ,prov edetrimenta l toth ebiologica l componento f

7 integrated control,bu tth enewe r fungicides against mildew,bupirimate , nitrothal-diisopro- pyl, andtriadimefo nca nb eused . The control techniques used atpresen t inou rintegrate d program fororchard s areliste d inTabl e 1.Thi s program (Fig.2) give s aharves t similar toconventiona l chemical control, though using only 4t o5 application s ofselectiv e insecticides peryear . This numberca n be reduced to1 t o3 ,o r Bacillus thuringiensis canb esubstitute d forcertai n chemical treatments,withou t anydange r toth eorchard , though yieldma ysuffe r andincidenc eo f insect-blemished fruit increases (Table 2;Gruys , 1975;Gruy s &Mandersloot , 1978).

Table 1.Contro l measures inth eintegrate d program fororchards .

Acari Panonychus ulrni typhlodromids release',whit e oil,benzoximate , fenbutatinoxide3 Lepidoptera Operophtera brumata Dimilin (diflubenzuron) Orthosis spp. Adoxophyes orana parasites, incl. Colpoclypeus florus; epofenonane1, Dipel2 (Bacillus thuringiensis) other tortricids Dimilin (noteffectiv e against allspecies) , epofenonane

Laspeyresia pomonella Dimilin Pammene rhediella

Stigmella malella Chrysocharis prodice release!Dimilin 3 Homoptera Eriosoma lanigerum endosulfan, inearl y spring; pirimicarb, ingrowin g season; Aphelinus mali aphids pirimicarb Hemiptera Lygus pabulinus suppress dicotyledonous weedsb yfrequen t mowing;whit eoi l atbu dburs t Hymenoptera Hoplooampa testudinea Dimilin (suppresses next generation); thiophanate-methyl Coleoptera Anthonomus pomorum Dimilin, inearl y spring Phyllobius oblongus Dimilin: strong suppressive effecto nnex t generation Diptera Dasineura mali endosulfan: spray atlo wtemperatur e Fungi Venturia inaequalis dodine, captan;d ono tus eMn-containin g fungicides! Podosphaera leucotricha bupirimate, triadimefon1, nitrothal-diisopropyl;d ono tus e sulphurno rdinoca p Pezicula spp. captan, thiophanate-methyl Fruit thinning naphthalene acetamide

1.Experimental ;no to nth emarket . 2. Effectiveness rather unsatisfactory. 3.No tnecessar y once theprogra m functions satisfactorily. James Grieve Chemical Integrated

Cox

Boskoop

Jonathan

Golden Del.

Average

i 1 1 1 r i 1 1 r- 0.5 1.0 Seasonal volumic yield (kg/m3)

Fig.2 .Averag eseasona lyiel ddivide db ytre evolum e (kg/m3)t omak eresult sindependen t ofdifference s intre esize .

Table2 .Proportio no ffrui tlow-classe dbecaus eo finsec tblemishe sunde rroutin e chemicalcontro lan ddifferen tvariant so fth eintegrate dprogra m in1977 .

Spraysagains tLepidopter a Spraysagains t Low-classed otherarthropods , fruit (%) number insecticides number routinechemica l 5 organophosphorus,3 carbaryl integrated 0 1-3 17 integrated 4 Dipel 0.2% 1-3 11 integrated 1 Dimilin 0.1% 1-3 6 integrated 3 Dimilin 0.1% 1-3 3

CONCLUSIONSAN DPROSPECT S

Theavailabilit yo fa norchar di nwhic hdifferen tapproache st opes tcontro lca nb e triedfreel yha sbee nindispensabl e forth eprogres so fintegrate dcontro l infrui tgrowing . Biologicalcontrol ,b ynativ eparasite san dpredators ,contribute sessentiall yt oth e integratedprogram .I tca nb ecombine dsuccessfull ywit hchemica lpesticides ,provide dthes e aresufficientl y selective.Furthe rresearc ho nnon-chemica l techniquesfo rinsec tcontro l willundoubtedl yreduc eth eamoun to fselectiv echemical suse di nth eprogram . Moreover,greate remphasi sshoul db eplace do ndevelopin gan dgrowin gvarietie s (partly) resistantt ofunga ldiseases ,becaus ei ti sthei rcontro ltha trequire sth egreate rpar to f thepesticide suse di norchard si nth eNetherlands .Fo rthi spurpose ,a collectio no fol d Dutch varieties has recently been put together,an d an orchard has been planted with cer­ tain of these and some scab-resistant apple varieties from the United States and elsewhere. Satisfactory functioning of an integrated program under experimental conditions does not necessarily mean itwil l be appropriate inpractice . Practical trialswer e needed and are described in Section 1.2.

REFERENCES

Frankenhuyzen, A. van &P . Gruys, 1971.Verantwoord e bestrijding van plagen op appel en peer. 3de druk, 1978.Plantenziektenkundig e Dienst,Wageningen . Gruys, P., 1975.Developmen t and implementation of an integrated control programme for apple orchards in the Netherlands. In:Proceeding s of the 8th British Insecticide and Fungicide Conference, Brighton, 1975. Vol. 3,p . 823-835. Gruys, P. &H.J . Mandersloot, 1978.Recen t developments in supervised and integrated control in orchards inHolland . In: Pests and Diseases,Proceeding s 1977 of the British Crop Pro­ tection Conference,Brighton , 1977.Vol . 3,p .245-254 . Mulder, R., K.Welling a &J.J . van Daalen,1975. A new class of insecticides.Di e Natur­ wissenschaften 62:531-532 .

10 Integrated control of insect pests in the Netherlands. Pudoo, Wageningen, 1980.

1.2 Implementation of integrated control in orchards

P.Gruys 1 (1),D.J .d eJon g (2)& H.J .Mandersloo t(3 )

1D eSchuilenbur gexperimenta lorchard ,Lienden ,TNO ,th eNetherlands . 2Researc hInstitut efo rPlan tProtectio n (IPO),Wageningen ,statione d atth eResearc h Institutefo rFrui tGrowing ,Wilhelminadorp ,th eNetherlands . 3Plan tProtectio nAdvisor yServic efo rHorticulture ,Wageningen ,Th eNetherlands .

INTRODUCTION

From 1950t o1970 ,th enumbe ro fspraying si nappl eorchard sincrease di nth eNether ­ lands.Usuall yroutin etreatment swer earrange da tth ephenologicall ycorrec ttim ebu t irrespectiveo fth epresenc eo fnoxiou sspecies .Roosj e (1967)mention sa naverag eo f 22spray sagains tinjuriou s fungian darthropod s inth e1960s . Intensivea si tha sbecome ,chemica lcontro li norchard s inth eNetherland sha sneve r evokedside-effect ss ograv ea st oforc eth egrower st oadop ta for mo fpes tcontro ldif ­ ferentfro mroutin eschedules .Th eproces so fintroducin gintegrate dcontro lint ofruit ­ growingmus ttherefor eb egradual .Ou rapproac hi st otes twhethe rmethod sar eapplicabl e withinth eeconomi cmargins ,an dt odemonstrat ean dexplai nt oth egrower stha tthes e methodswil lno timpai rfinancia lreturn san dwil lprobabl yb ebeneficial ,i nth elon g term,t osociet ya sa whole . Inthi sgradua lprocess ,w efin di tusefu lt odistinguis hclearl ybetwee nsupervise d chemicalan dintegrate dcontrol .Supervise dchemica lcontro lconsist so fpes tmonitorin g andapplyin gconventiona lpesticide si fan dwhe nth epests 'numbers ,relativ et oeconomi c thresholds,indicat eth enee dt od oso .I nintegrate dcontro li nth estric tsense ,utili ­ zationo fenvironmenta l factorsrestrainin gpest s (sucha snatura lenemies )i sprimar yan d theapplicatio no fpesticide sbase do npes tmonitorin gan deconomi cthreshold si ssecondar y thoughofte nindispensable .Th efunctionin go feffectiv ebiologica lcontrol srequire sdrasti c adaptationo fth epesticide sused .S oa nintegrate dprogra mi sa separat ean dmor edifficul t phaset ointroduce .

TESTSO FSUPERVISE DCONTRO L

Preliminaryguideline sfo rmonitorin gtechnique san dcontro lthreshold so fpests ,base d onth eexperienc eobtaine di ntrial so nintegrate dcontro l (Section1.1 )wer eteste di n 1971-1974i norchard so f1 t o5 hectares .Th etes tplot swer esituate di ncommercia lhold ­ ings,an dpest swer emonitore db yexperience dtechnicians .Insecticid ean dacaricid etreat ­ mentswer erestricte dt othos eindicate db yth eassessment san dwer edon eb yth eorchardis t

1.Presen taddress :Researc hInstitut efo rNatur eManagement ,Arnhem ,th eNetherlands .

11 inth eusua lway .Proportio no ffrui tdamage db yinsects ,th enumbe ro fspraying san dth e timeneede dfo rmonitorin gwer euse da scriteri ai nassessmen to fth eresults .An ylos s inyiel dcoul dno tb edetermine dreliabl ybecaus eo fth enatur eo fth etrials ,bu tth e controlthreshold smad esuc hlosse shighl yimprobable .A tfirst ,th eresult sfo rth etes t plotscoul db ecompare dwit hthos eo fth eres to fth eorchards ,treate daccordin gt oth e judgmento fth eorchardists .I nth ecours eo fth etest ,however ,thi sstandar dlos tit s usefulnessbecaus eth eorchardist sadapte dthei rdecision st oth etreatmen to fth etes t plots.Hence ,th eresult sha dt ob ejudge dagains ta genera lknowledg eo fconventiona l chemicalcontrol . Throughsupervision ,th enumbe ro fspraying sagains tpest scoul db ereduce dt o3. 2pe r yearo naverage ,wit ha nacceptabl eleve lo fdamag et oth efruit s (Table 1). Figure1

Supervised control Recommended March spraysi n routineschem e

Aphids,Caterpillars

April Aphids,Bug s Caterpillars Spider mite

May Aphids,Bug s Caterpillars Spider mite

June Adoxophyes Codling Adoxophyes Codling July Spider mite

Adoxophyes,Codling August Aphids

Adoxophyes

September

~~i i i i r 20 40 60 80 100 Proportion of orchards sprayed (%)

Fig. 1. Sprays needed under supervised control (left, average % test orchards sprayed from 1971-1974) in comparison to sprays recommended for a routine schedule (right).

12 Table 1.Trial so nsupervise dcontrol .

Year Numbero f Averagenumbe ro fspraying s Proportiono finsec t orchards damaget ofruit s (%) insecticides acaricides total

1971 11 2.1 0.8 2.9 2.3 1972 29 2.8 0.9 3.7 1.3 1973 24 1.7 1.1 2.8 2.7 1974 23 2.5 1.0 3.5 0.8

showsho wfa rth espraying so fth eroutin eprogra mrecommende db yth eadvisor yservic ea t thattim ewer ereall ynecessary .Th eaverag egrowe rapplie donl ysom e6- 8 ofth e1 0recom ­ mendedtreatments .Wit hth e1 0recommende dsprayings ,th edamag ewoul dno texcee d 11,bu t haphazardomission ,a sth eaverag egrowe rdid ,gav en obette rresult stha nthos eobtaine d byth esupervise dsystem . Thetim eneede dfo rpes tmonitorin gi na yea rfo ra give nare awa srathe rvariable , dependingo ncharacteristic so fth eorchard ssuc ha ssiz ean dnumbe ro fvarietie sgrown , withoutmuc hdifferenc ebetwee nyear s (Fig.2) .Simpl ecalculation sshowe dtha tth esaving s onpesticide soutweighe dth ecost so fmonitoring .

Hours per hectare 15-

5Hectare s Fig.2 .Tim eneede dpe rhectar epe ryea rfo rassessment so fpest s intes torchards . simpleorchards ,i.e . 1-3varieties ,i n197 1 (0), 1972(A) ,an d 1973(D ) . complicatedorchards ,i.e.> 3varieties ,i n 1971 (t),197 2(A) ,an d 1973(•) .

13 INTRODUCTIONO FSUPERVISE DCONTRO LI NPRACTIC E

In1973 ,on eo fth especialist so nplan tprotectio no fth eStat eHorticultura lAdvisor y Service,i ncooperatio nwit h8 orchardists ,too ku pth echalleng et otes tsupervise dcontro l againstth eroutin eschedule .Afte rthoroug hinstruction ,eac ho fth egrower sapplie dth e supervisedsyste mt opar to fhi sholdin gan dth eroutin eprogra mt oth eres to fit .Th e successo fthi stria lprompte dth eadvisor yservic et ostar tintroducin gth esupervise d systemal love rth ecountry .Th eprincipl eha sbee ntha tth eorchardist sshoul dremai n responsiblefo rpes tcontrol ,an dperfor mth enecessar yassessment sthemselves ;instruction , however,was ,an dis ,provide db yth eadvisor yservice . Instructiont oth eorchardist sbega ni nwinter ,whe nbackground so fpes tcontro lwer e explained ina numbe ro fmeetings .Initially ,muc hattentio nwa spai dt oth etechnique so f pestassessmen tan deconomi cthresholds .Sinc eman ygrower sar eno wfamilia rwit hthes e matters,th eemphasi sha sshifte dt oside-effect san dchoic eo fpesticide .Durin gth egrow ­ ingseason ,group so f10-1 5orchardist seac hmee tfou rtimes ,guide db yadvisor ystaff ,t o practiseth eassessment st ob eperforme di nth eperio dconcerned .Moreover ,genera linfor ­ mationo nth ephenologica ldevelopmen to fpest san dtimin go fassessment san dspray si s providedb yth eregionall yoperate dtelephon ewarnin gsystems . Thedevelopmen to fsupervise dcontro lsinc e197 3i sshow ni nTabl e2 .Abou t20° 6o fth e orchardistsno wus eth esystem .Th eremainin g80 1hav eals oreduce dthei rnumbe ro fsprays , asa resul to fth eattentio npai dt othes ematter sdurin grecen tyears .A sampl etake ni n 1978showe dth eaverag enumbe ro fspray sagains tanima lpest so nconventionall yoperate d holdingst ob e6 ,whic hi ssomewha tles stha nbefor e1973 .Th einitia leconomi cthresholds , atfirs tissue di na loose-lea fbookle t (VanFrankenhuyze n& Gruys ,1971) ,wer esomewha t simplifiedan dadapte di nth ecours eo fpractica lapplication .Thei rpresen tnatur ei s summarizedi nTabl e3 .An ychange sdeeme dnecessar yar ementione d ina nadvisor yleafle t onpes tcontro li nfrui tgrowing ,issue dannuall y (Rijksvoorlichtingsdienst, 1972).

Table2 .Supervise d controli npractice .

Year Numbero f Number Average number of sprayings Proportiono f advisory of insectdamag e groups growers insec­ acaricides total tofruit s (%) ticides

1973 1 8 0.6 1.3 1.9 1.9 1974 15 175 2.4 1.0 3.4 1.4 1975 37 400 2.2 1.4 3.6 1.0 1976 41 400 3.5 1.5 5.0 0.9 1977 45 600 3.4 1.4 4.8 1. 8 1978 41 700 3.0 1. 0 4.0 0.4

14 Table 3.Assessmen t ofpest s andeconomi c thresholds.

Time Pest Sample/ Economic Time fortreat ­ orchard threshold ment; remark s (spray ifover )

Before Panonyahus ulmi 40branche s eggsmor e abundant petal fall blossom than sporadic Arahips rosanus 5x 10spindle so r 5 eggmasse s petal fall 5x3 bushes Anthonomus pomorum 200mixe d budsa t 30wit h feeding assess onlyi f bud burst damage capped blossoms present inpre ­ vious year Operophtera brumata 100mixe d buds 10larva e before blossom Rhopalosiphum insertion 100mixe d buds 50wit h over4 before blossom aphids his plantaginea whole orchard presence before blossom Eriosoma lanigerum whole orchard presence before blossomo n early varieties Before Lygus pabulinus beat 100branche s 4 larvae before blossomt o and petal fall during Dysaphis plantaginea beat 100branche s presence beforeblosso mt o blossom petal fall Operophtera bmmata beat 100branche s 5 larvae before blossomt o Orthosia spp. petal fall Adoxophyes orana beat 100branche s 1 larva late June,whe n eggs hatch Adoxophyes orana 200 trusses 1 larva lateJune ,whe n eggs hatch Petal Dysaphis plantaginea 200tree s 10tree s infested continue sampling fall to 15June ;peta l fall toJun e Hoplooampa testudinea 100trusse s 10eg ginsertion s asses only ifattac k presenti n previous June Early Orthosia spp. 500 shoot tips 12larva e early June June Psylla pyri whole orchard abundant young early June larvae Eriosoma lanigerum whole orchard presence early June Late Panonyahus ulmi 50 leaveso f 5 leaves with over late June June clusters 5 mites Stigmella malella 200 leaveso f 20mine s July clusters Aphis pomi 500 shoot tips 25 severely infested late June Laspeyresia pomonella 400 fruitlets 4 entries late June;repea t sampling Late Adoxophyes orana 200 shoot tips 10-30 infested spraywhe n larvae July hatch inAugus t twice iflarva e hatch before2 0 August,onc ei f larvaehatc haf ­ ter2 0Augus t 30 infested spray twicewhe n larvae hatch inAugus t Panonyahus ulmi 50leave s 5 leaveswit h over late July 5 mites Laspeyresia pomonella 400fruit s 4 entries late July; repeat sample inmi d August Late Stigmella malella whole orchard 30%o fleave swit h petal fall next August mines year

15 TESTSO FINTEGRATE DCONTRO L

In1972 ,whe nth eintegrate dprogra mbega nt ofunctio nsatisfactoril y (Section1.1) , practicaltest so fintegrate dcontro lwer einitiate do nplot so f0. 5 to2 hectare s incom ­ mercialholdings .Th enumbe ro fplot swa sextende dt oabou t2 0i n1975 . Theprogra mi sa sdepicte di nTabl e 1,Sectio n1.1 ,wit h Bacillus thuringiensis (Dipel) andRyani ainstea do fdiflubenzuro n (Dimilin)an depofenonane ,whic hwer eno tavailabl ea t thetime ,cyhexati na sa nacaricide ,an da les srestricte dchoic eo ffungicides . Although thesyste mfunctione dproperl yi nsom eplots ,i tdi dno ti nsevera lothers . Circumstances imputablefo rth edifficultie sencountere dinclude dth efollowing . - Adoxophyes orana wasa persisten tpes ti nmos tplots ,muc hmor es otha na tD eSchuilen - burg,an d Bacillus thuringiensis (Dipel)prove ddisappointin ga sa contro lagent .Th e causeo fthi sdifferenc ei sno tclear .Smal lplot srelativ et oa larg esuppl yo fmoth s fromth eroutinel ytreate dsurroundin gorchard san dth elac ko fa nintegrate dhistor yi n thene wplots ,ma yhav esomethin gt od owit hit . -Smal lsiz eo fplot san dlarg edisturbance sb ydrif to funselectiv espray sfro mneighbour ­ ingorchards ,prevente dsucces so fbiologica lcontro lo fspide rmite s insom ecases . -Th eus eo fcertai npesticides ,whos etoxicit yt opredator ymite swa sno tknow na tth e time,interfere dwit hbiologica lcontro lo fspide rmites .Cyhexatin ,use dt osuppres s Panonychus ulmi whenth etyphlodromid swer eno tye tsufficientl yeffective ,cause dmuc h harm.Thi sacaricid eact sinsidiously ,sinc ei ti shardl yharmfu lt oadult sbu tver ytoxi c toegg san dlarvae ,a stest si nth elaborator yhav eshow nsinc e (Section 7.5).Similarly , manganese-containingbisdithiocarbamate sprove dfata lt oth epopulation so fpredator ymite s ifuse drepeatedly ,a ssom eorchardist sprefe rt od obecaus eo fth ebenevolen teffec to f thesefungicide st oth equalit yo ffoliage . -Th etrial si nman ydifferen tplace sconfronte du swit ha numbe ro f"minor "pest sagains t whichselectiv econtro lprocedure sstil lha dt ob edevised . Thankst oth eman ymishaps ,th eprojec tha sbee nver yusefu l inidentifyin gpractica l deficiencieso fth eintegrate dprogram .On econsiderabl eimprovemen tha sbee nth esubsti ­ tutiono fdiflubenzuro n (Dimilin)fo r Bacillus thuringiensis andRyania .Thi sinsecticide , however,i sineffectiv eagains t A. orana. Thene wdesig no fth etrial si n197 8shoul dachiev efurthe rimprovements .Effort sar e nowconcentrate do na smalle rnumbe ro flarger ,rathe risolated ,orchards .Thes econdition s allowus eo fth ejuvenil ehormon emimic ,epofenonane ,agains t A. orana (Section8.4) . Laboratoryan dsmall-scal efiel dtrial so nth eselectivit yo fpesticide s (Sections7. 5an d 1.1)hav eenable du st oadap tth eapplication so fpesticide st oth erequirement s forbiolo ­ gicalcontro lo fspide rmite . Maleconfusio nb ypheromones ,anothe rtechniqu erequirin gtest so na larg escale ,wil l beinclude da sa possibl econtro lo f A. orana andcodlin gmot hi nsom eo fth etes torchard s in1979 . Inth elates teditio no fth einstructio nboo k (VanFrankenhuyze n& Gruys ,1978) ,guide ­ lineso nth eintegrate dprogra mar egive nfo rth enort ho fth ecountr ywher e A. orana never develops intoa pest .

16 CONCLUDING REMARKS

The success of these trials as anucleu s fromwhic h integrated control canexten d grad­ ually intopractic e fullydepend s on the availibility of adequate control measures against certainpests ,notabl y A. orana. Some controlmeasure s require large-scale field trials to evaluate theirefficacy , for instance juvenilehormon emimics .Trial s like this then offer anexcellen t opportunity for government research and industry to cooperate in developing such compounds intomarketabl e pesticides.Pilo tproject s are indispensable formakin g an experimental integratedprogra m sufficiently foolproof tob e generally applicable.

REFERENCES

Frankenhuyzen,A . van &P . Gruys, 1971.Verantwoord e bestrijding van ziekten enplage n op appel enpeer . 3e druk, 1978.Plantenziektenkundig e Dienst,Wageningen . Gruys, P. &H.J . Mandersloot, 1978.Recen t developments in supervised and integrated control in orchards inHolland . In:Pest s and Diseases,Proceeding s 1977 of the British Crop Pro­ tection Conference,Brighto n 1977.Vol . 3,p .245-254. Roosje, G.S., 1967.Phytopathologica l consequences of changing agricultural methods.4 . Fruit crops in the open.Neth . J. PI. Pathol. 73:130-151 . Rijkstuinbouwconsulentschap voor Planteziektenbestrijding; 1972- (Annual). Bespuitingen ind e fruitteelt. State Horticultural Advisory Service,Wageningen .

17 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980.

1.3 Tortricids in integrated control in orchards

D.J.d eJon g

ResearchInstitut efo rPlan tProtectio n (IPO),Wageningen ,statione da tth eResearc hStatio n forFrui tGrowing ,Wilhelminadorp ,th eNetherlands .

INTRODUCTION

Orchard-dwelling tortricidsinclud eth efruit-piercin gspecies , Laspeyresia pomonella, Pammene rhediella and Pammene argyrana andsevera lleaf-roller sdamagin gth eski no f fruits,a sd o Adoxophyes orana, Arahips podanus, Arohips rosanus, Hedya nubiferana, Pandemis aerasana, Pandemis heparana and Spilonota ooellana. Allo fthes ear egenera lpest s except A. rosanus, whichi susuall ylocal . Fortyyear sago ,codlin gmoth , Laspeyresia pomonella, wasa majo rpes ti nappl ean d pearorchard s inth eNetherlands ,an dothe rtortricid swer eo fsom eimportance .Th edecreas e ininfestatio nwit hth ecodlin gmot hsinc ethe ncoincide dwit ha gradua lsubstitutio no f shrubsan ddwar ftree sfo rstandar dtrees .Sinc eshrub san ddwarf shav efa rles sbark-scales , whichserv ea shibernatio nsite sfo rth ecodlin glarvae ,the yar ea les sfavourabl ehabita t forthi sinsec ttha nstandar dtrees .Moreover ,insec tcontro li sgenerall ymor esuccessfu l ondwar ftrees . In1939 ,th esummer-frui ttortri xmoth , A. orana, wasobserve da sa ne wspecie si nDutc h orchards.I tsprea drapidl ythroug hth ecountr yan dsoo nbecam eon eo fth emos tseriou s orchardpests ,o nwhic hcontro lwa sconcentrated .Th etimin go fspray sagains t A. orana and codlingmot hlargel ycoincided ,contributin gt oth edeclin eo fcodlin gmoth .Similarly ,i n routinespra yprograms ,th eothe rleaf-roller sar esuppresse db ytreatment sdirecte dagains t otherinsects . Today, A. orana isth emai npotentia ltortrici dpes ti norchard si nmos tregion so fth e Netherlands.Damag ei sprevente db yadequat esupervise dcontro lprogram swit hbroad-spectru m insecticides.I nsuc hprograms ,th eothe rtortricid sincludin gcodlin gmot har eals ocon ­ trolled.I nintegrate dprograms , A. orana cannotb econtrolled ,becaus eth einsecticid e epofenonane (seeunde rcontrol )i sno tapprove dno ravailable .I nstric tsupervise dpro ­ gramsan dintegrate dprograms ,th eothe rtortricid sincludin gcodlin gmot hca nregai nsom e ofthei rforme rstatu san ds oals orequir eattention .

19 ADOXOPHYESORAN A

Bionomics and ecology

A. ovana usuallyha stw ogeneration spe ryear ,bu ta partia lthir dgeneratio nma yoccu r whenth eseaso ni sexceptionall yearly .Th elarva eo fth efirs tgeneration ,presen to nth e treesi nJuly ,inflic tth egreates tharm .Thos eo fth esecon dgeneratio ncaus eles sdamage , onlysmal lfeedin gscars ,becaus ethe yhibernat ei nth ethir dinstar ,the yar emuc hmor e harmful,however ,whe nthe ygiv eris et oa thir dgeneratio ni nth esam eyear .Afte rhiber ­ nation,th ecaterpillar sar ereactivate d inApri lan dfee di nth eflowe rcluster st opupat e atth een do fMa yo rth ebeginnin go fJune .The yd ono tcaus eeconomi cdamag ea ttha ttime . Whengrower sshifte dt osmal ltree san dstimulate dshoo tgrowt hb yincrease dprunin gan d fertilization, A. ovana becameimportan ta sa pest ;i nth efirs tgeneration ,man ylarva e inhabitth eshoo ttip san dyoun gleave sdurin gth egreate rpar to fthei rlife . Initially,a larg enumbe ro fspray si nsprin gan dsumme rseeme dnecessar yt oachiev e adequatecontrol ,particularl y ifth einsecticide suse dwer eno tpersistent .A detaile d studyo fth ebionomic so fth especie san dhabit so fth elarva eshowe dth ehatchin glarva e ofth efirs tgeneratio ni nJun et ob ehighl ysusceptibl et ocontac tinsecticides ,an d alloweda mor eaccurat etimin go fth esprays .Spray sdirecte dagains tth ehatchin glarva e inJun eappeare dmor eeffectiv etha ntreatment so fth ehibernate dlarva ei nApri l (D eJon g &Gruys ,197S) .A procedur ewa sdevelope dt ocalculat eth ehatchin gperio do fth elarva e inJun ean dth erigh ttim efo rsprayin gfro mcatche so fmoth si nligh ttraps ,an dth erela ­ tionshipbetwee ntemperatur ean dembryoni cdevelopmen t (DeJon ge tal. , 1965).A successfu l warningsyste mbase do nthi sprocedur ean da networ ko fligh ttrap sha sbee noperate db y theStat eHorticultura lAdvisor yServic esinc e1953 .I nth e1970s ,th eligh ttrap swer e replacedb ypheromon etraps . Since A. ovana isa polyphagou sinsect ,immigratio nfro msurroundin gwoodlan dan dor ­ chardsma yinfluenc eth epopulatio no fa norchard .Immigratio nma yb edecisiv efo rth esuc ­ cesso fcertai ncontro ltechnique san dwa stherefor estudie di ndetail .Releas eo fmass - -rearedmoth sshowe dtha tmale sma ycove rdistance so fu pt o20 0m i na week .Female scov ­ ereddistance so fonl y2 0m i nth esam eperiod . Severalhymenopterou san ddipterou sparasite swer ereare dfro mth elarva eo f A. ovana (Section 1.6),bu tparasitis mwa sneve rsufficien tt osuppres sth epopulatio nbelo wth e economicthreshold .

Samp ling

Fordecision so ncontro llate ri nth eseason , A. ovana populationsar esample di nMay . Sinceothe rtortrici dlarva ema yb epresent ,key sfo ridentificatio no flarva ean dpupa e weredevelope d (Evenhuise tal. , 1973;D eJon g& Vlug , 1974).Th esampl esiz eprescribe di n theinstruction so nsupervise dcontro li s20 0cluster san di stime-consumin g forth efrui t growers.Therefore ,a sequentia lsamplin gprocedur ewa sdevelope d (DeJon g& Va nDieren , 1974). Thesecon dmajo rperio dfo rsamplin gth epopulatio ni si nJuly ,whe nth elarva eo fth e

20 firstgeneratio nar epresen ti nth eshoo ttips .Th enumber spresen ta ttha ttim ean dth e subsequentphenolog ydetermin ewhethe rcontro lwil lb eneede di nAugust .I nyear swit ha n earlyfligh ti nAugust ,th eeconomi cthreshol dshoul db ereduce dbecaus eman y larvaewil l completethei rdevelopmen tan dthreate nth efrui tmor eseriousl ytha nwhe nenterin gdiapaus e atthei rthir dinstar .I norchards ,th efractio no fth epopulatio ngivin gris et oa thir d flightan dth erat eo fdamag et oth efruit sar eclosel yrelate d (DeJon g& Beeke , 1976). Quantitativephenologica linformation ,base do nth ecritica lphotoperio d forth einductio n ofdiapaus ei n A. ovana determinedb yAnkersmit ,enable su st opredic tth edange rfro ma thirdgeneratio nan dt oadjus tth eeconomi cthreshold .Th eoccurrenc eo fa thir dfligh t alsoha sa positiv eeffect ,namel ytha tman yo fth elarva eissue dfro mi twil lb eunabl e toreac hth einsta rrequire dfo rsuccessfu lhibernation .Thi sreduce sth epopulatio no fth e nextspring . Acompute rmode lha sbee ndevelope d includingbot hth enatura lfactor si nth epopulatio n dynamicso f A. ovana andth eeffec to finsecticid etreatment s (DeJon g& Va nDieren ,1974) . Iti suse dt ostud yth esuitabilit yo fnewl ydevelope dinsecticide si npes tmanagemen t programs.Fo rpubli chealt han dt oimprov epredator yactivitie si nsumme rtime ,som eo f theseprogram sai ma tapplyin g lesspoisonou sinsecticide san da trestrictin gus eo f insecticidest oth eperio dbefor emid-July .Thes eprogram sar eno wimplemente di nlong - termfiel dtrial san dma ycontribut et osafe rpes tmanagemen tfo rma nan denvironment .

Control

Theus eo fmass-reare dparasite swa sstudied .Som estrain so f Triohogramma embryophagum aacoeoiae (Hymenoptera,Trichogrammatidae) ,wer emass-reare dan drelease di nexperimenta l orchardst ocontro l A. ovana. Satisfactoryresult swer eobtaine di nsom etrials ,bu tba d weatherofte nlimite dth eactivit yo fth eparasite ss oth eeffect swer eunreliable .A lac k ofhost si ncommercia lorchard sseriousl ylimite dsurviva li nwinte ran drepeate drelease s ofthi seg gparasit ewer enecessary .Moreover ,th eparasite sprove dextremel ysusceptibl e topesticides .S othi smean so fcontro lha sbee nabandoned . Sofar ,expensiv epreparation so f Bacillus thuringiensis haveprove dinadequat efo r controlo f A. orana. Anuclea ran dcytoplasmi cpolyhedrosi sviru sdiscovere di nlarva eo f thisleaf-rolle rcontrolle dyoun g larvaesatisfactoril y intrial si na greenhouse .I n orchards,however ,th eresult swer e lesspromisin ginitially .Ba dweathe rhampere dth e effectivenesso fth eviru san dth eperio dove rwhic hth elarva ehatche dwa sto olon gt o keepth eviru spreparatio nwithou tdeterioration .Recen ttrial swit hth eviru ssho wmor e promise (Section9.2) . Trialso nreleas eo fsteril emale sagains tth esumme rfrui ttortri xshowe dtha tth e populationcoul db ereduce dbelo wth eeconomi cthreshold .Reinfestatio nfro msurroundin g vegetation,however ,woul dprobabl yinterfer ewit hsucces so na practica lscale .Moreover , theincreas ei npopulatio no fothe rtortricid san dwinte rmot h (Operophtera brumata) in theabsenc eo fbroad-spectru mspray sreduce sth eeffectivenes so fth etechnique .Mor e detailsar egive ni nSectio n1.8 . Theselectiv einsecticid ediflubenzuro nhardl yaffect sth epopulatio no f A. orana. The juvenilehormon emimic ,epofenonane ,t owhic honl yfifth-insta rlarva ear esusceptible ,

21 adequatelycontrol s A. orana inspring .Treatmen ti nsprin ggive ssufficien tcontro lfo r theres to fth eyea ra slon ga sreinfestatio nfro msurroundin gorchard san dothe rvegeta ­ tioni snegligible .S ocooperatio nbetwee nadjoinin gholding s ina norchar dare ai sneces ­ saryt oachiev eadequat econtro lwit hthi styp eo finsecticide .Epofenonan eis ,however , notapprove dfo rorchar dapplicatio nan dwil lno tb eproduce dfo reconomi capplication .Fur ­ therdetail sar egive ni nSectio n8.4 . Reductioni ntreatmen twit hbroad-spectru mchemical sincrease sth eincidenc eo fcodlin g mothan dcertai nleaf-roller smentione di nth eintroduction .Ryani ai sa selectiv einsecti ­ cideabl et ocontro lcodlin gmoth , Laspeyresia pomonella, tosom edegree ,bu ti ti sno tap ­ provedi nth eNetherlands .Sinc ecodlin gmot hi seffectivel yan dselectivel ycontrolle db y diflubenzuron,i tpose sn ogrea tproble mi nintegrate dcontrol .Trial so nth eus eo fviruse s andmal edisruptio nb ypheromone sagains ti tar eunde rwa y (Section6. 3 and9.2) . Pammene spp.causin gearl ywormines si nappl ear eoccasionall ya proble mi nintegrate dprograms , butca nb econtrolle dwit hdiflubenzuron . Ofth eothe rtortricid smentioned , Hedya nvbiferana isno ta reall yharmfu l leaf-roller onappl ean dpear ; Avchips podanus, Spilonota oeellana and Pandenris spp.,howeve rma yb e harmful.Diflubenzuro ni seffectiv eagains tthes ethre especie sbu tno tagains t Pandenris, whichma yals ocontinu et ocaus etroubl ei nintegrate dprograms .

CONCLUSION

Theinitia lproble mpose db yleaf-roller si nintegrate dcontro lha sbroadene dan dha s notye tbee nsolve dt oou rsatisfaction .Som epromisin gselectiv econtro ltechnique sma y bringth eproble mint opractica lcontro li nth efuture .

REFERENCES

Evenhuis,H.H. ,D.J .d eJon g &H.J .Vlug ,1973 .Di ePuppe nde ri nde nNiederlande na mApfe l vorkommendenBlattwickle r (Hepidoptera ,Tortricidae) .Z .angew .Ent .7 3 :351-365 . Jong,D.J .d e& H .Beeke ,1977 .Effec to fsprin gapplicatio no fa ninsec tgrowt hregulato r (IGR1o nth epopulatio ndevelopmen to fth esummerfrui t tortricidAdoxophye soran a (F.v.R.) ina nappl eorchar d inth eNetherlands .Meded .Fac .Landbouwwet .Rijksuniv .Gen t4 2: 1373-1381. Jong,D.J .d e &J.P.A .va nDieren ,1974 .Populatio ndynamic so f thesummerfrui ttortricid , Adoxophyesoran aF.v.R .i nrelatio nt oeconomi c threshold levels.Med .Fac .Landbouwwet . Rijksuniv.Gen t3 9 :777-788 . Jong,D.J .d e& P.Gruys , 1975.Practica lapproac ht oth eleaf-rolle r problemi nintegrate d controli norchards .C.R .5 eSymp .Lutt eintégré ee nvergers .In :L.Brade r (Editor) ComptesRendue s5 eSymposiu mLutt eintégré ee nvergers ,Bolzano ,1974 .Organisatio n Internationaled eLutt eBiologiqu e (OILB),p .227-235 . Jong,D.J .d e& H.J .Vlug ,1974 .Che fd'identificatio nde schenille sde s tordeusesd u pommierau xPay sBas .In :Le sorganisme sauxiliaire se nverger sd epommiers .Organisatio n Internationaled eLutt eBiologiqu e (OILB).No .3 .p .35-37 . Jong,D.J .de ,H .Beek e& H.J .Wondergem , 1965.Th epredictio no fsprayin gdate sfo rth e fruittre eleaf-roller ,Adoxophye sreticulan aHb. ,base d onligh ttra pcatche san d temperatures.Meded .Dir .Tuinbou w (Neth.)2 8 :539-54 2 (inDutch ,wit hEnglis hsummary) .

22 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 1.4 Population regulation of the fruit-tree red spider mite Panonychus ulmi by predators

M.va nd eVri e

ResearchInstitut efo rPlan tProtectio n (IPO),Wageningen ,seconde d toth eResearc h Stationfo rFloriculture ,Aalsmeer ,th eNetherlands .

DESCRIPTIONO FTH EPROBLE M

Thefruit-tre ere dspide rmite , Panonychus ulmi, hasbee na proble mi ncommercia lor ­ chardsi nth eNetherland ssinc eth emid-1950s ,whe npesticide s- mainl ytar-oi lwinte rwash ­ esan danorgani cfungicide s- wer e introducedan dwhe ncultura lpractice slik epruning ,fer ­ tilizationan dfruit-thinnin gwer eintensified .Tar-oi lwinte rwashe sar eno wknow nt ob e highlyinjuriou st omit ean dinsec tpredator so fth efruit-tre ere dspide rmite .Mos to f thesyntheti cinsecticides ,introduce di nth e1940 san d1950s ,suc ha sth eorganophosphate s andDDT ,ar eextremel ytoxi ct oth enatura lenemie so f P. ulmi; moreover,DD Tha sa stimu ­ lativeeffec to nth eovipositio no f P. ulmi. Thebiolog yan dtaxonom yo fthi smit ewa sstudie db yGeijske s (1938);Kuene n (1947,1949 ) studiedth ebiology ,host-plan trelationship san dth einfluenc eo fsom epredato rspecie so n thepopulatio ndevelopmen to fthi smite .I nth eNetherlands ,th efruit-tre ere dspide rmit e passesthroug h5- 7generation s ina season .Th esuccessiv egeneration sma yincreas e drastically;a smal lpopulatio ni nsprin gma ygiv eris et odamagin gdensitie swithi ntw o generations.Damag econsist so fpuncturin gth eleave sb yth emites ,followe db ybronzin g andleaf-dro p (Vand eVrie ,1956) .Consequentl yphotosynthesi san drespiratio nar eimpaire d andth enumbe ro fflowe rbud si nth efollowin gsprin gdecreases .I nlat esumme ran dautumn , diapausingwinte regg sar edeposite do nth ebranche san dtwigs ;the yhatc hth enex tspring . Organophosphoruscompound swer eintroduce d inth eearl y 1950sfo rcontro lo fman yorchar d pests,includin gth efruit-tre ere dspide rmite .Afte ra ninitiall ysuccessfu lintroduction , resistancet othes eacaricide swa snotice di n195 3an dbecam ewidesprea d inth efollowin g years.Resistanc et ochlorbensid e (4-chlorobenzyl4-chlorobenzy lsulphide) ,fenso n (4-chlorophenylbenzenesulphonate) ,an dchlorofenso n (4-chlorophenylp-benzenesulphonate ) developedwidel yafte rthei rintroductio ni nth emid-1950s . Destructiono fnatura lenemie san dresistanc et oacaricide sar eth emai nreason sfo rth e emergenceo f P. ulmi asa majo rpes ti nDutc horchards .Onc ea specie sha sbee nfree dfro m naturalan dchemica lcontrol ,a greate rpes tstatu si sinevitable .Natura lenemie sar erar e incommercia lorchards ,contrar yt oth esituatio ni nneglecte dorchard swher epredaciou s mites (Phytoseiidae)an dpredaciou sbug s (Myridae)hol dth ephytophagou smite si ncheck . Neglectedorchard sdiffe ri ntw omai naspect sfro mcommercia lorchards .Th especie scompo ­ sitiono fth earthropo dfaun ai smor edivers ean dth echemica lcompositio no fth ehos t

23 planti sdifferent ,mainl yi na lowe rnitroge nconten to fth eleaves . Inenvironment swher ebroad-spectru mpesticide sar eused ,th eenemie sar eofte nwors e affectedtha nth efruit-tre ere dspide rmit ean doutbreak so fth elatte rma yoccur .Som e pesticideseve nstimulat eth ereproductiv ecapacit yo f P. ulmi.

AIMAN DMOTIVATIO NO FTH ERESEARCH .

Theabilit yo f P. ulmi todevelo presistanc et oacaricides ,th edrasti creductio ni n predatorstha tcoul dreduc e P. ulmi populations,an dth edange ro fcontaminatio no fth e orchardenvironmen twit hbiologicall yactiv epesticide swer emotive sfo rexperiment so n managemento fthes enatura lenemies .A sgenera lpredator s like Anthoaoris nemorumo r Optus minutus leavefrui ttree si nsearc hfo rothe rpre ybefor e P. ulmi isreduce dt o acceptablelo wlevel s (Kuenen,1947) ,mos tattentio nwa so nphytoseii dmites .Som especie s arespecialize do n P. ulmi andth efruit-tre ehabitat ,a sar e Amblyseius potentillae, A. finlandicus and Typhlodromus pyri. Testswer econducte do nrelativ erate so fincreas e inpredato ran dpre yspecies ,pre ystag epreferred ,functional ,numerica lan dtota lresponse , ofth epredator ,an dsearchin gcapacity .Thes etest swer efollowe db yexperiment sunde r differentcondition so finitia lnumber so fpre yan dpredators .

RESULTSAN DDISCUSSIO N

Therear etw omai navenue st ounderstandin gmit eoutbreaks : -improve dnutritiona lcondition sfo rth ephytophagou smite ; -detrimenta leffect so fpesticide so nth enatura lenemies . Increasesi nmit epopulation shav ecommonl ybee nassociate dwit hhighe rnitroge nconten t ofth eleaves .Kuene n(1947 )wa sth efirs tt osho wtha t P. ulmi multipliedmuc hmor eo n leaveso ffrui ttree sunde rgoo dmanagemen ttha ni nneglecte dorchards ;i nwell-kep tor ­ chards,th eleave scontaine dmor enitrogen .Th epopulatio ndynamic so fthes efinding swer e studiedb yPos t (1962).Sh eshowe dtha tth ephysiologica lconditio no fth ehos tplan twa s crucial.I na norchar dwher e P. ulmi occurredonl ysporadically ,a nincreas ei npopulatio n densitycorresponde d toa nincreas ei nnitroge ncontent .I na plo twit ha hig hinitia l populationo f P. ulmi situatedi na well-kep torchard ,th epopulatio ndroppe dconsiderabl y afterth enitroge nconten to fth eleave sha dbee nreduce db ystoppin gnitroge ndressing , soilcultivatio nan dpruning .Pos tconclude dtha tpredaciou smite san dinsect swer eno t sufficientt ocounterac tth eincrease ddevelopmen to f P. ulmi inducedb ycultura lmeasures . Theinfluenc eo fhost-plan tqualit yo nmit edevelopmen tan dth einfluenc eo fmite so n thephysiolog yo fth ehos tplan twa sstudie db yStorm s (1971);Sectio n4.4 . Vand eVri e& Kropczynsk a (1965)studie dth einfluenc eo fpredaciou smite so nth epopu ­ lationdevelopmen to f P. ulmi onappl eunde rsemi-controlle d laboratoryconditions .The y showedtha t A. potentillae underthes econdition sha da stron gregulator yeffec to npopula ­ tionso f P. ulmi withouteliminatin gth epre yentirely .The yattribute dth eeffec tt o(1 ) distributiono fpre yan dpredator ,an dthei rfluctuation sdurin gth eseaso no nindividua l appleleaves ;(2 )th epreferenc eo fth epredato rfo rth ejuvenil estag eo fth eprey ;(3 ) thefunctional ,numerica lan dtota lrespons eo fth epredato rt opre ydensities ;(4 )pheno -

24 logicalsimilaritie so fpredato ran dprey .The ychos e A. potentillae asa mode lpredaciou s mite,becaus ei tcoul deasil yb eidentifie do nappl eleaves ,i tcoul db eeasil yculture d with T. uvtioae asfoo dan di squit ecommo ni nundisturbe dhabitats .Othe rspecies ,whic h alsofrequentl yoccu ro nappl ear e Amblyseius finlandicus and Typhlodromus pyri, butthe y haveno tbee nstudie di nth esam edetai la s A. potentillae inth eNetherlands . Vand eVri e& Boersm a (1970)conducte dexperiment swit h P. ulmi and A. potentillae, introducingth efinding so fKuene n (1947),Pos t (1962),an dStorm s (1971)o nth einfluenc e ofhost-plan tconditio no npopulatio ndevelopmen to f P. ulmi. Inthei rexperiments ,apple s weregrow nunde rthre elevel so fnitroge nfertilizatio nan dwit h A. potentillae absento r present.Th etota lnumbe ro fegg sproduce do nhigh-nitroge ntree swa smor etha nfou rtime s thato nlow-nitroge ntrees ,an dth efemale slive done-thir dlonge ro nth ehigh-nitroge n trees,thu sconfirmin gth eresult so fKuenen ,Post ,an dStorm s (Fig.1) .Figur e2 show s

Number ofegg s

500

N- High •—• N - Moderate • • •• N - Low 400

300

200-

100

1 r 10 15 Longevity of females(d ) Fig. 1.Numbe ro fegg sproduce db y2 0female so f Panonvchus ulmi onleave sfro mappl etree s withdifferen t levelso fnitroge nfertilization .Afte rVa nd eVri e& Boersma ,1970 .

2S Number of Panonychus ulmi eggs and mites per leaf

—• N-High A • - -• N-Moderate >-Predators ƒ I •• • • N - Low ƒ I

_o N-High / \ o- _o N-Moderate >+Predators ƒ 120- o. • o «4-Low 1

/ • //X- // il \ \ /l \ \ 80- f1 \ \ / / \ \ r \ \ j/ \ \ 71 \ \ \ \ \ \ • \ / • • \ \ 40- \ \ \ \ • • • \ • • \ \ Predators released^ # / • _ \ \ d • / D G \ \ • •-o . -\ N\ ' ••o.\\ ~s>A=l \ ". .o* '°-fc^o- o — o*'*- 0- 1 1 1 1 June July Aug. Sept. Fig. 2.Population s of Panonychus ulmi onappl e grownwit h low,mediu m andhig h levelso f nitrogen fertilizer,wit h andwithou t thepredaciou s mite Amblyseius potentitlae.

the efficiencyo f A. potentillae incurtailin g theP . ulmi population increase inspit eo f this inherently increased fecundity assumed tob enea r itsmaximu m during June -August . Inth eabsenc eo fpredator s onth ehigh -an dintermediat e levelso fnitroge n damaging popu­ lations developed. Iti sver y interesting tonot e that eveno nth ehigh-nitroge n treesn o damaging populations could develop,provide d thatpredator y miteswer e present.Thi s isdu e toth eeffec to fth epredator y mites thatprevente d P. ulmi from reaching high densities, andbecaus eo fth eshorte rperio d during which thesepopulation s were present.I ti sals o highly interesting tonot e thatth epredator s never annihilated theirprey . AlsoMcMurtr y &Va nd eVrie' s studies (1973)explai n theeffect s of A. potentillae on thepopulatio n development of P. ulmi interm so fpre y consumption, dispersion,an dtota l

26 responseo fth epredato rt oit spre ydensity . Thesefinding sar econtrar yt oPost' sopinio no nth ecapacit yo fpredator ymite san d insects.A critica lconsideratio ni swhethe rPos ti nhe rfiel dstudie swa sdealin gwit hth e bestpredato rspecie sfo rreducin go rpreventin g P. ulmi outbreaks. Typhlodromus dbevvans wasreporte dt ob eth emos tnumerou sphytoseii dspecies ;ver ylittl ei sknow nabou tthi s specieswherea s A. potentillae, A. finlandicus and T. pyri havebee nreporte dt ob eeffi ­ cientagains t P. ulmi. Probably,i nPost' sexperiment sth epredator sdi dno thav esufficien t timet odevelop ,o rth eisolate dpositio no fth eexperimenta lplo twa sresponsibl efo rth e observedphenomena .However ,Post' stransferrin gexperiment swit h P. ulmi populationso n pottedappl etree sfro mwell-kep torchard st oneglecte dones ,an dvic eversa ,ar eindica ­ tivefo rth eefficienc yo fth eloca lpredato rcomplex . Predatorymite sare ,i ngeneral ,mor esusceptibl et opesticide s thanthei rprey .Som e insecticidesan dacaricide sare ,however ,selectiv ei nthei raction .Pirimicar ban ddiflu - benzuronma yb eapplie dwithou treducin gth epredato rpopulations .Severa lfungicides ,lik e bipurimatean dcaptan ,als oca nb eapplie dwithou tdetrimenta leffect sfo rpredaciou smites . Resistance toacaricide so rinsecticide si nphytoseii dmite sha sno tye tbee nobserve d inorchard si nth eNetherlands .Thi sphenomeno nwa smanifeste d inCanada ,th eUnite dStates , andNe wZealan di nloca lpopulation so fsom especies .Thi sresistanc eha sstimulate dth e useo fpredaciou smite sconsiderably .

SIGNIFICANCEFO RAGRICULTURA LPRACTIC E

Themateria lpresente dabov eindicate sprope rmethod so fmanagin gphytoseii dpredator s foreffectiv econtro lo f P. ulmi, consistentwit hprofitabl efrui tproduction .Thi seffec t mayb erealize dmor eeasil yconsiderin gth egenera ltren dt oreduc eth eamoun to fnitroge n fertilizationo ffrui ttrees .

FUTUREOUTLOO K

Althoughth epracticalit yo fa nintegrate dcontro lapproac hfo rth efruit-tre ere dspide r miteha sbee nshown ,mor einformatio ni sneede dt omak ehandlin gth esyste mb yth efrui t growermor eeasily .Resistanc e inphytoseii dpredator st ogenerall yuse dpesticides ,a sha s beenshow ni nothe rfrui tgrowin gareas ,make sintroductio nan dmaintenanc eo fthes epreda ­ torsmor efeasibl ean dreliable .Ye tou rmethod so fproduction ,handlin gan dconservin gpre ­ daciousmite snee dimprovement .Considerin gth eregulativ ecapacity ,th ephenologica lsimi ­ larity,an dth egenera loccurrenc eo fthes epredators ,long-ter mcontro lo f P. ulmi popula­ tionsbelo winjuriou slevel sca nb erealized .

REFERENCES

Geijskes,D.C. , 1938.Waarneminge nove rhe tfruitspin t inverban dme tzij nbestrijding . Tijdschr.PIZiekt .4 4 :49-80 . Kuenen,D.J. , 1947.O nth eecologica lsignificanc eo ftw opredator so fMetatetranychu sulm i C.L.Koc h (Acari,Tetranychidae) .Tijdschr .Ent .8 8 :303-312 . Kuenen,D.J. , 1949.Th efrui ttre ere d spidermit e (Metatetranychusulm iKoch ,Tetranychidae , Acari)an dit srelatio nt oit shos tplant .Tijdschr .Ent .9 1 :83-102 .

27 McMurtry, J.A. &M . van de Vrie, 1973.Prédatio n by Amblyseius potentillae (Garman) on Panonychus ulmi (Koch) in simple ecosystems (Acarina: Phytoseiidae,Tetranychidae) . Hilgardia 42 : 17-34. Post, A., 1962.Effec t of cultural methods on the population density of the fruit tree red spider mite Metatetranychus ulmi Koch (Acari,Tetranychidae) .Dissertatio n University Leyden, 110p . Storms, J.J.H., 1971.Voedingsfysiologisch e betrekkingen tussenwaardplante n en spintmijten. (In Dutch, partly in English) Thesis,Univ . of Leyden. 74p . Vrie, M. van de, 1956.Ove r de invloed van spintaantasting op de opbrengst en groei van vruchtbomen. Tijdschr. PIZiekt. 62 :243-257 . Vrie,M . van de & D. Kropczynska, 1965.Th e influence of predatory mites on the population development of Panonychus ulmi (Koch) on apple. Proceedings 5th European Symposium Acarology, Milano, 1965.Boll . Zool. agr. Bachic, Serie II,7 :119-130 . Vrie, M. van de &A . Boersma, 1970.Th e influence of the predacious mite Typhlodromus (A.) potentillae (Garman) on the development of Panonychus ulmi (Koch) on apple grown under various nitrogen conditions. Entomophaga 15 :291-304 .

28 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 1.5 Biology and control of secondary insect pests in fruit crops

D.J.d eJon g

Research Institutefo rPlan tProtectio n (IPO),Wageningen ,seconde d toth eResearc hStatio n forFrui tGrowing ,Wilhelminadorp ,th eNetherlands .

INTRODUCTION

Somespecie so fharmfu linsec tan dmite si norchard sca ndevelo pexplosivel yunde rcer ­ tainconditions ,an dacceptabl emeasure sfo rcontro lwer eno talway sknown .I norde rt o preventeconomi cdamage ,a techniqu efo robservatio nan dadequat econtro lo fsuc hpest si s beingdevelope dunde rth eauspice so fth eWorkin gPart yo nIntegrate dContro lTNO . Failuret opreven texplosiv e increasei npopulatio nca nb edu et osevera lfactor s: Insufficientknowledg eo nth ebiolog yan decolog yo fth einsect ;inadequat efamiliarit ywit h currentpesticide san dtransitio nt one wones ;techniqu eo fapplication ,whic hshoul dfi t theecolog yo fth einsect .Restricte dsprayin gscheme sca nlea dt oa nincreas ei nnon-targe t insects.Dense rplantin ga si nmulti-ro wsystem sals ohampe rcro pprotection .Change si n culturepattern sca nhinde rcro pprotectio nan dcreat ene wproblems ,a sfo rstrawberr y blossomweevil .Th eba no npersisten tpesticide sha sals ocause ddifficulties ,whic hi n partstil lhav et ob esolved . Onemus ttherefor eb ealer tt ounexpecte dproblems .Researc ho nbionomic san dphenolog y ofth esusceptibl estage so fth epes ti softe nnecessar yalongsid etest so npesticides . Althoughth eproblem sar efrequentl yrelate dt oa singl einsec tspecies ,researc hshoul d bedirecte dt ocomplet escheme so fplan tprotection . AtWilhelminador p (Zealand),researc hi sbein gdon eo ninsect si nto pfrui tan do n strawberryblosso mweevi li nsof tfruit .

APPLECLEARWIN GMOTH ,AEGERI A (SYNANTHEDON)MYOPAEFORMI S

Thismot hha sa 2-yea rcycl ean doviposit snea rcallu stissue .Th elarva emin etha t tissue,causin gcanker .Th especie si sknow ni nolde rstandar dtree san dbus horchard sbu t seldomcause seconomi cdamage .Whe nth emot hemigrate st oyoun gappl eorchard snearby , theyespeciall yattac kth egraf tunio nan dca ndestro ysmal ltrees .Fiel dresearc hha s beendon eo nth ebiolog yan decolog yo fthi sinsec ta ssuppor ti nth esearc hfo rsuitabl e protectionmeasures ,observatio nmethod san ddamag ethresholds .Th e2-yea rcycl emake si t possiblet otackl eth einsec ta tdifferen ttimes .I twa salread yknow ntha ta sprin gappli ­ cationwit hsevera lpesticide scontrolle di tt oa certai ndegree ,bu ti ti sno tye tclea r ifthi ssuffice st ocur bheav yinfestations .Treatmen ti nautum ni sals opossible ,bu t

29 controldurin gfligh tan dovipositio nma yb epreferabl ebecaus eo fth epossibilit yo fcom ­ binedcontro lo fleaf-roller san dleaf-miners .A si nFrance ,a samplin gmetho dfo rsuper ­ visedscheme sca nb eused ,base do nth epresenc eo fempt ypupa lcase si nth ecanke rlesions . Controli snecessar yi fon eo rmor eempt ypupa lskin spe rtre ear efoun da ta ninspectio n ofa sampl eo f5 0tree spe rhectare .

LEAF-MINERS

Twospecie so fleaf-miner , Lithoaolletis blanoardella and Stigmella malella, playa majorrol ea tth emoment .A thir dspecies , Stigmella pomella, isonl yo floca linteres t and Leucoptera saitella usedt ob ever yinjuriou slocally .Leaf-miner sar eusuall yno tver y harmfulbecaus ethe yar econtrolle dtogethe rwit hmor eimportan tpest si ncomplet econtro l schemes.Restrictin gth enumbe ro fsprayings ,however ,ca nundesirabl yincreas eth epopu ­ lationan dmak especia lmeasure snecessary . unfortunatelyapplicatio nan dmaintenanc eo fth eHymenopterou sparasit e Chrysooharis pvodioe, whichca nkee p S. malella undercontrol ,i sno tpossibl ei nsimpl esupervise d controlschemes .Acceptabl echemical sha dt ob efound .Larva eo fth eleaf-miner sente rth e leafdirectl yfro mth ebotto mo fth eegg .Th enewl yhatche dlarva eca nb ekille db ypene ­ trativephosphoru scompounds ,bu tth eolde rlarva ei nth emine sar ehar dt ocontrol . Neitherth ene wpyrethroid sno rdiflubenzuro nca npenetrat eth eleaf ,s othei rus eshoul d beadapte daccordingly .Pyrethroid smus tb eapplie da tth ebeginnin go fth efligh tperiod , anddiflubenzuro nha sa satisfactor yan dselectiv eovicida lactio nan dca nals ob euse di n integratedcontro lscheme sb yapplicatio nbefor eeg ghatch .Contro lwit hdiflubenzuro nca n alsofrequentl yb ecombine dwit htha to fothe rinsects .

PEARPSYLLID ,PSYLL APYR I

Inth elas tfe wyears ,psyllid shav ecause dincreasin gtroubl eo npear ,includin gsuper ­ visedcontro lschemes .I n1977 ,w efoun dtha tth etechniqu eo fsprayin g influencedcontrol . Thelow-volum etechniqu eo fmis tsprayin gofte nresulte di nunsatisfactor ypenetratio no f theinsecticid eint oth efoliag ean dpenetratio nwa sessentia li npsylli dcontrol .Th eolde r stagesusuall yliv ei nlea faxil san dnea rth eshoo tbas ewher eth emis tdoe sno tpenetrat e sufficiently.T olimi tth eus eo finsecticides ,contro lmus tb ecombine dwit htha tfo rothe r insects.

ARCHIPSROSANU S

Thisleaf-rolle rusuall yoccur slocally .Th ecaterpilla rpopulatio ni nsprin gmus tno t beto ohigh .Contro lwit hjuvenil ehormon eanalogue sha sprove dfeasible .

STRAWBERRYBLOSSO MWEEVIL ,ANTHONOMU SRUB I

AfterDD Twa sprohibited ,n osuitabl econtro lagen twa sfoun dfo rstrawberr yblosso m weevil.Th ebehaviou ro fth einsec texclude dth eus eo fdiflubenzuron ,becaus eth elarv a

30 completesdevelopmen twithi na close dflowe rbud .Th ene wpyrethroids ,however ,offe rsom e control,a sth eweevi li sactiv ewhe nth eweathe ri swarm .Contro li sseriousl yhampere d byth enee dt oprotec thoney-bee san dt oavoi dpoisonou sresidue so nth efruits .Samplin g theinsect st oasses sthei rnumbe ro nsoft-frui tcrop si spossible ,bu ta complicatio ni s thatthi sspecie soccur so nvariou scrops :strawberry ,raspberr yan dblackberry .Th einsec t isals oknow nfro msom ewil dRosacea ean dtherefor ew ear eexaminin gth esignificanc eo f nearbysource so finfectio nsuc ha swil dbrambles .Mor eknowledg eo fth edispersa lo fth e weevili sessentia li nvie wo fth emutua linfluenc eo fth eman ysoft-frui tplot si na narea . Theblackberr ycultivar sThornles sEvergree nan dThornfre esee mt ob eunattractiv efo r oviposition.I n1978 ,a pyrethroi ddurin gth eperio dth eweevi lemerge di nsprin gu pt oth e floweringo fth ecro pyielde dsatisfactor yresult si nraspberry .I n1979 ,th eresult swer e lesssatisfactor ybecaus eo fth einfluenc eo frapi ddispersa lo fweevil sfro mnearb yplan ­ tations.

31 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 1.6 Relation between insect pests of apple, and their parasites and predators

H.H.Evenhui s

Research Institutefo rPlan tProtectio n (IPO),Wageningen ,th eNetherlands .

APHIDS

Thoughth ewooll yappl eaphid , Eriosoma lanigerum (Hemiptera,Aphididae) ,wa sintroduce d accidentally fromeaster nNort hAmeric aa searl ya sth een do fth e18t hCentury ,it smono - phagousparasit ei nit snativ earea , Aphelinus mali, (Hymenoptera,Aphelinidae) ,wa sonl y introduced inFranc efo rbiologica lcontro lafte rWorl dWa rI .Fro mFrance ,i twa sdistrib ­ utedt oothe rEuropea ncountrie san di n192 4materia lwa sreceive db yth ePlan tProtectio n Servicei nWageningen .Ye tsevera lyear spasse dbefor eth eparasit ebecam eestablishe di n theNetherlands . Itha sbee na matte ro fdebat ewhethe rintroductio nint oth eNetherland smarkedl yinflu ­ encedit shost .A si nothe rcountries ,th eecolog yo fhos tan dparasit ewer estudied . Reproduction,mainl yexpresse di nterm so fprogen ynumbe ran drat eo fdevelopment ,muc h favouredth eaphid sove rit sparasite .However ,winte rmortalit ywa shig hfo rth eaphi dan d muchles sfo rth eparasite .S oparasitis mi shig ha tth ebeginnin go fth eseason ,abou tth e endo fMay .I tcoul deve nb e 1001i fth efemal eparasite swer et ofin dal laphi dhost savail ­ able.A sthi si sno tso ,ther eremain sa nunparasitize d aphidpopulation ,whic hincrease s fastertha nth epopulatio no fth eparasite ,causin ga gradua ldecreas ei nparasitism .Para ­ sitismi slowes ta tth een do fJul yo rth ebeginnin go fAugust ,bu tincrease safterward sa s aresul to fa declin ei naphi dpopulatio ncause db ya changin gphysiologica lconditio no f thefoo dplant ,apple ,whic hdoe sno taffec t Aphelinus mali. DuringSeptembe ran dOctober , parasitismdecrease sa sth eparasit eenter sdiapause ,wherea sth eaphi dstil lreproduces . Theincreas ei nparasitis man dth edeclin eo fth eaphi dpopulatio ni nJul yan dAugus ti s oftenwrongl yinterprete da scaus ean deffect . Inth eNetherlands ,th eparasit ecanno tadequatel ycontro lth ewooll yaphid .N odoubt , however,i tmus tb eeffectiv et osom edegree ,bot hi nearl ysprin gan di nsumme rwhe nth e hostpopulatio ni slowes tan dparasitis mhighest .The nth esmal laphi dpopulation sar estil l morestrongl yreduce dan dth erapi dbuil du pi simpeded . Theothe rmajo rappl eaphids ,namel yth eapple-gras saphi d (Rhopalosiphum insertion), theros yappl eaphi d (Dysaphis plantaginea) andth egree nappl eaphi d {Aphis pomi) arepara ­ sitizedb ya numbe ro fAphidiidae(Hymenoptera) ,eac haphi dhavin gon emai nparasite , Monoctonus cerasi, Ephedrus persicae and Trioxys angelicae, respectively. M. cerasi, though mentioned inth eliteratur efro msevera laphi dspecie so na numbe ro ffoo dplants ,seem sa

33 strictlyspecialize dparasit eo f R. insertion onapple .I tha stw ogeneration si nspring , correspondingwit hth etw osprin ggeneration so fit saphi dhos to napple .Whe nth eaphi d migrates tograsses ,it ssumme rhost-plants ,th efull-grow nlarv ao fth eparasit eenter s diapause.Whe nth eaphi dreturn si nSeptembe ran dOctobe rt oit swinte rhost ,appl ean d relatedtree san dshrubs ,som eo fth eparasite scom eou to fdiapaus ean dth efemal e M. oerasi pararitizes theoviparae .Thi sma yb eo frea leconomi cimportance ,a sth enumbe r ofovipara eparasitize d isproportiona l toth ereductio ni nnumbe ro fwinte reggs .Whe n parasitism is,fo rinstance ,a shig ha s 50%,a sobserve doccasionally ,th eeconomi cthres ­ holdfo rcontro lo fth eapple-gras saphi dma yno tb ereached ,s otha tchemica ltreatmen t isunnecessary . E. persioae isa rathe rpolyphagou sparasit eo faphid slivin gwithi nlea fcurl so nsev ­ eraltree san dshrub san d T. angelicae isa parasit eo fsevera laphi dspecies ,mainl yo f thegenu s Aphis. Hyperparasitesma yseriousl yinterfer ei nth eactio no fth eprimar yaphidii dparasites , especially in A. pomi, whichaphi dma ysta yo nyoun gapple-tree swit hgrowin gshoot sfo r thegreate rpar to fth esumme rseason . T. angelicae mayb enearl ycompletel yeliminate db y hyperparasitesa tth een do fth esummer . Thethre ehost—parasit ecomplexes , R. insertion—M. oerasi, D. plantaginea— E. persicae and A. pomi— T. angelicae havefou rhymenopterou shyperparasite s incommon ,namel y Dendrocerus carpenteri (Proctotrupoidea,Ceraphronidae) ,an d Asaphes vulgaris, Asaphes suspensus and Pachyneuron aphidis (Chalcidoidea,Pteromalidae) .Cynipida eAlloxystina e (=Charipinae )see mgenerall ymor especialize dan dar erepresente dfo rth ethre ecomplexe s by Phaenoglyphis villosa, Alloxysta arcuata and Alloxysta pleuvalis, respectively. Ast oaphi dpredators ,adul tCoccinellidae ,especiall y Adalia hipunctata, Coccinella decempunctata and Propylaea quatordecimpunctata mayb eimportan t inearl yspring .The yca n thendestro ya larg eproportio no ffundatrice sbefor ethes ereproduce .Th erol eo fothe r predators liketh elarva eo fSyrphida ean dNeuropter ai sles sevident .Th especie sfrequent ­ ingappl eaphid sar epolyphagou saphi dpredators ,excep tfo r Cnemodon vitripennis. The larvaeo fthi sspecie sare ,a tleas ti nappl eorchards ,restricte dt oth ewooll yappl eaphi d asa prey .

LEAF-MINERS

Theappl eleaf-mine r Stigmella malella (Lepidoptera,Nepticulidae )i sth emos timportan t appleleaf-mine ri nth ecentr eo fth eNetherlands .It smos teffectiv eparasite , Chrysocharis prodice, controlsth elarva ewithi nth emine sa ta lo wpopulatio ndensit y (Section1.7) . Twoothe rcommo nlarva lparasite so fth eleaf-mine rar e Cirrospilus vittatus and Achrysocharella chlorogaster, whosenumber si nappl eorchard sar ei na proportio no fabou t onet othre eo rfour .Whe nth epopulatio ndensit yo fth eleaf-mine rincreased ,th edensit y ofth eparasit e C. vittatus generally increasedmor etha nproportionally ,indicatin gtha t theparasit eca ncontro lth eleaf-miner .A sth ebalanc ei sfa rabov eth eeconomi cthreshol d ofth eleaf-miner ,th eparasit eseem so flittl eus ei nbiologica lcontro lo f S. malella. Anotherdrawbac ko f C. vittatus istha tth etim eo femergenc eo fparasit ean dleaf-mine r dono tclosel ycoincide .Th esam ehold sfo rth eautumn ,en do fSeptembe ran dbeginnin g

34 October,whe nhardl yan yadequat estage so fth ehos tar eavailable .Thi ssuggest stha t C, vittatus, whichi sa pantophagou sparasit eo fleaf-miner so ntree san dshrubs ,mus thav e oneo rmor ealternativ ehost stha tar emor esuitable ,perhap s inquit ea differen thabitat .

LEAF-ROLLERS

Asleaf-roller s (Lepidoptera,Tortricidae )ar emajo rpest si nappl eorchards ,thei r parasitecomple xha sbee nstudied .Mor etha n5 0specie so fparasiti cHymenopter aan da fe w specieso fTachinida e (Diptera)wer ereare dfro mcaterpillar san dpupa eo na nartificia l diet.Th ehost sbelon gt oth eeigh tmor ecommo nleaf-roller so fapple , Adoxophyes orana beingth emos timportant .Almos tal lbiologica lcategorie so fparasite swer erepresented : ectoparasitesan dendoparasites ;solitar yan dgregariou sparasities ;monophagous , oligophagousan dpolyphagou sparasites ;egg ,larval ,pupal ,egg-larva lan dlarval-pupa l parasites;primar yan dsecondar yparasites . Hostspecificit ywa sstudie despeciall yi ntw o Asaogaster species,namel y A. rufidens and A. quadridentatus. Theforme rwa sfoun dt ob ea negg-larva lparasit eo fTortricida e Tortricinae,th efemale so fwhic h laythei regg si nbatches ,th elatte ro fTortricida e Olethreutinae,whic hla ythei regg sseparately .Th esearchin gbehaviou ro fth efemal e parasitewa ssuppose dt ob eresponsibl efo rth edifferenc ei ndiscriminatio nbetwee ntype s ofhost . Identificationo fth eparasiti cHymenopter agav elarg eproblems ,becaus emos to fthes e Hymenopterousgroup snee dthoroug hbiotaxonomi crevisions .A slon ga sthes erevision sd o notexist ,reliabl eidentificatio ni simpossible . Onechalci dspecies ,namel y Colpoolypeus florus, seemso fparticula rimportanc ei ncon ­ trol,especiall yo f A. orana. Thisoligophagou sgregariou sectoparasit eo fth eolde rlarva e ofTortricida eha sman ygeneration sa year .I nDutc happle-orchards ,however ,i twa sprac ­ ticallyneve robserve dbefor eth esecon dhal fo fJuly ,afte rwhic hi treproduce drapidly . Thusparasitis mi nSeptembe rma yb ealmos tcomplete .Th edrawbac ko fth eparasit ei stha t itslas tgeneratio ndevelop st oadult sa ta tim ewhe nther ear eonl yoverwinterin gyoun g larvalstage so fth ehos tan dthes ear eno taccepte db yth efemal eadul tparasite .Thu s theseparasite sdi ebefor ewinte rwithou tprogen yan drecolonizatio nha st ostar tnex tyea r fromoutsid eth eorchard . As C. florus isa noligophagou sparasit eo fTortricidae ,larg enumber so fleaf-rolle r caterpillarswer ecollecte dfro ma sman yplan tspecie si na sman yhabitat sa spossible .Th e caterpillarswer efe dseparatel yo na nartificia ldie tan dresulte dultimatel y inman yleaf - -rollerspecies ,bu tals oi nman yHymenopterou sparasite san dsom eDipterou sparasites .How ­ ever C. florus couldno tb erecovere di nth eNetherlands .Thu sho wthi sparasit ehibernate s remainsa mystery . Manyothe rparasiti cspecie swer ereared ,differen tfro mthos eobtaine dfro mappl eleaf - -rollers.Eve nth esam especie so fleaf-roller scollecte d fromappl ean dfro mothe rfoo d plants,ofte nyielde ddifferen tparasite so rth esam eparasite si nquit edifferen tpropor ­ tions.S oth evalu eo falternativ eleaf-rolle rhost so nth evariou s foodplant sinsid ean d outsideappl eorchard si sdoubtful . Severalstrain so f Irichogramma embryophagum cacoeoiae werereare di nmas san dapplie d

35 againstth eegg so fth eappl eleaf-rollers ,especiall yo f A. orana. Thoughthi ssometime s gavegoo dresults ,th eeffec twa sgenerall yunreliable .Thi swa softe nascribe dt oba d weather.Moreover ,th eparasit eprove dsusceptibl et oa variet yo fpesticide suse dagains t otherappl epest san dagains tdisease s (Section1.3) .

REFERENCES

Evenhuis,H.H. , 1962.Betrachtunge nübe rde nEinflus sde rBlutlauszehrwespe ,Aphelinu smal i (Hald.),au fde nMassenwechse l ihresWirtes ,de rApfelblutlau sEriosom alanigeru m (Hausm.).Z .angew .Ent .4 9 :402-407 . Evenhuis,H.H. , 1964.Th einterrelation sbetwee nappl eaphid san d theirparasite san dhyper - parasites.Entomophag a9 :227-231 . Evenhuis,H.H. , 1968.Th enatura lcontro lo fth eapple-gras saphid ,Rhopalosiphu minsertum , withremark so nth econtro lo fappl eaphid si nTh eNetherland si ngeneral .Neth .J .PI . Path.7 4: 106-117 . Evenhuis,H.H. ,W .Nikolov a& H.J .Vlug , 1971.Ei nVergleic hzwische nAchrysocharell a chlorogasterun dCirrospilu svittatu s (Hymenoptera,Eulophidae )al sParasite nde sApfel - blattminierers Stigmellamalell a (Lepidoptera,Stigmellidae )i nde nNiederlanden .Z . angew.Ent .6 8 :32-40 . Evenhuis,H.H. , 1974.Le sHyménoptère sparasite sde stordeuse snuisible sau xverger sd e pommiersau sPays-Bas .Le sorganisme sauxiliaire se nverge rd epommiers .Organisatio n Internationaled eLutt eBiologiqu e (OILB),p .53-59 .

36 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 1.7 Natural control of the leaf-miner Stigmella malella in apple orchards

P.Gruys 1

DeSchuilenbur gexperimenta lorchard ,TNO ,Lienden ,th eNetherlands .

INTRODUCTION

Inappl eorchard s inth eNetherlands ,severa lspecie so fleaf-mine roccur ,includin g Stigmella malella, Stigmella •pomella, Lithocolletis blancardella, Lithocolletis corylifoliella, Lenooytera scitella, Lyonetia clerkella, Ornix guttea, and Phytomyza heringiana. Froma practica lpoin to fview , S. malella isth emos timportant ,a si tma y causepersistan toutbreak swhich ,unti lrecently ,wer eno teas yt ocontro leve nwit hchem ­ icalinsecticides .Heav yattac kb y S. malella causesprematur e leaf-drop,whic hma yresul t ininsufficientl ydevelope dfruits .Outbreak so f S. pomella, I. blancardella, and L. scit­ ella arerare ,an dth eothe rspecie sar eno to fpractica limportance . Thetroubl ecause db y S. malella duringth efirs tyear so ftrial so nintegrate dcontro l atD eSchuilenbur g (Section1.1 )prompte da ninvestigatio nint oth ecause so foutbreaks , aimeda tecologica lo rselectiv echemica lcontrol .

METHOD

Relativepopulatio ndensitie so f S. malella, interm so fnumbe ro fmine spe rleaf ,wa s assessedi ndifferen tplot sa tD eSchuilenburg .Th eassessment swer econcentrate do nthre e situations:tw oneighbourin gplot sreceivin gn oinsecticides ,age d25-3 5an d3-1 0years , of1 an d0. 5ha ,respectively ,an da selectivel yspraye dplo to f1 ha ,5-1 5year sold ,par t ofa large rselectivel yspraye dare a20 0m awa yfro mth eunspraye dplots ,an dseparate d fromthes eb ya cherr yorchar dan da heavil yspraye dappl eorchard .Mortalit ywa sassesse d andth ecause so fi tidentifie da sfa ra spossible ,b yanalysin gsample so fmine san dbreed ­ ingparasite sfro mthese .Th ereproductiv epotentia lo f S. malella, potentialpredators , andsom edetail so fth ebiolog yo fth emos tnumerou sparasite swer estudie di nth elabora ­ tory.

1.Presen taddress :Researc hInstitut efo rNatur eManagement ,Arnhem ,th eNetherlands .

37 RESULTS

Biology and natural control factors

Inth eNetherlands , S. malella hastw oful lan da small ,practicall ynegligible ,partia l thirdgeneration .Th etin ydelicat emoth sar esensitiv et owin dan dlo wrelativ ehumidity . Theyfl ydurin gth eda ya twin dspeed sbelo wabou t3 m/s ,temperature sove r 15 C,relativ e humiditiesove r60°s ,an da novercas tsky .Unde rexperimenta l conditions,th eaverag enumbe r ofegg sdeposite dpe rfemal ei sabou t60 .Th eflattene degg sar eattache dt oth eundersid e ofth eleaves ,whic hth elarva eente rdirectl ywithou tgoin gint oth eopen .Th elarva epro ­ ducea nelongate dgaller yabou t4 c mlong ,whic hthe yleav ewhe nfull-grow nt ospi na cocoo n andpupat ei nth elitte ran dsoil .Th einsec thibernate sa sa pup ai nth esoil . Predatorso f S. malella larvaeinclud eth elarva eo fChrysopidae ,whic hpierc ean dsuc k themwit hthei rjaws , Forficula auvicularia, whichea tth elarva efro mth emines ,an dpreda ­ torybugs . Parasites,al lo fthe mchalcids ,probabl ycaus emor elarva lmortalit y thand opredators . Therear esevera llarva lectoparasites ,o fwhic h Cirrospilus vittatus ratesfirs tan d Achrysocharella chlorogaster secondi nabundance .The ykil lth e Stigmella-larvae atovi - position.Th eadul tparasit eemerge s fromth emin ei nth esam eyea ro rhibernate s inth e mine,i nth efalle nleaf . C. vittatus alsokill s Stigmella larvaethroug hhost-feeding .I t israr ean dcause slittl emortalit ydurin gth efirs tgeneratio no f S. malella butca nb e abundantdurin gth esecond . Thelarva lendoparasite , Chrysocharis prodice, isinconspicuou sbecaus ei temerge sfro m itshos tafte rth elatte rha sfalle nt oth egroun dan dspu nit scocoon ,bu tbefor e itpupates . Contraryt o C. vittatus, whichattack sman yspecie so fleaf-miners ,thi sparasit ei sspe ­ cialisedo n S. malella. Iti swel lsynchronize dwit hit shost ,emergin gabou tthre eweek s afterth emoth so f S. malella, atth etim ewhe nth ene wgeneratio no fmine si spresent . C. prodice attacksal llarva linstar so f S. malella. Hibernationoccur sa sa pup ai nth e soil,withi nth ecocoo no f S. malella. C. prodice cancaus econsiderabl emortalit y tobot h thefirs tan dth esecon dgeneratio no f S. malella. Athir dan dmino rcategor yo fmortalit yt oth elarva eo f S. malella isthroug hwha t appearst ob ea hypersensitivit y reactiono fth eleaf ,resultin g ina necroti cpatc hi n whichth emin estop san dth elarv ai ni tdies . A largepar to fth elarva lmortalit yi nth eorchar di sdifficul tt oattribut ebut ,judgin g fromexclusio nexperiments ,probabl ymainl yo fa bioti cnature . Nothingi sknow nabou tth ecause so fmortalit ydurin gth epupa lstage ,i nth esoil ,bu t itsrat eappear st ob ehigh . Thefluctuation s inpopulatio no f S. malella arecharacterize db yrelativel ylo wnumber s inth efirst ,an drelativel yhig hnumber si nth esecon dgeneration ,resultin gi na zi gza g patternwhe nnumber sar eplotte dagains tgeneratio n (Fig.1.) .Apparently ,generatio nmor ­ talityi s (far)belo wtha trequire d forth epopulatio nt ob establ ei nth efirs tgeneration , and (far)abov etha tlimi ti nth esecon dgeneration .I nth e 'unsprayed'plots ,th enumber s ofth emine sfluctuate da ta lo wleve l (Fig.1 A) ; inth eselectivel yspraye dpar to fth e orchard,the ywer es ohig hi n1969-197 1 thatsuppressio nwit hselectiv e insecticideswa s

38 Log Stigmella mines per leaf

Economic threshold

Parasitism (%) • Stigmella -100

-90

TirChrysocharis -80

-70 /A \ / \ / \ / f \ / \ ' -60 -50 V VA-* \ i -40 it if! 1 1 1 \ / { -30

-20 *' : •• * \/ \/ w " Cirrospilus^.0.^ W -10

1212121212121 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 Log Stigmella mines per leaf Sprays 24 B) ti 11 Release of Chrysocharis I

Cirrospilus ••o.. a-.-<ï ,-ft—-ft *-•*- -ft—ft—ft—A—'ft'

"1 1 1 r ""1 I 1 I I I T 1 1 1 12 12 12 1 2 12 12 12 Generations 1969 1970 1974 1975 1976 1977 1978 Fig. 1.Fluctuation s inth enumbe ro f Stigmella male lia minespe rlea fan d inparasitis m bytw oparasites .A .Orchar dno tspraye dwit h insecticides.B .Orchar d sprayedwit hselec ­ tiveinsecticides . necessary (Fig.1 B). Themortalit yo f S. malella inth etw osituation swa sfoun dt odiffe ri ncertai nrespects . Theparasit e C. prodiee, occurringi nth e 'unsprayed'plo tfro mth ebeginnin gan dcausin ga highmortalit yi nsom eyears ,wa sabsen ti nth eselectivel yspraye dplot . Sinceth edelaye ddensity-dependenc eo fmortalit ycause db ythi sparasit esuggeste dtha t itmigh tb eth eagen tregulatin gth epopulatio no fS . malella, itwa scollecte dan dre ­ leasedi nth eselectivel yspraye dpar to fth eorchar d (Gruys,197S) .It sincreas ewa sas ­ sociatedwit ha gradua ldeclin ei nth epopulatio no fit shos t (Fig.1B) .Presumably ,i tdi d notente rth eselectivel ytreate dare aearlier ,o nit sown ,becaus ethi swa seffectivel y screenedfro mth e 'unsprayed'are ab yth eintensivel yspraye dorchar di nbetween . Anattemp tt oobtai nexperimenta lproo fo fth eeffectivenes so f C. prodiee inbiologica l control,b ycreatin gplot si nth eselectivel ytreate dare awit han dwithou tth eparasite , failedbecause ,onc eintroduced ,i trapidl ydisperse dove rth ewhol earea . Thepolyphagou sparasit e C. vittatus waspresen ti nth eselectivel yspraye dare ai nth e yearso fhig hpopulatio ndensity ,bu tdi dno tcontro l S. malella. Soi ti sineffectiv efo r biologicalcontrol . Besidesth eorigina ldifferenc ei nth eoccurrenc eo f C, prodiee, therear eothe rdiffer ­ encesi nth epatter no fmortalit ybetwee nth eselectivel yspraye dan dth euntreate dareas , particularlydurin gth esecon dgeneration .I nth eselectivel yspraye darea ,mortalit ydurin g thelarva lstag ei nth emine swa shighest ,wherea spopulatio nreductio ni nth eperio dfro m pupationt oth enex tgeneratio n (mortalityi nth esoil? )wa sleast .Hig hmortalit yo fth e larvae,o funknow ncause ,wa sa tleas tpartiall yresponsibl efo rth eshar pdeclin ei npopu ­ lationi nth eselectivel yspraye dplo ti n1973-1974 . Amor edetaile danalysi so fmortalit y innatura lcontro lo f S. malella isi nprogress .

Insecticides

Therear efe wchemical scapabl eo fcontrollin g S. malella effectively.Th eorganophos - phatesazinphos-methy lan dparticularl ymethidathio nar eeffective ,i fapplicatio ni scare ­ fullytime dan drepeated .Howeve rthes einsecticide sar eunsuitabl efo rintegrate dcontro l sincethe yupset ,fo rinstance ,th espide rmit e— typhlodromidpredato rrelationship .Th e selectivebotanica linsecticide ,Ryania ,gav esufficien tcontro li fcarefull ytime dan dap ­ pliedrepeatedly .However ,fro ma practica lpoin to fview ,i ti sno ta ver ysatisfactor y controlagent ,bein gexpensiv ean ddifficul tt ospray . Recently,tw one wan dver yeffectiv eagent sfo rth econtro lo f S. malella havecom eont o themarket :diflubenzuro nan dth esyntheti cpyrethroids .Wherea s thelatte rd ono thol d muchpromis efo rintegrate dcontrol ,diflubenzuro nha sbee ninclude dsuccessfull y inth e integratedprogram ,t ocontro lsevera lpest s (Section 1.1).On eo fit sside-effect si st o reduceth epopulatio no f S. malella andit sspecifi cparasit e C. prodiee dramatically.Th e effecto fdiflubenzuro no nth eparasit ei sindirect :i ti sdu et oreductio ni nth enumber s ofth ehost .I nth efe whost sstil lpresen tafte rsevera lyear so fa spra yschedul einclud ­ ingdiflubenzuron ,th eparasit ewa sstil lpresent ,an dabl et ofin dit sscarc ehosts .Appar ­ ently,i tpossesse sa hig hsearchin gpower .

40 PROSPECTS

Althoughth eevidenc epresente d forth eeffectivenes so f C. prodice incontro lo f S. malella iscircumstantial ,th eparasit ei suse di nth eintegrate dprogram .Practica l introductiono fthi sprogra mwil lno tbrin gfurthe revidenc eo nth eindispensabilit yo f C. produce aslon ga sdiflubenzuro ni sanothe ressentia lpar to fit .

REFERENCE

Gruys,P . 1975.Integrate dcontro l inorchard si nth eNetherlands .In :L.Brade r (Editor). ComptesRendue s5 eSymposiu mLutt eintégré ee nvergers ,Bolzano ,1974 .Organisatio n Internationaled eLutt eBiologiqu e (OILB),p .59-68 .

41 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980.

1.8 The sterile-male technique in control of Adoxophyes orana (Lepidoptera: Tortricidae)

G.W. Ankersmit

Department of Entomology, Agricultural University, Wageningen, the Netherlands.

Theleaf-rolle r Adoxophyes orana ispresentl ycontrolle di nou rappl eorchard swit h broad-spectrum insecticideslik eazinphos-methyl ,permethri nan dcarbaryl .Thes ecanno tb e includedi nintegrate dcontro lprogram scurrentl ybein gdeveloped .Alternativ eselectiv e methodsar etherefor eneeded . Thesterile-mal etechniqu ecoul db esuc ha method .I trequire sa goo dknowledg eo fal l majoraspect so fth ebiolog yan dpopulatio ndynamic so fth einsect ,a goo dsterilizatio n method,chea pmass-rearing ,goo dmatin gcompetitivenes so nth epar to fth erelease dmales , alo winitia lpopulatio ndensit yo fth epes ti nth eare ao frelease ,lo wimmigratio nint o thereleas earea ,an dsuitabl emethod so freleas ean dmonitoring .

BIOLOGY

A. orana hasbee nsubjec tt oman ystudie si nth eNetherland s (DeJon ge tal. , 1971). Thispolyphagou sinsec tthrive so na wid evariet yo fperennials .I tusuall yha stw ofligh t periodspe ryear ,on ei nJun ean don ei nAugus tan dSeptember .Th especie shibernate sa sa third-instarlarv ao nth etree .Thes elarva ebecom eactiv ei nearl yspring ,fee do nth ebud s andleaves ,an dar eusuall yfull-grow nb yth een do fMay .Thei roffspring ,th esumme rgen ­ eration,fee do nleave san dfruits .The ycaus emos to fth edamage .Th eoffsprin gproduce d duringth esecon dfligh tar emor enumerou sbu tcaus eonl ysuperficia ldamag et ofruits .

STERILIZATION

Thefirs tproble mi nsterilizatio ni sa suitabl emetho dan da suitabl emomen ti nth e lifecycle .Chemica lsterilizatio nwa sno tstudie dbecaus eo ftoxicit yan denvironmenta l hazards.Irradiatio nwit hX-ray swa stherefor eused . Theeffect so fthi ssterilizatio nmetho dwer eextensivel ystudie db ySniede re tal . (1973). Theadult sprove dt ob emos tsuitabl efo rirradiation .Dose so f25 0G yo fX-ray st omal e mothsreduce dhatchin gb y 90-9S°Ó inegg slai db yuntreate d femalest owhic hth emale swer e mated.Th efe wsurvivin goffsprin gwer emostl ysterile .Becaus eo fthi seffect ,thi sdos e wasexpecte dt osuffic ei nlate rreleas etrials .Th edos ecause dcomplet esterilit yi nfe ­ males.Thi sallowe dsimultaneou sreleas eo fmal ean dfemal emoths .Almos tcomplet esterilit y couldonl yb ereache dwit ha dos eo f35 0Gy .Thi sdos ewoul dprobabl yhav ea mor edelete ­ riouseffec to nth equalit yo fth erelease dmoths .

43 MASS-REARING

Anartificia lmediumwa sdevelope d (Ankersmite tal. ,1977a )an dth erearin gtechniqu e wasoptimate db yanalysin g therearin gsyste man dmodellin gi twit ha compute rprogra m writteni nFortra nIV .I tindicate da rearin gcos tpe rmot ho fƒ 0.015- /0.03 0i n1973 , dependingo nwage san dsiz eo fculture .Condition so frearin gwer e 20 C,70 ?«relativ e humidityan dligh tan ddar kphase so f16. 5an d7. 5h . Ahighe rtemperature ,thoug hspeedin gu pdevelopment ,decrease dproductio npe rrearin g unitan dtherefor eraise dcost .A thighe rrelativ ehumidity ,mould sdevelope do nth emedium . Thisma yseriou sreduc eth edail youtpu to fmoths .I nou rculture ,a dail yproductio no f 5000-1 000 0moth swa sobtained .Thi ssuffice dfo ra releas etria li norchard so f1- 2ha . Inth eculture ,a multiplicatio nrat epe rgeneratio no f1 5time swa sfound .Thi sallowe d rapidadaptatio no fcultur esize .

QUALITYCONTROL .

Competitiveness inmatin gan dfligh tactivit yar eth emos timportan taspects .Qualit y canb eaffecte db yth eus eo fa laborator ystrain ,th erearin gmediu mo rb yirradiatio n effects.Competitivenes s inmatin gwa sstudie dwit hmoth s labelledwit h 32P.Thes emoth s producelabelle dspermatophore swhic hca nb edistinguishe d inth eburs acopulatri xfro m unlabelledones .Test swit hlabelle dan dunlabelle dmoth si nfiel dcage sindicate dtha t thedos eo f25 0G yha dlittl eeffec tbu twit hth elaborator ystrai nmatin gwa sreduce db y 40-50°6a sjudge db yspermatophor etransfer .Th eselectio no fa laborator ystrain ,however , seemsth eles slikel yexplanatio no rthi sselectio nmus toccu rwithi non egeneratio na s matingcompetitivenes s innewl ycollecte dstrain swa ssimila rt otha to fth elaborator y strainafte ron egeneration .A neffec to fdie to nmatin gcompetitivenes sseeme dpossible . Flightactivit yo freare dirradiate dmoth swa sreduce dtoo .Whe nequa lnumber so firra ­ diatedan dunirradiate dmoth swer ereleased ,recaptur ei npheromon etrap so firradiate d maleswa sreduce db y 201.Al lmoth swer emarke dwit hRoto rdye s (ICI,London) .Th eeffec t ofmarkin gha dt ob estudie di ntrial soutsid eth enatura lfligh tperiod .Recaptur eo f markedmoth swa sreduce db yabou t25$ .

MIGRATION

Calculationswit hth eBerryma nmode lfo rth esterile-mal etechniqu eshowe dtha timmigra ­ tiono fnativ efertil emoth seasil yupset sal lreleas eprograms . Dispersalo f A. orana wasstudie db yBare l (1973).Release dmale sca nb erecapture dt o adistanc eo fa fe whundre dmetres .Onl y 1- 2%o fth emal epopulatio nemigrate dfro ma n orchard.Immigratio nint oth eorchar ddepende dmuc hupo npopulatio ndensit yi nth esurround ­ ingarea .A sth emoth stende dt oavoi dope nspaces ,meadow sma yprovid ea barrie rfo rmi ­ grants. Duringreleas etrials ,a neffor twa smad et omeasur eimmigration .W eassume dtha tth e

44 Table 1.Calculatio no fth enumbe ro fimmigrate dmale s Adoxophyes ovana. FromAnkersmi te tal .(1977b) .

Year Flight Corrected Expected Counted Immigration ratioo f ratioo f native (approx.) released native males moths moths

1973 June 0.11 129/1170 490 700 August 0.05 51/1020 800 200 1974 June 0.07 251/3586 160 3400 August 0.28 203/725 90 600

ratioo frelease dmoth srecapture dt otota lnumbe rrelease dwoul db enearl yth esam ea sth e numbero fcapture dnativ emoth st oth etota lnumber so fnativ emoths .A sfligh tactivit y ofreare dirradiate dmarke dmoth swa slower ,th enumbe rrecapture dwa scorrecte db ya facto r 0.6.Fro mth erati oan dth enumbe ro fcapture dnativ emoths ,w ecalculate dth eactua lnum ­ bero fmoths .A sa nabsolut eestimat ewa smad eb ycounting ,th edifferenc ebetwee ncalcu ­ latedan dcounte dwa sattribute dt oimmigration .A tth elo wpopulatio ndensity ,emigratio n wasneglected .Th eresult s (Table1 )indicat ea nimmigratio no fusuall ya fe whundre dmal e mothst oa nisolate dorchar do f1. 9ha ;i non eestimate ,eve na fe wthousand .S oimmigra ­ tionseriousl yinterfere swit hreleas etrial so f A. orana. Immigrationb yfemale si sno t evaluatedi nthi sway .Beside sactiv eflight , A. orana maydispers ea sfirst-insta rlarva e floatingo nthei rthread si nth eair .

RELEASETRIAL S

Invie wo fimmigration ,eradicatio nseeme dunlikely .I twa sdecide dt oai ma tkeepin gth e populationlow .Accordin gt ocalculations ,a populatio no f100 0moth si nJun ecoul db ere ­ ducedi ntw ofligh tperiod st o10 0wit ha releas erati oo f20:1 ,provide dimmigratio nwer e ofmino rimportance . Twotrial swer emade ,on ei n197 1o n 1.4h anea rOverber g (Utrecht)an da secon di n197 3 and197 4o n1. 9h anea rLiende n (Betuwe)(Ankersmi te tal. ,197 7b) . Populationi nbot hwa s reducedb ychemica ltreatmen tbefor eth etrial .Fligh tactivit ywa smonitore da tOverber g withligh ttrap san da tLiende nwit hpheromon etraps .Accordin gt othes etraps ,th eattempt ­ ed20: 1rati owa shardl yeve rachieved ,eve nwhe nconsiderabl enumber swer erelease d (Table2) . Mothswer ecollecte dfro mth emas sculture .Th etota lyiel dpe rda ywa sweighed ,the n sampledfo rindividua lweigh tan dchecke dfo rse xratio .Thi sallowe destimatio no ftota l number.Subsequentl ythe ywer emarke dan ddivide dove ra larg enumbe ro fsmal lrefrigerato r boxes.Irradiatio nwa sa troo mtemperatur ewit h 250G yo fX-ray s froma 60 Cosourc ea tth e PilotPlan tfo rFoo dIrradiatio ni nWageningen .The ywer erelease db ywalkin ga tconstan t lowpac ethroug hth eorchards .B ythi smethod ,onl yactiv emoth swer ereleased . Countswer emad ewhe nlarva ewer efull-grow ni nMa yan dJuly .Additiona lcount so nyoun g larvaei nSeptembe rgav esom epreliminar y impressiono fth eresult .I nmos ttrial swhol e treeswer eexamine di norde rt oobtai na nabsolut eestimate .Count smus tb efinishe dbefor e

45 Table2 .Captur ean dreleas edat ao fth etw otrials .Al lfigure srefe rt onumbe ro fmal e Adoxophyes ovana inth ewhol eorchard .

Number caught Ratio Number

Flightperio d native releaE ed native: releas ed released

OverbergJun e197 1 244 929 1 4 4100 0 August197 1 423 5368 1 13 5600 0 LiendenJun e197 3 129 1133 1 9 1700 0 June197 4 251 2379 1 9 5500 0 August 1974 203 4313 1 21 2600 0

themoth semerg eo rth elarva eente rdiapause .Thi srestrict sth ecountin gperio dan dthere ­ foresampl esize .Statistica lanalysi so fth ecount swa s impossiblebecaus eo fth efe wlarva e found.I nSeptember ,whe nlarva ear estil lmor enumerous ,w eestimate dth epopulatio nwit h S (x)/x =0.2 8 in1973,an d0.2 1 in 1974.Th esmal lnumbe ro flarva eitsel fan dth econtinuou s decrease innumbe ro f A. ovana canb eregarde da sstron gevidenc efo reffec tt oth emetho d (Table 3).Winte rmortalit yreduce dth epopulatio nfro mSeptembe r197 1t oMa y 1972t o 16°È; fromSeptembe r197 3t oMa y 1974t o 13%an dfro mSeptembe r197 4t oMa y 1975t o 6%. Inth e lastperio dparasitis mwa shigh . Spilonota ocellana increasedrapidl yfro mles stha n10 0pe rh ai n197 3t oalmos t500 0 perhectar ei n1975 . Operophtera brumata becamenumerou stoo .Leaf-rolle rdamag et ofruit s byothe rspecie stha n A. ovana amountedt o4 %i n197 3an d 9%i n1974 . Themos tlikel yexplanatio no fincreas ei nothe rpest si somissio no finsecticida lappli ­ cations,bu ta slarva eo f A. ovana areagressiv ean dattac kan yintrude ri nthei rterritory , competitionma yals ocontribute . Thesterile-mal etechniqu eca nreduc eth epopulatio nt oa nextremel y lowlevel ,bu tth e ultimategoa li sno treache da schemica lcontro lagains tothe rleaf-roller sremain sneces ­ sary.Th emetho drequire scontinuou sreleas eo flarg enumber so fmoth spe rgeneratio nt o dealwit himmigrant san dseem stherefor eto ocostly .

Table3 .Number so f Adoxophyes ovana and Spilonota ocellana perh ai nth e orchardnea rLienden .

Date Numberso f Numberso f A. ovana S. ocellana

May 1973 500 65 July 1973 830 May 1974 170 62T July197 4 100 May 1975 40 4830

46 REFERENCES

Ankersmit, G.W., R. Rabbinge, &H . Dijkman, 1977a. Studies on the sterile male technique as amean s of control of Adoxophyes orana (Lepidoptera Tortricidae).4 . Technical and economical aspects of mass rearing. Neth. J. PI. Path. 83 :27-39 . Ankersmit, G.W.,C.J.A . Barel, J.D. Mobach, I. Schout-Parren &G . Wassenberg-De Vries, 1977b. Studies on the sterile male technique as amean s of control of Adoxophyes orana (Lepidoptera Tortricidae).5 . Release trials. Neth. J. PI. Path. 83 :73-83 . Barel, C.J.A., 1973.Studie s on dispersal of Adoxophyes orana F. v. R., in relation to the population sterilization technique.Meded . Landbhogesch. Wageningen 73-7 : 1-107. Jong, D.J. de,G.W . Ankersmit, C.J.A. Barel &A.K . Minks, 1971. Summer fruit tortrix moth Adoxophyes orana, F.R.; Studies on biology behaviour and population dynamics in relation to the application of the sterility principle. In:Applicatio n of induced sterility for control of lepidopterous populations. International Atomic Energy Agency, Vienna, p. 27-29. Snieder, D., G.W. Ankersmit &H.J . ter Velde, 1973. Studies on the sterile-male technique as amean s of control of Adoxophyes orana F.R. (Lepidoptera Tortricidae).2 .Dose - -response curves after irradiation of the moth with X-rays or fast neutrons. Neth. J. PI. Path. 79 :148-155 .

47 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980.

1.9 Threshold of economic injury for apple powdery mildew and scab

H.A.Th,va nde rSchee r

ResearchStatio nfo rFrui tGrowing ,Wilhelminadorp ,th eNetherlands .

INTRODUCTION

haera leucotricha, causingappl epowder ymildew ,overwinter si nfrui tan dwoo d buds.Th ediseas eoccur sa s 'primarymildew 'o nflowe rtrusse san dshoot semergin gi nth e spring.Myceliu mo f 'secondarymildew' ,whic harise sfro mconidia l infectionso nleaves , cansprea dan dinvad eaxillar yan dtermina lbuds .Conidi aca nals oinfec tbud sdirectly . Epidemicso fappl escab ,cause db y Venturia inaequalis, originatefro mascospore sdis ­ chargedfro mperitheci apresen to noverwintere dleave so nth eground .Unde rcondition s favouringth efungus ,liberatio no fth eascospore s leadst ovisibl einfectio no fth eleave s andth efruits ,an dsubsequentl yt oproductio no fconidi adurin gth eres to fth eseason .I n theNetherlands ,ascospore sar edischarge d inApril ,Ma yan dJune ,reachin ga pea ka tth e beginningo fMay . Damageb ypowder ymilde wcomprise sreductio no fshoo tgrowt han dnumbe ro fleave so n extensionshoots ,los so ffrui tqualit yan despeciall yo ffrui tyiel di nth enex tyear .Sca b causesmainl ylos so ffrui tquality .Unti lnow ,fungicid eapplication shav ebee nnecessar y forcontro lo fth edisease so nsusceptibl ecultivar so fapple .I npractice ,mos to fth e sprayapplication safte rflowerin gar ecompose do fa fungicid emixtur et ocontro lbot hdis ­ easesa tth esam etime . Criticaleconomi ccircumstance san da nincreasin gconcer nfo renvironmenta lpollutio n willcaus ea cut-bac ki nus eo ffungicides .A supervise dcontro lprogra mmeet sthi sneed . Toadop tsupervise dcontro lo fappl epowder ymilde wan dsca bi npractice ,economi cthresh ­ oldso finjur yan dth eepidemiolog yo fbot hdisease shav et ob eknow ni ndetail .S ofro m 1975,th esprea do fpowder ymilde wan dscab ,th eeffec to ffungicida lsprays ,an dth e effecto fth edisease so nfrui tqualit yan dyiel dwa sstudie do nfou rappl ecultivars .

MATERIALSAN DMETHOD S

Thetria linclude dfull-grow nappl etree so fth ecultivar sCox' sOrang ePippin ,Golde n Delicious,Jame sGrieve ,an dJonathan .Th etree swer eabou t3 m i nheight ,plante d infiv e isolatedfields ,eac hsubdivide d intoequal-size dplots ,wit h6- 8 treeso fa cultiva ri na rowdependin go nth erootstoc ktype ,whic hdi dno taffec tth edevelopmen to fth edisease s andwil ltherefor eb edisregarded .

49 Until 1976,th etria lwa smanage da susual ,wit ha mixtur eo fcapta nan ddinoca pfo r controlo fsca ban dpowder ymildew . Inth esprin go f1976 ,sca bwa sno tobserve dan dprimar y mildewwa sobserve donl yoccasionally ,excep tfo rtw oplot swit htree so fth ecultiva rJo ­ nathano nwhic ha mino rattac kwa snoticed .I n1976 ,197 7an d 1978,fungicid espray swer e appliedregularl yi fnecessar yt oslo wdow nth esprea do fsca ban dpowder ymildew :capta n 83%(w/w )wettabl epowde r (1.0k go factiv eingredien ti n18 0litre so fwate rpe rhectare ) andbupirimat e 50°Ó (W/W)wettabl epowde r (0.225k go factiv eingredien ti n110-18 0litre s ofwate rpe rhectare )o rtriadimefo n25 1 (w/w)wettabl epowde r (0.04k go factiv eingredien t in18 0litre so fwate rpe rhectare )wer euse dfo rthi spurpose . In1976 ,capta nwa sno tapplie dfo rsca bcontrol .I ntha tyear ,bupirimat ewa sapplie d weeklyi n3 field sfro mmid-Jun et oth een do fJuly ,t oslo wdow nth esprea do fsecondar y mildewo nplot swher emor etha n 20%o fth eleave swa smildewed .I n1977 ,al lfield swer e sprayedwit hcapta nan dbupirimat efro mth ebeginnin go fJun et oth een do fJuly ,th eon e halfo feac hfiel dreceivin gapplication sonc ea wee kan dth eothe rhal fonc ea fortnight . In1978 ,al lfield swer espraye dwit hcapta nan dtriadimefo nonc ea wee k (beforeblosso m oncepe r1 0days )a ssoo na scircumstance sfo rinfectio nbecam efavourable .O non ehal fo f eachfiel dth eapplication swer eomitte dafte rth ebeginnin go fJun efo rcontro lo fsca b orafte rth een do fJun efo rcontro lo fpowder ymildew .O nth eothe rhal fo feac hparcel , sprayingwa scontinue dunti lth ebeginnin go fAugust ,triadimefo nbein greplace db ybupiri ­ mate. InAugus tan dSeptembe ro f197 6an d 1977,capta nwa sapplie d6 time sfo rcontro lo f fruitrot .I nAugus tan di nSeptembe r 1978,thiofanat emethy l70° 6(w/w )wettabl epowde r (0.84k go factiv eingredien ti n18 0litre so fwate rpe rhectare )wa sapplie donc efo rtha t purpose.

RESULTSAN DDISCUSSIO N

Someo fth eresult shav erecentl ybee npublishe d (Vande rScheer ,1978) .Wit hth esam e (small)amoun to fprimar ymilde wi nspring ,secondar ymilde wspread sfaste ro nGolde nDeli ­ cioustha no nCox' sOrang ePippi nan dJonathan ,althoug hth elas ttw ocultivar sar eknow n tob emor esusceptible .Howeve rth efungu soverwintere dbette ri nth ebud so fCox' sOrang e Pippinan dJonatha ntha ni nthos eo fGolde nDeliciou san dthi sparamete rstrongl ydetermine d howquickl yth ediseas espread .A secon dfacto rcontributin gt oth eultimatel yhighe rsus ­ ceptibilityo fCox' sOrang ePippi nan dJonatha nt o P. leuaotrioha isth ehighe rtoleranc e ofGolde nDeliciou s toth epathogen .Wit hth esam eproportio no fattacke dleaves ,th egen ­ erallea fconditio nwa svisuall ybette ro nGolde nDeliciou stha no nCox' sOrang ePippi no r onJonathan .

Asi nsupervise dcontro lo finsects ,i twa shope dtha tcontro lmeasure scoul dawai t infection.Fo rpowder ymildew ,tha tprocedur ewa ssuccessfu li n1976 ,becaus eth eplot s werealmos tfre eo foverwinterin g inoculum (Table 1). In1977 ,however ,primar ymilde w occurred,afte rth ebuild-u pi n1976 .Sprayin gwit hbupirimat ei n1977 ,afte rdiagnosin g theamoun to fprimar ymilde wafte rflowering ,limite dth esprea do fth ediseas eonl yt o someexten ti ntha tyea ran drussetin gdu et omilde wwa ssee no nJonatha napples .I ncon -

50 Table 1.Effec to ffungicid e sprayingo naverag e incidenceo fpowder y mildewo nfou rappl ecultivars .

YearTime so fsprayin g Numbero femergin g Proportiono f budswit hprimar y leaves withse - mildewi na 10- m condarymilde w (%) rowo ftree s June July/August

1976occasionall y inJul y 5 10 7 1977fro mJun eever y 7day s 36 26 14 fromJun eever y 14day s 14 32 36 1978ever y 7day s - 1 2 every7 day sunti l - 1 3 endo fJun e

trastt oth esituatio ni n1977 ,th efungu sha dn ochanc ei n197 8t osprea drapidl ybecaus e ofregula rsprayin gi ngoo dtime .Terminatio no fsprayin gafte r2 2Jun e 1978o npart so fth e fieldsle dt oa naverag eincreas eo f1 1i ndisease dleave si nAugust . In1978 ,th eyiel dwa sno taffecte db yth eamoun to fdisease dleave si nth esam eyear , butb ytha to fdisease d leavesi nth eprecedin gyear .A naverag eincreas eo f22 1i ndis ­ easedleave si n197 7le dt oa decreas ei nyiel di n1978 ,whic hprove dt ob ecorrelate dsig ­ nificantlya tth e5' oleve lonl yi nth eJonatha ncultiva r O =- 0.64) .Regressio nanalyse s showedtha ta nincreas ei ndisease dleave si n197 7o nJonatha nle dt oa decreas ei nyiel d in197 8o f0. 1 kgpe rtree .Thi sagree swit hth eresult sobtaine db yBut te tal . (1977). Incidenceo fsca bo nth eleave sstarte di nJul y 1976an dth ediseas esprea dexplosively . Howeverth eproportio no fscabbe dapple si ntha tyea rwa slimited ,als ob yth esprayin gwit h captanagains tfrui trot ,an dexceede d H onlyi nsom eplots .Thi sepidemi cresulte di nover -

Table2 .Effec to fearl y terminationo fsprayin gwit hfungicid eo nincidenc e ofsca bo nfou rappl ecultivars .

Cultivar Termination Shootswit h Scabbed ofspra y scabbed leaves (%) fruits (%) applications 3Augus t atfrui t at pickingtim e pickingtim e

Cox'sOrang e Pippin 7Jun e 2 a2 3a 0.26a 10Augus t 1 a 1a 0.02a Goldendeliciou s 7Jun e 21 b 63b 1.60a 10Augus t 1 a 1a 0.40a Jonathan 7Jun e 13 b 30b 0.20a 10Augus t 1 a 3a 0.08a JamesGrieve 1 7Jun e 29 a 35b 5.22b 10Augus t 15 a 8a 1.2 0a

1.Prematur elea fdro pdu et osca battack . 2.a ,b :pair so fvalue swit h thesam elette rar eno tstatisticall ysignificantl y different.

51 Table3 .Correlatio nbetwee nth eproportio no fshoot swit hscabbe d leavesa tpickin g (y) ando fscabbe d fruits (x) infou rappl e cultivars.

Cultivar RegressioRegressionn CorrelatioCorri ncoef f

Cox'sOrang ePippi n a: = 0. 11 y - 0.0004 0.77 GoldenDeliciou s x = 0.02 y + 0.0019 0.61 Jonathan x = 0.01 y - 0.0004 0.84 JamesGriev e x = 0.13 j/ + 0.0035 0.61

winteringinoculu man dsubsequentl y inattac ko fth erosett eleave sfro mth eblosso mbud si n 1977.Regula rsprayin gwit hcapta nafte rdiagnosin gth eamoun to fsca bo nth erosett eleaves , wasno tsufficien tt opreven tfrui tattack .S oi n197 8sprayin gwa sstarte da ssoo na scir ­ cumstancesfavoure dinfectio nwit hsca ban dwa sstoppe da tth ebeginnin go fJun eo nhal fo f eachfield .Th eproportio no fsca btha toccure di n197 8o nth efou rappl ecultivar s issum ­ marizedi nTabl e2 ,an dth erelatio nbetwee nth eproportio no fshoot swit hscabbe dleave s ando fscabbe dfruit si nTabl e3 .Th ecultivar sdiffere dwidel yi nsusceptibilit yt oscab , JamesGriev ebein gth emos tsusceptible ,wit ha lo wrati obetwee nproportio no fshoot swit h scabbedleave san do fscabbe dfruits .

FUTUREOUTLOO K

Thefirs tstep stoward ssupervise dcontro lo ffunga ldisease shav ebee ntaken .I fsca b orpowder ymilde wi ssee ni na previou syear ,contro lcanno tawai tdiseas esymptoms .Thi s isi ncontras tt oth emanagemen ti nsupervise dcontro lo finsects .A decreas ei nth enumbe r ofspraying sfo rcontro lo fpowder ymilde wseem spossibl ea tth een do fth eroutin espra y programwithou teconomi cinjury .Fo rcontro lo fscab ,thi smanne ro fdiseas emanagemen ti s somewhatmor erisk ytha ntha tfo rcontro lo fpowder ymildew ,especiall yo nsusceptibl ecul ­ tivarswit ha lo wrati obetwee nproportio no fshoot swit hscabbe dleave san dtha to fscab ­ bedfruits .

REFERENCES

Butt,D.J. ,M.E .Coo k& R.D .Souter ,1977 .Disease-los sappraisa l (05012).Rep .E .Mailin g Res.St n (1976): 134 . Scheer,H.A.Th ,va nder ,1978 .Overwinterin g ofth epathoge nan dratin go f 'secondarymildew ' inrelatio nt osusceptibilit y ofappl evarietie s toPodosphaer a leucotricha.Meded .Fac . Landbouwwet.Rijksuniv .Gen t4 3 :901-907 .

52 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 1.10 Fungi from phyllosphere and carposphere in relation to integrated control in an apple orchard

G.va nde nEnd e

Sectiono fExperimenta lEcology ,Departmen to fBotany ,Catholi cUniversit y ofNijmegen , theNetherlands .

DESCRIPTIONO FTH EPROBLE M

InD eSchuilenbur gexperimenta lorchar da tLienden ,th elas ttwelv eyear shav ebee n spenti ntrial so nbiologica lan dintegrate dcontro lo finsects .However ,funga ldisease s wereno tincluded .S oi n197S ,a projec twa sstarte dt ofin dway sfo rintegrate dcontro l offunga ldiseases ,suc ha sappl escab . Inlaborator yexperiments ,th efollowin gfung iwer eused : Venturia inaequalis, thecaus e ofappl escab ;whos econidia lstag ei scalle d Spilocaea pomi, Nectria galligena, thecaus e ofappl ecanker ;an d Nectria cinnabarina, whichcause sdyin go fbranche s indeciduou strees . Thesethre estrain swer eobtaine dfro mth eCentra lBurea uo fFunga lCulture sa tBaarn . Thefollowin gsaprophyti cstrain swer eisolate dfro mth ephyllospher eo fappl ea tth e orchardi nLienden : Alternaria alternata, Cladosporivm cladosporioides, Phoma macrostoma andsevera lyeas tstrains .

AIMAN DMOTIVATIO NO FTH ERESEARC H

Becausefunga ldisease sma ycaus egrea tlosse so fyiel di norchards ,a progra mo ffun ­ gicidalspraying swa sestablished .A spra yschedul ewit h 12-16treatment sa yea ri sno t uncommon.Th ecost sfo rsuc hsprayin gprogram sar ehig han dth efungicide suse dtil lno w havea wid eactio nspectrum . Littlei sknow nabou tth einteractio nbetwee nvariou sfunga lspecie si nth ephyllospher e orlea fecosystem ,an dth ecarpospher eo rfrui tecosystem .Th eai mo fthi sstud ywa st o learnmor eabou tthes emutua lrelation si norde rt odevelo pa neffectiv e integratedcontro l ofplan tdiseases .

WORKINGPROCEDUR E

Theresearc hcomprise dthre esteps . - Identifyingth efung ipresen ti nth ephyllospher ean dcarpospher eo fappl eunde rnatura l conditions,b yth eplat edilutio nmethod . - Isolationo ffung ifro mleave so fappl ean dtestin gthei rmutua lrelations .

53 -Stud yo fth einfluenc eo fpollen ,presen twhil eth etre e isi nflower ,i nrelatio nt o germinationo fspore so fphyllospheri cfungi .

RESULTSAN DDISCUSSIO N

The fungal population

Inth eorchar dth ecompositio no fth efunga lpopulation s inth ephyllospher ean dcarpo - spherei ndifferen tplot swa sdetermine dafte rvariou spretreatment swit hpesticide s: -intensiv echemica lcontro lwit hinsecticide san dfungicide s (dodine,capta nan ddinocarp) ; - integratedcontro lo finsects ,combine dwit hth efungicide sdodine ,captan ,an dbupirimate ; -untreated . Forth esurve yth esaprophyti c fungiwer edivide dint oeigh tgroup so fgenera .Th eresult s gatheredi n197 7o nth ephyllospher eo fth eappl ecultivar s 'Schoneva nBoskoop 'an d 'Golden Delicious'indicate dth efollowing : -Th ecount so ffungi ,especiall ywhit ean dpin kyeasts ,i nth ephyllospher eo f 'Schoneva n Boskoop'wer ehighe rtha ni nth ephyllospher eo f 'GoldenDelicious' . -Ther ei sals oa grea tdifferenc e inth enumbe ro fth ephyllospher efung ibetwee nth eun ­ treatedplot san dth etw otreate dplots .Th e Aureobasidium groupan dth e Vhomagrou pwer e evenabsen ti nth etreate dplot so fth evariet y 'Schoneva nBoskoop' . -Whit ean dpin kyeast swer eth edominan tfung ifoun di nth ephyllosphere . - Inth euntreate dplot ,mos tgroup s (whiteyeasts ,pin kyeasts ,th e Aureobasidium, Vhoma and Cladosporium groups)showe dtw opeak sdurin gth eseason .Th efirs tcoincide dwit hth e spreado fappl epolle nan dth ebeginnin go ffrui tsetting .Th esecon dpea kwa sa tth een d ofJul yo rAugust ,an di sa sye tunexplained . -Ther ewer esometime sdifference si nth edensit yo fth efunga lpopulatio nwit hintegrate d controlan dheav yspraying . Thesurve yo fth ecarpospher eo f 'Schoneva nBoskoop 'i nth euntreate dplo tfro m2 3Ma y till2 Octobe r 1976,indicate dth efollowing : -Highes tnumber swer eo fth ewhit eyeasts ,followe db yth e Cladosporium groupan dthe nb y thepin kyeasts . -Thes ethre egroup sshowe dtw opeaks .Th e Vhomagrou pals oha stw opeak sbu tjus tafte r thoseo fth ethre egroup smentioned .Th e Aureobasidium groupha sonl yon epea ka tth een d ofAugust .Th e Alternaria, Venicillium andth eunidentifie d groupfollowe da sinusoida l coursedurin gth eseason ,wit ha nincreas efo rtw ogroup sa tth een do fth eseason .

Interrelations of fungi isolated from the phyllosphere

Thecounte dphyllospher efung ian dthei rinterrelation sar es onumerou stha ta choic e hadt ob emad eo ncultivatio nmethod san dth ecombination so finteractin g fungiincludin g thestud yo fth einfluenc eo fsom eparasite so nyeast sstrain s fromappl eleaves .Th ein ­ fluenceo fmetaboli cproduct so fhypha l fungi, Alternaria atrata, Cladosporium oladosporioides, Vhoma maerostoma andthre eparasite s Venturia inaequalis, Nectria galligena and N. ainnabarina wereteste do na whit ean da pin kyeast ,th elatte rbein gstimulate di n

54 growthb ymetaboli cproduct so fth ephyllospher efung ian dth ethre eparasites . Theexperimen twit hth ethre ephyllospher efung iwa srepeate dwit heigh tyeas tstrain s isolatedfro mappl eleaf ,4 whit ean d4 pink .Th emetaboli cproduct so fth ethre ehypha l phyllospherefung istimulate dgrowt ho fth eyeasts ,especiall ythos eo f C. cladosporioides. Theinfluenc eo fth emetaboli cproduct so fthre ehypha lphyllospher efungi ,tw oyeast s andth ethre eparasite supo ngerminatio no fth econidi ao f C. cladosporioides and P. macrostoma wasa sfollows : -Metaboli cproduct so f A. atrata stronglyinhibite dspor egerminatio no fbot hspecies . -Th econidi ao f C. cladosporioides germinatedles si nal lmetaboli cproduct s testedtha n inth econtrol . -Th econidi ao fP . macrostoma resultedi na highe rpercentag egerminatio ni nth emetaboli c productso fth ethre eparasites , C. cladosporioides and P. macrostoma itself.

The influence of apple pollen

Applepolle nstimulate dgerminatio no fth espore so fth ephyllospher efung i C. cladosporioides and Botrytis cinerea. Thiseffec twa ssmalle rfo rconidi ao f A. atrata.

PROSPECTS

Forintegrate dcontro lo fappl escab ,i ti snecessar yt okno wth emicro-organism si n phyllospherean dcarpospher ean dthei rmutua lrelation swit heac hothe ran dwit h Venturia inaequalis. Thelaborator yexperiment shav eshow nsom easpect so fthes emutua lrelations . Toreac ha neffectiv eintegrate dcontrol ,i ti smos tpromisin gt ous eorganism sfro mth e phyllospherean dcarpospher eo fappl etrees ,whic hsho wn oo rlittl edamag eb y V. inaequalis. Sucha situatio napproximate sfairl ywel lth eendemi crelatio nbetwee nth epathoge nan dth e host.Th eeconomi c losscause db y V. inaequalis issmal lan dshow sa sinuou scours edurin g theyears .Th eide ai sno wt ocu tof fth ehighes tpeak so fthi ssinusoi db ymanipulatin g themicro-organism so rothe rbioti cfactor ssuc ha spolle ni nth ephyllospher ean dcarpo ­ sphere.Th emetaboli cproduct so f A. atrata thatinhibi tth egerminatio no fth econidi ao f otherfung ima yallo wthis .Anothe rapproac hwoul db et ostimulat eth esaprophyti cphyllo ­ spherefung ib ypolle ni norde rt oinhibi tgerminatio nan dinfectio nb y V. inaequalis.

REFERENCES

Beech,F.W . &R.R .Davenport ,1970 .Th erol eo fyeast si ncider-making .In :A.H .Ros e& J.S.Harriso n (Editors),Th eyeasts .Academi cPress ,London ,Vol .3 ,p .73-147 . Ende,G .va nden ,J .Klerkx ,I .Latour ,K .v.d .Oeve r& G .Schraven ,1978 .Fung io fphyllo ­ spherean dcarpospher e inrelatio nt oa nintegrate dcontro l ina nappl eorchard .In : Centrod iStudi od iFitofarmacia ,Bologna ,Lutt edirigé econtr ele smaladie scryptogami - quesde sarbre sfruitiers .Réunio nd eBologna ,1978 .p .73-94 . Preece,T.F .& C.H .Dickinson , 1971.Ecolog yo flea f surfacemicro-organisms .Academi c Press,London . Scheer,H.A.Th ,va nder ,1978 .Researc ho nsupervise do rintegrate d controlo fdisease si n applei nth eNetherlands .In :Centr od iStudi od iFitofarmacia ,Bologna .Lutt edirigé e contrele smaladie scryptogamique sde sarbre sfruitiers .Réunio nd eBologna ,1978 .p . 95-97.

55 2 Field crops

InNorth-Wes tEurope ,aphid sar eth emajo rinsec tpest so narabl ecrops .A svector so f virusdiseases ,the yca nquickl ysprea dviruse s inpotat oan dsugar-bee tfields .A networ k ofobservatio npoint st omonito raphi dflight san dt oestablis hearl y liftingdate sfo r seedpotatoe sha sbee noperatin gfo rmor etha n2 5year san dca nb econsidere da son eo fth e oldestexample so fintegrate dcontro l (2.1).I naddition ,th emechanism so fth etransmissio n ofth epotat oleaf-rol lviru sha sbee ndescribe d indetai li na fundamenta lstud y (2.2). Insugar-beet ,th eeffec to fchemica lcontro lo faphid sha sbee ninvestigate d (2.3). Althoughth eaphi dspecie sfeedin go ncereal sar eno tviru svectors ,the yca ncaus emuc h damage (2.4).Finally ,a stud yha sstarte do nth esignificanc eo fpredator so nth edevelop ­ mento faphi dpopulation s (2.5). Insugar-bee tcrops ,changin gcultura lpractice shav eincrease dth echanc eo finfestation s bypest ssuc ha ssoi larthropod s (e.g.springtails )an dmangol dbeetles .Th eproble mha sno w beenidentifie dan dne wline so fresearc har esuggeste d (2.6).A stud yo nth eoccurrenc eo f soilarthropod san dothe rcomponent so fth esoi lmesofaun aha sbee ninitiate d (2.7). Invegetabl ecrops ,th esterile-mal etechniqu efo rcontro lo nth eonio nfl ywa sa majo r topici nresearch .Thi sprojec tstarte dabou t1 5year sago .Afte rman yyear so fpreparator y studieso nrearing ,sterilizatio nan decolog yo fth einsect ,a releas etria lo na practica l scaleove r2 0h ao fonion swa sstarte di n1978 ,an dextende dt oalmos t4 0h ao fonion si n 1979. Theresult sar eencouraging :chemica lcontro lwa sno tlonge rneeded .A tpresent ,a privatecompan yi spreparin gt otak eove rfurthe rpractica lapplicatio n (2.8).Anothe r approacht ocontro lth eonio nfl yma yb egenetic ,b yus eo fchromosom erearrangement s (2.9). Asecon dprojec to nintegrate dcontro li noutdoo rvegetabl ecrop swa sstarte dsom eyear s ago. Particularattentio ni sbein gpai dt opes tinsect si ncabbag ean dcarrots :th ecabbag e rootfly ,cabbag eaphid san dvariou s lepidopterousspecie si ncabbage ,an dth ecarro trus t fly.Ther ei sa nurgen tnee dfo rselectiv echemica lcontro lwit hselectiv einsecticide so r ifno tpossible ,b yselectivel yactin gformulation so rdosage so fth einsecticides .Estab ­ lishmento fa warnin gsyste mi si nprogress .Attempt sar ebein gmad et oimprov econdition s forpredator san dparasite sb y intercropping (2.10).

57 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 2.1 Integrated control of aphid-borne viruses of potatoes

D.Hill eRi sLamber s

Centre forAphi dResearch ,Bennekom ,th eNetherlands .

INTRODUCTION

Overa hundre dyear sbefor eleafrol lwa srecognize da sa ver ynoxiou sviru sdiseas e transmittedb yth eaphi d Myzus persicae (OortwijnBotjes ,1920) ,see dpotat ogrower sha d alreadydiscovere dmethod st oreduc einfection :th etuber sha dt ob eplante da searl ya s nightfrost spermitted ,an dth ecro pharveste da searl ya spossible .Roguing ,removin g plantswit hviru ssymptoms ,becam eusag eafte rth enatur eo fth ediseas ewa sknown .B yan d bymor eviru sdisease so fpotatoes ,transmitte db yaphids ,wer ediscovered ,bu tth eentomol ­ ogicalaspect sreceive dlittl eattention .

POPULATIONSTUDIE S

Elze (1927)studie dth elife-histor yo f4 o fth e9 aphid slivin go npotato .I n1936 ,th e authorwa saske dt oloo kint oth erelatio nbetwee naphi dnumber san dviru sspread .Sprea d ofleafrol lcoul db ecorrelate dwit hth etim ean ddensit yo faphi dcolonizatio nshortl yaf ­ terth eplant scam eup .Th eresult swer econsidere dclassifie dinformatio nan dwer eno tpub ­ lished.Attempt st odescrib equantitativel yabioti can dbioti cfactor sinfluencin gth ede ­ velopmento fpopulation so fpotat oaphid swer ediscontinue d in1940 .Developmen to f5 syrphids , 3coccinellids ,3 chrysopa san don ebraconi dwa sstudie da t5 temperature san dthei rimpac t examinedb yprovidin ga surplu so fprey ,dail yrenewed ,i nmicr oPetr idishes .Th eparasiti - zationo faphid san dlarva lpredator scollecte d inpotat ofield swa sfollowe db yrearing . Thenetwor ko finteraction sbetwee nth evariou saphid san dsom e5 0othe rinsect spresen ti n randomlychose npotat ofield swa s farto ocomplicate dfo rquantitativ eanalysis .Howeve ra rapidan dver ysimpl esamplin gmethod ,threshin gstandin gplant sove ra 5 0c mx 4 0c mboar d dividedint osquare so f1 0c mx 10cm ,whic hdislodge dpre yan dpredator salike ,mad ei tpos ­ siblet oobtai ninformatio no nth epopulatio nan dit sfutur edevelopment .Recognitio no fth e aphidspecie swa staugh tt oa numbe ro fco-worker san dthreshin gdat acoul db euse dfo rde ­ terminingmor esensibl edate sfo rvariou spart so fth ecountry .

EFFECTO FA CONTAC TINSECTICID E

Atria li n193 8o naphi dcontrol ,i nwhic hsmal lplot swit hviru ssource swer edouse d

59 twicea wee kfro mabov ean dbelo wwit h0.2° 6nicotin esulphat eha dn omeasurabl eeffec to n thetransmissio no fleafrol lan dY virus ,althoug hthroughou tth etria lth eaphi dpopulatio n onth etreate dplant sconsiste do fonl ysom ealata ewit hyoun gprogeny .A stick ytra pcon ­ sistingo fa 5 0c mx 5 0c mcoppe rscree nmounte dverticall yo nth eri mo fa bicycl ewhee l ona perpendicula raxis ,place di nth efiel dgav esom einformatio nabou tflight sbu twa s considered impracticalfo rgenera luse .

OVERWINTERINGO FMYZU SPERSICA E

In1945 ,th eprojec t 'Overwinteringo f Myzus persiaae' wasstarte dunde rth eauspice so f theNetherland sAgricultura lResearc hCouncil .I ntha tsam eyear ,Britis haphi dworker s soughtcontac tan da nadvisorshi pt otha tgrou pwithi nth eBritis hAgricultura lResearc h Councillea dt oth esolutio no fman yproblems . Peach (Prunus persioa) anddwar falmon d (P. tenella) (probablyth eorigina lwinte rhost) , wereknow na ssuitabl ewinte rhost sthoug hman yegg swer elai do nothe r Prunus spp.(Hili e RisLambers ,1946) . In1946 ,i twa s foundtha t P. serotina, anAmerica nbirdcherry ,plante d inmillion sb yforesters ,coul db ea nexcellen toverwinterin ghos tfo r M. persiaae andthere ­ forea sourc eo fvector si narea swher epeac htree swer eextremel yrar e (HilleRi sLambers , 1951).Method sfo restimatin gsprin gflight sfro mthes evariou stree swer edevelope dan d introducedint opractice .Bu t M. -persiaae canals ooverwinte ro nherbaceou splant sa scolo ­ nies,an dth ediversit yan ddistributio no fthes ehos tplant smak ea reasonabl edirec tes ­ timateo fth eimportanc eo ftha tmod eo foverwinterin g impossible.However ,b yutilizin g themorphologica ldifference sbetwee nwinge dspecimen sbor no nherb san dthos ebor ni nth e first2- 4generation so npeac han dth eothe r Prunus spp.a sfirs tfoun db yGillett e& Taylo r (1908), itwa seas yt odetermin ewha tarrive dfro mth e Prunus spp.an dfro mherb searl yi n summer.

CORRELATIONSBETWEE NAPHI DNUMBER SAN DVIRU SSPREA D

Nobodyi nth eDutch—Britis hgrou pcoul dfin dsatisfactor ycorrelatio nbetwee nth eaphi d populationsi nfield san dviru ssprea di nthos esam efields .Bu tBroadben t (1950)foun da strongcorrelatio nbetwee nth etota lannua lcatc ho fwinge dvector so nstick ytrap san dvi ­ russprea di nfields .Tha tmad eth eautho rconclud etha tther emus tb ea correlatio nbe ­ tweencatche spe rda yan dviru stransmissio npe rday .Fo rtha tstudy ,ver ylarg ecatche s werenecessary .

THEMYZU SCERTU SCOMPLICATIO N

However,befor elarge-scal etrappin go faphid scoul dbegin ,anothe rproble mha dt ob e solved.Sinc e 1929,I ha dknow ntha tanothe r Myzus speciesoccurre di nth eNetherlands ,co ­ lonieso fwhic hcoul deasil yb edistinguished . Itwa s Myzus certus. Itlive swithou thos t alternationo nsom eherbaceou splant sbu tno tpotato ,ca ntransmi tY viru sbu tno tleaf - roll,an di twa ssuspecte dt ofl yearlie rtha n Myzus persiaae. Ifth ewinge daphid scoul d notb edistinguishe d fromthos eo f M. persiaae andfle wearlier ,considerabl e lossesi n

60 yieldwoul dresul ti fliftin gdate swer ebase do nflight so f Myzus. Ittoo kal lo ftw o yearsbefor edea dwinge d M. aertus couldb ereliabl ydistinguishe d from M. pers-iaae bya trainedan dver yexperience dspecialist .Trappin gcoul dbegin .Th etra pcatche si nfollow ­ ingyear sshowe dth egrea tnee dt odistinguis hbetwee nalata eo fth etw ospecie s(Hill e RisLambers ,1959) .

TRAPSAN DTRAPPIN G

Abattery-drive nsuctio ntra pwa sdevelope dbu tjus tbefor eth eorde rfo rmass-productio n hadt ob egiven ,Moericke' s (1950b)pape ro nhi syello wwaterpan scam ein .Th ePain tInsti ­ tuteTN Oselecte da dy ewit ha maximu mremissio ni nth ewavelengt hfoun doptimu mfo rprobin g inearlie rresearc hb yMoerick e (1950a)an d13 2larg eMoerick etrap swer ei noperatio nwithi n afe wweeks .Initiall y6 trap swer eplace di neac ho fth efields ,bu tlate rtw ower eplace d ineac hfield .Al ltrap swer eemptie ddail yan dth ecatche swer emaile dt o"Bennekom "fo r immediateexamination .Afte r3 years ,regiona lNAK 1 laboratoriessorte dth ecatche sfirst . Througha fluke ,th esyste mbecam ea nimmediat esuccess .I n195 1i nFrieslan dn omor e than1 0aphid swer efoun dpe rplan tbu ta tth esam etim etra pcatche so falat evector swer e aslarg ea sthe ywer ei nth esouth-wes twher ever ylarg epopulation so faphid swer epresen t onth ecrop .Agains tvehemen topposition ,NA Kbase dth eliftin gdate so nth etra pcatches , noto nth eaphi dcount so nplants .Friesia ngrower swh olef tthei rcro pi nfo reve na fe w daysbeyon dth eliftin gdat efoun di truine db yleafroll .A naphi dfligh tfro ma nare aabou t 90k mawa yha dcarrie dleafrol lviru sint oth eFriesia nfields .Th enumbe ro ftrap sha dt o beincrease dt o250 ,th emaximu mtha tcoul db ehandled .Fro mthe non ,interes ti naphi d countsi nth efiel ddwindle dan dth ewholesal eus eo fth emetho dwa slate rabandoned .

ASYSTEMI C INSECTICIDEA SA RESEARC HTOO L

In195 1too ,Reestman ,Scheper san dth eautho rbega nexperiment swit ha systemi cinsec ­ ticide,Systox ,agains taphid si nconnexio nwit hvirus-spread . Ifoun ddoubl erow so foat s effectiveagains tth esprea do fviru sfro mon eplo tt oth enex ti nresearc ho nbee tyellows , andth esam ewa sfoun di nwor kwit hpotat oviruses .Th eresult swer ever yinterestin g (Fig.1). (HilleRi sLamber se tal. ,1953 ;Scheper se tal. , 1955). Spreadwithi nth efiel dfro mth eviru ssource st ohealth yplant swa svirtuall ystoppe d byth eearlies tthre eapplication so fSysto xwhe nleafrol lwa s involved.Late rapplication s hadver y littleeffect .Th emetho do fplanting ,liftin gan dreplantin gmad ei tpossibl et o distinguishbetwee nsprea dwithi nth ecro pan dinfectio nfro moutside .If ,however ,Y virus , anon-persisten tviru s (seebelow) ,wa sinvestigate di nth esam eway ,ther ewa sn omeasurabl e differencei nvirus-sprea dbetwee nplot streate dwit hSysto xan dthos etreate dwit hwater . Onlywhe na larg enumbe ro fexperiment so nY viru sove ra numbe ro fyear san dal love rth e countrywer epoole dwa sa smal lstatisticall yreliabl edifferenc efoun dbetwee nSysto xan d waterplots .

1.Genera lNetherland sInspectio nServic efo rSeed san dPlants . XXXXXXXXXXXX'XX'XX' • OOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOO XXXXXXXXXXXX'XXXX'X XXXXXXXX X'XX'X

III I

• ••o»»»««**»»X*»***» •x*»*xx****»*x»»» • • • «x»X»X»*XX»X»*XX* xxx-xxxoxx«x«x«x«x«» oooooooooooooooooo OOOOOOOOOOOOOOOOOO xx*xx»xxxx x«*xx**x»

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i II

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II IV

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IV III Fig. 1.Sprea do fleafrol l (afterScheper s et al.). 62 •' X •• • • KXX X •• • X •XXXX-««OXXXXX X OOOOOOOOOOOOOOOOOO oooooooooooooooooo • XXX...XXX.XXXXX-X.0

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IV II

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III IV

»iiX»X»««"XXttX''X»X xxxxxx.xx.xxx-xx.-.x oooooooooooooooooo oooooooooooooooooo XXXXXXXXXX.XXX..-XO

1=Spraye d with ••••• • »«x.X**X*.*.** water(8x ) 11=Spraye d with I III Systox(8x ) 111=Spraye d with Systox(3x ) •X XX' 'XX'X' IV= Sprayed with XXXX.XX.'XXXXX'XXXXX DDT (5x) oooooooooooooooooo oooooooooooooooooo XXX. .XXXX XXXXXO.X.. •X... X XX X X X • X OX X-X..X... 0= implanted second season leafroll x= spreado f leafroll 11 I •= n oleafrol l

63 CONCLUSIONS

Experimentsove rman yyear sprove dsevera lthings . -A vecto rfre eo fviru slandin go na leafrol lsourc epoisone dwit hSysto xingeste dth e insecticidewit hth eviru san dwa sdisable do rdea dbefor eth ecirculatio ntim eo fth eviru s init sbody ,24-5 2h ,ha dpassed .Tha taccounte d forth esuppressio no fsprea dwithi nth e field. -A vecto rwit hleafrol lviru sread yfo rus ecoul dno tb eprevente dfro minfectin ga tleas t onepotat oplan to nwhic hi tstarte dfeeding .S oinfectio nfro moutsid eth efiel dcoul dno t bestopped . -Th eeffec to flate rtreatment so fa serie swa smuc hles stha ntha to fth eearlie rtreat ­ ments,despit elater ,muc hlarger ,aphi dflights .Apparentl y leafroll infectionoccurre d earlyi nth egrowin gseason . -Sinc etreatment swit hnicotin eha dn oeffec to nleafrol ltransmissio nalthoug hth eaphi d populationwa sreduce dt oabou tth esam eleve la swit hSystox ,alat eaphid scomin gfro m outsideth efiel dwer eresponsibl e forbot hsprea do fviru swithi nth efiel dan dsprea d fromoutsid eth efield . ForY virus ,thi swa seve nmor econspicuou sbecaus eviru ssprea di na fiel dwith ,say , 3000vector spe rplant ,wa sver ynearl yequa lt osprea di na fiel dwit hnea rzer oaphid s perplant ,provide dth eaphid swer eno tshake nfro mplants .

IMPORTANCEO FEARL YFLIGHT S

Theseresult sfocuse dattentio no nearl yaphi dflights .I tha dlon gbee nknow ntha t potatoplant swer emuc hbette rsource sfo rviru swhe nthe ywer eyoung ,an dmor esusceptibl e toviru sinfection .Studie so npeac htree sshowe dtha tbetwee nth ebeginnin go ffligh tfro m peachan dth efirs t Myzus catchi na Moerick eo rsuctio ntrap ,ther ewa sa ninterva lo f3- 6 weeks.I nothe rwords ,trap swer euseles s forregisterin gearl yflight so flo wdensity .I f indirectcontro lo fleafrol lsprea db yinsecticide sshoul db euse da tall ,i twa snecessar y topoiso nth eplant sa searl ya spossible ,preferabl ybefor ethe ycam eup . Consequently theemigratio nfro mpeac hha dt ob estudie dmor eintensively ,an dth emetho d wasintroduce do f1000-plan tcounts ,(eac hplan tbein guse da son etrap) ,i nwhic hu pt o 3000smal lpotat oplant spe rare awer ethreshe dove ra smal lrimme dboard .Th ecatche swer e sentin ,th especie so fwinge daphid sdetermined ,an dth e M. persiaae sortedaccordin gt o provenance.Advic et ospra ywit hsystemi cinsecticides ,a swel la sadvic eno tt ospray ,wa s giveno nth ebasi so fstudie so npeac han do ncount so fwha tha dlande do npotatoes .Wit h thecombinatio no finsecticid eapplicatio nan da nearl y liftingmetho dbase do ntra pcatche s of M. persiaae, leafrollcease dt ob eth emos timportan tviru sproble mi nsee dpotatoes .

PROBLEMSO FNON-PERSISTEN TVIRUSE S

Before 1959,non-persisten tviruse swer eno ta seriou sproblem .Th eol dtyp eY viru s causedsuc hconspicuou ssymptom so neve nver yyoun gplant stha tthe ycoul db erogue d straightaway .Bu ti n1959 ,a ne wtyp eo fvirus ,know na sne wY o rY penetratedfro mGer -

64 many,an dwa ssoo nfoun deverywher ei nth ecountry .Th ecustomar ymeasure ,earl yroguing , wasofte nno tver yeffectiv ebecaus eth esymptom so fth ediseas eofte nappea rlate ,an d thenroguin gma yresul ti ndisseminatio no fviruliferou saphids ,wit ha negativ eeffect . Chemicalcontro lo faphid sha dn osignifican teffect :n opoiso ncoul dkil la winge daphi d withinth efe wminute stha ti tneed st otransmi ta non-persisten tvirus .Wor ki nAmeric ao n somenon-persisten tviruse sha dshow ntha tver yman yaphi dspecie sincapabl eo flivin go n theviru shos twer enevertheles sefficien tvector so fsuc hvirus .A nexperimen twa smad e in196 3wit hon eo fth emos tunlikel yaphi dspecies , Rhopalosiphum padi, thebirdcherry - -oataphid ,i nwhic h fieldcondition swer eimitate di na tripartit ecag e (3compartment s separatedb ydoubl ewide-mes hscreen ,vecto rcultur ei nth efirst ,viru ssourc ei nth e second, healthyplant si nth ethird) .Th ecag ecoul drotat e18 0 andth epositivel yphoto - tacticalata eproduce di nth efirs tfle wtoward sth eligh tt oth ethird .Afte rsom etime , thecag ewa srotate dresultin gi nfligh ti nth eopposit edirection .Th eoperatio nwa sre ­ peatedman ytimes .Ninetee nou to ftwent ypotat oplant sbecam einfecte dwit hY virus. Workb yEasto pi nAfric aan dMoerick ei nGerman yha dshow ntha tcolou rattractio ndiffere d betweenaphi dspecies ,an dtha tou rMoerick etraps ,thoug hhighl yattractiv efo rth evector s ofleafroll ,gav ea distorte dpictur eo fth eabundanc eo fothe rpotentia lvector so fY n virus.S oi n1970 ,a 40-foo tsuctio ntrap ,develope dan downe db yRothamste dExperimenta l Station,wa serecte dnea rWilhelminador p (Provinceo fZeeland) . Itrandoml ysample dvolume s ofai rfo rorganism srangin gfro maphid st obirds .Catche swer eexamine ddaily :o fth eman y aphidspecie scaught ,4 2wer eseparatel ycounte da spotentia lviru svectors .

SHORTCOMINGSO FTRAP S

Hopestha tthi stra pmigh tb eabl et oregiste rflight so f M. persioae earliertha nMoe ­ ricketrap sprove didle .Th e 1000-plantcount sremaine dnecessary .Howeve rdat aabou tth e abundanceo fth evariou ssuspecte daphi dspecie sbecam eavailable ,thoug hinformatio nabou t theirefficienc ya svector swa slacking .Late rwor kb yD rva nHoo fsupplie dsom einformation . Eveni fcomplet einformatio no nth eefficienc yo fsuspecte dvector swer eavailable ,thi s kindo ftra pwil lprobabl yneve rprovid esufficien tinformatio nabou twha thappen si nth e mostdangerou sperio do fpotat odevelopment ,th e3- 6week safte rcomin gu p (Woodford 1975). Aphidstudie shardl yaltere dth eY nviru sproble mwhic hwa sfurthe rcomplicate db ya nimmens e increasei ndisease dgroundkeepers .Recen twor ko nY nviru scontro lvi aminera loil swoul d seemt ob emor epromising .

BY-PRODUCTSO FTH ERESEARC H

Othersha dbegu ninvestigation sint oth efeasibilit yo fgrowin gpotatoe sa sa secon d crop.Th egrea tdifficult ywa stha tlat ei nth eseason ,potat obligh tcoul dofte nno tb e controlled.Whe na variet y (Spartaan)wa sbre dtha twa sresistan tt oal lfamilia rphysio' s ofblight ,th eprojec tbecam efeasible .Studie so fth eaphi dpopulatio no nplant san do f vectorflights ,ha dmad ei tpossibl et ochoos esuc ha plantin gdat etha tjus twhe nflight s hadceased ,th eplant scam eup .A sudde ndro pt ozer ooccurre donl ywher eth eflight sha d beenver ylarge .An donl yther ecoul da secon dcro po fsee dpotatoe swit hver ylo wviru s

65 infectionb eobtained .I narea swher efligh twa ssmall ,i tneve rreache dzer oor ,i fi tdid , farto olat ean dsecon dcrop sgrow nther ebecam eheavil yinfecte dwit hvirus .Afte rsevera l yearso fsuccess ,a ne wphysi oo fth ebligh tfungu sattacke dSpartaa nwhic hpu ta nen dt o thiseconomicall ysoun dpractice .I nthi scase ,th eearlies tpossibl edat efo rplantin gha d tob eforecas tlon gbefor eflight sreache dzero . Lateroguin go fsprin gcrops ,hardl yavoidabl efo rY virus,coul ddisseminat evirulife - rousaphids ,wit hnegativ eeffects .Therefor esprayin gwit ha naphicid efou rday sbefor e lateroguin gwa sadvised .Bu tman yo fth eno waphid-wis efarmer sadde dth eultra-chea ppara - thiont oal lthei rspray sagains tpotat oblight ,a nunnecessar ythrea tt oth eenvironment . Butthoug hpotatoe sar esometime sseriousl yaffecte db ytoprol lcause db ya variet yo fth e aphid Maorosiphum euphorbiae, themeasur ema yhav eprevente dth eproble m insee dpotatoes , howeve rbadl ywar epotatoe swer eaffected .

REFERENCES

Broadbent,L. , 1950.Th ecorrelatio no faphi dnumber swit hth esprea do flea frol lan d rugosemosai c inpotat ocrops .Ann .appl .Biol .3 7 :58-65 . Elze,D.L. , 1927.D everspreidin gva nvirusziekte nva nd eaardappe l (Solanumtuberosu mL. ) doorinsekten .Meded .Landbouwhogeschoo l 32 :1-87 . Gilette,C.P .& E.P .Taylor ,1908 .A fe worchar dplan tlice .Colorad oExpt .Sta .Bull . 133 :1-47 . HilleRi sLambers ,D. , 1946.Th ehibernatio no fMyzu spersicae .Bull .ent .Res .3 7 :197-199 . HilleRi sLambers ,D. , 1951.D eoverwinterin gva nd eperzikbladlui s alsei .Tijdschr .Plan - tenz.5 7 :128-129 . HilleRi sLambers ,D. , 1952.liebe rMyzu spersica eSulzer .Beitr .z .Entom .2 :119-121 . HilleRi sLambers ,D. , 1959.Myzu s (Nectarosiphon)certu s (Wlk.)a sa proble m instudie so n flightso fMyzu s (Nectarosiphon)persica e (Sulz.)(Hom .Aphid.) .Entom .Ber . 19: 17-19 . HilleRi sLambers ,D. ,A .Reestma n& A .Schepers ,1953 .Insecticide sagains taphi dvector s ofpotat oviruses .Neth .Journ .agric .Sc .1 : 188-201 . Moericke,V. ,1950a .Uebe rda sFarbsehe nde rPfirsichblattlau s (Ilyzodespersica e (Sulz.)) Zeitschr.Tierpsychol .7 : 265-274 . Moericke,V. , 1950b.Ein eFarbfall ezu rKontroll ede sFluge svo nBlattläusen ,insbesonder e desPfirsichlaus ,Myzode spersica e (Sulz.).Nachr .Deutsch .Pflanzenschutzdiens t 3:2. OortwijnBotjes ,J.G. ,1920 .D ebladrolziekt eva nd eaardappelplant .Doctora l thesisWage ­ ningen. Schepers,A. ,A.J .Reestma n& D .Hill eRi sLambers ,1955 .Som eexperiment swit hSystox . Proc.Secon d Conf.o npotat oviru sdisease sLisse-Wageningen .Veenman ,Wageningen ,p .75-83 . Woodford,J.A.T. ,1975 .Ecolog yan dcontro lo faphid sinfestin graspberrie san dothe rcrops . Ann.Rept .Scott .Hort .Res .Inst .p .92 .

66 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 198

2.2 Transmission of potato leafroll virus

M.B.Ponse n

Laboratoryo fVirology ,Agricultura l University,Wageningen ,th eNetherlands .

Potatoleafrol li son eo fth emos timportan tviru sdisease so fth epotat oplan tan di s characterizedb ynecrosi so fth ephloem .A vecto ro fthi sviru si sth egree npeac haphid , Myzus persicae .Th eaphi dfeed smainl yi nth ephloem ,t owhic hth eviru si sre ­ stricted;it sstylet spenetrat eth eplan ttissu et oreac hth esiev etubes .Th eviru si sin ­ gestedwit hth eliqui dfoo dan dcirculate si nth edigestiv etract ,fro mwhic hi tpasse s intoth ehaemolymph .Thenc eth eviru si sdistribute dt oth evariou sinterna lorgan sinclud ­ ingth esalivar yglands ,whic har eresponsibl efo rth etransmissio no fth eviru swit hth e salivaint oth ephloe m (Fig. 1). Thestyle tbundl elie si na dorsa lgroov erunnin galon gal lthre esegment so fth elabiu m (proboscis).Ther ear etw opair so fchitinou sstylets ,on emaxillary ,on emandibular .Th e maxillarypai ri salway sfirml yinterlocke dan dform sa singl estructur eenclosin gtw o minutecanal sforme db yopposin ggrooves .Th edorsa lcana lo rfoo dcana lcommunicate swit h thepharyngea lduct ,whil eth eventra lon ejoin sth esalivar ypump .Th emandibula rstylet s areclosel yapplie dt oth emaxillar ypair . Eachstyle toriginate sfro ma retort-shape dorga nsituate di nth eposterio rpar to fth e head.Thes eorgan sar eresponsibl e forth esecretio no fa ne wstyle ta teac hlarva lmoult . Thefou rstylet sar eeac hconducte db ya groov eo fth eepipharyn xo nth eventra lfac eo f theclypeo-labru man dlabrum .The yar es oarrange dtha tth estylet sfi tsnugl yint oth e grooves,bein ghel dfirml yi nposition ,a tth esam etim ehavin gperfec tfreedo mo fmovemen t forprotractio no rretraction .Afte rleavin gth ehead ,th estylet scros sove rint oth elon ­ gitudinallabia lgroov ean dexten dalon gi tt oth eextremit yo fth erostrum .Th estyle t bundleshow salon git slengt ha torsio no f18 0 andth elabiu mtelescope st oexpos eth e styletsdurin gfeeding . Thepharyn xca nb edivide di nthre epart s :th epharyngea lduct ,valve ,an dpump .Th e pharyngealduc ti sa prolongatio no fth efoo dcana lan di sforme db yth eepipharyn xan dth e hypopharynxlip .Thi sportio ndoe sno texer tan ysuckin gaction ,an di ssimpl ya duct ,whic h conveysth eplan tjuice sint oth epharyngea lpump .Th eepipharyn xi smarke db ya thic kscle - rotizedplat ean dreveal sa media nro wo feigh tsensillu mpores ,whic hcommunicat ewit hth e pharyngealduct .Th ecup-shape dpar to fth efloo rbefor eth evalv ei sprovide dwit htw osen ­ sillumpores . Thepharyngea lduc ti sseparate d fromth epharyngea lpum pb ya valve ,o fwhic hbot hth e dorsalwal lan dventra lwal lar emarke db ytw ocuticula rdome-shape dprotuberances ,th e

67 Fig. 1.Dorsa l (A)an dsagitta l (B)vie wo fa one-day-ol d Myzus persicae larva,ao :ana l opening;asg :accessor ysalivar ygland ;csd :commo nsalivar yduct ;f .foregut ;hg :hindgut ; i:intestine ;lb :labrum ;mc :myoepithelioi d cell;pb :proboscis ;php :pharyngea lpump ;phv : pharyngealvalve ;psg :principa lsalivar ygland ;r :rectum ;sb :style tbundle ;sep :sensillu m pores;sp :salivar ypump ;st :stomach .

pharynxprotuberances .Th edorsa lwal lo fth evalv ei scontrolle db ytw opair so fmuscles , andeac hlatera lsid eb yonl yon emuscle .I na close dposition ,th eopposit epharyn xpro ­ tuberancesan dth evalv eitsel ffi tclosel ytogether . Thepharyngea lpum po rsuckin gpum pcontinue sfro mth evalv ean dtraverse sth emiddl e regiono fth ehea dt ojoi nth eforegu ti nfron to fth etentoria lbar .I tact sa sa pumpin g organt obrin gth eliqui dfoo dthroug hth efoo dcana lan dt oforc ei tint oth eforegut . Themovemen to fth eflexibl edorsa lwal lo fth esuckin gpum pi scontrolle db y2 9pair so f dorsalelevato rmuscles .Clos et oth etentoria lba rth efloo ro fth epum pi sattache db y muscles,on epai roriginatin g fromth etentorium ,an don epai rfro mth episto no fth esali ­ varypump . Theforegu t (oesophagus)i sa unifor mthi ntub ewhic htraverse sth ethora xt oterminat e atth eoesophagea lvalve .I tconsist so fa singl elaye ro fsquamou sepithelia lcell swhic h areline dwit ha chitinou s intima,formin ga stellat enarro wlumen .Th eoesophagea lvalv e

68 isa ninvaginatio no fthe ;foregu tint oth estomach .Th erol eo fth evalv ei st opreven t regurgitationo fingeste dfoo dfro mth estomac ht oth eforegut ,althoug hi tdoe sno thav e anymuscl efibres . Thestomac h isa dilatio no fth emidgu tan di sline dwit ha singl elaye ro fcells .Th e anterioran dposterio rregio no fthi sorga nconsist so fcuboida lepithelia lcells ,whil e themiddl eregio ni soccupie db ytall ,finger-lik ecolumna rdigestiv ecells .Th elatte r secretemateria lb yconstrictin gapica lcel lparts .Th ecell so fth eposterio rregio nse ­ cretemateria lb yformin gbuds .Bot hprocesse scontinu edurin glarva llif ewithou tan ydegen ­ erationo rmultiplicatio no fcells .Th eintestin ei sth etubula rportio no fth emidgu tan d afterseve nloop si nth eabdomina lcavit yi temptie sint oth ehindgut .I nth efirs tpar to f theintestin eth esquamou scell sfor ma stellat enarro wlumen ,whil ei nsecon ddivisio nth e stronglyvacuolate dcell sar esituate daroun da wid elumen . Thehindgu ti sa highl ytransparent ,sac-lik eorga nconsistin go fa singl elaye ro fflat ­ tenedepithelia lcells .Th einne rwal lo fth ecell si sstrongl yfolde dan dcoate db ya del ­ icateintima ,whic hcontinue si ntha to fth erectum .Th elatte ri sa tubula rcontinuatio n ofth ehindgu tan di scompose do fcolumna rcells .I topen sint oa ninvaginatio no fth eepi ­ dermisi nwhic hth eana lopenin gi ssituated . Fromth efoo dcana li nth emaxillar ystylet sth eplan tjuice swit hth eviru spasse sint o thepharynx ,foregut ,stomach ,intestine ,an dfinall yth ehindgut ,th elas torga no fth edi ­ gestivesystem .Fro mth ehindgut ,the yar eexcrete dthroug hth eana lopenin ga shoneydew . Thisviscou sflui dwhic hstil lcontain s theviru si sdeposite do nplan tleave sbu tth eviru s isno ttransmitte di nthi sway . Themechanis mo fviru stranspor tfro mth egu tlume nt oth ehaemolymp hi spresumabl yre ­ strictedt oth etubula rpar to fth emidgut .Thi spar to fth egu ti sline dwit hepithelia l cellswhic hhav ea larg elumina lsurfac ean da well-develope dmicrovilla rsystem .Moreover , Forbes (1964)mention sth epresenc eo fmembran evesicle si nthes ecell sfro mwhic hh econ ­ cludestha ttranspor to fviru sparticle sthroug hth egu twal lt oth ehaemolymp htake splac e bypinocytosis .Afte rmultiplicatio ni nth efa tcells ,i ti sthe ntransporte dt oth esali ­ varyglands .Th eviru sma ysubsequentl yb esecrete dagai nwit hth esaliv aint oth esiev e elementso fth eplant . Thesalivar yglan dsyste mi spaire dan deac hhal fo fth esyste mi scompose do fth eprin ­ cipalan dth eaccessor ygland .Th educt sfro mbot hprincipa lgland sjoi nt oa singl eon et o form,togethe rwit hth educ to fth eaccessor ygland ,a commo nsalivar yduct .I trun sfor ­ wardsan dpasse sint oth eafferen tduc tformin ga nS-shape d flexuret oente rth epum pcham ­ bera tth eventra lsid eo fth epum pcylinder . Theaccessor yglan di scompose do f3- 4cell so funifor msize .Th ebasa lpar to fthes e cellsshow slaminate dstructure san di nth ecytoplas mman ybranchin gcanalicul ioccu rwhic h crossth ecuticula rlinin go fth esalivar yduct . Theprincipa lglan dha stw olobes ,eac hcontainin ganteriorl ysi xcove rcell san dposte ­ riorlyfiftee nprincipa lcells ,whic har esituate daroun dth einterna lsalivar yduct .Eac h celli sconnecte dwit hth echitinou slume no fth esalivar yduc tb ya nintercellula rcana - liculum.Al lthes ecell sharbou ra mas so fsecretor ygranule swhic har erelease db yth e cellint oth ecanaliculi .Th edista lpar to fth etw olobe so feac hprincipa lglan di scon ­ nectedb ya myoepithelioi dcell .Th ebul ko fth ecytoplas mi soccupie db ymyofibril sorient -

69 edi na ninterwove npattern .Thi scontractil emas sha sth eopportunit y toadmi thaemolymp h intoth elume no fbot hinterna lsalivar yducts .Th eadmissio no fhaemolymp hint oth elume n ofth esalivar yduct spresumabl yserve st odissolv eth egranula rsecretor yproduct sextrud ­ edb yth eacina rcell so fth eprincipa lgland ,an dt oremov ewast emateria l fromcircula ­ tionwit hth esaliva .Vi ath educt ,th ehaemolymp hwit hsaliv ai stransporte dthroug hth e salivarypum pint oth eplant . Thesalivar ypum plie si nth ehypopharyn xbeneat hth epharyngea lpump .I tconsist so fa chitinoustulip-shape dcylinde ran da pumpstem ;i nit sope nend ,a U-shape dpisto nfits , connectingwit hthei rlip so nth eedg eo fth ecylinder .Th episto ni sprovide dwit ha ten ­ don,t owhic hmuscle sar eattache doriginatin gfro mth etentoria lba ran dth epharyngea l pump.O nbot hsides ,th ecylinde rha sa chitinou sprojectio nt owhic hmuscle sar eattached ; thesemuscle soriginat efro ma chitinou sridg eleadin gfro mth ehypopharyn xwal lt oth e tentorialbar .Th eexi topenin gfro mth epumpchambe ri ssituate do nth edista len do fth e cylinder,an dlead sint oth epumpste ma sa narro wduct .A tth efoo to fth epumpstem ,th e ductha stw osensillu mpores .Th educ tpasse sint oth eefferen tsalivar yduc tt oterminat e inth esalivar ycana lenclose db yth emaxillar ystylets . Thesalivar ygland so f M. persicae alternatelyproduc ea water ysecretio nan da viscou s one (Bradley, 1959).Accordin gt oMile s (1968),th enongellin gwater ysecretio ncontain s enzymes,whic hserv et odissolv eth elayer so fth emid-lamella edurin gpenetratio no fth e styletsint oplan ttissues ,whil eth eviscou sflui dform sth estyle tsheath .Th elatte r actsa sa supportin gstructur efo rth estylets . Theextensiv esyste mo fminut eintracellula rcanalicul i inth eaccessor yglan dcell s pointst oa rapi ddischarg eo fexcretor yproduct st oth echitinou s lumeno fth esalivar y duct.Thes egland spresumabl yexcret eth ewater ysuspensio nwhich ,durin git sdischarg et o thesalivar ypump ,i sdehydrate db yth educ tcell st ofor mth efina lviscou s fluid.Thi s fluidcontain swax ydroplet swhic hrende rth estyle tsheat hwaterproof . Onth eothe rhand ,th ecell so fth eprincipa lsalivar ygland scontai na mas so fsecretor y granules.The yar erelease dthroug hth eintercellula rcanalicul iint oth elume no fth esali ­ varyduc tt odissolv e finallyi nth ehaemolymph .Th ehaemolymp hi spumpe dint oth elume no f bothduct sb ypulsation so fth emyoepithelioi dcell .Throug hth educt, ,th ewater ysaliv a withit senzyme si stransporte db yth esalivar ypum pint oth eplant .Th eenzyme si nth ewa ­ terysecretio nserv et odissolv eth elayer so fth emid-lamella edurin gpenetratio no fth e styletsint oplan ttissues ,an di nth esiev etube st ostimulat eth esa pstream ,t opreven t coagulationo fth esap ,an dt oassis ti ndigestio n (extra-intestinaldigestion) .Th eviru s circulating inth ehaemolymp hma yb etransporte dthroug hth emyoepithelioi d cellsan din ­ jectedwit hth ewater ysaliv aint oth elume n(Ponsen ,1972) .

REFERENCES

Bradley,R.H.E. ,1959 .Los so fviru sfro mth estylet so faphids .Virolog y 8: 308-318 . Forbes,A.R. , 1964.Th emorphology ,an d finestructur eo fth egu to fth egree npeac haphid , Myzuspersica e (Sulzer) (Homoptera:Aphididae) .Mem .ent .Soc .Can .3 6 :1-74 . Miles,P.W. ,1968 .Insec tsecretion s inplants .A .Rev .Phytopathol .6 :137-164 . Ponsen,M.B. ,1972 .Th esit eo fpotat oleafrol lviru smultiplicatio n init svector ,Myzu s persicae:a nanatomica l study.Meded .Landbhogesch .Wageninge n 72-16. 147p .

70 Integrated control of insect pests in the Netherlands. Pudoa, Wageningen, 1980. 2.3 Aphids in sugar-beet

J.Gut 1

Research Institutefo rPlan tProtectio n (IPO),Wageningen ,th eNetherlands .

DESCRIPTIONO FTH EPROBLE M

Insugar-bee tfield si nth eNetherlands ,aphid sca nb econsidere da majo rpest ,bein g responsiblefo rth etransmissio no fviru sdiseases .Tw oviruse scaus eyellowin gan don e causesmosai csymtoms .A sfa ra si sknown ,thes eviruse sar eno ttransmitte dthroug hseed , sobee tseedling sar evirus-free . Thegree npeac haphi d (Mysus persiaae) andth ebea naphi d (Aphis fabae) arevector so f beetyellows .Th egree npeac haphi doverwinter sa seg go npeac han do n Prunus serotina. Thebea naphi doverwinter si nth eeg gstage ,mainl yo n Euonymus europaeus. Numericaldat a onth eoverwinterin gstage sar eusefu li nforecastin glate roccurrenc ean dsprea do fbee t yellows. However,mor efactor sar einvolved .Th ebee tyellow soverwinte ri nsee dbeet ,mangol d clamps,bee tvolunteer san di nsom eweeds .Neithe rth eshiftin go fsee dpropagatio nfro m thesouth-wes to fth eNetherland st oothe rregions ,no rth eearl yremova lo fth emangol d clampssolve dth eviru sproblems .Ther ewer epresumabl yothe rviru ssources .I nEngland , thegree npeac haphi dwa sshow nt ohibernat ei nmangol dclamp scarryin gth ebee tyellow s viruses. Especially inmil dwinters , M. persiaae hibernatesals oo nweed sgrowin gi nsheltere d conditions.Th eaphi di sals ocontinuousl ypresen ti ngreenhouses ,fro mwhic hi tca nescap e intoth eopen .Unde rthes econditions ,ther ei sn obisexua lreproduction :th elif ecycl ei s anholocyclic.Unde rsuitabl econditions ,fo rinstanc ei ngreenhouses ,th eanholocycli c formsmultipl yrapidl yand ,whe nthe ylate rfee do nvirus-infecte dplants ,becom ever y earlyvector so fth evirus . Otheraphi dspecies ,especiall ythos ehibernatin ganholocyclically ,ma yb esignifican t vectorso fbee tyellows .Littl ei sknown ,however ,o fthei rrole . Alataear epossibl yth emai nmean so fviru sspread .I faptera ewer esignifican ti nsprea d killingo fal laphid si nth efiel dshoul dlimi tprimar yinfections .Failur eo finsecticide s tolimi tprimar yinfectio ncanno tb eattribute d toineffectiv espraying .S oth ealata ear e incriminatedfo rtransmission .

1.Presen taddress :Divisio no fTechnolog y forSociety ,Organizatio n forIndustria lResearc h TNO,Delft ,th eNetherlands . SPECIFICPROBLEM SAN DAIM SO FRESEARC H

Thecontro lthreshol di stha tleve lo finfectio no rinfestatio na twhic hth elos si n yieldo fsuga requal sth ecos to fcontrol .Th ecos to fcontro lca neasil yb ecalculated , butth elos si nyiel di sdifficul tt oassess .Fo rthi sassessment ,health yo rnearl y healthyfield sar eneede dbu ti nfiel dtrial ssuc hfield swit ha lo wpercentag eo finfec ­ tionar erare .Moreover ,tw oform so fyellow soccu rsimultaneousl y andar edifficul tt o distinguishi nth efield .Thes edifficultie smus tb eface dt odetermin eth econtro lthres ­ holda saccuratel ya spossible ,i norde rt oreduc eth eenormou samount so fpesticide suse d onbeet ,an dt oimprov eth eprofitabilit yo fsugar-bee tgrowing .

WORKINGMETHOD S

Inexperimenta l fieldswit hplot so f10 0m 2,al lplant si na middl ero wwer einfecte d with M. yersioae originatingfro mbeet swit hyellows .I nsuc htrials ,ther ewa sn ocertaint y whichtyp eo fviru swa suse dno rwhethe rth eaphid sremai no nth einfeste dplants . Theda yafte rth eaphid swer etransferred ,th einfecte dplant swer etreate dwit ha naphi - cide:TEPP ,oxy-demeton-methyl ,fenvalerate ,pirimicar ban dwate ra scontro lwer ecompared . Systemiclon gter maphicide sca nb eeffectiv eagains tth esprea do fpersisten tviruses . Fromtha tmoment ,furthe rsprea do fth ediseas ewa sfollowe daccurately .Th estron gtyp e ofyellow sviru s (BYV)i sconsidere dt ob esemi-persistent ,an dth ewea ktyp e (BMYV)t ob e persistent.I twa sexpecte dtha tth eaphi dwoul dinfec tth eplan twit hBY Vbefor ea nap ­ pliedsystemi cinsecticid ecoul dsto pit . Toobtai na nimpressio no fth einfluenc eo fviru so nproduction ,th eyiel dan dsuga r contentso fth eartificiall y infectedrow swer ecompare dwit houte rrow si nwhic hles stha n 6°6o fth eplant sha dbee nvirus-disease dove rsevera lyears .I twa sno tpractica lt otes t eachplan tfro mth efiel dsinc ea sman yplant si na naphid-fre egreenhous ewoul db eneede d asther ewer ei nth efield .B yelectrophoresis ,w einvestigate dth eexten tt owhic haphi d strainsresistan tt ocertai npesticide soccurred .

RESULTSAN DDISCUSSIO N

Treatmentwit hth eaphicide sha dlittl eeffec to nth enumbe ro finfecte dplants .Th e artificiallyinfeste drow sbecam ecompletel ydiseased ,bu ti nth eoute rrow sman yplant s remainedhealth ydurin gth egrowin gperiod .I n197 3an d 1974,year swit h agenerall yhig h incidenceo fyellows ,almos tal lplot sbecam eheavil yinfected .I nthos eyears ,ther ewer e noclea rdifference si nroo tyiel dan dsuga rconten tbetwee nartificiall y infectedan doute r rows.Surprisingl yals oi nth e197 6an d197 7wit hver ylo wgenera lviru sinfection ,ther e weren oclea rdifference si nyiel do fbeet san dsuga rconten tbetwee nth etreatments .Th e insecticideswer en omor eeffectiv e inheavil yinfecte darea stha ni nles sheavil yinfecte d areas.Indee di n1978 ,th esuga rconten to fdisease dbeet swa s0.4 *percentag euni tles s thantha to fhealth yplants ,bu tth emea nroo tweigh twa s 10.61higher ,whic hampl ycompen ­ satedth elowe rsuga rcontent s (Table 1). Differencei nth ecompositio no fth eyellow sviru s complexcoul dhav eplaye drole .Insecticid eresistanc e inaphid scoul db ea nexplanation , butn oevidenc eo nthi smatte rwa sfound . 72 o o o o O O

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W Î-I CD }-( +J rt 4-t ca O M O öO O 3 O 3

73 COST-EFFECTIVENESSO FCHEMICA LCONTRO L

Beetgrower sus echemical st ocontro lweeds ,nematodes ,variou s insectsan dfungi .Aldi - carb (TemikG )doe sno tonl ykil lth ebee tcys tnematod ebu tals ovariou s insects,includin g aphids.Thi sdua leffectivenes sha smuc hencourage dit suse .I n1977 ,treatmen twit htha t chemicalcos t27 0guilde rpe rhectare ,i n197 823 0guilde rpe rhectare . Oxy-demeton-methyl (MetasystoxR )soo nafte rapplication skill sonl yinsect ssuckin go n beetplants .I ti suse dagains tviru syellow san dca nreduc efeedin gdamag eb y Aphis fabae. Costsar eles sthe n10 0guilde rpe rhectare .Pirimicar b (Pirimor)i sa carbamat ewit ha strongaphicida leffec tan di sselectiv eenoug ht ospar enatura lenemies .It sus ei sincreas ­ ing,mainl ybecaus eresistanc ei sgrowin gu pagains torganophosphorou scompounds .Sometime s iti suse di ncombinatio nwit hoxy-demeton-methyl ,whic hconsiderabl yreduce sth eselectiv e effecto fpirimicarb .A combine dtreatment ,commonl ypirimicarb ,aldicar ban doxy-demeton - methyl,ca neasil ycos t35 0guilde rpe rhectare . Invie wo fcurren tsuga rprices ,a ninsecticid etreatmen twoul dhav et opreven ta los s inroo tweigh to f 7%t ob eremunerative .I nou rfiel dtrials ,thi slimi twa sno treached . Establishing lossesfro mnatura linfectio nb yth eyellow si sextremel ydifficult .I nyear s withmuc hyellows ,a strang eirregularit ybecome sapparent .I nth eNetherlands ,ver yho t summerscoincid ewit ha hig hincidenc eo fyellows .However ,thi styp eo fweathe rals ofa ­ voursroo tproductio nan dsuga rconten to fth ebeets ,an dca nsometime scompensat eth eef ­ fecto fth edisease .

FUTUREOUTLOO K

Asfo roxy-demeton-methyl ,th efrequen tus eo fpirimicar b canlea dt oresistan taphi d clones.Recentl yi nth e197 8season ,a naphi dwa sfoun dtha twa salmos tcompletel yresistan t topirimicarb .Agains theav yinfestation swit h A. fabae, pirimicarb canb eusefu lfo rth e timebeing . Inth efuture ,advic eo nchemica lcontro lwil lstil lb ehampere db yunknow nfactor stha t appeari never yseason .Researc hshoul dprovid emethod sfo rrapi didentificatio no fviru s bothi nplant san di naphid swit himmunological ,electrophoretica l andelectro nmicroscop ­ icaltechniques . Presentknowledg eo fcontro lthreshold scompel su st ovie wth eus eo finsecticide scrit ­ ically.I nth eNetherlands ,a tleas ta quarte ro fth eare ai streate dwit haldicar b ( 30000 0k gpe ryear )an dabou ta thir di streate dtwic ewit hoxy-demeton-methy l (6400 0 1pe ryear) .An yreductio ni nthes eamount stha tca nb eachieve dwit hwell-founde dadvic e iswort hwhile ,no tonl yfo rth eenvironmen tbu tals ot oavoi dselectin g forinsecticid e resistance.

74 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 2.4 Aphids on wheat

P.H.Vereijken 1 &W.P .Mante l

ResearchInstitut efo rPlan tProtectio n (IPO),Wageningen ,th eNetherlands .

INTRODUCTION

Thegenera lconcer no fgrower sabou tth eoccasionall yexplosiv eincreas ei ncerea laphid s inpas tyear sresulte di nworld-wid eresearc hprograms .Curren tresearc ha tth eResearc h Institutefo rPlan tProtectio ni nWageninge nstarte di n1974 .A ta late rstage ,researcher s andstudent so fth eAgricultura lUniversit ycooperated .Th eresearc haime dt oclarif yth e mainaspect so fproductionphysiolog yan dproductio necolog yi nth eaphid-whea trelation ­ ship.I twa sconsidere d thatsuc hfundamenta lresearc hcoul dyiel dknowledg enecessar yt o developscheme sfo rsupervise dan dintegrate dcontrol .Th eprogra mwa sorganize dt oanswe r thefollowin gquestions .Wha ti sth esignificanc ei naphi dpopulatio ndevelopmen to ftemper ­ ature,parasites ,predator san dpathogens ,hos tplan tan ddensity-dependen teffects ?Wha t factorsar einvolve di nlos so fyiel dan dwha tar eth equantitativ easpect so fyiel dloss ? Ankersmit& Rabbing e (Section10.2 )studie daphi dpopulatio ndynamic si nrelatio nt oabio ­ ticfactor sa stemperature ,an dnatura lenemies .The yprepare da preliminar ysimulatio nmod ­ elfo rpopulatio ndevelopment ,whic hwa srelate dt oa damag emode lb yRabbing e& Vereijke n (1979).W estudie dth einfluenc eo fag eo fth eplant ,nitroge ndressin gan dfeedin gsit eo n populationdevelopment .W edetermine dth einfluenc eo fthes efactor san dals oo faphi dspe ­ ciesan dhoneyde wo nlos so fyield .Th eeffec to fdensit yo npopulatio ndevelopmen tan dlos s inyiel dwa sstudie dwit h Sitobion avenae, whichappeare dt ob eth emos tinjuriou scerea l aphidspecies .

RESULTSAN DDISCUSSIO N

Influence of the host plant on the population development of Sitobion avenae, Metopolophium divhodum and Rhopalosiphum padi

Intrial si na climat eroom ,th epopulatio ndevelopmen to f3 cerea laphi dspecie so n wheatwa sstudie dfro mth etim eth eea rbecam evisible .A tth esam etime ,th epossibl ein ­ fluencewa sestablishe do ffla glea fan dea ra ssubstrate ,th eag eo fth eplan tan dnitro -

1.Presen taddress :Researc hStatio nfo rArabl eFarmin gan dFiel dProductio no fVegetables , Lelystad,th eNetherlands .

75 gendressing .Specia lattentio nwa spai dt oefficienc yo ffoo dutilizatio nb y S. avenue. Beforeth emilky-rip estag eo fth egrain , M. dirhodvm multipliedo nth efla glea fi nnum ­ berstwic ea squickl yan di nbiomas s3 time sa squickl ya s S. avenae and R. padi. Onth e ear,however ,5 . avenae multipliedtwic ei nnumber san dmor etha n3 time si nbiomas smor e quicklytha no nth efla gleaf .O nth eear , R. padi multipliedi nbiomas s lesstha nhal fa s quicklya s S. avenae. Inth ecours eo fth emilky-rip estage ,th emultiplicatio nrat eo nth e flaglea fdecrease dstrongl ywit h M. dirhodvm andhardl ychange dwit h S. avenae. Onth eear , themultiplicatio nrat edecrease dbot hwit h R. padi andwit h S. avenae, butwit hif . padi therat ewa sgreater .I nth esecon dhal fo fth emilky-rip estage ,th emultiplicatio nrat e of S. avenae onth eea rha ddiminishe db yhalf . In M. dirhodum and R. padi, alateproductio ni nreactio nt ocrowdin gwa sles srapi dtha n in S. avenae, whichproduce dalata esoone ro nth efla glea ftha no nth eear .Nympha lmortal ­ ityi n M. dirhodum and R. padi wastwic ea sgrea ta si n S. avenae. Onth efla gleaf , S. avenae produced 2t o3 time sa smuc hhoneyde wa so nth eear .O fth e nitrogen,phosphoru san dpotassiu mpresen t inth efood ,nitroge nwa sutilize dbest :65 1fro m thefla glea fsa pan d83 1fro mth erachi ssap .I nvie wo fth eenerg ybudge to f S. avenae, itwa sestimate dtha tfo rth eproductio no f1 m go faphid ,5 m go fphloe msa pfro mth eea r and1 1m go fphloe msa pfro mth efla glea fwa sneeded ,base do ndr ymatter .Base do nenergy , 29%an d13 ?»o fth esa pwoul db econverte d intoaphi ddr ymatter ,respectively . M. dirhodvm feedingo nth efla glea futilize dit sfoo dabou ta sefficientl ya s S. avenae atth esam e feedingsite .Efficienc yo ffoo dutilizatio nb y S. avenae onth eea rincrease dan dalat e productionan dconsequentl ymigratio ndecreased ,whe nth eplan twa sgive na nextr anitroge n dressing.Thoug hther ewa sals oa ris ei nmortality ,th eincreas ei nth enumbe ro fapterou s adultsi nth ecolonie s ledt oa markedl yhighe rpopulatio nleve li nth enex tgeneration .

Population development of Sitobion avenae, especially in relation to crowding

Inth eriver-cla yare ai nth eenvironmen to fWageningen ,fiel dobservation swer emad e inth eyear s 1974t o1977 .Migrant so f Sitobion avenae colonizedwinte rwhea tespeciall y duringheadin gan dflowering .Immigratio nreache dit spea ki nth eweek safte rflowering . Invie wo fth elarg enumbe ro fapterou sadult ssubsequentl ybor ni nth ecrop ,immigratio n inthi sphas ecoul dhardl ycontribut ean ymor et opopulatio ngrowth . Fieldobservation san dlaborator ytrial ssuggeste dth efollowin ggenera lconclusions .A s soona sth eear sar evisible ,th eimmigrant sprefe rt osettl eo nthem .Apterou sadult sde ­ velopingo nth eleave sals omov eo nth eear .O nth eleaves ,a relativel ysmal lnumbe ro f aphidsremains . S. avenae isver ysusceptibl et ocrowding :i ncolonie swit ha naverag eo f 5o r1 5individuals ,50° 6o r95 %o fth enewbor nnymph sdevelo pwings .Consequentl yth esec ­ ondgeneratio ndevelopin go nth eea ri salread ymostl ywinged .Th emajorit yo fth eyoun g alataeemigrate ss oth enumbe ro fadult sincrease s lessstrongly .A ta certai nmoment ,mor e adultsdi etha nar eadde dt oth ecolony ,whic hreache sit smaximu mdensit ywhe nth erapidl y accumulatingsu mo femigratio nan dmortalit y isbalance db yth edecreasin gbirt hrate .Afte r that,th epopulatio nquickl ydecreases . Fromlaborator yresearch ,i tseem stha tcrowdin gals oadversel yeffect slongevity ,weigh t andthereb yrat eo freproduction .Howeve rth erat eo freproductio ni sals odirectl yreduced .

76 Ifth einfluenc eo fnatura lenemie san dth eripenin go fth eea rar eno ttake nint oaccount , wingformatio nfollowe db yemigratio nlimit spopulatio ngrowt han deve nresult si na popu ­ lationdecreas eb ymor etha nhalf .

Injury and damage to wheat, caused by Sitobion avenae, Rhopalosiphum padi and Metopolophium dirhodwn

Fieldan dlaborator ytrial so ninjur yan ddamag ewer eperforme dwit hwhea tfro mth estag e offlowerin gonwards .Aphi dinfestatio nca nlea dt oa decreas ei nth eaverag eweigh to fth e grains.Normall yth enumbe ro fgrain si sno tinfluenced .N odifferenc ecoul db edetecte di n theeffec to nyiel do f R. padi and S. avenae, bothfeedin go nth eear ,o rth eeffec to f M. dirhodwn and S. avenae, feedingo nth efla gleaf .Infestatio no fth eea rlead st olos s inyiel da tlowe rpopulatio ndensitie stha ninfestatio no fth efla gleaf . S. avenae lives mainlyo nth eear ,i ncontras tt oth etw oothe rspecies ,an di stherefor ecomparativel yth e mostinjurious .Ther ewa sn oeffec to ftim eo finfectio nan dnitroge ndressin go nth ede ­ creasei nyiel da tcomparabl edensities . Honeydewo nth eplan tstimulate sth edevelopmen to ffungi ,especiall yblac kmoulds .I n 3fiel dtrial swit h S. avenae, thiscause dabou ta smuc hdamag ea sth euptak eo fsap .Afte r correctionfo rth emoul deffect ,th eestablishe d lossescause db y S. avenae didno tdiffe r muchfro mthos ecalculate do nth ebasi so fit senerg ybudget .Therefor estyle tinsertio n andinjectio no fsaliv ahav en onotabl einfluenc eo nth egrowt ho fth egrains .

Quantitative aspects of attack by Sitobion avenae and its effect on yield; their relevance to supervised and integrated control

Theaphi dinde xo fRautapa a (1966)i sles ssuitabl efo rrelatin gdamag et oth eintensit y ofattack .I ti sbette rt ous eth eaphi dpopulatio nmaximum ,whic hi scorrelate dt odamag e toth esam eexten tbu tdoe sno thav et ob ecalculated . Ina syste mo fsupervise dcontrol ,th ecriterio nfo rtreatmen tca nbes tb eexpresse da s thepercentag eo finfecte dears ,whic hi sclosel ycorrelate dwit hth eaverag enumbe ro f aphidspe rea ran dca nb edetermine drelativel ysimpl yan dquickl y (Fig.1). Until 1978,w eassume dtha tdamag eb y S. avenae wasreasonabl ypredictabl e frombiomas s productionan defficienc yo ffoo dutilization .Th efungu seffec tcoul db eneglecte dbecaus e afungicid etreatmen to fth ewhea ta tth ebeginnin go fflowerin gwa sa routin emeasur ei n theNetherlands .Th eresult so fa Dutc hresearc hgrou po nth eimprovemen to fwhea tyiel d (DeVos ,pers .commun. )an dth eresult so fDutc hgrower si n197 8(Rijsdijk ,pers .commun. ) changedou ropinion .Fo rth efirs ttime ,w ewer econfronte dwit hcrop stha tdi dno tripe n prematurelyunde rth einfluenc eo fdiseases ,hea to rlac ko fmineral san dwate ran dthereb y yielded 2-3t/h a (0.2-0.3kg .m -2)mor etha nth eaverag e5- 6 t/ha. (0.5-0.6kg .m -2). Only inthes elong-livin gcrop sdi dhoneyde whav eth etim et orealiz eit sful lyield-reducin g capacity,considerin gth eunexpectedl yhig hlosse scause db ymoderat einfestations .Thi s effectsuggeste dtha thoneyde wha sals oa direc teffec to nproduction .I nou rtrial swit h theusua lcrops ,th ehoneyde weffec twa sapparentl yneutralize dfo rth emajo rpar tb yth e combinedeffec to fvariou sothe ryield-depressin gfactors .

77 ected ears (%)

10 100 Mean numbero faphi ds pe rea r

Fig. I.Th e percentage of infected ears as a function of the average number of aphids/ear before the population maximum. Correlation coefficient R =0.94 . Regression formulas; probit it= 1.58 + 1.52 log 100 x, 100 log x = -0.69 + 0.59 probit y. Calculations were made or.4 9 samples of 100 ears, taken in the years 1973-1977.

So aphid damage is interrelated with a complex of other stress factors.Damag ewil l only be predictable ifbot h aphid population development and crop growth canb e predicted from factors such as availability ofwate r andminerals ,weather , diseases and honeydew. The sim­ ulation model approach seems promising in forecasting but much of the quantitative data for it is still lacking.

Growing techniques are improving rapidly and so isyield . Consequently, an increasing significance ofhoneyde w canb e expected. Therefore,w e suggest that the current criterion of control should be lowered from 15 aphids per ear to 5 and 10aphid s per ear equalling 801 and 901 of the ears infected for the respective periods before and during the milky- ripe stage.Unti l the above models are available,thi s advice may serve as a preliminary compromise with the demand of the growers,no t to risk a serious loss in yield and theen ­ vironmental requirement ofminima l use ofpesticides .

REFERENCES

Rabbinge, R. &P.H . Vereijken, 1979.Th e effect of diseases or pests upon the host. Proceed­ ings of the 3rd International Congress of Plant Pathology, Munich, 1978. Rautapaa, J., 1966.Th e effect of the English grain aphid Macrosiphum avenae (F.) (Hom., Aphididae) on the yield and quality of wheat. Ann. Fenn. 5 :334-341 . Vereijken, P.H., 1979. Feeding and multiplication of three cereal aphid species and their effect on yield of winter wheat. Agric. Res.Rep . (Versl. Landbouwk. Onderz.) 888.Pudoc , Wageningen. 58 p.Als o doctoral thesis. Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980.

2.5 Significance of predators on the development of insect pests in crops

W.Nijveld t

ResearchInstitut efo rPlan tProtectio n (IPO),Wageningen ,th eNetherlands .

INTRODUCTION

Theman yreport stha tCarabida ean dStaphylinida ewer emajo rpredator so finsects ,in ­ jurioust ocrops ,cause dth eResearc h Institutefo rPlan tProtectio n (IPO)t ostar ttrial s onth eusefulnes so fpredator si ncontrollin ginsec tpest si nagrcultura lan dhorticultura l crops.

AIM

Theai mo fou rinvestigations ,fro m197 5t o1978 ,wa st oestablis hth eoccurrenc eo f carabidsmainl yo nfield so fwinte rwhea ti nth eIJsselmee rPolders ,th eresult so fwhic h havepartiall ybee npublishe d (Basedowe tal. , 1976).Th efeedin gbehaviou ro fsom especie s havebee nstudie dan dw etrie dt ofin dou twhethe rundersowin gwit hspurr yinfluence dth e carabidpopulatio ni nvegetabl ecrops .Fiel dtrial swer estarte dt oestablis hwhethe rchang ­ edpopulation so fcarabi dbeetle sar einversel ycorrelate dwit hthos eo fsom evegetable - -eatinginsects .

WORKINGMETHOD S

Carabidpopulation s inwhea tfield swer eassesse db y 10simpl epitfal ltrap smad efro m 10c mdiamete rplasti cpot sburie d flushwit hth esoi lsurface ,abou t5 0m fro mth eborde r anda tinterval so fa tleas t1 0m .Th etrap sha dbee nfille dwit ha U formalinsolutio n andthe ywer eprotecte db ya transparen tplasti cli dagains trainfall .Th ecatc hwa scount ­ edfortnightly . Thefeedin gbehaviou rwa sstudie di nth efiel dan di nth elaborator yb yusin glabelle d preyanimal san db yth eapplicatio no ffluorescin gre dpowde raroun dplant swit hpes tin ­ sects.Th etrace so fth ecarabid scoul db eobserve d laterb yexposin gth eplant st oultra ­ violetradiatio ni ntota ldarkness .Carabid swer e labelledwit hradioactiv eisotope san d examinedfo rradio-activit yb yJ.Ph.W .Noordin k (IPO). Toestablis hwhethe rchange dpopulation so fcarabi dbeetle swer einversel ycorrelate d withthos eo fsom evegetable-eatin g insects,plot sabou t2 0m square ,plante dwit hcabbage s andundersow nwit hspurry ,wer eenclose dwit hplasti cbarrier s 20c mhig han dt oa dept h

79 of5 cm .Fiv epitfal ltrap swer eplace di neac hplot .O nsom eplots ,th ecarabid swer e eliminatedb ytrapping ;o nothe rplots ,th epopulatio no fcarabi dbeetle swa sartificiall y increasedb yadditio no fbeetle sfro melsewhere .

RESULTSAN DDISCUSSIO N

Pitfalltrappin go nfield so fwinte rwheat ,fro mMa yt oAugus tshowe dtha tthes efield s supporteda nabundan tpopulatio no fcarabi dbeetle san dtha tthei ractivit ywa saffecte d byweathe ran db yapplication so fherbicide san dinsecticides .Th ecatche sindicate dtha t thefollowin gspecie swer edominant : Agonum dorsale, Anisodaotylus binotatus, Bembidion ustulatum, Pterostichus cupreus, P. niger, P. strenuus and P. vulgaris. Othercommo nspecie s were Amava familiaris, Bembidion rupestre, Harpalus pubescens, Nebria brevicollis, Ptero­ stichus vernalis, Stenolophus mixtus, Treahus discus and T. quadristriatus. Pterostichus vulgaris, Harpalus rufipes and Nebria brevicollis areknow nt oea ta wid erang eo ffood , but Agonum dorsale feedprimaril yo naphids .Basedo w (1973)state dtha ti nGerman ypreda ­ toryarthropod scause dlosse so f43-58° st olarva lpopulation so fth eyello wwhea tmidg e (Contarinia tritici KirbyJ ando f0-43° 6t oth eorang ewhea tmidg e (Sitodiplosis mosellana Gêhin).Accordin gt oBasedow ,th eabundanc eo findividual si ncerea lfields ,a sdetermine d bymean so fgri dcounting , was6 000-1 200 0pe rhectar efo rth ecarabid s Agonum dorsale and6 000-1 600 0fo r Pterostichus vulgaris. In1975 ,th einsecticid elindan e (pellets)an dth eherbicid e 2,4-D/MCPA/MCPPreduce d carabidst oa lo wleve lb yabou t85 1o na fiel do fwinte rwhea ti nSout hFlevoland .However , investigations,base dupo nth epitfal ltra pmetho di n1976 ,showe dn ofurthe reffec to f thischemical so nth ebeetl epopulation . Laboratorytest sshowe dtha tth ecarabid s Amara convexiuscula and Pterostichus vulgaris ateaphid s (Myzus persicae) onpotat oplants . Berribidion ustulatum, Pterostichus cupreus and P. vulgaris ateth eaphid s Metapolophium dirhodum and Sitobion avenae onwhea tplants . Agonum dorsale, Clivina fossor, Harpaleus aeneus, H. pubescens and Notiophilus biouttatus atedea dan dlivin gaphid sfro mth esoi lsurface .Larva eo f Mamestra brassicae and Evergestis forficalis andals oth eaphi d Breviaoryne brassicae wereeate nb y Amara convexius­ cula, A. spreta, Broscus cephalotes, Calathus erratus, Harpalus aeneus, H. pubescens, Nebria brevicollis, Pterostichus cupreus and P. vulgaris. Fieldtest si ncabbag efield swit hlabelle dpre yanimal sdemonstrate dtha t Bembidion lampros, Broscus cephalotes and Calathus erratus fedo n Bvevicoryne brassicae and Mamestra brassicae. Labelled3rd-insta rlarva eo f Evergestis forficalis indicatedtha tthe ywer e eatenb y Amara spreta, Broscus cephalotes, Calathus erratus, C. melanocephalus, Nebria brevicollis and Pterostichus vulgaris. Investigationswit hpitfal ltrap snea rLiende n (Schuilenburg)showe ddistinc tdifference s betweenexperimenta lvegetabl efield swit han dwithou tundersowin go fspurr y (Spergula arvense). Inth eperio d 18May-1 8Octobe r37 7carabid s (of2 6species )wer ecaugh to nplot s withan d 169carabid s (of2 0species )withou tspurry .De nOude n& Theunisse n (Section 2.10) observeda significan teffec to fspurr yo nth eoccurrenc eo fcabbag einsects .Carabids , staphylinids,spider san dothe rpredator smigh thav eplaye dsom erole . In1978 ,trial swer ese tou tt odetermin eth eimportanc eo fcarabids ,staphylinid san d

80 spiders aspredator s of insectpest s on Brussels sprouts and cauliflower.Thoug h we suc­ ceeded inincreasin g only the carabid population onon eplo tb y about 100°«,n o distinct influence on the development of cabbage aphid, cabbage diamond back moth, cabbagemoth , cabbage rootfly and cabbagewhit e butterfly was observed. However,compare dwit h 1977,pop ­ ulations ofpredator s and cabbage insectswer e small in thatarea .

CONCLUSION

Muchwor k stillneed s tob e done inth eNetherland s todetermin ewhethe r and inho w far predators cancontro l insectpests .Thoroug h studies of their occurrence in cultivated crops, theirfeedin gbehaviour ,th e influence ofcroppin gmeasure s such as crop rotation and undersowing),o f chemicals ando fweathe r on theirpopulatio n density areurgentl y need­ ed. Ifw e obtain apositiv e impressiono f their activities, itwoul d bewort hwhil e taking them into accountwhe nestablishin g integrated programs inth egrowin g of agricultural and horticultural crops.

REFERENCES

Basedow, Th., 1973.De r Einfluss epigäischer Raubarthropoden auf die Abundani phytophager Insekten inde r Agrarlandschaft. Pedobiologia 13 :410-422 . Basedow,Th. ,A . Borg, R.de Clercq,W . Nijveldt &F . Scherney, 1976.Untersuchunge n über das vorkommen der Laufkäfer (Col.: Carabidae)au f Europaischen Getreidefeldern. Entomo- phaga 21(1) :59-72 .

81 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980.

2.6 Approaches to integrated control of soil arthropods in sugar-beet

W.Heijbroe k (]),CF . vand eBun d (2),P.W.Th .Maa s (2),CA.A.A .Maenhou t(3) , W.E.Simon s (4)& G.M .Tichelaa r(5) .

1Institut eo fSuga rBee tResearch ,Berge no pZoom ,th eNetherlands . 2Plan tProtectio nService ,Wageningen ,th eNetherlands . 3Researc hStatio nfo rArabl eFarmin gan dfo rVegetabl eGrowin g inth eOpen ,Lelystad , theNetherlands . 4Departmen to fNematology ,Agricultura lUniversity ,Wageningen ,th eNetherlands . 5Researc hInstitut efo rPlan tProtectio n (IPO),Wageningen ,th eNetherlands .

DESCRIPTIONO FTH EPROBLE M

Inth epas ttwent yyears ,cultura lpractice si nsugar-bee tgrowin ghav echange ddrastic ­ ally.Th edrillin gdistanc ei nth erow sha sincrease dan ddevelope d intoplantin gt oa stando na larg epar to fth esugar-bee tarea .Wee dcontro lha simprove db yincrease dappli ­ cationo fsoi lherbicide sa tdrilling .Thes echange shav eha dth efollowin gconsequence s forinfestation sb ysoi larthropods : -equa lpes tpopulation scaus emor edamag etha ni nth epast ; -th etoleranc et oth epes tha sdecreased ,sinc eles splant sca nb emissed ; -weed stha tserve da sa nalternativ efoo dsuppl yfo rpolyphagou sarthropod sar en olonge r present,s otha tconcentratio naroun dsuga rbee tseedling sincreases . Theus eo finsecticide sa sa see ddressing ,see dfurro wtreatmen to roveral lsoi ltreat ­ mentfo rcontro lo finfestation sb ypygm ymangol dbeetle s {Atomaria linearis) andspring - tails (Onychiurus spp.)ha sincrease ddrastically .Overal ltreatment sca nhav eseriou s implications,becaus epredator sar ekille dto oan dsoi lan dcrop sar emor econtaminate d withpesticides .S oa nintegrate dapproac hwa sinvestigated . Onychiurus speciesca nunde r certaincondition scaus edamage ,bu tthe yar eals obeneficia lb ypreyin go nnoxiou snema ­ todes.

INTEGRATEDCONTRO LO FONYCHIURU SARMATU S

Weaime da ta combinatio no floca lchemica lcontro lo rsee dtreatmen tan dbiologica l methodslik ecreatin galternativ efoo dsuppl ybetwee nth erow so fsugar-bee to rmodificatio n ofseed-be dpreparation .Th einfluenc eo finsecticides ,method so fwee dcontro lan dcroppin g practices,lik edrillin gdistanc ean dseed-be dpreparation ,o nth epopulatio ndynamic so f Onychiurus spp. (mainly 0. armatus) andth eresultin gdamag ewer estudie di nfiel dtrial s andb ysimulatio ni ngreenhous ean dlaboratory .Th epopulation swer eassesse db ytakin g soilsamples ,fro mwhic hth eCollembol aan d A. linearis wereextracte db ydifferen ttech ­ niques. Soilsample sfro msom earabl efield sshowe dtha t 0. armatus hibernated indeepe rlayers . Whensoi ltemperature sris eabov eS ° Ci nearl yspring ,the ymigh talread ybecom eactiv ean d canmigrat et oth eseedbed . 0. armatus ishighl ysensitiv et odesiccatio nan dtherefor eit s presence inth eseed-be di slargel ydependen to nmoistur econtent .I fth ewate rconten to f theseed-be dincreases ,man y 0. armatus migratet oth esurfac enea rth eseedlings .S odamag e isconsiderabl ei na sprin gwit hperiod so fcoo lan drain yweather .I tals omigrate sa shor t distancehorizontall y ifweed soffe ra nalternativ efoo dsuppl ybetwee nth esugar-bee trows . Inplot swher esoi lherbicide sha dno tbee napplie dan dweed swer econtrolle dmechanicall y aftersingling ,a par to fth edamag ewa sprevente dan dconcentratio no f 0. armatus inth e beetrow swa sconsiderabl yless . Thephysica lstructur eo fth eseed-be dals oinfluence sth eexten to fdamage ,a sspring - tailshav edifficult y inpenetratin ga compacte dsoil .Th elayou to fa shallo wseed-be dan d compactionbefor edrillin gha da beneficia leffect . 0. armatus canfee do nsoi lfung ian d hasa preferenc efo rsom especie stha tar ecommo ni narabl esoil .I fth espac ebetwee nrow s wastreate dwit hmolasses ,a byproduc to fsuga rindustr ytha tstimulate sfunga lgrowth , fewer 0. armatus migratetoward sth esugar-bee trows ,bu tthi smetho dcanno tcompletel y preventdamag ean dha st ob ecombine dwit hsupplementar ysee dtreatment . Multiplicationo f 0. armatus inth esoi li sstimulate db yth egrowin go fclover san d grassesa sgree nmanur ean db yley so rgras sfo rsee dproduction .

ROLEO FSOI LORGANISM SI NSEEDLIN GESTABLISHMEN T

Thisprojec ti scoordinate db yth eInternationa lOrganisatio nfo rBiologica lContro l (IOBC)an dth eInternationa l Institutefo rSugar-Bee tResearc h (IIRB).Th einfluenc eo f differentinsecticide ,herbicid ean dcro ptreatment so nth ecompositio no fth esoi lfaun a andinfestation so fseedlin gpest sha sbee nstudie dfo rsevera lyears .Specia lattentio n hasbee npai dt oth epredator so fspringtail san dth epredator yactivit yo f Onyohiurus spp. onnematodes . Apermanen ttria lo nth eeffect so fcro protation ,applicatio no faldicar ban dlindan e andsoi lherbicide so nth ecompositio no fth esoi lfaun aan dth einterrelation sbetwee n predatorsan dprey swa slai do na nexperimenta lfarm .Al lsoi larthropod swer eextracte d fromth edifferen tsoi lsample sb yTullgre nfunnel san dth esurface-dwellin garthropod s werecaugh ti npitfal ltraps .Cyst-formin gan dfree-livin gnematode swer eextracte dfro m separatesoi lsample swit happropriat eelutriators .Soi lfung iwer eidentifie d fromth e rhizosphereo fseedlings .Damag ewa sassesse db yseedlin gcount san ddifferen twee dspecie s werecounte dafte remergence .A tharvest ,sugar-bee tsample swer ecollecte dfro mever yplo t todetermin eroo tweight ,sucros econten tan djuic equality .Thoug hth eweathe rwa sdr yi n thefirs tyea ro fth etria l (1976)ther ewa sconsiderabl edamag eb y 0. armatus. Adequate plantprotectio nwa sobtaine db yoveral lsoi ltreatmen twit h lindanean dt oa lesse rexten t seedfurro wtreatmen twit haldicarb .Modifie dwee dcontro l (nosoi lherbicides ,chemica lo r mechanicalcontro la tsingling )als oprove deffective .Th esam eresult swer eobtaine di n 1977,whe nw efoun da nincrease doccurrenc eo fweed si nth elindane-treate dplot ssinc epar t ofth espringtai lpopulatio nfeedin go nwee droot sha dbee nkilled .Onl ysligh tinfestation s couldb eobserve di n1978 . Thenumbe ro f Collembola and Aaari particularly Cryptostigmata inth eshor tter mwer e affectedb ylindan ean dt oa lesse rexten tb yaldicarb .Th enumbe ro f Tarsonemini increased inth ealdicarb-treate dplots .Som edecreas ei nth ediversit yo fspecie scoul db edetecte d

84 afterapplicatio no feithe rlindan eo raldicarb .Al lthes eeffect swer etemporary .I nth e plotswit hcontinuou ssugar-bee tfewe r Pergamasus spp., Isotoma notabilis and Cryptostigmata werefoun dtha ni nthos ewit hwhea ta sa nalternativ ecrop . Thenumber so fbee tcys tnematode s (Heterodera schaohtii) remainedlo wals oi nth eplot s withthre eyear so fcontinuou ssugar-beet .Th esam ewa stru efo rfree-livin gpathogeni cnema ­ todes.I nth eplot swit hsugar-bee tfo ron eyea ran dwinte rwhea tfo rtw oyear s Pratylenchus spp.increase di nnumbers .Infestation so fseedling sb ypathogeni csoi lfung iwer ever ylow . Thenumbe ro ffung ii nth erhizospher ean dth ediversit ywer esmall . Onlyi nplot streate dwit haldicar ban dlindan ea significan tincreas ei nroo tyiel dove r untreatedcoul db edemonstrated .

BIOLOGICALCONTRO LO FSEEDLIN GPEST SB YNEOAPLECTAN ACARPOCAPSA E

Intw otria lfield swit ha hig hinitia lpopulatio ndensit yo f 0. armatus and A. linearis, respectively,suspension so f Neoapleatana cavpoaapsae werespraye di nth eope nsee dfurro w atdrilling .Population so fseedlin gpest san dplan testablishmen twer eassesse da sabove . Seed-furrowapplicatio na ta dos eo f25 000 0pe rm o fro wha dn oeffec to nth eoccurrenc e ofan ddamag ecause db y 0. armatus, whichwa sconfirme db ylaborator ytests .Thi swa sals o foundfo r A. linearis atrate so f8 000 0an d 1000pe rm o fro wi na fiel dwit hseriou sdam ­ age.

SIGNIFICANCEFO RAGRICULTURA LPRACTIC EAN DPROSPECT S

Parto fth edamag ecause db y Onyahiurus canb eprevente db ya fir mseed-bed ,i nwhic h thesee di sdrille dshallow ,avoidanc eo fclove ran dgras scrop si nth erotation ,an dwee d controlafte rsingling .Th eeffec to fth elas tmethod ,however ,depend so nth epopulatio n densityo fth eweeds .Applicatio no fmolasse sbetwee nrow smigh tsolv eth eproblem ,bu t furtherresearc hi sneede dbefor ethi sca nb edon eo na practica lscale . Theinvestigation sint oth erol eo fdifferen tsoi lorganism si nseedlin gestablishmen t havetaugh tu smuc habou tth epredator-pre y interrelationship inth esoi lan dprovide sa basefo rcontro lo fpolyphagou sarthropod si nsuc ha wa ytha tthei rbeneficia leffec to n otherpathogen si sno taffected .Trial sar eplanne di nwhic hth emesofaun aan dparticularl y nematodepredator sar estimulate db yapplicatio no forgani cmaterial .I nthi swa yw ehop e tocontro l Heterodera sahaahtii, whichi sth emai npes to fsugar-bee ti nth eNetherlands .

85 Integrated control of pests in the Netherlands. Pudoc, Wageningen, 1980.

2.7 Mesofauna of arable soil

C.F.va nd eBun d

PlantProtectio nService ,Wageningen ,th eNetherlands .

INTRODUCTION

AfterProtozo aan dNematoda ,mite s (Acarina)an dspringtail s (Collembola)ar eth emos t abundantanimal si nsoil .Thes esmal lanimal srespon dquickl yt ochange si nthei renviron ­ ment.A sa consequenc eo fthei rsmal lsize ,mite san dspringtail shav ea restricte dhome - range,whic hi smostl ysevera lcubi ccentimetre so rdecimetres .Th efauna lcompositio no f microarthropodsextracte dfro msoi lcore sca nb etake na sa respons et oth eenvironmen tan d toevent stha tha dhappene di nan dnea rth esoi lcore .Fo rthi sreaso nan dbecaus ethei r ubiquity,abundanc ean drang eo fspecies ,springtail san dmite sar eusefu lindicator so f disturbanceso fth eenvironment ,especiall yo fpollution ,fo rinstanc eb ypesticide si nth e soil. Unfavourablecondition s forth esoi lfaun aar ebar esoil ,extremel yhig han dlo wtemper ­ atures,dryin gou to fth esoil ,compactnes so fth esoil ,shortag eo forgani cmatter ,mechan ­ icaldisturbanc eo fth esoil ,larg edressing so fminera lfertilizer san dapplicatio no f pesticides.Mos to fthes eunfavourabl econdition soccu rregularl yi narabl esoi lan dbecom e morefrequen twit hintensiv efarming ,whic hma ydecreas eth ediversit yo fth esoi lfauna . Theimpoverishe dsoi lfaun abecome smor eunstabl ean dcertai npest san ddisease so nth e cropsbecom emor elikely .A wel lknow nexampl ei sth espringtai l Onyohiums armatus, which maybecom ea nimportan tpes to ngerminatin gseed san dyoun gplant so fsugar-beet . Fora bette runderstandin go fth erelation sbetwee nth edifferen tspecie so fth esoi l faunaan dwit hth emicroflora ,th ewee dflor aan dwit hcro pplants ,a thoroug hknowledg e isneede do fth efaun ao farabl esoil .Suc hdat aca nimprov eth esucces so finvestigation s onintegrate dcontro lan da nindicatio nca nb eobtaine do fside-effect so fpesticide so n thesoi lfauna .

AIMO FTH E INVESTIGATIONS

Theai mo fth einvestigation swa st oestablis hth eoccurrenc eo fspringtail san dmite s inth esoi lo farabl efields .Littl ewa sknow no fth emesofaun ai nDutc harabl esoil sunde r normalfarmin gpractice .S oth einvestigation sconcentrate do nfield so fsugar-bee tan do f winterwhea twher esugar-bee tha dbee ngrow nth epreviou syear .Side-effect so faldicarb , lindanean dcertai ncommonl yapplie dherbicide so nth esoi lfaun awer estudied ,i npartic ­ ularb yHeijbroe ke tal . (Section2.6) .

87 WORKINGMETHOD S

Fromeac ho f1 0site sal love rth eNetherlands ,2 4soi lsample so f12 5m lwer etake n duringth ewinter so f1975 ,197 6an d1977 . Duringsprin go f197 6an d1977 ,2 4packet so ffilte rpape rweighin g 3g wer eburie da t thesam esite s5 c munde rth esurfac eo fth esoil .Afte rsi xweeks ,the ywer erecovere dan d extractedi na cylinder-extractor . Eachsoi lsampl erepresente da cor eo f0-2 0 cmdepth .The ywer etake nwit ha nauge ro f diameter5, 7cm .Eac hsoi lcor ewa sdivide dint oa par t0-1 0 cman da par t 10-20cm . Thesoi lfro meac hpar to fth ecor ewa sgentl ybroken ,crumble dan dmixed .Afterward s themixe dsoi lo feac ho fthes etw olayer swa spu tint ocylinder sseparatel yan dwa sextract ­ edb ya modifie dTullgre nextractio napparatus ,a cylinder-extracto r (Vand eBund ,1965) . Allth eextracte dspecimen so fmite san dspringtail swer etransferre d intocavit yslide s filledwit h lacticacid ,counte dan didentifie dt oth especie sor ,whe nspecifi cidentifi ­ cationwa sno tpossible ,t oth esmalles ttaxonomi eleve lpossible . Adisadvantag eo fal ldr yextractio nmethod si stha ta direc tcompariso no fth efaun a extractedfro mdifferen ttype so fsoi li softe nno teasil ypossible .A considerabl enumbe r ofmicroarthropod swil lb etrappe dan dremai ni nth esoi lsample sdurin gextractio nbecaus e ofshrinkag eo fth esoi li nsample stha thav ea hig hconten to fsilt ,fo rinstanc ecla yo r loesssoils .Als oth enumbe ro fextracte dmicroarthropod s fromsample so farabl esoi li s oftenver ylow . Torthes ereasons ,a trappin gmetho dwa sals oused .Certai namount so forgani cmatte r (filterpaper )i nbag so fnylo ngauz eo fmes h1, 5m mwer eburie d5 c munde rth esurfac eo f thesoi lfo rsi xweeks .Natura lproduct slik estra wo rtre eleave sma yb eles ssuitable , becausedea dplan tmateria lma yvar yconsiderabl yi nstructur ean dchemica lcomposition , andma yb econtaminate dwit hunknow namount so fapplie dpesticide so rma yb esubjecte dt o pollutedair .S onatura lproduct sma ycaus eunknow nan dundesire deffect so nth enumbe r andspecie so fth eextracte dsoi lfauna .B ycontrast ,filte rpape ri shomogeneou sindustria l productconsistin gmainl yo fpur ecellulose .Th ebreakdow no fcellulos e ison eo fth emai n biologicalactivitie s inth esoil . Thetechniqu edoe sno tmeasur epopulatio ndensit ybu tindicate sth eactivit yo fsoi l animalstha tmigrat ean dbecom eestablishe di nth efilte rpape rfro mth esurroundin gsoi l inassociatio nwit hmicro-organism s thatattac kan dbrea kdow nth ecellulose .

RESULTSAN DDISCUSSIO N

Thenumbe ro fspringtail san dmite swa sgenerall y low,bu tther ewa sobserve da consider ­ ablevariatio ni nnumbe ri nth einvestigate dsite s (Tables 1an d 2). Therewer emor eindi ­ vidualsi nsand ysoil stha ni ncla ysoils .Th enumbe ro fmicroarthropod swer e largeri nth e loesssoi ltha ni nth eclay .Ther ewa sno tmuc hdifferenc ei nth enumbe ro fspecie sfro m clayan dsand ysoil ,bu tmor especie swer eextracte d fromloes ssoil . After 15year so finvestigation so nth esoi lfauna ,I hav erecorde d 100specie so fmit e and4 1o fspringtai l inDutc harabl esoils .Fro mth e1 0site si nth etria ldescribed ,8 8 specieso fCollembol aan dAcarin awer eextracte dfro mth esoi lsample san dfro mfilte rpaper . Table 1.Numbe ro findividual san dspecie so fmicroarthropod si n3 litre so farabl esoil . Meanbetwee nsites ;1 0sample so f 125m lsoi l (0-20c mdepth )a teac hsite .Th efigure si n parenthesis arestandar ddeviations .

Numbero findividual s Numbero fspecie s

Collembola Acarina Collembola Acarina

Clay soil (4sites ) 68 (+45 ) 88 (+57 ) 6,8 (+3,5 ) 16( +3,5 ) Loesssoi l (1site ) 154 178 11 27 Sandysoi l (5sites ) 232 (+183 ) 380( +282 ) 6,4 (+1,8 ) 15,6 (+4,9 )

Table2 .Numbe ro findividual san d specieso fmicroarthropod s in3 g o ffilte rpape rburie d inarabl e soil.Mea nbetwee nsites ;2 4replicate sa teac hsite .Figure si nparenthesi sar e standarddeviations .

Numbero findividual s Numbero fspecie s

Collembola Acarina Collembola Acarina

Claysoi l (4sites ) 262 (+160 ) 305 (+196 ) 7,3 (+3,1 ) 11,8( +6,9 ) Loesssoi l (1site ) 108 1332 7 22 Sandysoi l (5sites ) 308( +196 ) 1415 (+183 )5, 8 (+2,4 ) 14,4( +3,8 )

Fewspecie swer eubiquitous .Onl yon especies ,th emit e Pygmephorus blumentritti, wasrecov ­ ereda tal lsites .Onl y 12specie so fmit ean d6 o fspringtai lwer erepresente di nmor etha n halfth esite s (Table 3).Als oth efrequenc yo foccurrenc ei nth esoi lsample san dfilte r paperswa slo wan ddi dno texcee d50 1fo rnearl yal lspecies .Onl y9 specie so fspringtai l

Table3 .Numbe ro fsite s (of 10arabl efields )i nwhic hmicroanthropo d speciesextracte d fromsoi lan dburie d filterpaper .Specie soccurrin g onhal fo rles so fth esite sar eno tlisted .

Soilsample s Filterpape r

Springtails Hypogastrura dentioulata (Bagnall) 7 Onyohiurus armatus (Tullb.) 6 Tullbergia krausbaueri (Borner) 9 8 Isotoma notabilis (Schäffer) 8 6 Folsorrria Candida Willem 9 7 Folsomia fimetaria (L.) 7 7 Mites Atliphis siculus (Oudemans) 9 9 Aratoseius oetratus (Sellnick) 7 7 Hypoaspis aouleifer (Canestrini) 6 Rhodaoarellus silesiaous (Willman) 8 Histiostoma feronarium (Dufour) 9 9 Tyrophagus dimidiatus (Hermann) 8 6 Rhizoglyphus robini (Claparède) 6 6 Oppia nova (Oudemans) 6 6 Pygmephorus blumentritti Krczal. 9 10 Pygmephorus sellnicki Krczal. 7 Pygmephorus sp.mainl yjuv . 9 7 Variatipes quadrangularis (Paoli) 6

89 Table4 .Frequenc yo foccurrenc eo f springtailan dmit especie srespectivel yextracte d from24 0soi lsample so f 125m lan d24 0filte rpape rpacket so f3 burie d intoth esoi la t 10site so nDutc harabl eland .Represente d areonl yth especie swit ha frequenc yo f> 10 % ofth eextracte d soilsample so rth efilte rpape rpackets .0 = relativ eabundanc yo f> 10 5 ina tleas to nsite ;+ = frequenc yo foccurrenc eo f> 50 %i nth esample si ns tleas ton e site.

Numbero f Number of soilsample s fi Iter paperpacket s Springtails Hypogastrura denticulata (Bagnall) 59, 0, + Hypogastrura manubrialis (Tullb.) 39, 0, + Onychiurus armatus (Tullb.) 42, 0, + Tullbergia krausbaueri (Borner) 153, 0, + 102, 0, + Isotoma notabilis Schäffer 76, 0, + Folsomia fimetaria (L.) 51, 0, + 27, 0, + Folsonria Candida Willem 45, 0, + 45, 0, + Isotomina sp. 0 24, 0, + Pseudosinella alba (Packard) 37, 0, + Mites Mesostigmata Arotoseius aetratus (Sellnick) 33, 0, 99, 0, Arotoseius semiscissus (Berlese) 32, 0, Alliphis siculus (Oudemans) 50, 0, 82, o, Hypoaspis aculeifer (Canestrini) 0 25 Dendrolaelaps rectus Karg 25 Dendrolaelaps lasiophilus Hirschmann 40 Rhodacarellus silesiacus Willm. 49, 0, + Astigmata Histiostoma feronarium (Dufour) 0, + 85 Tyrophagus dimidiatus (Hermann) 0, + 111 Rhizoglyphus robini Claparède 0, + 104 Histiostigmata Oppia nova (Oudemans) 50, 0, 60, Prostigmata Pygmephorus sellnicki Krczal 43, 0, + 110, 0, + Pygmephorus blumentritti Krczal 0, + 55, 0, + Pygmephorus sp.mos tjuv . 24, + 40, 0, + Variatipes quadrangularis (Paoli) 24 Tarsonemus sp. 25,

and1 5o fmit eoccurre di na tleas t10? .o fth eextracte dfilte rpaper so rsoi lsamples . (Table 4).The yma yb econsidere da sth ecommo nspecie si narabl esoil .I twa sstrikin g thatth espringtai l Onychiurus armatus wasmainl ycommo ni ncla ysoils .I twa susuall yab ­ sento rs oscarc ei nsand ysoi ltha tw edi dno tsuccee di nextractin gi tfro msoi lsample s atsevera lsand ysites .Othe rcommo nspecie sbu tles sfrequen tar e Isotomodes productus in somesand yarabl elands , Pvoisotoma minuta insoi lwit hlarg eamount so fdecayin gorgani c matter, Isotoma olivacea, Isotoma viridis and Isotomorus palustris, whoseadult soccu r mainlyo nth esurface .I nsoi lsample san di nfilte rpapers ,juvenil e formswer emor eusual . Thatwa sals os ofo r Lepidocyrtus cyaneus butadult swer esometime sobserve di nth esoil . Aver ycommo nspecies , Bourletiella hortensis, occurredregularl yo nth esurfac ean di nth e herbaceous layerbu twa srarel yrepresente di nth esoi lsamples . Thepredaciou smite s Pergamasus runcatellus, Pergamasus mirabilis, Pergamasus quisqui-

90 liarum, Pergamasus longicornis, Pergamasus norvegicus, Veigaia nemorensis and Veigaia pla- nicola occurredregularl ybu ti na lo wfrequenc yan dsmal lnumber si nth esoi lsamples . Theyca nb econsidere da smajo rpredator so fCollembol aan dma yb eo fimportanc ea spreda ­ torso f Onychiurus armatus. Pergamasus and Veigaia speciesoccurre despeciall y insoi lwit h aloos estructure ,nea ran di nclod so forgani cmatte ran dnea rth eroot so fplants .Mos t ofth eobserve dpredaciou smite swer epredator so nnematodes .Thes epredator swer eth emos t commonspecie san dwer ewel lrepresented ,ofte ni nconsiderabl enumber s inth esoi lsample s andfilte rpapers . Theinterrelation sbetwee nnematode san dmicroarthropod sca nb econsidere da simportan t (Bunt,1975 ;Va nd eBund ,197 2a an db) .W eobserve db yourselve spreyin go nnematode sb y Onychiurus armatus, Onychiurus bioampatus, Folsomia fimetaria, Folsomia Candida, Alliphis siculus, Hypoaspis aculeifer, Lasioseius penicilligev, Lasioseius fimetorum, Rhodacarellus silesiacus, Rhodacarus calcarulatus, Rhodacarus roseus and Rhodacarus ancorae. Iobserve d Onychiurus armatus invitr ofeedin go ncyst so f Heterodera trifolii ando nfree-livin gnem ­ atodes.Gilmor e (1970)als oobserve d feedingo nfree-livin gnematode sb ysom eIsotomida ean d Entomobryidaeincludin g Isotoma viridis and Isotomorus palustris. Thesespecie sar ecommo na s surfacedweller so narabl elan di nth eNetherlands .Feedin go nnematode sb yCollembol aha s beenreporte dals ob yDoncaste r (1962)an dMurph y& Doncaste r (1957).The yobserve d Onychi­ urus armatus, Achorutues spp., Folsomia spp.an d Isotoma spp.feedin go n Heterodera cysts. Alsoth efeedin go nnematode sb yth eCryptostigmati cmit e Pergalumna spp.(Rocket t& Woodring,1966 )an dth efeedin go nplantparasiti cnematode sb yth ebulbmit e Rhizoglyphus echinopus Fum.e tRob . (Sturhan& Hampel ,1977 )indicat etha tth ehabi to ffeedin go nnem ­ atodesb ecommo namon gman yspecie stha tar econsidere dsaprophagou so rmicrophytophagous .

CONCLUSION

Althoughth enumbe ro findividual so fmite san dspringtail si ssmalle ri narabl esoi l thani nfores tsoil san dgrasslan dsoils ,thes earthropod sca noccu ri nlarg enumber snea r ando nth eroo tsystem so fcro pplant swher ethe yca nhav ea larg einfluenc eo nplan tgrowth . Thisma yb eindicate db yth eoccurrenc eo fman yspringtail san dmite so ndisease dpart so f rootsan drottin gspot so nth eroot swher ethe yca ninterfer ewit hth epopulation so fnema ­ todesan dmicro-organisms .Prédatio no nnematode si sa widesprea dhabi tamoun gAcarin aan d Collembolaspecie stha tar ecommo ni narabl esoil . Therei slittl einformatio no nho wthes einterrelation s affectan dar eaffecte db yth e growingcondition so fth ecrop .Tha tinteractio nca nb efurthe rstudie di ntrial so ninte ­ gratedcontro lo fspoilpests .

REFERENCES

Bund,C.F .va nde ,1965 .Change si nth esoilfaun acause db y theapplicatio no finsecticides . Bull.Zool .agr .Bachic .II ,7 : 186-189 . Bund,C.F .va nde ,1972a .Enkel ewaarneminge naa nLasioseiu sfimetoru mKar g 1971 inee nge ­ zelschapva nmijten ,springstaarte ne nnematode ntusse nd ewortel sva nwitt eklaver .Ent . Ber.,Amst .3 2 :6-12 . Bund,C.F .va nde ,1972b .Som eobservation so npredator yactio no fmite so nnematodes . ZeszytyProblemow ePostepó wNau kRolniczyc h 129 :103-110 .

91 Bunt, J.A., 1975.Effec t and mode of action of some systemic nematicides.Meded . Landbhogesch. Wageningen 75-10 :88-90 . Doncaster, C.C., 1962.Predator s of soil nematodes. Parasitol. 52 : 19pp . Gilmore, S.K., 1970.Collembol a prédation on nematodes. Search Agriculture,Ne w York,Entomo ­ logy and Limnology 1 : 1-1 Karg, W., 1961.Oekologisch e Untersuchungen von edaphischen Gamasiden (Acarina,Parasiti - formes). 2.Pedobiologi a 1, 77 :98 . Murphy, P.W. & C.C. Doncaster, 1957.A culture method for soil mesofauna and its application to the study of nematode predators.Nematolog y 2 :202-214 . Rockett, C.L. &J.P .Woodring , 1966.Oribati d mites as predators of soil nematodes.Ann .ent . Soc. Am. 59 :669-671 . Sturhan, D. &G . Hampel, 1977.Pflanzenparasitisch e Nematoden als Beute der Wurzelmilbe Rhizoglyphus echinopus (Acarina Tyroglyphidae).Anz . Schädlingskd. Pflan. Umweltschutz 50 : 115-118.

92 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 2.8 Sterile-insect technique for control of the onion maggot, Delia antiqua

J.Ticheler ,M .Loosje s& J .Noorlande r

ResearchInstitut efo rPlan tProtectio n (IPO),Wageningen ,th eNetherlands .

INTRODUCTION

In196 2onio ngrower swer ealarme db yth efailur eo fth echlorinate dhydrocarbo ninsecti ­ cidest ocontro lth eonio nmaggot .B y1965 ,resistanc eha dsprea dal love rth eNetherland s and,althoug horganophosphate sbecam eavailable ,concer nabou tfutur econtro lcalle dfo r researcho nnon-chemica lmeasures .Developmen to fresistanc et oth einsecticid edichlofen - thioni n196 8confirme dth efears .Graduall yove rth eyears ,th ecal lfo ra nintegrate d approacht opes tproblem sa sa mean so freducin gth epesticid eloa di nth eenvironmen tpro ­ videda nadditiona ljustificatio nfo rresearch . Oniongrowin gi sconcentrate di nth ecentr ean di nth esouth-wes to fth ecountry ,an d thesterile-insec ttechniqu eseeme da promisin gavenue ,havin gshow nit smerit sagains t thescrew-wor mfl yi nth eUnite dStates .Release so fsterilize donio nflie si nthes etw o areaswoul dprovid eprotectio nt osom e90 %o fth eare aunde ronions . Asth esterile-insec ttechniqu ei sa comple xbiologica lmethod ,a considerabl enumbe r ofaspect sha dt ob estudie dconcurrently ,amon gthe mrearin gevolvin gint omas srearing , sterilizationincludin gqualit yo fth ereare dan dsterilize dinsects ,ecolog yo fth efl y withemphasi so ndispersal .

REARING

Initiallya rearin gmetho dwa savailabl e (Ticheler& Noordink ,1968) ,usin gonion si n traysa sovipositio nsit ean da smediu mfo rth elarvae .Whe nfull-grown ,th elarva epupate d inth esoi li nwhic hth eonion swer eplanted .Th eadult sfe do nyeas ta sa slurry ,hone y andwater . Itsoo nbecam eclea rtha tth ewell-bein go fth eperso ni ncharg eo frearin gwoul ddepen d onth edevelopmen to fa semi-artificia ldie tfo rth elarvae .Som ebeautifu lpupa ewer eob ­ tainedwhe nlarva efe do na die to fcarro tpowde ran dyeast ,lik etha tdevelope di nHawai i forMediterranea nfruitfly .Th eyield ,however ,expresse d asnumbe ro fpupa epe rhundre d younglarva eo regg sremaine dextremel ylow .Tediou splayin garoun dwit hnutritiona lvalue , vitamins,lipoids ,differen ttype so fyeast ,differen tbase so fdie tlik ecarrot ,whea t germ,whea tbra nan dlucerne ,an dwit hantibiotic sdi dno tproduc etangibl eresults .How ­ everwhe ngroun dfilter-pape rwa sadde dt oth eorigina ldiet ,th eyiel dros et o55-60 %an d

93 hasremaine daroun dtha tleve leve rsince .Th eadul tflie sar eno wfe do na dr ymixtur eo f sugar,mil kpowder ,brewer' syeas tan dsoy abea nhydrolysate . Foregg-laying ,Noorlande r (Ticheler,1971 )develope da ningeniou sdevice .I tconsist s ofth ebotto mhal fo fa cla yflowe rpot ,unde rwhic ha nonio nslic ei splaced .Th epo ti s putupsid edow ni na Petr idis han dth efemale sla ythei regg sbetwee nroughene dri man d dish.Egg sca nb estore di na refrigerato rfo rsi xday swithou tlos so ffertility .Mas s rearingi sgreatl yfacilitate db yth ekeepin go ftwo-day-ol dpupa ei na coldroo ma t3 ° C forperiod su pt oa year .Histologicall ythi sstag ei scomparabl et odiapause ,wit hth e addedadvantag etha tdevelopmen tca nb eresume da tan ychose nmoment .Temperatur ei nth e rearingchambers ,2 3 C,wa schose nt oprovid e fora weekl yrhyth mo foperations ,leavin g weekendsfre eexcep tfo reg gcollection .Th escal eo fmass-rearin g increasedove rth eyear s fromth eproductio no fa fe wpupa et oa maximu mo f1. 2millio ni na week .

Quality of insects

Thereare dinsect shav et ocompete ,whe nreleased ,wit hthei rwil dcounterparts ,a t leasti nmatin gbehaviou ran ddispersal .S othei rqualit yi so futte rimportance .Th eai m hasbee nt orea rinsect scomparabl e insize ,a smeasure db ypupa lweight .Th emai nfacto r isaddin ga slittl eantimicrobia lagent sa son edares ,balancin go nth ebri mo fdeteriora ­ tiono fth emedium .Anothe rfacto ri st oexer ta slittl elaborator yselectio na spossible . Twoway sar efollowe dt oachiev ethis ,namel yb yadaptatio no fth erearin gsyste mt oth e insectrathe rtha nth erevers ean dth esucces si sprove nb yth elate rgeneration sdoin g equallywel li nth elaborator ya sth efirs tgenerations .An dals ob yregula rcollectio no f freshwil dstock ,whic hmad ei tpossibl et oreleas einsect si nsufficien tnumber safte rlab ­ oratoryrearin gfo r3- 6generation sonly .

STERILIZATION

Insevera lexperiment s (Ticheler& Noordink ,1968 ;Noordink ,1971) ,irradiatio nprove d asuitabl etoo lfo rth einductio no fsterilit yi nth eonio nfly .X-ray so f7. 7kC/k g (3kR ) emittedb yeithe rX-ra yequipmen to relectro ngenerator ,o rgamma-ray semitte db ya 137Cs or60 Cosource ,applie dt opupa eth eda ybefor ehatchin gstarted ,sterilize dalmos t100° 6 ofth esper mcell so fth emale san dprevente ddevelopmen to fth eovarie so fth efemales . Irradiationearlie ri nth epupa lstag eharme dth einsect .

Quality of the sterilized insects

Cageexperiment s (Noordink,1971 )wit hmixe dpopulation so firradiate dan dunirradiate d fliesi nvariou sratio sshowe dtha tcompetitivenes swa sno timpaire db yth eradiatio ntreat ­ ment.Field-releas etrial ssuppor tthi sconclusion .

Histology and radiopathology Oneaspec to fqualit ycontro lwa sconsidere do fprim eimpor ­ tance,namel yth einfluenc eo fth eradiatio ntreatmen to nth einsect .Qualit yi nthi sre ­ spectinclude sbot heffectiv esterilizatio nb yinductio no fdominan tlethal si nth esper m

94 ofth emale san dth eabsenc eo fside-effects .Th eproble mwa sapproache db yhistologica l tests.Method suse dinclude dphase-contras toptic sfo rth estud yo flivin gcells .B yligh t microscopy,fixe dcell swer einvestigate dfo rnorma lan dpathologica lhistolog yo fth e onionfly ,includin gchromosom eaberrations .Electro nmicroscop yserve dt oelucidat esom e aspectso fth enorma lhistolog yo fth etestis . Itsoo nbecam eapparen ttha tdetectabl ehistopathologica leffect so firradiatio ni nth e doserang eo fabou t8 kC/k gcoul db efoun donl yi nth ereproductiv eorgan s :ovarie san d testes.N osign so fsuc heffect swer efoun di nothe rtissue san dorgans ,whic hcoincide s withth eabsenc eo fcel ldivision .S oth eemphasi so fth estud ywa slai do nth enorma l histologyan do nth eradiopatholog yo fthes ereproductiv eorgans .Identificatio no fth e variousgermina lan dsomati ccel ltype si nuntreate dovarie san dteste swa sth ebasi st o establishradiatio neffect s (Theunissen,1976) .Characteristi cpattern so freaction st o radiationhav ebee nfoun di nth edifferen tcel ltype so fmale san dfemale streate dwit h variousdose so fhar dX-ray s (Theunissen,1977) .

ECOLOGICALRESEARC HAN DRELEAS ETRIAL SWIT HSTERILIZE DINSECT S

Thispar to fth eresearc hwa sstarte di n1970 ,aimin ga tassessmen to fth efiel dsitua ­ tionfo rpopulatio ndensity ,reproductio nan ddispersa lan da tdevelopmen to freleas ean d evaluationmethods . Aserie so ffou rreleas etrial sstarte di n197 1 (Theunissene tal. , 1975),an dwa scon ­ cludedb ya 1-h atria li na nonion-growin g areai n197 4 (Loosjes,1976) .

Methods

Inth efiel dresearch ,severa lmethod sha dt ob edevelope do radjuste dt oth eonio nfly . Hence,a considerabl epar to fth etim ewa sspen to nthis .Populatio ndynamic san ddispers ­ al,wit ha nemphasi so nth elatter ,wer eanalyse db yrelease-recaptur e techniqueswit hsi ­ multaneousrelease so fdifferen tG marke dinsect sfro mdifferen tsites .Flie swer emarke d atemergenc ewit hdaylight-fluorescen tdye-powder s inu pt othirt ydifferen tcolour san d mixtureso ftw oo rthre ecolours .Fo rrecaptures ,a flight-interceptio ntra pwa sdeveloped , butrecentl yw eshifte dt oa simpl etyp eo fshelte rtrap .Markin gwa schecke db ysqueezin g outth eptilinu munde ra microscop ewit hultraviole tlight .Combinatio no ftest so npopula ­ tiondynamic san ddispersa lwit h large-scalerelease sfo rcontro lprovide ddat ao nten so f thousandso frecapture dflies .Also ,dispersa lwa sanalyse db ycompute rsimulatio nwit ha modeltha taccounte d forheterogeneit ybot hi nspac ean dtime . Releasemethod swer edeveloped ,reachin gth eleve lo f1. 6millio nflie srelease dpe r flightfro ma smal laeroplane ,a tu pt ofort ysites .Th emai nproble mi nrelease swa spréd ­ ation.Thi scoul donl yb eprevente db yreleasin gflie sinstea do fpupae ,an db ya nimme ­ diateextensiv esprea do fth eflies ,requirin gaircraft .Th equalit yo fth eflie swa sshow n nott ob eimpaire db yth esudde nflo wo fai ra t16 0km/ h (45m/s )tha twa suse dt oblo wth e fliesou to fth econtainers . Theeffec to fsterile-fl yrelease swa sa tfirs tevaluate db yth erati oo fsteril et o fertileamoun gth eflie strapped ,th esterile sbein gidentifie db ythei rdye-mar kor ,i n

95 females,b yinspectio no fth eovaries .Late rw etrie dt oestablis h therati oamon gth eeggs , butth edevelopmen to fa nefficien tegg-tra pha ss ofa rfailed . Damagewa sobserve do nrandoml yplace dcontro lplots ,preferabl yo f1 m o fonio nrow , generallywit hsom estratificatio no fth eonio nfield .O na large rscale ,roug hestimate s wereobtaine dfro mpseudo-rando mplots ,chose nb ystick-throwin gshortl ybefor eharvest . Therelatio no fdamag et onumbe ro fpupa ewa sestablishe d fordifferen tcontro lmethod sb y soilsamplin gan dextractio no fpupa eb ysimpl eflotation .

Results

Someaspect so fth eonio nfly' slife-cycl ewer eanalysed ,e.g .predictio no femergenc e andincidenc eo fdiapause .Also ,th etest syielde dsom edat ao nth efly' sniche ,e.g .o n Entomophthora infection. Analysiso fth espatia ldistribution so fdamag ean dpupa eshowe dtha tthes edi dno tfi t thenegativ ebinomial .Du et olo wpopulatio nan dhig haggregation ,n oreliabl econfidenc e limitscoul db eobtained .Densitie so fdiapausin gpupa ei nchemicall ytreate dfield sar e generallysom e1. 5pe rsquar emetre ,rangin gfro mles stha n0.0 1 toove r5 pe rsquar emetre . Ovipositionfrequencie swer eestimate dfro mrecapture san danalysi so fth eovaries . Fromthe man dth elife-spa ndata ,fecunditie swer eestimate da tabou t4 0an d1 5fo rth e twosubsequen tflights ,wit hcorrespondin g reproductionfactor so f7 an d3 .Thes ewer ees ­ timatedfro mpopulation so fpupae ,incidenc eo fdiapaus ean drati oo fsteril et ofertil e flies. Dispersalwa sfoun dt ob edependen to ntemperature ,bu ti ngenera lindependen to fwin d direction.I tcoul db edescribe db ya diffusio nprocess ,wit hdiffusio ncoefficient so f about200 0m 2/day inonio nfield san d1 400 0m 2/dayoutsid ethese ,value sfoun db yoptimi ­ zationo fparameter s inth ecompute rmodel .Th edifferenc ebetwee nth etw ocoefficient s accountsfo rth eaccumulatio no fth eflie si nonio nfields .Unde rth eprevailin gcircum ­ stances,thi smean sdispersa ldistance so frarel ymor etha n2 km .Whe nrelease di na nonio n field,nearl yhal fth emale s leavebefor emating .Migratio ni sreduce ddurin gperiod so f matingan doviposition .Th eimpac to fimmigratio nint oa nare atreate dwit hsteril einsect s islimite db yth elimite dmigratio no ffemale sbetwee nmatin gan dsubsequen toviposition . Inth efiel dtrial stoo ,isolatio nprove dn oproblem . Preliminary fieldtrial swit hsteril einsect swer ese tu pnea rWageningen ,fa rfro monion - -growingarea sa sdispersa lwa sthe nunknown .Th eresult swer epromisin g (Theunissene tal. , 1975).I n197 4o nFlakkee ,on eo fth emajo ronion-growin gareas ,successfu lcontro lb yster ­ ilemale swa sobtaine do na nunisolate d1-h afield .Th epopulatio nwa sreduce dt oa quar ­ ter,wherea so na contro lplo tth ereproductio nfacto ro na yea rbas ewa s 13.Damag et oth e cropwa snegligible ,2.4°s .

SEMI-COMERCIALTRIAL S

Byth een do f 1974,th eresearc hphas ewa sconclude dand ,afte rampl econsideratio no f theeconomi can dothe rprospects ,i twa sdecide dt oundertak ea tleas tpar to fth edevelop ­ mentphase .No wth emai nai mwa st osho wth eapplicabilit yo fth esterile-insec ttechniqu e

96 ona semi-commercia lscale ,som e2 0h ao fcommercia lonions ,i n197 8an d1979 . Asfro mmi d 1976,method swer edevelope d formas sproductio no fth emillion so finsect s requiredan da numbe ro ffacilitie swer ebuilt .Rearin gbega nb yth een do ftha tyea rwit h theparenta l generations.A fiel dlaborator ywa sinstalle d ina farmhous ean da choic ewa s madefo rreleas efro maircraft . Thefirs tyea ro fth esemi-commercia lprogra mwa ssuccessful .O nth eeigh tonio nfields , thepopulatio nwa sreduce dt oa tent ho naverage ,an dth edamag ewa s0. S to2.5% .Onl yo n asilverski nonio nfiel ddi dth epopulatio nescap eth edesire dleve lo fcontro lfo rsevera l reasons,althoug hn onoticeabl edamag eoccurred .

Outlook

Controlo fth eonio nfl ywit hth esterile-insec ttechniqu ei swithi npractica lreach . Howevera tth emoment ,i tcompete swit hcontro lwit ha biocid etha tals oreduce seelwor m damage.S other ear eproblem s inapplicatio no fth esterile so nheavie rsoils ,whic hfor m asuitabl ehabita t forste meelworm .Fo refficien tcontrol ,isolatio ndoe sno tsee mt ob e arelevan tfactor .Th emai nproble mi sth epredominanc eo fexpenditure s inth efirs tyea r ortw oo fapplication .Th esterile sshoul db eapplie dfo ra tleas tfiv eyear st omak ethe m economicallyattractive . Thepresen tdevelopmen tphas eha sbee nlimite di norde rt oconvinc eth efarmer stha t themetho dwork sunde rpractica lcircumstances .T oachiev eefficien tcontrol ,ther ei s stillnee dt odevelo psimpl emethod so festimatin gpopulatio nan dt olear nmor eabou tth e reproductionfactor si nrate .I nmass-rearing ,labour-savin gmethod sawai tdevelopment . Althoughth efarmer sar ei ngenera lpositiv ean da privat ecompan yi spreparin gt oin ­ troducesteril eonio nflies ,th egovernmen tbodie sar estil lundecided .O ntha tdecision , dependsth efutur eo fthi scontro lmethod .

REFERENCES

Loosjes,M. , 1976.Ecolog yan dgeneti ccontro lo fth eonio nfly .Deli aantiqu a (Meigen). Agric.Res .Rep .857 ,Pudoc ,Wageningen , 179p . Noordink,J.Ph.W. ,1971 .Irradiation ,competitivenes s andth eus eo fradioisotope s inster ­ ile-malestudie swit h theonio nfly ,Hylemy aantiqu a (Meigen).In :Sterilit yprincipl e forinsec tcontro lo reradication .I.A.E.A. ,Vienna ,p .323-328 . Theunissen,J. , 1976.Aspect so fgametogenesi san dradiatio npatholog y inth eonio nfly , Hylemyaantiqu a (Meigen). 1.Gametogenesis .Meded .Landbhogesch .Wageninge n 76-3.16 3p . Theunissen,J. , 1977.Aspect so fgametogenesi san dradiatio npatholog y inth eonio nfly , Hylemyaantiqu a (Meigen).2 .Radiatio npathology .Meded .Landbhogesch .Wageninge n77-12 . 132p . Theunissen,J. ,M .Loosjes ,J.Ph.W .Noordink ,J .Noorlande r &J .Ticheler ,1975 .Small-scal e fieldexperiment so nsterile-insec t controlo fth eonio nfly ,Hylemy aantiqu a (Meigen). In:Controllin g fruit fliesb yth esterile-insec t technique.I.A.E.A. ,Vienna ,p .83-91 . Ticheler,J. , 1971.Rearin go fth eonio nfly ,Hylemy aantiqu a (Meigen),wit ha vie wt ore ­ leaseo fsterilize d insects.In :Sterilit yprincipl e forinsec tcontro lo reradication . I.A.E.A.,Vienna ,p .341-346 . Ticheler,J. , &J.Ph.W .Noordink , 1968.Applicatio no fth esterile-mal e techniqueo nth e onion-fly,Hylemy aantiqu a (Meigen),i nth eNetherlands .Progres sreport .In :Radiation , radioisotopes andrearin gmethod s inth econtro lo finsec tpests .I.A.E.A. ,Vienna ,p . 111-115.

97 Integrated control of insect -pests in the Netherlands. Pudoc, Wageningen, 1980. 2.9 Genetic control of the onion fly, Delia antiqua, with chromosomal rearrangements

A.S.Robinso n& C .va nHeemer t

Institutefo rAtomi cScience si nAgriculture ,Wageningen ,th eNetherlands .

Theonio nfl y Delia antiqua isth eke ypes to fth eonio ncro pi nth eNetherlands .Repeat ­ edoccurrenc eo fresistanc et oinsecticide sprompte dth edevelopmen to falternativ etech ­ niquesfo rcontro lan dpreliminar yresearc hwa sbegu ni n196 5t odevelo pth esterile-mal e technique.Late ri n1970 ,i twa sdecide dt otr yt odevelo pothe rway so fgeneti ccontro lb y chromosomaltranslocations .Thes ecoul dhav eth eadvantag etha tafte risolatio nan dsubse ­ quentreleas eint oth efield ,the ycoul dconceivabl yreduc ecosts .Th ewor ko nth einduc ­ tionan disolatio no ftranslocation sha sbee ncarrie dou ta tth eInstitut efo rth eApplica ­ tiono fAtomi cScience si nAgricultur e (ITAL)an da tth eDepartmen to fGenetic so fth eAgri ­ culturalUniversit y inWageningen .

WORKINGMETHOD S

Geneticcontro ltechnique shav ebee ndevelope da tITA Lusin gmainly ,bu tno texclusively , chromosomaltranslocations ;thes ear echange si nth epositio no fth egeneti cmateria lbetwee n twochromosomes .Suc hchange sd ooccu rnaturall ybu tthei rfrequenc yca nb egreatl yincreas ­ edb yradiation .Th eexpertis ei nradiatio ndosimetr yan dth edifferen ttype so fradiatio n availablea tITAL ,facilitat einductio no fsuc hchromosom echanges . Asrelate dt ogeneti ccontrol ,translocatio nheterozygote shav etw oimportan tproperties . -Suc ha nindividua lwhe nmate dwit ha norma lindividua lcause sa reductio ni nfertilit yb y abouthalf . -Th esurvivin gprogen yo fsuc ha matin gconsis tfo rabou thal fo fnorma lindividual san d forhal fo ftranslocatio nheterozygotes ,s otha tth etranslocatio ni sinherite dove rman y subsequentgenerations . Aradiation-induce dtranslocatio nca nb eselecte db y2 methods .Firstl yb yobservin gth e phenomenono finherite dsemi-sterilit yan dsecondl yb ycytologica lexaminatio no fth echromo ­ somes.A translocatio nca nb eobserve dquickl ywhe nth eexchange dpiece so fchromosom ear e differenti nlength .Afte risolation ,th etranslocatio nlin eca nb eincrease d innumber sb y crossingwit hnorma lindividuals . Ina populatio ncontainin gtranslocatio nheterozygote s andnorma lindividuals ,mating s canoccu rbetwee ntranslocatio nheterozygote san da proportio no fth eprogen ywil lb etrans ­ locationhomozygotes .Suc hindividual sar efull yfertil ean dbree dtrue ,jus ta sth enorma l individualsand ,whe nthe yar emate dwit hnorma lindividuals ,al lth eprogen ywil lb etrans -

99 locationheterozygote s (semi-sterile).Th eproductio no fdifferen thomozygou stranslocatio n linesfollowin gsuc hinbreedin gconstitute dth ebackbon eo fth eproject .Th elac ko fgeneti c markers inth eonio nfl ygreatl yincrease dth enee dfo rscreening ,becaus eparent so fa par ­ ticularcros scoul donl yb eidentifie dafte rcytologica lexaminatio no fthei rprogeny .

Translocationsca nals ob euse da na sai dfo rsterile-insec treleas ei nth efollowin g way.Durin grelease so fsteril einsect si ti softe nadvantageou s ifonl ymale sar erelease d forth efollowin greasons : -Females ,althoug hsterile ,ca nstil lcaus edamag et oth ecrop . - Ifonl ymale sha dt ob ereare di nth emass-rearin gsystem ,ther ewoul db ea considerabl e financialsaving . Iti stherefor eadvantageou st oproduc egeneticall yaltere dline swhic hproduc eonl ymale s anda sindicate dearlier ,translocation s inwhic hth emale-determinin gchromosom ei sinvolve d canb euse dt eregulat eth ese xrati oo flaborator ypopulation sbefor erelease . Whati srequire di ssimpl yth elinkag eo fa particula rgen et oth echromosom etha tde ­ termineswhethe ra nindividua li sa male ,s otha tever ymal ecarrie stha tgen ean dfemale s donot .Fo rexample ,suc ha gen ecoul db ea mutatio nconferrin gresistanc eagains ta certai n insecticide.Ther ear eman yexample so fsuc hconditiona llethe lgenes .I fmale scarryin g sucha gen ear eirradiated ,a translocatio nbetwee nth emale-determinin gchromosom ean d anotherchromosom ecarryin gth eresistanc egen eca noccur ,an dth eresistanc egen ean dmale - nessbecom elinked .Th eresul to fthi si stha ta stoc kca nb ebuil tu pi nwhic hal lmale s areinsecticid eresistan tan dal lfemale sar esusceptible .Subsequentl y ina mass-rearin g systema treatmen to fth epopulatio nwit ha lo wdiscriminativ edos eo fa certai ninsecticid e wouldeliminat eal lfemale sbu tth emale swoul dremai naliv ean dcoul db euse dfo rreleas e inth efield .

RESULTSAN DDISCUSSIO N

Seventy-onechromosoma ltranslocation shav ebee ninduce dwit hradiatio nan disolated ; bothX-ray san dfas tneutron shav ebee nused .Schem e 1show sth eclassificatio no fthes e translocations.Sixt ywer ereciproca ltranslocation swit ha naverag efertilit yo f63.13 % ando fthe m1 7wer esymmetrica lexchange s (i.e.th eexchange dpiece swer eabou tequa li n size);thes ewer eno tstudie dfurther .Th easymmetrica ltranslocation swer eeasie rrecogniz ­ edcytologically .Th egrou po ftranslocation sexhibitin gmor ecomplexit ywer erelativel y moresteril ean dth estock so fman ytranslocation swer elos tbecaus eo fhig hsterility . Forinstanc ecycli ctranslocation s (Scheme1 )contai n3 breakpoint san ds oar emor esterile . In4 7o fth ereciproca ltranslocations ,i twa spossibl et oestablis hwhic hchromosom earm s wereinvolve dand ,o nth eassumptio ntha teac hchromosom eha sa chanc erelativ et oit s lengtho fbein ginclude di na translocation ,chromosome s 2an d6 wer epreferentiall yinclud ­ edi nth etranslocations . Fourteeno fth easymmetri ctranslocation swer einbre dt oproduc ehomozygote san dtw o lineshav ebee nproduce d (Fig.1).Thi scompare sfavourabl ywit hdat afro mothe rinsects , butman ymor ehomozygou sstock sar eneede dt omak ecrosse st oproduc edoubl eheterozygote s forrelease .O nman yo fth eteste dline sman yhomozygou s individualswer eidentified ,bu t

100 Scheme 1.Chromosoma l rearrangements isolated in the onion fly after irradiation (numbers and fertilities)

Translocations

42 asymmetric (64.07%) 7 with "duplication larvae" (71.10%) 60 reciprocal (63.13% 17 symmetric (60.17%) 35withou t "duplication larvae" (62.15%) 1 unidentified 9 triple (51.54%) 6 cyclic (48.10%) 3 a-cyclic (57.27%) 1 quadruple (31.75%) 1 two translocations (44.6%) (from one event)

Inversions 2 pericentric (77.0%)

Translocation and inversion 3

low fitness prevented the lines frombein g established. After release of a translocation homozygote into a field cage,i tbecam e apparent that the sensitivity to diapause of the laboratory strains had greatly increased. This significant result lead to an expansion of thewor k on the genetics of diapause induction and, after 5generation s of selection, a non-diapausing strainwa s isolated. For development of a genetic sexing system for the onion fly, dieldrin-resistant and dieldrin-susceptible lines have been obtained from Canada and,wit h amale-linke d translo-

- *• *55

Fig. 1.A : Normal pair of chromosomes of the onion fly; B: Translocation-heterozygote; C: Translocation-homozygot e of the same translocation; D: Sex linked translocation between the chromosomes 2 and Y. 101 cation (Fig. 1D),a genetic sexing system isbein g developed. First the resistance gene was introduced into thegenom e of themale-linke d translocationb y an appropriate crossing scheme.Thi sha sbee n accomplished and the lineha sbee n irradiated to link the gene to themale-linke d translocation.

SIGNIFICANCE FORAGRICULTURA L PRACTICE

The demonstration in 1978 that the fertility ofa field cagepopulatio no fonio n flies couldb e reducedb y SOI illustrates thepotentia l ofthi smetho d for insect control in agriculture.However ,t o succeed,muc h morewor k isneede d first inth e laboratory and then inth e field to test different system.

REFERENCES

Heemert, C.van , 1975.Chromosoma l rearrangements in the onion fly Hylemya antiqua, induced and isolated for genetic insect control purposes.Thesis .Agric . Univ.,Wageningen . Heemert, C.van , 1977.Isolatio n of ahomozygou s X-linked translocation stock with two addi­ tional sex-chromosomes in the onion fly Hylemya antiqua Meigen. Theor.Appl . Genet. 49 :123-132 . Robinson,A.S. , 1976.Progres s in the use of chromosomal translocations for the control of insect pests.Biol . Rev. 51 :1-24 . Robinson,A.S. , 1977.Geneti c control of Hylemya antiqua 1.X-ra y induced effects in the Fo +F i generations.Mutat . Res.4 2 :77-88 .

102 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 2.10 Integrated control of pests in outdoor vegetable crops

H.de nOude n& J .Theunisse n

ResearchInstitut efo rPlan tProtectio n (IPO),Wageningen ,th eNetherlands .

AIMAN DMOTIVATIO N

Insectpest si noutdoo rvegetabl ecrop si nth eNetherland sinclud ethos eo fth ecabbag e pestcomplex :cabbag eroo tfly , (Delia brassicae) cabbageaphid s (Brevicoryne brassicae) andvariou sLepidoptera .Othe rroo tfl yproblem sar ecause db yth ecarro trus tfly , Psila rosae, andonio nfly , Delia antiqua. Severalcrop sar eattacke db ycutworms ,especiall y Agrostis segetum. Mostpest sar econtrolle dwit hinsecticides .Th ecentra lproblem ,however , isth elac ko fknowledg eo npes tbiolog yan dpes tmanagemen tt oenabl egrower st ous einsec ­ ticidesi na rationa lway . Thisca nb eachieve db yselectin gsuitabl einsecticides ,formulation san ddose san db y improvingth etimin go fapplications .A prope rtimin grequire sa functiona lnationa lo r regionalwarnin gsyste man dsimpl ean dchea pmonitorin gsystem sfo rtarge tspecie st oestab ­ lishthei rpresenc elocally .Studie so nth erelatio no fpopulatio nsiz ean dlos so fyiel d canb euse dt oestablis hcontro lthresholds . A long-termgoa li st odevelo pmethod stha tca nserv ea selement si na tota lintegrate d controlprogra mt ominimiz eo reve nexclud epesticides .

WORKINGMETHOD S

Twoitem sar edescribe dher et oillustrat eth eapproac han dit sresult si nsom emor e detail.On esubject ,th edevelopmen to fslow-releas e formulationso fbiologicall yactiv e compoundsha dit sorigi ni nconsideratio no fth etarre drin garoun dth estembas eo fcabbag e plants,introduce d inth elas tdecade so fth eNineteent hCentur y (Slingerland, 1894).I t wasconsidere dt ob ea nacceptabl etechniqu efo rcontro lo fth ecabbag eroo tfl ya ttha t time.Fro m 1918til labou t 1950,th erepellen tnaphthalen ewa sapplie dfo rtha tpurpos e (Rostrup,1918) . Iti sa componen to fta ran dha da simila reffec tbu trepeate dapplicatio n wasnecessar ybecaus eo fit svolatility . Inou rtrials ,a mor emoder nencapsulatio no fnaphthalen etha nth eol dtarre drin gwa s used.W eapplie dCurasol ,a non-phytotoxi cpolyme rdispersio nsol dfo rpreventio no fsoi l erosion,whic hafte revaporatio no fth esolven tform sa water-permeabl eshee tan dalmos t saturatesth esoi lsurface .Anothe rmatri xwa sAqualit h (Heslinga,1976) ,a mixtur eo f poly (vinylacetate )an da styrene-malei canhydrid ecopolyme rtha ti ssubjec tt op Hadjust -

103 abledegradatio nb ychemica lan dphysica l factors.Granule san dsheet sloade dwit hnaphtha ­ lenewer esprea do rspraye da sa dis caroun dth estem-bas eo fcauliflower .Stan dscores , countso fpupa ean destimatio no froo tdamag eindice sserve da scriteri ao fsuccess . . Theothe rite mi sinvestigatio no nintercroppin g inintegrate dsystem so fpes tcontrol . Fortw oyears ,intercroppin gha sbee nstudie di nfiel dtrials .I nplot so fBrussel s sprouts, Spergula arvensis hadbee nundersow nbefor eplantin gth ecrop .Th edensit yo fth e S. arvensis rangedfro mzer o (=bare-soi lunde rth eBrussel ssprouts )throug ha variabl e numbero fstrip so f S. arvensis inth ecro pt ocomplet e (100$)cove ro fth esoil .A tregula r intervals,th epresenc ean dabundanc eo fcaterpillar so fvariou sspecie san dincidenc eo f cabbageaphi dwer esystemacicall yrecorde db ytakin gsamples ,countin gth ecaterpillar san d evaluatingth eaphi dincidence .A tharves t thedegre eo finfestatio no fth esprou tbutton s byth e3rd-generatio ncabbag eroo tfl ywa sassessed .

RESULTSAN DDISCUSSIO N

Theapplicatio no fth epolyme rdisc sresulte di na considerabl y improveddevelopmen to f thecro pove rth ever ypoo rstan do funtreate dplants .Additio no fnaphthalen et oCuraso l gavea bette rdevelopmen to fth ecro ptha napplicatio nwithou tth erepellent .Thi scombi ­ nationalmos tequalle dth eeffec to fth einsecticid etrichloronate . Aqualithgranule swit h 30%naphthalen edi dno tperfor mwell ,i ncontras tt onaphthalene - -loadeddisc so ftha tmaterial .Non eo fth etreatment sreduce droo tdamag et ozero ,a sob ­ tainedb ytrichloronate .Consequentl yPupa ewer eno tver y lowunde rtreate dplants .I nun ­ treatedroo tsystem sver ylo wnumber sdevelope dbecaus eo fovercrowdin go fth emaggots .S o 100%mortalit ywa sno tobtaine db yapplicatio no fth ediscs .Mechanica lbarrier swit ho r withoutth erepellen tnaphthalen epartl yo rtemporaril yprotec tth eplan tan da considerabl e levelo ftoleranc eca nb ebuil du pi nth eroo tsyste mi nth efirs tmont hafte rplantin g (Den Ouden& Theunissen ,1980) . IntercroppingBrussel ssprout swit h S. arvensis seemedt oreduc epopulation so fman y pests. Mamestra bvassicae and Evergestis forficalis graduallydecreased ,wherea s Vieris rapae didno trespon dt ointercropping .Population so f Breviaorine brassieae weresignifi ­ cantly loweronl yi nplot swit hmaximu mintercropping .Infestatio no fsprou tbutton sb y Delia brassieae larvaeals oshowe da gradua ldecreas ei nplot swit hincreasin gdensitie s of S. arvensis. Thereason sfo rth ephenomen aobserve dar eprobabl ycomplex .Factor scoul db eenhance d survivalan dactivit yo fpredators ,interferenc ewit hovipositio nan dattraction ,an din ­ fluenceo nmicroclimat ei nplot swit hintercroppin g (Theunissen& De nOuden ,1980) .

Currentpes tcontro lpractice s inoutdoo rvegetabl egrowin gi nth eNetherland sdiffe r muchwit hcro pan dpest ,bu tthe yhav ei ncommo ntha tchemica lcontro lmethod sar eapplie d only.I ncrop slik ewhit ecabbage ,on et othre espray sar esufficien tt opreven tan ydamag e offoliag eb yinsects ,wherea si nBrussel ssprout sweekl yspray swit hparathio nfo rman y weeksd ono tpreven tdamag eb ycabbag egal lmidge .Som epest sar ereadil ycontrolled ,e.g . caterpillars.Other sagai nar evirtuall yuncontrollabl e atthi smoment ,e.g .cutworm so r cabbageroo tfl yattac ko nsprou tbuttons .Chemica lcontro lo froo tflie si sroutin ebu t

104 probablyofte nunnecessary .Mos tvegetabl epest sar econtrolle deffectivel yb ychemica l treatments,bu tth eagricultura l andeconomi cefficienc yo fthes etreatment si sdoubtful . Thisi swher eresearc ho na mor erationa lus eo finsecticide sca ncaus econsiderabl ysa ­ vingsb yth eus eo fbette rdosage san dformulation san dprope rtimin go fth eapplicatio n bymean so fmonitorin gan dwarnin gmethods .Replacemen to fchemica lmethod sb yothe rcon ­ trolmethod s isa long-ter mgoal .Combine dmethod s likeusin gtrap-crop so rintercroppin g andus eo frepellent so rattractant sshoul deventuall yresul ti na nefficien tprotectio n ofth ecrop .T oachiev ebot himmediat ean dlong-ter mgoals ,mor einformatio nha sstil lt o becollecte do nth ebiolog yo fpes tspecies .

REFERENCES

Heslinga,A. , 1976.Water-degradabl epolyme rblend sb ypolyelectrolyt e formationi npoly ­ vinylacetate .Internationa l symposiumo nmacromolecules ,Stockholm ,1976 . Ouden,H .de n& J .Theunissen , 1980.Controlle d releaseo fnaphtalene :a repellen tagains t ovipositiono fth ecabbag eroo tfly ,Deli abrassicae .Neth .J .PI .Path .8 6 :17-25 . Rostrup,S. , 1918.Unders«5gelse tfverr Kaalfluen ,Tidskr .PlAvl.25 . Slingerland.M.V. , 1894.Th ecabbag eroo tmaggot .Bull .Cornel lUniv .Agrid .Exp .Stn.78 . Theunissen,J .& H .de nOuden ,1980 .Effect so fintercroppin gwit hSpergul aarvensi so n pestso fBrussel s sprouts.Entomologi aexp .appl . (inpress) .

105 3 Greenhouse crops

Vegetablesi ngreenhouse sar eanothe rcro po nwhic hth eWorkin gPart yha sconcentrate d attention,becaus eheav yus eo finsecticide sinduce dresistanc eo fspide rmite sa ta nearl y date. Breakthroughs inth edevelopmen to fbiologica lcontro lunde rglas swer eDosse' sdiscover y ofth epredator ypotential so f Phytoseiulus persirnilis, andmas sproductio no fthi smit eb y acommercia lfir mb yth een do fth e 1960s.It ssucces sprompte dresearc hint oothe rbenefi ­ cialarthropods .Condition s forth esuccessfu lus eo f Enaarsia formosa againstglasshous e whiteflywer eestablished ,a sa resul to ffruitfu lcooperatio no finvestigator sprimaril y interestedi nfundamenta laspect so fparasite-hos trelation san dworker sengage di nth e practiceo fbiologica lcontro l (3.1).Thes ebeneficia larthropod sar eno wproduce do na largescal ean dbein gapplie db ya commercia lfir move r30-40 %o fth eare aunde rthes e crops.Unde rglas sa swel la si norchards ,selectiv econtro lprogram smus tdea lwit hmino r pests.Hence ,apar tfro mth enee d forne wbiocontro lagent san dselectiv epesticides , resistanceo fusefu lpredator s (andparasites )t opesticide sma yprov eindispensabl e (3.2). Theshortcomin go f Phytoseiulus persirnilis tosurviv eperiod so fpre yscarcit yevoke d thescreenin go fothe rpredato rspecies ,lik e Amblyseius bibens, whichspecie smigh tb e useful ingreenhouse si fregulatio nove ra longe rperio di sconsidere d (3.3). Inflowe rcrop sunde rglass ,spide rmite sar eth emos tseriou sproblem st oth egrowers , particularlyt oth eros egrowers .Intensiv eapplicatio no fa wid evariet yo fsyntheti cpesti ­ cidesi nth eperio dbetwee n195 0an d196 Sresulte di nmultipl eresistance s (3.4).Surpris ­ ingly,mit epopulation sinsid eth egreenhouse swer edifferen tfro mthei routdoor srelatives , notonl yi nresistanc et oinsecticides ,bu tals oi necologica lan dreproductiv ebarrier s (3.6). Infact ,th espide rmite sfro ma greenhous eca nb econsidere da s"residents" ,wit h adaptationswel lpreserve di na geneti ccontinuum .Som einvestigation shav eaime da tbreak ­ ingthi scontinuum ,fo rinstanc eb ygeneti ccontro l (3.7)an db yexploitin gfactor sgov ­ erningth einductio nan dterminatio no fdiapaus e (3.5).

107 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 3.1 Integrated control of vegetable pests in greenhouses

J.C.va nLentere n (1),P.M.J .Ramaker s (2)& J .Woet s(3 )

1Departmen to fEcology ,Zoologica lLaboratory ,Universit yo fLeyden ,th eNetherlands . 2Researc hInstitut efo rPlan tProtectio n (IPO),Wageningen ,th eNetherlands . 3Glasshous eCrop sResearc han dExperimen tStation ,Naaldwijk ,th eNetherlands .

DESCRIPTIONO FTH EPROBLE M

Inth eNetherlands ,460 0h ao fgreenhouses ,includin g 1000h ao funheate dhouses ,ar e usedfo rth eproductio no fvegetable s (datafo r1978) . Ourresearc ho nintegrate dcontro lan dguidanc et oextensio nofficer si slimite dt o tomato,cucumber ,swee tpeppe ran dgherkin .Thes ecrop sconstitut e80° so fth eeconomi cval ­ ueo ffoo dcrop sunde rglass .Integrate dcontro li nlettuc e (thethir dmos timportan tcrop ) isno tye tfeasible . Thetwo-spotte dspide rmit e (Tetranychus urticae) wasa majo rpes ti ncucumber sdurin g the1950 san d1960s .Becaus eo fincreasin gresistanc et osom epesticides ,Bravenboe rdevel ­ opeda goo dmetho do fbiologica lcontro lwit hth epredator ymit e Phytoseiulus persimilis, butthi smetho dwa sno tuse di npractic eunti lth een do fth e 1960s (Hussey& Bravenboer , 1971). Becausepowder ymilde wan dspide rmit ewer eth etw omai npathologica lproblem si ncucum ­ bergrowing ,som epesticide sactiv ebot ha sfungicid ean da sacaricid ebecam epopular . In1969 ,th eintroductio no fth esystemi cmilde wfungicid edimethyrimo l (Milcurb),whic h doesno tkil lth espide rmite sbu tca nb eintegrate dwit hbiologica lcontro lo fspide rmite , encourageda commercia lfirm ,Kopper tCompany ,t oproduc ean ddistribut eth epredator ymit e P. persimilis. Thesetw olong-workin gan dlabour-savin gagent swer euse db y3 0grower si n 1969an d20 0grower si n1970 . Buti n197 1th egreenhous ewhitefl y (Trialeurodes vaporariorum) becamesuc ha nepidemi c thatfrequen tapplicatio no finsecticide sagains tthi spes tlargel yprevente dth eus eo f P. persimilis. Atth esam etime ,powder ymilde wbecam eresistan tt oMilcurb .S ogrower s againstarte dt ous eth edouble-actio npesticides .Ver ysoon ,however ,severa lne wmor e specificfungicide sagains tpowder ymilde wbecam eavailable .Fo rbiologica lcontro lo fspi ­ dermites ,a specifi cmetho do fcontro lagains twhitefl ywa sals onecessary .Researc ho n thiscomple xmatte rstarte di nth eearl y1970s . Forth ehistor yo fresearc han dus eo fbiologica lcontro lunde rglas si nEurop eunti l 1973, seeGreathea d (1976,p .52-64) .

109 AIMAN DMOTIVATIO N

Indevelopin gbiologica lcontro lmethods ,w ear econcentratin go ndevelopin gcomplet e schemesfo ra particula rcrop ,becaus ei fcontro lo fon epes tcontinue st odepen do nth e useo fpesticides ,th efutur eo fbiologica l controlo fan ypes to ntha tcro premain suncer ­ tain. Atth estar to fth e1970s ,integrate dcontro li ngreenhouse swa sapplie do na smal lscale . Itwa sth eresul to fprivat eenterpris ean dit sbasi swa sno tfirml yfounded .Becaus eo fth e successes,however ,researc hwa sstarted ,bot ht oestablis ha stabl ebasi sfo rintroductio n ofbiologica lcontro lan dt osearc hfo rbiologica lcontro lmethod sagains tsevera lne w pests. Thestartin gpositio nfo rresearc hwa srathe rgoo dbecaus ebiologica ldat aabou ttw o mainpest swer epresent ,sinc ea nEnglis hresearc hgrou pha dalread ydevelope da schem efo r integratedcontro lo fpest si ncucumbers .Thi sschem edi dnot ,however ,sui tth erathe r highstandard so fqualit yan dlo wpopulatio ndensit yo fth epes trequire db yDutc hgrowers . Thepositiv eattitud eo fth egrower stoward sbiologica lcontro l isa nimportan tfactor . Althoughbiologica lcontro lrequire smor eknowledg eabou tpes tan dcontro lorganism ,man y growersprefe ri tfo rth efollowin greasons . -Chemica lcontro lo fwhitefl yan dspide rmit ei sdifficult ,an dmor etim ei srequire dt o applychemical stha nt odistribut ean dchec knatura lenemies . -Durin gth efirs tweek so fa crop ,severa lmanipulation shav et ob ecarrie dou twit hever y singleplant ,s other ei splent yo ftim et omak eth enecessar ycheck sfo rearl ysymptom so f pestattac kan dt ointroduc eth enatura lenemies .Thereafte rth esyste mi sreliabl efo r severalmonth swit honl yoccasiona lchecks .A ssoo na sharvestin gstarts ,th egrowe rha s littletim efo rcro pprotection .B ycontrast ,chemica lcontro lrequire scontinuou satten ­ tionan daction . -Youn gplant sar esusceptibl et oth etoxi ceffect so fpesticides ,especiall yi nwinter , whenth eplant sar eweak .Pesticide sca nals ocaus eabortio no fflower san dyoun gfruits . - Incucumbers ,gherkins ,swee tpepper san dtomatoes ,fruit shav et ob eharveste dtwic eo r thriceweekly .Afte rapplicatio no fchemicals ,a tleas tthre eday smus tpas sbefor epickin g isallowe dagain .Thi ssafet yperio d isno trequire dwhe nbiologica lcontro li sused . Incontras tt ooutdoo rcropping ,indoo rcroppin gha sth efollowin gspecifi cadvantage s fordevelopmen tan dintroductio no fbiologica lcontro lmethods . -Becaus eo fth eannua lremova lo fplan tdebri san dsoi ldisinfection ,nearl yal lpest sar e killedbefor eth ene wcroppin gseason ,s opes tpopulation salway sstar tlow . -Th enumbe ro fpes tspecie si non ecro pi sver ylimited . -Testin go fcontro lcapabilitie so fnatura lenemie si ngreenhouse si srathe reasy ,sinc e wehav eidentica lhouse swit hcontrolle dclimate . - Insectpopulations ,especiall yi nwinter ,ca nb econsidere da sislan dpopulations .S obio ­ logicalcontro lca nb eapplie db yindividua lgrower swithou tinterferenc e fromneighbourin g crops.

110 WORKINGMETHOD S

Theusua lsequenc ei nthi skin do fresearc hi scollectin gnatura lenemies ,stud yo frele ­ vantbiologica lpropertie sfo rselectio no fcandidates ,assessmen to fus efo rpes tcontro l infiel dtests ,an ddevelopmen to fa metho do fintroductio nan dmas srearing .Existin gknowl ­ edgeabou tth enatura lenemie sw estudie dwa sver yvaried .Som ewer ealread yuse di ncon ­ trolan dothe rspecie swer ene wt otaxonomy .

RESULTSAN DDISCUSSIO N

The two-spotted spider mite (Tetvanyehus urticae)

Ametho do fmas srearin gan dintroductio nfo ra natura lenem yo fth etwo-spotte dspide r mitewer ealread yavailabl ewhe nou rresearc hwa sstarted .I ncucumbers ,cro pprotectio n isdirecte dt opowder ymilde wan dspide rmite .Agains tbot horganisms ,effectiv epesticide s areavailabl ean dca nb euse di nmixe dpreparations ,s otha tchemica lcontro li sbot heas y andchea pi nlabour .Despit ethis ,nearl yhal fth egrower sus e Phytoseiulus againstspide r mitei nth emai ncro p (Table 1). Thisi spossibl ebecaus eo fth eavailabilit yo fsevera l powdery-mildewfungicide stha td ono thar m Phytoseiulus seriously.W eexpec ttha tus eo f Phytoseiulus willincreas eeve nmor ea ssoo na sth epowdery-milde wresistan tcucumbe ri s introducedo na large rscale . Ingherkin ,w eals ofin da nincreasin gus eo f Phytoseiulus againstth espide rmite :i n 1978i twa sapplie do n1 6o fth e22 0h ao fheate dgreenhouses .Diseas econtro lraise ssom e problemsbecaus eBC Mfungicide s (e.g.benomyl )agains t Phomopsis sclerotoides interfere with Phytoseiulus. Biologicalcontro lo fspide rmit ei nswee tpeppe ri seffective ,bu tintegratio nwit h chemicalcontro lo fothe rpest si sdifficult . Biologicalcontro lo fth emite si sno tadvise dfo rtomat ocrop sa sresult sar eno tofte n

Table 1.Are a (ha)o fth ethre emos t importantgreenhous efoo dcrop s inth eNetherland si n which biologicalcontro l isapplie d (excepthothouses) .Tota lare ai nth emai ncroppin gpe ­ riod,th eare aan dproportio n(% ) ofsuccessfu lbiologica lcontro lo fgreenhous ewhitefl y by Enoarsia fovmosa intomat oan do ftwo-spotte d spidermit eb y Phytoseiulus persimilis in cucumberan d sweetpepper .

Tomato Cucumt>e r Sweet pepper

total Eno. X total Phyt. % total Phyt. %

1969 2200 - - 860 25 2 - - - 1970 2380 - - 870 200 25 - - - 1971 2430 4 - 750 75 10 70 - - 1972 2290 20 1 840 100 12 75 - - 1973 2040 120 5 790 150 20 150 10 7 1974 2090 400 20 785 150 20 160 12 10 1975 2060 500 25 780 200 25 160 15 10 1976 2040 600 30 720 300 40 160 20 12 1977 2090 550 25 770 350 45 175 30 15 1978 2000 530 25 750 400 50 180 40 20

111 good.Probabl yther ear etw oreason sfo rpoo rcontro lb y Phytose-iulus: lowtemperature san d tooslo wpes tpopulatio ndevelopmen ti ntomato .

The greenhouse white fly (Trialeuvod.es vavorariorwn)

Thefirs tyear so f Enaarsia applicationagains tth ewhitefl y (1971an d 1972)gav ebot h goodan dba dcontro lresult si ncucumbe ran dtomato ,successe si ntomat ower einexplicabl y morefrequent .Therefor ew estarte dt odevelo pbiologica lcontro lfo rtomatoes ,an dgav e theadvic eno tt oappl y Enaarsia incucumbe ran deggplant . Firstth ereliabilit ywa steste do fth eintroductio nschedul edevelope db yWoet s (1978) introductionso f1 parasit epe rplan t (attwo-wee k intervals).Dat ao fa nintensiv esam ­ plingprogra mi na norma lgreenhous e (0.75ha )showe dtha t (1)th enumbe ro fwasp sintro ­ ducedwa ssufficien tt ocontro lth ewhitefl ypopulation , (2)th eintroductio no fwasp si n aregula rpattern ,instea do fputtin gmos tparasite sa tinfeste dpatches ,i ssufficient , and (3)multipl eintroduction sar erequire dt ostabiliz efluctuation s inpopulation .On e introductioni scertainl yinsufficien t (VanLentere ne tal. , 1976).Th eintroductio nsched ­ uleha sbee nsuccessfull yapplie dfo r6 year snow . Inth eautum ncroppin gperiod ,a nincreasin gnumbe ro fgrower sd ono tspra yagains t whitefly:the ywai ttil l E. formosa 'spontaneously'enter sth egreenhouse ,a si sno tun ­ usuali narea swit hman ytomat ogrower san dextensiv e Enaarsia applicationsdurin gth e maincroppin gperiod . Researchi nth elon gter mwa saime da tunderstandin g therelationshi pbetwee nth epara ­ site E. formosa, itshos t T. vaporariorum andsevera lhost-plan tspecies ,i norde rt oim ­ provebiologica lcontro lfo rthos ecrop swher econtro lha dfaile du ptil lthen . Flightexperiment san dobservatio no fth ebehaviou ro fwhiteflie safte rlandin go nfou r plantspecie s (eggplant,cucumber ,tomat oan dswee tpepper )showe du stha ti twa sonl yafte r landingtha tth ewhitefl ycoul ddetec twhethe ri tha dlande do na suitabl ehos tplant . Thebehaviou ro fth ewhiteflie so nplant so fth efou rspecie sdiffer swidely .Afte r landing,th ewhitefl yprobe sa plan twit h itsstylets .O nsom ehos tplant s (eggplantan d cucumber),the yremai nquie tafte rth efirs tprobe ,hardl ychangin gthei rposition ,an d theyd ono tofte nleav eth eplant .O nothe rplant s (tomatoan despeciall yswee tpepper) , theyofte nchang epositio nan dofte nleav eth eplant .I ncag eexperiment swit hth efou r differenthos tplant stogethe rwher ewhiteflie swer ereleased ,a fas tan dconsistan tchang e wasobserve di nal lexperiment safte rth efirs tlandings :th enumbe ro fflie so neggplan t andcucumbe ralway sincrease dan do ntomat oan dswee tpeppe rth enumbe rdecreased .Mos t flieswer epresen to neggplan tan di ndecreasin gnumber s inth eorde rcucumber ,tomat oan d sweetpepper . Westudie dth epossibl emechanica lbarrier stha tmigh tpreven ta whitefl y adulto rlarva e fromfeedin go na plan t (VanLentere ne tal. , 1977).Neithe rth edistanc ebetwee nth elea f cuticlean dvascula rtissu eo fth ehos tplant swa sto olarg et opreven tth einsec tfro m reaching itsfoo dsource ,no rcoul dw e findan ymechanica lbarrier st opreven tpenetratio n ofth einsect' smouthparts .Th ephloe mcontent so fth efou rspecie so fhos tplan tha sno t yetbee nanalyse dchemically . Therat eo fdevelopmen to fwhitefl ypopulation so nth efou rplan tspecie swa sestimate d

112 tofin dou twhethe rth epreferenc eorde rreflect sa host-plan tqualit yorder .W etherefor e measuredlife-span ,ovipositio nfrequency ,developmenta lperio dan dmortalit yo fdevelop ­ mentalstage so nth efou rspecie so fplant .Th efollowin gcorrelation swer efound :th ehigh ­ erth enumbe ro fwhiteflie so na plan tafte rsom etim e (indecreasin gorde reggplant ,cucum ­ ber,tomat oan dswee tpepper) ,th elarge rth enumbe ro fegg slai dpe rfemale ,th ehighe rth e ovipositionfrequency ,th elonge rth elife-spa no fth efemales ,th eshorte rth ecomplet e developmentalperiod ,an dth elowe rth emortalit yo fal lstages .S ofo rthos efou rhost - -plantspecies ,host-plan tselectio napparentl yha sa biologica lsignificance :th emor ea planti schosen ,th ebette ri sit squalit yfo rth ewhitefly . Recentlypar to fth eexperiment swa sconducte dfo rthre eothe rcrops :melon ,gherki n andgerbera .Withi nth eCucurbitacaea ean dSolanaceae ,th egenera lpictur eremain sth esame : ahig hovipositio n frequencycorrelate swit ha larg enumbe ro feggs ,a lon glife-span ,a highrat eo fdevelopmen tan da lo wmortalit yo fdevelopmenta lstages .Th eonl yplan to n whichthi scorrelatio nwa sno tfoun dwa sgerbera :certai naspect smeasure d indicatea goo d quality (life-span,tota lnumbe ro feggs) ,wherea sothe rsugges ta ba dqualit y (oviposition frequency,rat eo fdevelopmen tan dmortalit yo fdevelopmenta l stages).Therefor epreferenc e alonecanno tsimpl yb euse dt odetermin ehost-plan tquality .Mor ereliabl einformatio nabou t host-plantqualit ymigh tb eobtaine dwit ha combine dtes to fovipositio nfrequenc yan dmor ­ talityo fdevelopmenta lstages . Toestimat eth esucces so fwhitefl ycontro lb y E. formosa, thedat ao fovipositio nfre ­ quencyan dlife-spa nwer etransforme dint osimpl eline sfro mwhic hth epotentia lrat eo f developmentan dgeneratio ntim ecoul db ecalculate d (Fig. 1).Th eplo tindicate stha tbio ­ logicalcontro lo fth efl ywoul db eeasies to nswee tpeppe ran dhardes to neggplant .Som e ofth efiel ddat ad osuppor tthi sconclusion :contro li seas yo nswee tpepper ,tomat oan d melon,difficul to neggplant ,cucumbe ran dgherkin .Howeve rw efoun dsom eexceptions .Con ­ trolo neggplant ,fo rexample ,prove dt ob eeasie rtha no ncucumbe rwher ealmos tever y trialo nbiologica lcontro lende di na failure ,althoug hwhitefl ypopulation sdevelope d fastero neggplan t (forbot hspecie sa muc hhighe rnumbe ro fparasite swa sintroduce dpe r planttha nfo rtomato) .Ther emus tb ea tleas ton eothe rfacto rtha tinfluence sth econtrol : apparentlyeithe rth ehost-plan to rth ehos tinfluence sth eparasit edifferently . Enoarsia formosa femalesd ono tsho wa preferenc efo ra certai nhost-plan tspecies .The y do,however ,prefe rplant sinfeste dwit hwhitefl y larvaet ouninfeste dplants ,an dthe yca n traceinfeste dspot sfro ma lon gdistanc eb ya nodou rproduce db yth ehos tinsects . Aftera was parrive so nth eundersid eo fa lea fwit hhosts ,searchin gbecome srandom . Allhost stha tth eparasit eencounter sar eexamine dthoroughly .Larva eo fth ethir dan d fourthstage sar eselecte dfo rovipositio nan dthe yproduc eth ehighes tpercentag eo foff ­ spring.Hos tfeedin goccur spredominantl yo nyoun glarva ean d 'pupae'.Parasite sca ndis ­ tinguishbetwee nparasitize dan dunparasitize dhost san dthe yrejec tparasitize dhost sfo r oviposition.I fmos to ral lhost sencountere di na certai npatc har eparasitized ,th ewas p willleav eth esite .Thi sphenomeno ni simportan tfo rth eparasitizatio nefficienc yo fthi s wasp. Duringth eobservation so nfindin gan dacceptin ghosts ,w esa wtha tth elea fstructur e ofth eplan tstrongl yinfluence d thewalkin gspee dan dpatter no f E. formosa. Wetherefor e measuredthes eo nth eleave so fvariou splan tspecies .Th ehair ycucumbe ran dgherki nbot h

113 Rate of egg laying (per day) Solanaceae 15- Eggplant

10- I Tomato

5-

/ Sw.Pepper \ 0- ^ i , 10 20 30 40 50 60 Time(d )

Rateo feg glayin g(pe rday ) Cucurbitaceae

Gherkin 10- Cucumber

10 20 30 40 Time(d) Fig. 1.Numbe ro foviposition spe r Trialeurodes vapovariovum femalepe rda yo ndifferen t vegetablecrop s (simplified graphs).

havelarg estif fhair so nth eleaves ,whil etomat oan dgerber ahav emuc hsmalle rhairs .Egg ­ plantha srelativel yfew ,bu tlarg ean dstellat ehairs .A hairles scucumbe rmutan tan d sweetpeppe rhav en ohair sa tall .Highes twalkin gspeed sar ereache do nth esmoot hleave s andwalkin gspee di sinversel yproportiona lt ohairiness . Theseresult ssuppor tth ehypothesi stha tth estructur eo fth elea fsurfac einfluenc e thewalkin gspee dan dtherefor eth eparasitizatio nefficiency .Th edat ama yexplai nwh y controlo ncucumbe ri swors etha no neggplant ,thoug hwhitefl ydevelop sfaste ro neggplant . Incompariso nwit heggplant ,th ewasp sar emuc hmor ehindere db yth estif fhair so ncucum ­ berleaves ,whic hreduc ethei rwalkin gspee dmor ean dthu sdiminis hthei rparasitizatio n efficiencymor edrastically .Thi seffec ti sstrengthene db yth elarge ramoun to fhoneyde w thati sretaine do nleave swit hlarg ehair stha no nsmoot hleaves .O na lea fwit ha lo to f honeydew,th ewasp sspen dmuc htim epreenin gthei rbodies ,whic hbecom ecovere dwit hhoney - dew.Therefor eth eparasitizatio nefficienc ywil lb emor ereduce dtha nestimate d fromwalk ­ ingspee donly .Th epractica limplication so fthes eresult swil lb eclear .I ti sver yprob ­ abletha tbiologica lcontro lca nb eimprove db yusin gvarietie so fplan twit hfe whair s ofnone .Ou rmeasurement so nth ehairles scucumbe rmutan ttha tD ePont i (Section5.8 )re ­ centlydiscovere dsho wtha t E. formosa walks 3.5time sa sfas to nthi smutan ta so na hair y variety.A greenhous eexperimen tshowe dtha tth eparasitizatio nefficienc ywa sabou t20° s highero ntha tmutant . Somemor egreenhous etest shav et ob edon et osho wtha t 'smooth'leave salon eincreas e

114 theparasitizatio nefficienc yo ncucumbe rsufficientl y forreliabl econtrol .I fnot ,i t willb enecessar yt ochec kwhethe rther ear ecucumbe rvarietie stha tar epartiall yresist ­ antt owhitefly .Integratio no fbot hstrategie swil lmak ebiologica lcontro lo fwhitefl y possible inth esecon dlarges tgreenhous ecrop . A futureproble mwil lb eth econtinuatio no fbiologica lcontro lo fwhitefl y intomatoes . Becauseo fhig henerg yconsumptio ni ngreenhouses , muchresearc h isunde rwa yt odevelo p varietiestha tproduc ewel la tlowe rtemperatures . Enoarsia cannotthe nkee pth epest sa t lowpopulatio nlevels .T ocop ewit hthi sproblem ,w ear ecollectin gan dcomparin gdat ao n parasitizationefficienc yo fne wwhitefl yparasite san dstrain so f E. formosa.

The tomato leaf-miner (Liriomyza bvyoniae)

Chemicalcontro lo fleaf-miner smake sbiologica lcontro lo fth ewhitefl yimpossible .A t present,leaf-mine rpest sar emor efrequen ttha nbefore ,bot hi nchemicall yan dintegrate d controlledtomat ohouses ,an dth eare ao fbiologica lcontro lo fwhitefl yo ntomat oi sstart ­ ingt odecreas e (Table 1). Leaf-minerca nbecom ea pes tb ypupa etha tsurviv ei nth esoi l fromon egrowin gseaso nt oanother ,i fsoi li sno tproperl ydisinfecte deac hyear . Threeparasite sar equit ecommo nan dappea rspontaneously ,i nDutc hgreenhouses : Opius pallipes, Daonusa sibirioa and Diglyphus isaea, andi fleaf-miner soccu rlat ei nth eseaso n (fromMa yonwards )the yar eapparentl ykep ta tlo wlevel sb ythi snatura lbiologica lcontrol . Laboratoryexperiment sshowe dtha tth eparasite s Opius and Daonusa arepromisin gcandi ­ datesfo rbiologica lcontrol :thei rdevelopmen tfro meg gt oadul ti squicke rtha ntha to f thehost ,adul tlife-spa nan deg gproductio nar eabou tth esam ea stha to fth ehost .Also , massproductio ni sno tdifficult ,bu tprobabl yexpensive .A syet ,w ehav eno tteste d Diglyphus, anectoparasite ,becaus emas sproductio nwil lb emor edifficult .Thi sparasite , however,ha sprove dt ob ea goo dnatura lenem yo fth echrysanthemu mleaf-mine r Vhytomyza syngenesiae.

The onion thvips (Thrips tabaci)

Pesticidesuse di ngreenhouse sar emainl ybroad-spectru mbu tshort-actio norganophosphoru s compounds,an dmor especifi cchemical sagains tfungi ,mite san daphids .Th eonio nthrip si s killedb yorganophosphoru scompounds ,bu tbecaus eo fth epresenc eo funvulnerabl estage s (eggsi nth eleaves ,pupa ei nth esoil) ,repeate dapplication sar enecessar yt okee pnum ­ berslow .Incidenta lus eo forganophosphoru s compounds isn oproble mfo rth ebiologica lcon ­ trolo fspide rmite s (seethi sbook ,p . 227),bu tfrequen tus ema ydistur bth ebalanc ebe ­ tweenpes tan dpredator .I nswee tpepper ,thrip scause scosmeti cdamag et oth efruits ,s o thetoleranc et oth einsec ti slo wi nthi scrop . Integrationo fchemica lcontro lo fonio nthrip san dbiologica lcontro lo fwhitefl y iscom ­ pletelyimpossible . Entomophthora epizooticsma ydestro ythrip spopulation s insumme ran dautumn .Thi sproces s wasobserve dbot hou to fdoor san di ngreenhouses ,an ddetail sabou tth ebiolog yo ftw o Entomophthora spp.wer estudie di nvitro . Researcho nth epractica lvalu eo fthes epathogen si shampere dbecaus emethod so freacti -

115 vatingrestin gspore san do fcultivatin g thefung io nartificia ldiet sar eunknown . Inautumn ,greenhous ecrop sar efrequentl yinhabite db ypredator ymite so fth egenu s Amblyseius, preyingmainl yo nyoun gthrip slarva e (Ramakers,1978) .Bot hpre yan dpredato r aredestroye db yth eannua lsoi ldisinfection ,bu tne wthrip spopulation sdevelo pmor e quicklyb yimmigratio no fadult sflyin gi nfro madjacen tgreenhouses .Afte r'spontaneous ' occurrencean dafte rartificia lintroductio no fthes epredators ,lo wpopulatio ndensitie s ofthrip scoul db eachieve dan dmaintained .Dispersa lo fth epredator sove rth egreenhous e afterintroductio na ton espo ti squit efast .Method sfo rmas srearin gar ebein gstudied . Probablya nalternativ ehos twil lb enecessary ,becaus emas srearin go fth eonio nthrip s isno teasy .

Aphids (Myzus persicae, Aphis gossypii)

Inintegrate dcontro li ngreenhouses ,ther ei sn oimmediat enee dfo rbiologica lcontro l ofaphids ,becaus ethe yca nb edestroye db yth eselectiv echemica lpirimicarb .However , increasingresistanc eo faphid st othi schemica li sbein greported .I nth eliterature ,sev ­ eralnatura lenemie sar ementione d ascandidate s foraphi dcontro li ngreenhouses .Tw oo f themwer eteste dfo rthei rlong-ter meffec to npopulation so f Myzus persicae onswee tpepper . Thebraconi d Aphidius matriaariae isfrequentl yobserve da sa parasit eo f Myzus persicae inhothouse sthroughou tth eyear .Mas srearin gan dcol dstorag ear epossible .Th eparasit e completes itslarva ldevelopmen tfaste rtha nothe rknow nparasite so f M. persiaae, andha s ashorte raverag egeneratio ntim etha nthi saphid .Adul tparasite soviposi tver yrapidly ; theypreven twastag eo fegg sb ydiscriminatin gbetwee nparasitize dan dunparasitize daphid s ('t Harte tal. , 1978).Beside skillin gaphid sb yparasitization ,th eparasit ecause slos s ofaphids ,probabl yb ydisturbance .Whe nth eproportio no fparasitize dhost sreache sabou t 5'oo fth eaphi dpopulation ,thi spopulatio nstop sincreasin gan dwithi na fe wweek sth ema ­ jorityo fth epopulatio ni sdestroyed .Th eparasit econtrol sth eaphi dunti lth een do f spring,whe nth ebalanc ema yb eupse tb yhyperparasites .Th epossibl eus eo fthi sparasit e mighttherefor eb erestricte dt owinte ran dspring . Thececidomyii d Aphidoletes aphidimyza preyso ngreenhous eaphid sfro mJun e (immigrating adultsfro moutdoo rpopulations )unti lOctobe r (starto fdiapause ,induce db yshor tphoto - period). Afte rartificia lintroduction ,thi spredato rca nb euse dfro mMarc honwards ,an d withprolonge dphotoperio ddurin gth eentir eyear .Method so fmas srearin ghav ebee ndevel ­ opedan dapplie di nRussi aan dFinland .Unlik esevera laphi dpredator sobserve di ngreen ­ houses,i testablishe sa permanen tpopulation ,s oon eo ronl yfe wintroduction spe rseaso n mayb enecessar y (Markkula& Tiittanen ,1977) .A singl epredato rlarv ama ycomplet edevelop ­ mentb yfeedin go nles stha n1 0aphids ,bu tkill sman ymor eaphid swhe ndensit yi shigh . (Markkula,pers .comm.) . Inhothouses ,w eobtaine drapi ddestructio no fpopulation so f Myzus persiaae and Aphis gossypii byintroducin gthi spredator .A tth emoment ,w ear estudy ­ ingth equalit yo fcontro la tlo waphi ddensity .

116 SIGNIFICANCE

Twofactor sinfluenc eth eus eo fintegrate dcontro li ngreenhouses .First ,th eavailabil ­ ityo feffectiv enatura lenemies ,togethe rwit ha metho do fmas srearin gan dintroduction , being P. persimilis againstspide rmite ,an d E. formosa againstwhitefly .Secondly ,th e availabilityo fapprove dspecifi cpesticide s (insecticidesan dfungicides) . T. urtioae and T. vaporariorum canb econtrolle db ynatura lenemies ,bu tno ti nal lcrop s (Table1) . TheKopper tcompan yproduce sbot hnatura lenemies .Fro mthi sproduce ro rhi sdealers , growersbu yth eagents ,an dspecialize dguidance ,whic h isessentia lfo rsuccessfu lbiolog ­ icalcontrol ,i sinclude di nth eprice .Stat eextensio nofficer sca ngiv emor egenera lin ­ formation.Guidanc eo nbiologica lcontro ldeal swit hrecognitio no fearl ysymptom so fpes t attack,introductio no fth econtro lagent ,estimatio no fth equalit yo fcontro lan dintegra ­ tionwit hchemica lcontro lo fothe rpest san ddiseases . Eachyear ,a governmenta l advisorycommitte efo rdiseas ean dpes tcontro l invegetable s issuesa plan tprotectio nguide ,whic hinclude sintegrate dcontro lscheme sfo rth efou r cropsmentione dabove .Th eguid eals ocontain sa tabl eprovidin gdat aabou tsusceptibilit y topesticide so fnatura lenemie san dhoneybee s (thisbook ,p .227) . Besidesgenera ladvantageou saspect so fbiologica lcontro l (laboursaving ;safet yfo r applicant,consume ran denvironment ;absenc eo fresistanc eproblems) ,ther ear esom especi ­ ficpositiv easpect si nit sus efo rgreenhouse s (see"Ai man dmotivation") .Thi sbranc ho f horticultureha shig h investmentan dca nachiev ehig hprofits .Becaus eo fthis ,ther ear e highdemand sfo rqualit yi nth eplant sa sproductio nunit san di nth efrui ta seconomicall y valuableparts .I nspit eo fthes edemands ,whic har eusuall ysee na slimitation sfo rbiolog ­ icalcontrol ,th eare awit hintegrate dcontro lha sincrease dmarkedl yi nth elas tseve n years (Table1) .

FUTUREOUTLOO K

Futureproject s forresearc hhav ebee nmentioned .Th eprospect s forapplicatio no fne w methodso fbiologica lcontro lar egood :grower sas kfor ,rel yo nan dus ebiologica lcontrol . Governmentalorganization sd oal lresearc ho nbiologica lcontro lan dextensio nwork ; othergovernmenta lorganization sprovid elegislatio nfo rpesticide suse dan dchec kcorrec t applicationb yth egrowers .Thi sstron ginfluenc eo nal lthes easpect sallow sth egovern ­ mentt odevelo pa nactiv epolic yo nbiologica lcontrol ,which ,t osa yth eleast ,i slackin g now,b y (1)organizin gan dstimulatin gresearc ho nbiologica lcontro lan dextension ,(2 )a betterchec ko nth eillega lus eo fpesticides ,an d (3)changin gth epolic yo npesticid eap ­ proval,tha ti saskin gth epesticid e industryt oprovid edat aabou tside-effect so fproduct s onnatura lenemie san dallowin gn one wchemical stha tinterfer eto ostrongl ywit hbiologica l control.

REFERENCES

Greathead,D.J. , 1976.A revie wo fbiologica l control inWester nan dSouther nEurope .C.I.B.C . Techn.Comm .7 ,Commonw .Agric .Bur. ,Slough . 182p . Hart,J . 't,J.d eJonge ,C .Collé ,M .Dicke ,J.C .va nLentere n& P .Ramakers ,1978 .Hos tse -

117 lection, host discrimination and functional response of Aphidius matricariae Haliday (Hymenoptera: Braconidae),a parasite of the green peach aphid, Myzus persicae (Sulz.). Med. Fac. Landbouwwet. Rijksuniv. Gent 43/2 :441-453 . Hussey, N.W. &L . Bravenboer. 1971. Control of nests in glasshouse culture by the introduc­ tion of natural enemies. In: C.B. Huffaker (Editor), Biological Control. Plenum Press, New York. p. 195-216. Lenteren, J.C. van,M.H . Eggenkamp-Rotteveel Mansveld &F.J.M . Ellenbroek, 1976. The para­ site-host relationship between Encarsia formosa (Hymenoptera: Aphelinidae) and Trialeuro- des vaporariorum (Homoptera :Aleyrodidae) .V . Population dynamics of Trialeurodes vapo- rariorum and Encarsia formosa in a glasshouse. Bull. O.I.L.B./S.R.O.P. 1976/4 : 151-164. Lenteren, J.C. van, J. Woets,N . van der Poel,W . van Boxtel, S. van de Merendonk, R. van der Kamp, H. Nell &L . Sevenster-van der Lelie, 1977.Biologica l control of the green­ house whitefly Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae) by Encarsia formosa Gahan (Hymenoptera: Aphelinidae) in Holland, an example of successful applied ecological research. Med. Fac. Landbouwwet. Rijksuniv. Gent 42 (2) :1333-1342 . Markkula,M . &K . Tiittanen, 1977.Us e of the predatory midge Aphidoletes aphidimyza (Rond.) (Diptera; Cecidomyiidae)agains t aphids in glasshouse cultures. Proc. XV Intern. Congress of Entomology, Washington, 1976.p . 41-44. Ramakers, P.M.J., 1978.Possibilitie s for biological control of Thrips tabaci Lind. (Thysa- noptera: Thripidae) in glasshouses. Med. Fac. Landbouwwet. Rijksuniv. Gent 43 (2):463-470. Woets, J., 1978.Developmen t of an introduction scheme for Encarsia formosa Gahan (Hymenop­ tera: Aphelinidae) in greenhouse tomatoes to control the greenhouse whitefly, Trialeuro­ des vaporariorum (Westwood) (Homoptera: Aleyrodidae).Med . Fac. Landbouwwet. Rijksuniv. Gent, 43 (2) :379-385 .

118 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 3.2 A strain of Phytoseiulus persimilis (Acari: Phytoseiidae) resistant to organophosphorus compounds

G.G.M.Schulte n

Departmento fAgricultura lResearch ,Roya lTropica lInstitute ,Amsterdam ,th eNetherlands .

INTRODUCTION

Thepredator ymit e Phytoseiulus persimilis isfrequentl yuse dfo rth econtro lo fspide r mitesi ngreenhouses .Th eus eo fthi spredato ri nintegrate dcontro lprogram si slimite d becauseo fit ssusceptibilit y topesticides .T oenlarg eth escop eo fintegratin gchemica l controlwit hbiologica lcontro lwit h P. persimilis, aselectio nprogra mfo rresistanc et o organophosphoruscompound swa sstarted .

WORKINGMETHOD S

Thebas epopulatio noriginate dfro ma smal lcultur etha tha dbee nmaintaine d inth elab ­ oratoryfo rExperimenta lEntomolog y (Amsterdam)fo rabou t4 years .Thi sstrai nwa sderive d fromth eorigina l P. persimilis straini nNaaldwij k (theNetherlands )abou tth etim eth e originalstrai nha dbecom eavailabl ecommercially . Thesusceptibl estrai nwa sobtaine dfro mth eGlasshous eCrop sResearc hInstitute ,Little - hampton,Sussex ,G.B . Selectionfo rresistanc ewa sdon eb yregula rsprayin go fbea nplant sinfeste dwit ha re ­ sistantstrai no f T. urticae andwit h P. persimilis with increasingconcentration so fpara - thion (a.i.)i nwater ,startin gwit h5 0mg/litre ,aime dt oobtai na 50-70 %mortalit ya t eachspraying . Susceptibilityt oth epesticid ewa steste db yth eslid edi pmethod .Twent yegg-layin g femalesabou t1 wee kol dwer estuc ko na slid ean ddippe dfo r1 mi ni nth einsecticida lso ­ lution.Mortalit ywa sdetermine dafte r2 4h .Durin gthi sperio dth eslide swer ekep tove r wateri na close ddessicato ra t2 5 C.Eac htes twa srepeate dfou rtimes . Forcrossin gprocedures , P. persimilis strainswer emaintaine do ndetached-lea fculture s with T. urticae asfoo da t2 5 Ca trelativ ehumidit y 70-80%.Fo rcrossin gexperiments , singleegg so rlarva ewer eplace do ndetached-lea fculture san dsom eday slate rmale so f theopposit estrai nwer eadded .A ssoo na seg gproductio nstarte dth efemale swer epoole d andthei rprogen ywa stested . Todetermin eth eeffec to fpesticid eresidue so neg gdepositio nan djuvenil edevelopmen t inth eresistan tstrain ,detache dbea nleave swer espraye dwit h 2m lo finsecticid esolu ­ tionwit ha spra y (Potter)tower .Th einsecticide steste dwer ecommerciall yavailabl eemul -

119 sifiableconcentrates ,whic hwer edilute dt oconcentration suse di npractice .Smal lcell s weremad eo f1-cm-thic kPlexiglas swit ha circula rhol e3 c mi ndiameter .Th eto po fth e cellwa sclose db ya smal lglas splat ean dth ebotto mb ya spraye dbea nlea fwhic hwa skep t freshwit hmois tfilte rpaper .Th elea fwa sinfeste dwit hresistan tspide rmite san da da y laterwit ha fertilize dfemal eo f P. persimilis. After4 days ,th emortalit ywa sassesse d andth enumbe ro fdeposite degg san djuvenile swa sdetermined .Eac hexperimen twa srepli ­ cated 15times .

RESULTSAN DDISCUSSIO N

After8 selections ,a strai nwa sobtaine dtoleran tt osprayin gwit hparathio n (a.i.) inwate ra t100 0mg/litre .Th esusceptibl estrai nsuccumbe dt o2 5mg/litre . Usingth eslid edi pmethod ,dosage—mortalit y lineswer edetermine d inth esusceptibl e andresistan tstrai nfo rparathio nan ddemeton-S-methyl .A resistanc efacto ro fove r10 0 wasfoun dfo rparathio nan do fabou t3 0fo rdemeton-S-methyl .Th eF io fth ecross :suscep ­ tiblex resistan tstrai nan dit sreciproca lha da simila rsusceptibilit yt oparathio nan d demeton-S-methyla sth eresistan tstrain .Testin go fth ebackcros s (susceptiblex resistant ) xsusceptibl eclearl yshowe dth epresenc eo ftw ocategorie so fsusceptibl ean dresistan t mites ina nalmos t 1: 1 rati oove rth econcentratio nrang eo f250-200 0an d125-20 0mg/litr e forparathio nan ddemeton-S-methyl ,respectively .S obot hresistance sar ecause db ya domi ­ nantmajo rfacto rfo rwhic hth esymbo lO Pha sbee nproposed . Thecommerciall yavailabl estrai nprove d latert ohav ea neve nhighe rresistanc etha n theselecte dstrain .Thi smake si tlikel ytha tothe rfactor sma ycontribut et oth eultimat e resistancea swell .Wit hth eslid edi pmethod ,th ecross-resistanc epatter nt oa numbe ro f insecticideswa sdetermined .Th eresistanc e factort oorganophosphoru scompound swa srathe r variable,e.g .parathio n> 143 ;diazino n292 ;demeton-S-methy l 33;mevinpho s2 3an dphospha - midon2 .N ocross-resistanc ecoul db eestablishe dt oth ecarbamat epirimicar bbu tb yanothe r testmetho d (onresidues )resistanc ewa sdetecte dt opropoxur .N ocross-resistanc ewa sfoun d toendosulfan ,lindan ean dPyrethrin s+ piperony lbutoxide . Bybreedin gth eresistan tstrai no nresidue sa sfoun dunde rpractica lcondition so fth e mentionedorganophosphoru san dcarbamat einsecticides ,i tcoul db edemonstrate dtha tth e resultantstrai nproduce dabou tth esam enumbe ro foffsprin ga so nuntreate dleaves . Anorganophosphoru sresistan tstrai no f P. persimilis canthu sb euse di nconjunctio n withothe rpesticide si nintegrate dcontrol .

REFERENCES

Schulten,G.G.M .& G .va nd eKlashorst .Genetic so fresistanc et oparathio nan ddemeton-S - -methyli nPhytoseiulu spersimili sA.H . (Acari:Phytoseiidae) .Proceeding sIV .Interna ­ tionalCongres so fAcarology ,Saalfelden ,Austria ,1974 .(i npress) . Schuiten,G.G.M. ,G .va nd eKlashors t &V.M .Russell ,1976 .Resistanc eo fPhytoseiulu spersi ­ milisA.H . (Acari:Phytoseiidae )t osom einsecticides .Z .ang .Ent .8 0 :337-341 .

120 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 3.3 Evaluation of the predacious mite Amblyseius bibens

L.H.M.Blommers 1 &W .Hell e

Laboratoryo fExperimenta lEntomology ,Universit yo fAmsterdam ,th eNetherlands .

INTRODUCTION

Thestud yo fth epredaciou smit e Amblyseius bibens Blommers (Acarina:Phytoseiidae ) followedo ninvestigation s inMadagasca ro nth efeasibilit yo fusin gloca lphytoseii dmi ­ tesfo rcontro lo fspide rmit ei ncrops .Th eactivitie si nMadagasca rreveale dth epresenc e ofsevera lne wphytoseii dspecies .A preliminar yevaluatio no fthes especie sdre wspecia l attentiont oth especie s A. bibens, whichi scommonl yfoun di nvariou sarea so fth eisland . Thefiel dstudie si nMadagasca rindicate dtha t A. bibens isa nimportan tmortalit yagen to f Tetranychus specieso ntruc kcrop san dcotto ni nmor ehumi dan dirrigate darea s(Blommers , 1976a). Theenvironmen to fgreenhouse si ntemperat ezone sseem st omee tth eabioti crequirement s for A. bibens tosom eextent .Investigation swer einitiate di nAmsterda mt oevaluat eth e useo fthi sspecie sfo rcontro lo fspide rmit ei ngreenhouses .W eexamine dreproductio nan d prédationo f A. bibens underexperimenta lconditions .Specia lattentio nwa spai dt oth estud y ofth esurviva lo f A. bibens atlo wdensitie so fprey .I ngreenhouses ,mit epredator shav e restrictednumber so fprey .Th egrea treproductiv ecapacitie so fphytoseii dmite san dthei r specificity towardsspide rmites ,coul deasil ycaus eextinctio nthroug hstarvation .Th eabil ­ ityo fa predato rt osurviv eperiod so fextrem escarcit yo fpre yi sa nessentia lconditio n forprolonge dregulatio no fspide rmite si na greenhouse .

EXPERIMENTSAN DRESULT S

Experimentso nth emite' slif ehistor ywer econducte di ncabinet sa tconstan ttempera ­ turean dhumidity ,usin glea fdisc so fharico tbean sfo rsubstrate .A sprey ,variou sstage s ofspide rmit ewer eoffere di nampl esupply . Thereproductiv equalitie so f A. bibens metth enumerica lrequirement sfo rsuccessfu l controlo fal l Tetranychus species,particularl ya thighe rtemperature san dhumiditie s (Fig.1 an dTabl e 1). Becauseth enatura lmortalit ywa salmos tzer oi nwel l fedjuvenile s andyoun g females,th espee do fdevelopmen t (eggt oegg )an deg gproduction ,plu sth e sexratio ,suffice d forth eestimatio no fth eintrinsi crat eo fnatura lincreas e [r ). max

1.Presen taddress :Laborator yo fParasitology ,Universit yo fLeyden .

121 15 20 25 30 35 temp(°C) Fig. 1.Maximu mpopulatio ngrowt h (percentagepe rda y= 10 0( em -1))i n A. bibens and2 ofth emos tprolifi cspide rmite si nrelatio nt otemperature .6 = A. bibens atrelativ e humidity 70%;+ = Tetranychua oinnabarinus atrelativ ehumidit y38 %(afte rHaza ne tal. , 1973);x = T. urticae atrelativ ehumidit y50 %(afte rGutierrez , 1974).Humiditie sar enea r optimum.

The r to1 7° C(Fig .1 )wa sestimate di nthi sway .Becaus eth edevelopmenta lspee d andth edail yeg gproductio no fyoun gfemale sincrease dalmos tlinearl ywit hth etem ­ peraturei nth erang e 17t o3 1 C,th etemperature-tim esu mca nb euse dt oestimat e a reliable r incondition so fchangin gtemperatures . A. bibens attacksal lstage so fth espide rmite ,bu ttend st ofee dpredominantl yo n Tetranychus eggs.Th erat eo fconsumptio no fpre yegg swa srelate dlinearl yt oambien ttem ­ peraturesbetwee n1 7an d3 1°C .Thi srelatio nca nb edescribed :numbe ro fpre yegg scon ­ sumedpe rda yi s1. 3time sth evalu eo ftemperatur ei ndegree sCelsiu sminu s19.3 . Therate so fincreas ei nexperiment so npotte dplant scorresponde dt oth e r , calcu­ latedfro mresult sobtaine dwit h individualpredator so nlea fdiscs .Th emaximu mrat eo f increasea sdetermine dexperimentally ,represent sth erea lrat eo fincreas eo f A. bibens inth epresenc eo fsufficien tprey .Ordinar ycontro l (=exclusion )method stogethe rwit h theresult smentione ds ofa rwil lmos tprobabl ypermi tu st oforecas tquantitativel yth e abilityo fthi sphytoseii dmit et ochec koutbreak so f Tetranychus sp.i noperationa lsitua ­ tions. Whether A. bibens isals oabl et omaintai nlo wdensitie so fpre ymor epermanentl yi s

Table 1.Averag e fecundity,maximu m lengtho fovipositio n periodan dintrinsi crat eo fincreas eo f A. bibens at3 temperatures.Relativ ehumidit y 70^ 10% . Temp. (uc) 22 25 29

Fecundity (eggs/o) 65.0 64.1 62.4 Ovipositionperio d (days) 43 27 23 r (intrinsicrat eo fincrease ) 0.242 0.326 0.434

122 Table2 .Averag e fecundityan d durationo fovi - positioni nrelatio nt oth enumbe ro ffres hegg s of spidermit eoffere ddail y toindividua lfemal e predators.Temp .2 5° Can drelativ ehumidit y 70%.N =numbe ro fobservations .

Preyoffere d Fecundity Oviposition (eggs/day) (eggs/?) period (days) N

20 57.1 20.1 8 10 58.7 23.1 9 5 56.5 47 2

stillope nt oresearch .Wherea sthi sspecie sha sa pronounce dappetit efo rtetranychids , itaccept spolle no fvariou splant swhe nth epreferre dpre yi sabsent .Althoug hpropagatio n inpollen-fe d A. bibens isslow ,a mass-rearin gexclusivel ywit hpolle no f Vicia f aba on detachedleave scoul db econtinue d forove ra year .A nexperimen to npotte dplant sindica ­ tedtha tth epresenc eo fpolle nenable sth epredato rpopulatio nt osurviv ean dmultipl yi n theabsenc eo fprey . Life-tablestudie sshowe dtha t A. bibens hasa nextraordinaril y longlife-span .Th epro ­ portiono ffemale saliv ea tth een do fth eovipositio nperio dunde ridea lcondition s is0. 8 ormore .Th epost-ovipositiona lperiod sar ea slon ga s 1month ,compare dwit ha duratio no f theovipositio no fhardl y3 week sa t2 9°C .Wherea ssuc ha nextende d life-spani sclearl y oflittl eus eunde ridea lconditions ,i tseem so fmajo rimportanc eunde rcondition so fpre y scarcity.I ti srelate dobviousl yt oth efacult yo fnumerica lresponse ,becaus ei tpermit s themaintenanc eo ffecundit yove ra wid erang eo fsuboptima lpre ydensitie s (Table 2). The longpost-reproductiv e life,a spresent sitsel funde rampl epre yconditions ,reflect si n factth ereproductiv eopportunis mo f A. bibens. Thisphenomeno nprovide s— inou ropinio n — circumstantialevidenc eo nth eadaptednes so fthi spredato rt ocondition so flo wpre y density. Adela yi nreproductio nca nals ob eachieve db y limitationi nsper msupply .I n A. bibens, nofor mo fparthenogenesi soccurs ,egg sbein gproduce donl yafte rfertilization .I fmatin g ishel du ptil lmid-life ,th etota leg gproductio ni sachieve di nth esecon dhal fo fth e lifetime.

DISCUSSION

Indiscussin gth eapplicabilit y of A. bibens forcontro lo fspide rmit eunde rgreenhous e conditions,i ti sappropriat et ocompar e Phytoseiulus persimilis Athias-Henriot.Thes e phytoseiidshav emuc h incommon .The yar ebot hspecialize dpredator so ftetranychi dmite s withgrea treproductiv ean dpredator ycapacities .Bot hca nexterminat ecolonie so fspide r mitei nth egreenhous e ina shor ttime . P. persimilis isth emos tprolifi cspecies ;it s maximumrat eo fincreas eexceedin gtha to f A. bibens, especiallya thig htemperatures .I n situationswher eth eai mi sonl yinstantaneou scontrol , P. persimilis ist ob epreferred . Theresul tis ,however ,ephemeral ,sinc ethi sphytoseii dwil lbecom eextinc tbecaus eo fit s completedependenc eo ntetranychi dprey .Re-infestatio nb yspide rmites ,therefore ,ha st o befollowe db yre-introductio no f P. persimilis.

123 Althoughals oa specialize dpredator , A. bibens hasa definit echanc eo fsurvivin gpe ­ riodso flo wpre ydensity .I nth eabsenc eo ftetranychi dmites , A. bibens willaccep tal ­ ternativefood ,a sdemonstrated .S oi nscheme sfo rintegrate dcontro l ingreenhouses ,thi s speciesi sa candidat e forregulatio no fspide rmites .

REFERENCES

Blommers,L. ,1976a .Som ePhytoseiida e (Acarina:Mesostigmata )fro mMadagascar ,wit hde ­ scriptionso feigh tne wspecie san dnote so nthei rbiology .Bijdr .Dierk .4 6 :80-106 . Blommers,L. , 1976b.Capacitie s forincreas ean dprédatio ni nAmblyseiu sbiben s (Acarina: Phytoseiidae).Z .ang .Ent .8 1 :225-244 . Blommers,L. ,P .Lobbes ,P .Vink ,& F .Wegdam , 1977.Studie so nth erespons eo fAmblyseiu s bibens (Acarina:Phytoseiidae )t ocondition so fpre yscarcity .Entomophag a2 2 :247-258 . Gutierrez,J. , 1976.Etud ebiologiqu ee técologiqu ed eTetranychu sneocaledonicu s (Acariens, Tetranychidae).Travau x& Document sO.R.S.T.O.M . 57.17 3p . Hazan,A. ,U .Gerson ,& A.S .Tahori ,1973 .Lif ehistor yan dlif etable so fth ecarmin espi ­ dermite .Acarologi a 15: 414-440 .

124 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 3.4 Genetics of resistance in spider mites from rose houses

W.P.J.Overmee r& W .Hell e

Laboratoryo fExperimenta lEntomology ,Universit yo fAmsterdam ,Amsterdam ,th eNetherlands .

DESCRIPTION

Soonafte rparathio nha dbee nintroduce di n195 0fo rpes tcontro li nth eglasshous eare a ofAalsmeer ,Holland ,spide rmite sdevelope dresistance .Withi ntw oyears ,parathio nresist ­ ancewa sfull yestablishe di ntha tarea .Thereafte rth espide rmit epopulation sbecam ere ­ sistanti nsuccessio nt omor eeffectiv eorganophosphoru scompound ssuc ha sdemeto nan d azinphos-methyl,t ospecifi cacaricide ssuc ha stetradifon ,chlorobenzilate ,chloropropylat e anddicofol ,an dfinall yt obinapacryl ,withi na perio do f1 5years .Non eo fthes ecompound s waseffectiv efo rmor etha nthre eyears . In196 6a ne wspecifi cacaricide ,dienochlor ,wa spu to nth emarke tfo rus eo nornamen ­ tals,an dthi scompoun dha sbee neffectiv eeve rsinc eit sintroduction .N ocase so fresist ­ ancet odienochlo rhav ebee nreporte ds ofar . Thesuccessio ni ndevelopmen to fvariou stype so fresistanc earouse dinteres ti nth ege ­ neticso fresistance .Mor eknowledg eo fth egenetic so fresistanc ei nspide rmite smigh t shedligh tupo nproblem si nchemica lcontro l ingreenhouses .

WORKINGMETHOD S

Resistancewa sanalyse dgeneticall yb ymean so fMendelia ncrosses .A favourabl epoin t ingeneti cstudie so fspide rmite si stha treproductio ni sbase do narrhenotoky .Unmate d femalesproduc ehaploi d (male)offsprin gonly ,wherea smate dfemale sproduc ehaploi dan d diploid (malean dfemale )offspring .Thi speculiarit y allowsspecia lcrossin gscheme sfo r analysis.B ymas scrossin go fsusceptibl et oresistan tspide rmite san db ytestin gth e hybridsan dth ehaploi dprogen yo fth ehybrid ssuccessivel ywit ha serie so fdosage so f thepesticide ,a direc tanalysi so fth egeneti cbasi sshoul db eobtained . Byrepeate dbackcrossin gwit hsusceptibl emale sa srecurren tparen tunde rinsecticid e selectionpressure ,th egene(s )fo rresistanc ear eintroduce dint oth egenom eo fth esus ­ ceptiblestrain ,a tleas ti fth etyp eo fresistanc e isinherite ddominantly .B yproducin g astrai nthereafte rtha ti shomozygou sfo rth eresistanc egene(s) ,th eprope rcharacteris ­ ticso fth egene(s )fo rresistanc eca nb estudied .Informatio nca nthe nb eobtaine dabou t thedegre eo fprotectio ntha tth egen eo rgene sprovide ,th ecross-resistanc epattern ,an d thefitnes so fth ebeare ro fth egene(s) .

125 Whereth eactio no fa pesticid eagains tadult swa sstudied ,tox ico logica ltest swer e performedb yexposin gadul tfemale st oth eresidu eo nth eleave so fpesticide-treate dbea n plants,th efemale sbein gkep ti nPlexiglas scage so nth eleave s (Helle,1962) ,o rb yth e slide-diptechniqu e (Schulten,1968) ,i nwhic hadul tfemale swer eglue ddorsall yt odouble - sidedstick ytap etha twa s fixedo nmicroscop eslide san ddippe di nsuspension so fth epes ­ ticide.Th eresidu emetho dwa sals ouse dfo rselectio na tdiscriminatin g dosages,als ot o selectmale si frequired . Theactio no fovolarvicide swa smeasure db ysprayin gegg stha tha dbee nlai do ndetache d beanleave splace do nwe tcotto nwool .Leave swit heggs ,eithe rpurel yhaploi degg so rmix ­ tureso fhaploi dan ddiploi degg swer etreated .Tota lmortalit ywa smeasured ,i.e .mortalit y ofegg san djuvenil estage s (Overmeer,1967) .

RESULTSAN DDISCUSSIO N

Resistancet oparathio nprove ddu et oth eoperatio no fa singl enearl ydominan tgen e (Helle,1962) .Cross-resistanc ewa sfoun dt oinclud eals oothe rorganophosphoru scompounds . Populationstha twer ehomozygou sfo rthi sgen ewithstoo da concentratio no fparathio nsom e 250time sa shig ha sfo rsusceptible ,a smeasure db yth eresidu emethod .Th eresistanc e factorfo rdiazinon ,wa so fa simila rmagnitude ,abou t200 .Schulte n (1968)confirme dthes e resultsb yth eslide-di ptechnique .H efoun dtha tth egen efo rresistance ,whic hh ecalle d OP,wa sals oresponsibl e fora decrease dsensitivit ytoward sothe rorganophosphates ,suc h asdemeto nan dazinphos-methyl .However ,th eresistanc e factorswer emuc h lower,1 2fo r demetonan d1 1fo razinphos-methyl .Schulte ndemonstrate dtha ta hig h levelo fresistanc e toth elatte rcompound swa sdu et oth eactio no fmodifiers .Th egen eOP ,however ,i sbasi c forresistanc et oal lorganophosphates . Theunderlyin gmechanis mfo rO Presistanc e isa naltere dCholinesteras etha ti sles s sensitivet oorganophosphates .Thi styp eo fresistanc e iscommo ni nAalsmeer ,a selsewher e inth eworld .Anothe rtyp eo fO Presistance ,base do na nincrease drat eo fhydrolysis , whichwa sfoun di nth eUSA ,ha sno tbee nfoun di nth eNetherlands . Schulten (1968)demonstrate dalleli crelationship sbetwee nth eresistanc efactor si n differentstrains .H efoun dtha ttw odifferen tallele sar et ob edistinguished ,whic hh e calledO P andO P ,respectively .Competitio nexperiment sreveale dtha tO P gavea sligh t disadvantaget oit sbeare rcompare dwit hth e+ allele ,wherea sO P didnot .Fo rtha tinves ­ tigation,homozygou sbackcros sstrain swer eproduce di nwhic hO P andO P ,respectively , wereintroduce d intoth egenom eo fS . Resistance isgenerall yassume dt ob epreadaptive ,resistanc egene sarisin ga sa conse ­ quenceo frando mmutation .I fprolonge dselectio ni sapplied ,fo rinstanc eus eo finsecti ­ cidesfo rcontro lpurposes ,resistan tpopulation sca narise .I na nattemp tt omeasur eth e mutationfrequenc yfo rsuc ha resistanc egene ,a nambitiou sprogra mwa sconducted .Startin g froma 100° &susceptibl ecolony ,w ebre da larg enumbe ro findividual san dteste dthe mdail y overa perio do fapproximatel yon eyear .Som e3. 4millio nindividual swer eteste dfo rO P resistancea ta diagnosti cdosag eo fparathion ,bu tn opositiv eresult swer eobtained ;al l descendantso fth ecolon yappeare dsusceptibl et oorganophosphates . Resistancet otetradifo ntoo klonge ri nappearin g inth eAalsmee rare atha nt oparathion ,

126 threeyears .Als oher eresistanc ewa sfoun dt ob ebase do na singl enearl ydominan tgene . Theresistanc efacto rwa smor etha n20 0 (Overmeer,1967) . Testsfo rallelis mindicate dtha tresistanc et otetradifo nsuc ha sthi si nvariou spopu ­ lationswa sdu et oa mutatio na tth esam elocus .Cross-resistanc ewa sfoun dt oinclud eCPA S andanimert ,bu tno torganophosphates ,dicofo lno rchlorbenside .Th egen efo rtetradifo n resistancedi dno tsee mdisadvantageou st oit sbearer . Alsofo rresistanc et otetradifon ,a nattemp twa smad et omeasur eth emutatio nfrequenc y starting froma 100° ssusceptibl ecolony .Ove r 1millio negg shav ebee nteste di nsuccessiv e generationswit ha lo wdiscriminatin g dose,bu tn oresistanc eha sbee nobserved . Bycontrast ,i na searc hfo rvisibl emutation sa tou rlaboratory ,ther ewa sa mutatio n rateo f1 0 h foralbinis man dwhit eey ei na ninitiall y 100°sgenotypicall ywil dtyp ecolony . Resistancet odicofo lwa sdu et oa singl enearl yrecessiv egene .Th egen eprovide dit s carrierwit ha resistanc e factoro fabou t 15.Cross-resistanc ewa sfoun dt ochlorobenzilat e andchloropropylate ,bu tno tt oothe racaricide so rorganophosphates .Dr .J.E .Cranha m foundresistanc et obinapacry lt ob eunde rmonogeni ccontro l (Helle& Overmeer ,1973) . Sofa rn oresistanc eha sbee nfoun dt odienochlor .Occasionall ysample so fpopulation s weresen tt oou rlaborator ysuspecte do fshowin gdecrease dsusceptibility ,bu ti ntoxicolo - gicaltest sther ewa sn osig no fresistance .

FUTURE

Atpresent ,chemica lcontro lo fspide rmite so nornamental s inglasshouse s iswit h dienochloronly .Spide rmite sar esubjecte dt oorganophosphate s aswell ,whe nth egrowe r usessuc hcompound sagains tothe rpests .Bu tspecifi cacaricide sothe rtha ndienochlo rhav e beendiscontinue di nros ehouses .I fresistanc et odienochlo reventuall yarises ,furthe r investigations intopesticid eresistanc ei nspide rmite sma yb enecessary .However ,w eca n onlyspeculat ewhethe rresistanc et odienochlo rwil leve rappear .

REFERENCES

Helle,W ., 1962 .Genetic so fresistanc et oorganophosphoru s compoundsan d itsrelatio nt o diapausei nTetranychu surtica eKoch .Tijdschr .PIZiekt .6 8 :1-41 . Helle,W .& W.P.J .Overmeer , 1973.Variabilit y intetranychi dmites .A .Rev .Ent . 18: 97-120. Overmeer,W.P.J. , 1967.Genetic so fresistanc e totedio ni nTetranychu surtica eC.L .Koch . Archsneer .Zool . 17: 295-349 . Schulten,G.G.M. ,1968 .Genetic so forganophosphat e resistance inth etwo-spotte dspide r mite (Tetranychusurtica eKoch) .Publication so fth eRoya lTropica l Institute,Amster ­ dam,th eNetherland s5 7p .

127 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 3.5 Induction and termination of diapause in the spider mite Tetranychus urticae

A.Veerma n

Laboratoryo fExperimenta lEntomology ,Universit yo fAmsterdam ,th eNetherlands .

INTRODUCTION

A largebod yo fliteratur eha saccumulate do nth eecolog yan dcontro lo fth espide rmit e Tetranychus urticae. Diapauseha sbee nstudie di nsom edetail .Knowledg eo fth efactor sin ­ ducingan dterminatin gdiapaus e iso fimportanc efo rmethod so fcontro lo fman ypes tspecie s intemperat e zones.A mor eprofoun dstud yo fth ephysiologica lmechanism so finitiatio nan d terminationo fdiapaus ei n T. urticae wasinitiate dafte rpreliminar yexperiments ,whic hdem ­ onstrated agrea tsensitivit y tophotoperiod .Wor ko ndiapaus ewa sals ostimulate db yth e presencei nou rLaborator yo fa serie so funiqu epigmen tmutants ,whic hwer eexpecte dt ob e usefulfo rth eanalysi so fth efirs tstep so fth einductio nprocess .Notwithstandin git s fundamentalnature ,th eresearc ho nspide rmit ediapaus ewa sinclude di nth eproject so f theIntegrate dContro lWorkin gParty ,sinc ei twa sfel ttha ti tmigh tlea dt oa ne wmean s ofcontrol ,especiall yi ngreenhouses . Themai naim so fthi sstud ywer et oanalys eho wphotoperio dan dtemperatur eexer tthei r combinedinfluenc edurin ginductio nan dterminatio no fdiapause ,t oidentif yth epigment s involvedi nphotoperiodi cinduction ,an dt oanalys eth emechanis mo freceptio no fphoto ­ periodi nspide rmites .Thi spape rsummarize sresult ss ofar .

RESULTSAN DDISCUSSIO N

In T. urticae, onlyadul tfemale sma yunderg oa facultativ ediapause ,induce db yshort - -dayphotoperiod sdurin gth elarva lan dnympha lstages .Th emos tconspicuou scharacteristi c ofth ediapaus ei sth edee porang ecolou ro fth ediapausin gfemales ,a scompare dwit hth e greenish-yellowo fth e 'summer'females .Thi schang ei ncolou ri sbase do na mor etha ntwo ­ foldincreas ei nth eketocarotenoi dconten to fdiapausin g females (Veerman,1974) .Furthe r differences fromth esumme rfor mar emorphological ,physiologica lan dbehavioral ,th emos t importantbein garres to ffeedin gan doviposition . Thephotoperiodi c responseo f T. urticae iso fth elong-da ytype ,showin ga sharpl yde ­ finedcritica ldaylengt ho f 14h i nth estrai ntested .Th erespons ecurv efo rinductio no f diapausei nthi sstrai nshow sa remarkabl etrait ,whic hthes emite shav ei ncommo nwit h onlya fe wspecie so finsects .I nconstan tdarkness ,diapaus ei sno tinduced ,bu twit ha photoperiodwit hligh tan ddar kphase so f1 an d2 3h ,diapaus eincidenc ei salread ycomplet e

129 (Veerman,1977a) .Thi sabrup tchang eo fth erespons ebetwee n0 an d 1h ligh tpe rda yin ­ dicatestha tphotoperiodi c timingstil lproceed sa tunnaturall yshor tdaylengths ,bu ti s notoperativ eunde raperiodi ccondition s likecontinuou sdarknes so rcontinuou slight . Theinfluenc eo ftemperatur eo ndiapaus einductio nwa sinvestigate d ina serie so fex ­ periments,i nwhic ha thermoperio dwa sapplie di ncombinatio nwit ha photoperio do ri ncon ­ tinuousdarkness .Wit hshor tdays ,diapaus einductio nwa sabolishe dcompletel yb yconstan t temperatureo f2 5 Can dabove ,whil ea t1 5 Cdiapaus eincidenc ewa scomplete .Combinatio n ofligh tan ddar kphase so f1 2h eac hwit htemperatur ephase so f1 5an d2 5 C,whic halter ­ natedregularl ya tth elight/dar kan ddark/ligh ttransitions ,strongl yinduce ddiapaus ewhe n thelo wtemperatur ecoincide dwit hth escotophase ,bu tdiapaus eincidenc ewa snegligibl eun ­ derth ereverse dconditions .S oonl yth edar kphas eseem stemperature-responsiv e fordiapaus e inductioni n T. uvtioae. Whenth emite swer eexpose dt oth esam ethermoperio di nconstan t darkness,n odiapaus eoccurred ,whic hdemonstrate sth eabsenc eo fa thermoperiodi cresponse . Althoughtemperatur einfluence sdiapaus einductio ni nthes emite s toa considerabl eextent , lowo rperiodicall y fluctuatingtemperature salon ed ono tinduc ean ydiapause .Whe nth ecom ­ binedinfluenc eo ftemperatur ean dphotoperio di sconsidered ,temperatur eappear st ohav e onlya modifyin geffect ,whic hemphasize sth epredominatin g importanceo fphotoperio dfo r theinductio no fdiapaus ei nthi sspecie so fspide rmites . Evidence forth efunctiona linvolvemen to fcarotenoid s inth ephotoperiodi creactio no f spidermite swa sobtaine di ngeneti cexperiment swit hsom ealbin omutant so f T. urtiaae. Diapauseinductio ni shampere d inalbin omites ,th ediapaus eresponse so ffou ralbin omu ­ tantsrangin gove r0 - 80° si ndifferen ttest sunde rexperimenta lcondition swher eal lothe r pigmentmutant sa swel la sth ewil dtyp estrain ssho wa 100 %diapause .Th eabilit yt odia ­ pausecoul dno tb eimprove di nalbin ob yselectio nfo rdiapaus eove rsi xgenerations ,no r bya serie so fback-crosse s towil dtype ,sotha tth ealbin olocu smus texer ta pleiotropi c effect,influencin gbot hpigmentatio nan ddiapaus einduction .I ncrosse sbetwee nwil dtyp e andalbino ,ful ldiapaus ei nalbin owa sachieve donl yi fth ealbin odaughter scam efro m hybridphenotypicall ywil dtyp emothers .Apparentl ya materna leffec ti sresponsibl efo r thecomplet einductio no fdiapaus e inalbin ofemale s (Veerman& Helle ,1978) .S omaternall y derivedcarotenoid sar eprobabl yutilize db yth eembry oi nth eformatio no fa recepto rpig ­ mentconcerne di nth einductio no fdiapause . Animportan tquestio ni nresearc ho nphotoperiodis mi sstil lho worganism smeasur eth e lengtho fda yo rnight ,ofte nwit hsuc hprecision .A curren thypothesi sattibute sa centra l rolei nth etimin gmechanis mo finsect st ocircadia nrhythms ,bu ti nsom ecase sso-calle d 'hourglass'mechanism shav ebee nfoun da swell .Th emai ndifferenc ebetwee nbot htheoretica l mechanismso ftim emeasuremen ti stha tth e 'hourglass'mechanis mrequire sa ne wstartin g pulseever ytim ei tcomplete sa tim emeasuremen t (the 'hourglass'ha st ob e 'turnedover') , whereasth ecircadia noscillation snee dt ob estarte donl yonce ,afte rwhic hthe yma yru n forsevera lo rman ysuccessiv ecycles .T oanalys eth ephotoperiodi ctim emeasuremen ti n spidermite sa mathematica lmode lha sbee ndeveloped ,consistin go ftw ointeractin g'clocks' , bothoperatin gaccordin gt oth e 'hourglass'principle .Th emode lshow sa goo dfi tfo rth e photoperiodicrespons ecurv ean dfo ra numbe ro fothe rexperiment sbase do na perio dlengt h of2 4h .Thes econsis to fnigh tinterruptio nexperiment swit h 1h 'lightbreaks' ,whic hsys ­ tematically 'scan'throug hth edar kphase ,an dexperiment si nwhic hphotoperiod sar eapplie d

130 containing twoligh tpulse so fequa l duration,on eo fwhic h 'moves'throug hth edar k inre ­ lationt oth eother .Th eresult so fnigh tinterruptio nexperiment s in T. urticae showa remarkablesimilarit yt othos eobtaine dwit hsom especie so finsects .Tw odiscret epoint s ofsensitivit y toth eligh tbreak swer ereveale di nth elon gnigh to fa photoperio dwit h lightan ddar kphase so f1 0an d 14h .On epoin to fsensitivit yoccur searl yi nth enigh t anda secon d latei nth enight .I nth emiddl eo fth enigh tsensitivit y toligh tinterrup ­ tionsseem sconsiderabl y less.Th egrea tsensitivit yt oligh tinterruption san dth eshar p responsesmak eth estrai no fmite suse d inth eexperiment seminentl ysuitabl e foranalysi s ofth emechanis mo fphotoperiodi ctim emeasuremen t inspide rmites .Th evalidit yo fth e methematicalmode lwil lb eteste di nfurthe rexperiment swit h 'ahemeral'photoperiods ,i n whichth ecycl e lengthi seithe rlonge ro rshorte rtha n2 4h . Diapause in T. urticae isterminate di nnatur eb ya perio do fchilling .However ,dia ­ pausedevelopmen tha sbee nshow nt ob eunde rphotoperiodi ccontro l aswel l (Veerman,1977b) . Inth efirs ttw omonth so fdiapause ,mite sca nb ereactivate db yexposin gthe mt olon gday - lengthsan dtemperature so f17-2 3 C,shor tdaylenght sbein gfa rles seffective .Fo r examplea t 17°C ,hal fth emite sterminate ddiapaus ei nlong-da ycondition safte ra col d resta t4 ° Co nonl y8 days ,bu ti nshort-da ycondition sdiapaus ei nhal fth etes tpopula ­ tionwa sterminate donl yafte ra col dres to f5 4days .Thes eexperiment sshowe dtha tadul t femaleso f T. urticae arestil lsensitiv et ophotoperiod ,a tleas tdurin gth efirs tfe w monthso fdiapause .Abou t2. 5mont hafte rth ebeginnin go fdiapause ,th ephotoperiodi csen ­ sitivityo fdiapausin g femalesha dapparentl ydisappeared ;th ecomplet epopulatio nwa s reactivated fromtha tmomen ti nshor to rlon gdays .Sinc eth emite shav elon glos tthi s photosensitivity inth esprin gwhe ndiapaus eterminate si nnature ,th eecologica lsignifi ­ canceo fthi ssensitivit yo fdiapausin gmite st ophotoperio d isno tt ob esough ti nth e terminationo fdiapause .Rathe ri tseem st ob efunctiona li nretainin gth ediapaus estat e inth eautumn ,whe noccasiona lwar mday smigh tbrea kdiapaus ei npar to fth epopulation , whiledurin gth ewinter ,diapaus ewoul db esustaine dan dprolonge db yprevailin glo wtemper ­ atures.Thi svie wi ssupporte db yth efac ttha tth ephotoperiodi cmechanis mwork sonl ya t highertemperatures ,bu ti sabsen tdurin gth ecol dres ta t4 C.Fo rth eterminatio no f diapause,a respons ecurv ecoul db edetermine db yexposin gdiapausin gmite stha tha dspen t 20day si ncol dstorag et odifferen tphotoperiod s at1 9 C. Inth erang eo fecologicall y significantdaylengths ,thi srespons ecurv eappeare dalmos tt omirro rth erespons ecurv e forinduction .Th ecritica ldaylengt h fordiapaus eterminatio ncorresponde dalmos texactl y withtha tfo rdiapaus einduction .Thes eresult ssee mt oindicat etha tth esam ephotoperiodi c mechanismi sa twor kbot ha tth einductio no fdiapaus ei nlarva ean dnymphs ,an ddurin gdia ­ pausei noverwinterin gfemales .

Althoughpractica lapplicatio no fth eresult si nno tye tfeasible ,furthe rresearc ho n diapausei nspide rmite si scertainl ypromising .

REFERENCES

Veerman, A., 1974.Carotenoi d metabolism in Tetranychus urticae Koch (Acari:Tetranychidae) . Comp. Biochem. Physiol. 47B : 101-116. Veerman,A. , 1977a.Aspect s of the induction of diapause in a laboratory strain of the mite Tetranychus urticae. J. Insect Physiol. 23 :703-711 .

151 Veerman,A. , 1977b. Photoperiodic termination of diapause in spider mites.Natur e 266 :526-52 7 Veerman, A. &W . Helle, 1978.Evidenc e for the functional involvement of carotenoids in the photoperiodic reaction of spider mites.Natur e 275 :234 .

132 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 3.6 Isolation mechanisms in populations of spider mite in rose houses

W.P.J.Overmeer ,A.Q .va nZo n& W .Hell e

Laboratoryo fExperimenta lEntomology ,Universit yo fAmsterdam ,th eNetherlands .

STABILITYO FACARICID ERESISTANC E INGREENHOUS EPOPULATION S

Theintroductio no fth eacaricid edienochlo rabou t196 6pu ta sudde nen dt oth eproble m ofcontrollin gspide rmit ei nros ehouse si nth eAalsmee rdistrict .A ttha ttime ,resistanc e tosevera lacaricide se.g .severa lorganophosphoru scompounds ,tetradifon ,chlorobenzilate , dicofolan dbinapacryl ,ha dbecom ewidesprea dan dinterfere dwit hadequat econtro lo fth e two-spottedspide rmite , Tetranychus urtiaae particularly inros ehouses .Dienochlo rprove d tob ehighl yeffectiv eagains tth emultipl yresistan tmites ,an dafte r196 6onl ydienochlo r hasbee nuse dfo rspide rmit econtro li nros ehouses .Specifi cacaricide ssuc ha stetradifon , chlorobenzilatean ddicofo lwer ediscarded .S oselectio nfo rresistanc et oth eacaricide si n greenhousepopulation scease di n1966 .Th equestio naros ewhethe rabsenc eo fselectio ni n thesepopulation swoul dresul ti nreversio nt osusceptibility .T oobtai ninformatio nabou t thisprocess ,sample sfro mte npopulation so f T. urtiaae werecollecte dfro mros ehouse s inth eAalsmee rdistric ti n1973 ,an dhav ebee nreare dsinc ethe nunde rlaborator ycondi ­ tionsa sseparat estrains .A simila rprocedur ewa s followedfo rmit epopulation scollecte d fromoutdoo rplants ,suc ha selder ,nettle ,ground-iv yan drose ,a tdifferen tdistance s fromros ehouses .Wit ha serie so fdosage so fpesticide s (parathion,teradifo nan ddicofol) , dose-mortalitycurve sfo reac ho fth estrain swer eworke dou t (Overmeer,e tal. ,1975 ;Va n Zon& Overmeer ,1975) . Theresult so fth esurve yca nb esummarize da sfollows . Populationssample dfro mgreenhouse sshowe dpartia lresistanc et oparathion ,tetradifo n anddicofol .A hig hfrequenc yo fresistan tphenotype soccurre dfo rparathion ,a sexpecte d sincecholinesterase-inhibitor s arestil luse di nmos tgreenhouse sfo rcontro lo fothe r pests.Bu tals ofo rtetradifon ,hig hfrequencie so fresistan tphenotype soccurre di nmos t samples.Fo rdicofol ,resistan tphenotype swer efoun di n9 o fth e1 0sample sexamined ,i n varyingfrequencies . Sampleso fpopulation stake nfro moutdoo rplant sexhibite dful lsusceptibilit y topara ­ thion,tetradifo nan ddicofol ,a slon ga sth esample sha dbee ntake nsom edistanc efro ma greenhouse. Themos tsalien tconclusio ni stha teradicatio no fspide rmite scanno tb eachieve db y regularchemica lcontro love ra perio do fmor etha nsi xyears .Gene sfo rresistanc et otet ­ radifonan ddicofo lca nb econsidere da sgeneti cmarker s forrose-hous epopulations ,an d

133 specificallytypica l forpopulation soriginatin g in196 6an dbefore .Th epresenc eo fthes e genesi n1973 ,roughl y 100generation s later,unequivocall ydemonstrate stha tresiden tpop ­ ulationsmaintai nthemselve si nspit eo fintensiv echemica lcontro lmeasures . Asecon dconclusio ni stha timmigratio n fromoutsid eseem sinsignificant ,i fon econsid ­ ersth erelativel yhig hfrequencies ,fo rinstance ,o ftetradifon-resistan tphenotypes . Thesefinding swer ereaso nt oinvestigat eth efactor stha thampe rintrogressio nfro m outside.Thre epoint scom et oth efore .Th efirs ti swhethe rmite sfro moutsid eca nreadil y integrategeneticall y intoa greenhous epopulatio nan dmi xwit hit .Th esecon dpoin ti s whetherth eecologica lcondition so fa greenhous eca nb ewithstoo db yth eimmigrants .Th e thirdi swhethe rth eoccasiona lus eo forganophosphoru scompound sma yretar dreversio nt o susceptibility ingeneral .Thes epoint swil lb econsidere dbelow .

HYBRIDSTERILIT Y

Whencrossin gdifferen tstrain so f T. uvtiaae , thehybri dfemale sma yexhibi tsom ede ­ greeo fsterility :par to fth eegg s (F2)produce db ythes ehybrid sd ono thatch .A nestimat e ofthi skin do fhybri dsterilit yca nb egive nb yth epercentag eo funviabl ehaploi degg s producedb yunmate dhybri dfemales .I ncrosse swithi na strain ,th epercentag eunviabl e eggsi susuall yles stha n5'» ,bu ti ncrosse sbetwee nstrains ,th epercentag ei sconsider ­ ablyhighe ran dma yb eu pt o100» . Overmeer& Va nZo n (1976)investigate dnin edifferen tpopulation ssample dfro mros ehous ­ esi na nare ao fnearl y2 5km 2 inth eAalsmee rdistrict .Reciproca lcrosse sbetwee nthes e populationswer emade ,implyin g 72combinations ,an dth edegree so fsterilit ywer eestimated . Theresult sar estriking .Eac hpopulatio npossesse d itsow ngeneti cidentit ysinc epar ­ tialhybri dsterilit ywa sfoun dt ooccu ri nal l7 2combinations .I n3 8o fth ecombinations , lethalityo fth ehaploi degg sexceede d 50%,an dsom ecombination sha dcompletel yunviabl e eggs (100$mortality) .Simila rhybri dsterilitie sexis tbetwee nindoo ran doutdoo rpopula ­ tionsi nth eAalsmee rare a (VanZo n& Overmeer ,1975) . Theresult sraise dth equestio nho wfa rhybri dsterilit ywa sa norma lfeatur efo radjacen t populationso f T. urticae. Sow einvestigate dth egeneti ccompatibilit ybetwee n T. uvtiaae populationsfro mwil dplant swithi na nare ao f2 5km 2 inth edune si nHolland . Thestud yreveale dtha tcrosse sbetwee n T. uvtiaae fromdifferen thollow s inth edune s dono tresul ti nhybri dsterility :practicall y allgav ea full yviabl ehaploi dF 2.S ohybri d sterilityi n T. uvtiaae mayb etypica lfo rpopulation so ncrops ,fo rinstanc ei ngreenhouse s butth eorigi no freproductiv ebarrier si sstil lobscure . T. uvtiaae isregularl ytranspor ­ tedove rlarg edistances ,an dth epopulation s ingreenhouse sma yb eo fdifferen tgeographi c origin.Howeve rthe yma yb eendemic ,reproductiv ebarrier shavin gbuil tu pb yspatia lan d ecologicalisolation . Wefirs tsuspecte dchromosoma lrearrangement sa sreaso nfo rth egeneti cincompatibilit y betweenpopulation s (Helle& Overmeer , 1973),bu trecen texperiment shav eshow ntha tth e basiso fhybri dsterilit yi sprobabl ygeni ean dno tchromosoma l (Overmeer& Va nZon ,1976) .

134 ABILITYT ODIAPAUS E

Thegreenhous eenvironmen tholds ,a necologica lparado xfo r T. urtioae: shortday si n theautum ninduc ediapause ,bu tth erequire dperio do fchillin gnecessar yfo rreactivatio n ofth ediapausin gfemale si sabsen ti nheate dros ehouses .A surve y (VanZo n& Overmeer , 1975)showe dtha t T. urtioae populationsfro mros ehouse sd ono trespon do rno tfull yt o short-daytreatment .Th epopulation sfro moutdoor srespon dnormall yb yenterin gdiapause . Inrose ssubjecte d toa restin gperio di nth ewinter ,th emit epopulatio nbelongin gt oi t appearedmixe di nabilit yt odiapause .I nros ehouse sheate dthroughou tth ewinter ,dia ­ pausewa sinduce donl yi na lo wpercentag eo fth epopulation .Doubtless ,immigran tmite s fromoutsid ear etrappe db yth epeculia renvironment ,whic hact sa sa necologica lbarrie r betweenth egreenhous epopulatio nan doutdoo rpopulations .

INSECTICIDESELECTIO N

T. urtioae fromros ehouse si sresistan tt oorganophosphoru scompound swherea sloca l mitesfro mwil dplant sar enot .I nfact ,th elatte rar ever ysensitiv et omos to fth e cholinesterase-inhibiting pesticidesuse di nros ehouses .Ther ei sn ocross-resistanc et o tetradifonan ddicofol ,an dth eresiden tpopulation so fth emid-sixtie scanno tb econsidere d homozygouslyresistan tt oth ethre epesticide smentioned .Howeve rth eus eo forganophos ­ phoruspesticide sundoubtedl y increasedth efrequenc yo fth egene sfo rresistanc et otetra ­ difonan dt odicofol ,a sindicate db ycompariso no fth efat eo fmultipl yresistan tindivid ­ ualsan dsusceptibl eimmigrants .An yreversio nt osusceptibilit ywil ldefinitivel yb ere ­ tardedb yth eus eo forganophosphoru scompounds .

DISCUSSION

Comparativestudie so npopulation so f T. urtioae ingreenhouse san doutdoor sreveale d thatfre eintrogressio no floca l T. urtioae materialfro moutdoo rplant sint oresiden tros e housepopulation sar ehampere di fno tprevente dfo rvariou sreasons . T. urtioae fromros e housesi sresistan tt oorganophosphoru scompound swherea s localmite sfro mwil dplant sar e not,i nfac tth elatte rar ever ysensitiv et omos to fth echolinesterase-inhibitin gpesti ­ cidesuse di nros ehouses . Anisolatin gmechanis mi sth edifferen tresponse s towardsshort - -daycondition so fresiden tan doutdoo rmaterial .A considerabl ereproductiv ebarrie rpro ­ tectsth erose-hous epopulatio nagains tintrogressio nfro moutdoo r T. urtioae. Thedegre eo fisolatio no fresiden tgreenhous epopulation san dth eabilit yo fresiden t populations tosurviv eintensiv echemica lcontro love rlon gperiod sar easpect stha tde ­ servespecia lattention .Studie so nho wt oeradicat eresisten tgreenhous epopulation sfro m timet otim ear efel tmos tappropriate .A possibl eexterminatio no fmultipl yresistan tmi ­ tesb yan yalternativ emetho dwoul db efa rmor eusefu ltha nregulatio no fpes tnumber sb y chemicals.

135 REFERENCES

Helle, W. &W.P.J . Overmeer, 1973.Variabilit y in tetranychid mites. A. Rev. Ent. 18: 97-120. Overmeer,W.P.J . &A.Q .va n Zon, 1976.Partia l reproductive incompatibility between popu­ lations of spider mites.Entomologi a exp. appl. 20 :225-236 . Overmeer,W.P.J. , A.Q.va n Zon &W . Helle, 1975.Th e stability of acaricide resistance in spider mite (Tetranychus urticae) populations from rose houses.Entomologi a exp. appl. 18 :68-74 . Zon, A.Q. van &W.P.J . Overmeer, 1975.Th e occurrence of pesticide resistance in red spider mite populations (Tetranychus urticae Koch) collected fromwil d plants in the glasshouse district of Aalsmeer, the Netherlands. Z. ang. Ent. 79 :213-222 .

136 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 3.7 Genetic control of the greenhouse spider mite Tetranychus urticae

A.M.Feldman n

Institutefo rAtomi c Sciencesi nAgricultur e (ITAL),Wageningen ,th eNetherlands .

Since 1965,differen tgeneti cmethod so feradicatin gspide rmite s Tetranychus urticae ingreenhouse shav ebee nseriousl yconsidere di norde rt ocounte rth eestablishmen to fsuc ­ cessivetype so fresistanc et opesticide s inresiden tpopulation s (Section3.6) .Hell e& Pieterse (1965)foun dpartia lincompatibilit ybetwee nadjacen tgreenhous epopulation so f T. urticae. Theide aaros etha tincompatibilit yresultin gfro ma cros sbetwee na translo ­ cationhemizygou smal ean da wild-typ e femalecoul dreduc eth epopulatio nfertilit ys o muchtha tthi scoul db euse di ncontrol .Th eeffectivenes so fthi smetho dcoul db eincreas ­ edsignificantl y ifi twer epossibl et oreleas etranslocatio nhemizygou smale swhic hwer e alsoresisten tt oa nacaricid et owhic hth epes tpopulatio nwa ssusceptible .A fundamental conditionwa stha ta 100° sincompatibilit ybarrie rb ecreate dbetwee nth erelease dmateria l andth ewild-typ emateria li norde rt opreven tescap eo fth eresistenc egene sint oth ewil d population.Hig hincompatibilit ybarrier sdi dno toccu ri nnature ,s oartificia linductio n ofchromosoma ltranslocation swa sattempted .Th einductio nb yX-ray so fstructura lchromo ­ somalaberration san dbreedin gthe mfo rhomozygosit ywa sver ysuccessful .Th eai mo ffindin g astructura lchromosom emutatio nwit ha 100 »reductio ni nfertilit yi nheterozygou scondi ­ tionwa sno tachieved .Howeve rfundamenta lknowledg eo fth eradiobiologica lpropertie so f T. urticae wereseriousl ylackin gan dothe rtopic so fgeneti ccontro lneede dt ob eevalua ­ ted.Thi sresearc hfiel dwa sassigne dt om ei n1971 .

RADIOBIOLOGICALSTUDIE S

Theradiobiologica lstudie sdemonstrate dtha tsignificantl ydifferen tresult swer eob ­ tainedafte rirradiatio no feithe rsper mo roocyte swit hX-ray so rneutrons .Th edos ere ­ quiredt oobtai nsteril emale swa s 240G yan d16 0G yfo rX-ray s andneutrons ,respectively . Femaleswer esterilize db y8 0G yfo rneutron sbu tfo rX-ray sa highe rdos ewa sneeded .Man y heritableeffect s (structuralchromosom emutation san drecessiv e lethals)wer einduce di n spermbu tno ti noocytes .T oinduc eheritabl eeffect si nsperm ,X-ray swer emor eeffectiv e thanneutrons .Irradiatio nwit hX-ray so fmatur esper ma t4 0G yresulte di nfull ysteril e Fifemales ,wherea sth esam edos eo fneutron st osper mlef t8 1o fth efemale sstil lfertile . Thedos eo f4 0G yo fX-ray si ssuitabl efo robtainin gsemisteril emales ,whic hca nb euse d ina geneti ccontro lprogram .Howeve rther ewa sa significan tincreas ei nmal efertilit y within7 day so firradiatio ntreatment .A significan tincreas ei nF jfemal efertilit ywa s

137 observedi nth esuccessiv ebrood sfro mth eirradiate dmales .Studie so ncompetitio ni nmal e matingshowe dtha tirradiatio no fmale swit h4 0G yo fX-ray s impairedmatin gan daccelerate d ageing.S ofurthe rstudie so nth efeasibilit yo fth esteril einsec ttechnique sha dt oawai t resultsfro mstudie so nothe rtopic so fgeneti ccontro lbefor ea prope rassessmen tcoul db e madeo fwhic hmetho dshoul db estudie di nmor edetail . Thenex tobservation so nth einductio no fstructura lmutation so fchromosome swer erele ­ vantt oth eus eo fth etranslocatio ntechniqu efo rpes tcontrol .Afte ra doz eo f1 5G yo f X-rays tosperm ,ther ewa sa maximu mpercentag eo fstructura lchromosom emutation sassocia ­ tedwit hrecessiv e lethals.Th efrequenc yo fassociatio no frecessiv e lethalswit ha struc ­ turalmutatio nwa sver ylo wafte ra dos eo f1 0G yo fX-ray st osperm ,wherea sth epercent ­ ageo fstructura lmutation swithou trecessiv elethal swa smaximu ma ttha tdose .Thi si s animportan tobservatio nbecaus ei ti sdifficul to rimpossibl et oobtai na chromosoma lre ­ arrangementhomozygou si frecessive d lethalsar eassociate dwit hsuc ha rearrangement .Neu ­ tronso fenerg y 1.5Me Vwer eles seffectiv etha n25 0kV pX-ray so f25 0ke Vpea kvalu efo r inductiono fstructura lchromosom emutation safte rirradiatio no fmatur esperm .

TRANSLOCATIONTECHNIQU E

Experimentswer estarte dt oobtai n 17lines ,homozygou sfo rdifferen tchromosoma lre ­ arrangements.Th eline swer ethe ncrosse dwit heac hothe ran dwit hwil dtype .Som eo fth e linesshowe dver yhig hfitness .Hig hlevel so fincompatibilit ywer efound .N ocros swa s 100%incompatible ,a snecessar yfo ra successfu lapplicatio no fthi smethod .S oi twa sthe n decidedt ore-irradiat ea line ,homozygou sfo ra structura lmutatio ni norde rt oisolat e lineswit hhighe rincompatibility ,du et oa mor eintricat echromosoma lrearrangement .Fou r lineswer eobtaine dhomozygou s fora structura lchromosoma lrearrangement .Thei rlevel so f incompatibilitywer ehighe rtha nbefore .Th edecreas ei nfitnes so fth ene wline scas t doubto nwhethe rre-irradiatio no fstructura lchromosom emutatio nhomozygou s lineswa sth e bestwa yo fcreatin g lines.I tremain sdebatabl ewhethe rline swit h 1001incompatibilit y canb eobtaine db yirradiatio no fsperm .A muc hlarge rtes twoul db eneede dt oanswe rtha t question.A positiv eresul to fth ewor ki stha tgoo dan dstabl elines ,homozygou sfo ra structuralchromosom emutation ,ca nb eobtaine db yirradiatio no fmatur esper mwit hX-ra y orfas tneutrons .

POPULATIONDISPLACEMEN T

Apreliminar yassessmen to fth eabilit yo fa strai nhomozygou s fora structura lchromo ­ somemutatio nt odisplac ea wild-typ epopulatio nwa smad eb yestimatin g life-tabledat a andcompetitivenes so fmale si nmating . Thelif ecycl ewa sstudie dt ocompar eth ewil dtyp ewit ha particula rstrai nhomozygou s fora structura lmutatio ntha tshowe dver ygoo drearin gcharacteristics .Bot hstrain sha d thesam erat eo fdevelopmen tan dabou tth esam eproductivit yunde rstandardize dexperimen ­ talconditions .Th eintrinsi crat eo fincreas e (r) fo rth ewil dtyp ean dth enewl ysynthe ­ sizedstrai nwer e0.26 4an d0.278 ,respectively . Behavioraldifference sbetwee nstrain sescap equantitativ ecomparisons ,thoug hthe yar e

138 nextt oth elatte ro fparamoun timportanc efo rth esucces so fpopulatio ndisplacement .Th e studieso fmal ematin gcompetitivenes so fth esam epromisin g linetha twa suse dfo rth e lifetabl estudie sshowe dtha tthi slin eha da reductio no fonl y 121.Th eage-dependen tre ­ ductioni nmatin gcompetitivenes swa sn odifferen tfro mth ewil dtype . Studieso nfitnes strait sshowe dtha tpopulatio ndisplacemen to fth ewil dkaryotyp eb y thenewl ysynthesize dkaryotyp ewa spossibl ei fth ereductio ni nmatin gcompetitivenes so f thene wstrai nwa sartificiall ycompensated . Theexperiment swer eperforme db yreleasin ginseminate dfemale so fbot hth estandar d strainan do fa strai nhomozygou sfo ra structura lchromosom emutatio no n3 whol ebea n plants {Phaseolus spp.)a tthre edifferen tinitia lratios ,10:10 ,13: 7an d16: 4fo rth e femaleswit hchromosom emutation san dstandar dfemales ,respectively . Of 14line steste ds ofar ,3 showe da nunstabl eequilibriu maroun d6S°4 .Fixatio no fth e rearrangedkaryotype si nth eexperimenta lpopulatio nwa sobserve da ta ninitia lreleas e ratioo f80 %o fth erearrange dkaryotype . Equilibriumo reithe rslo wfixatio no rexterminatio no fth erearrange dkaryotype so f these3 line swa sobserve da ta ninitia lrati oo f65% .Rapi dexterminatio no fth erearran ­ gedkaryotype sfro mth eexperimenta lpopulatio nwa sobserve dfo ral l1 4line steste da ta n initialrati oo f S0%. Sensitivityanalysi so nsom epopulatio nparameter si ncompute rsimulatio no fkaryotyp e displacementreveale dtha tth eprobabilit yo fa femal ematin gwit ha mal eo fcorrespondin g genotypei sth epivo tfo reithe rfixatio no rexterminatio no fa genotype .Th eprobabilit y ofdisplacemen to fth estandar dkaryotyp eb ya rearrange dkaryotyp ewa ssignificantl yin ­ creasedi fmale so fth elin ewit hchromosom emutatio nwer erelease dwhe nth efirst-genera ­ tiontenera lfemale sappea ri nth epopulation .Th epopulatio nexperiment sshowe dtha tth e releaseo fmale swit hchromosom emutatio nincrease dsignificantl yth eprobabilit yo fpopu ­ lationdisplacemen to fth estrai nwit hth ecorrespondin gchromosom emutatio ni fth einitia l releaserati oo fth echromosom emutatio nfemale swa sclos et oth epoin to funstabl eequilib ­ rium (0.65).

OUTLOOK

Atth emoment ,experiment sar egoin gon ,designe dt oisolat econditiona l lethals,mor e specificallytemperature-sensitiv e lethals.Conditiona l lethals,suc ha stemperature-sen ­ sitivelethals ,ca nb einduce di na larg enumbe ro fgenes .B ytreatin ga line ,homozygou s fora structura lmutatio nwit ha mutage n (ionizingradiatio no rethylmethanesulphonate )a varietyo fposition so nth echromosom eca ncontai na temperature-sensitiv e lethal.I ti s verylikel ytha tsom eo fthes elethal sar es oclosel yassociate dwit hth ebreakag epoin t ofth erearrangement ,tha trecombinatio nwit hth ewil dallel ei sabsent .Afte rbreedin g thesetemperature-sensitiv e lethalstrue ,ther ei sa prospec to fpractica lapplication . Becauseo fth eshor tgeneratio ntim ean dth elarg enumbe ro fgeneration spe ryear ,popula ­ tiondisplacemen to fa residen tgreenhous epopulatio no f 1, urtiaae shouldb epossibl e withina fractio no fa yea rwit htemperature-sensitiv epopulation .Th eus eo ftemperature - -sensitive lethalsa sa contro ltechniqu e ispromisin g forapplicatio ni ngreenhouses ,be ­ causeo fisolatio npropertie san do fth eartificiall ytemperature-controlle d greenhouse

139 environment. Cost-benefit analysis as an indication of economical feasibility for different greenhouse crops must await greenhouse trials.

REFERENCES

Feldmann, A.M. 1979.Fundamenta l aspects of genetic control of the two spotted spider mite Tetranychus urticae (Acari:Tetranychidae) .Thesis ,Amsterdam . 150p . Feldmann,A.M.,1978 .Dose-respons e relationships and R.B.E. values of dominant lethals in­ duced by X-rays and 1.5-MeV neutrons in prophase-1 oocytes and inmatur e sperm of the two-spotted spider mite Tetranychus urticae Koch (Acari:Tetranychidae) .Mutat . Res.: 361-376. Feldmann,A.M.,1977 . Mating competitiveness and the effect of X-rays and ageing on males of Tetranychus urticae (Acari:Tetranychidae ) in relation to genetic control. Entomolo- gia exp. appl. 21 : 182-191. Feldmann,A.M.,1975 .Inductio n of structural chromosome mutations inmale s and females of Tetranychus urticae Koch (Acari:Tetranychidae) .In : Sterility Principle for Insect Con­ trol 1974, IAEA, Vienna, STI/PU3/377.p .437-445 . Helle,W . &A.H . Pieterse, 1965.Geneti c affinities between adjacent populations of spider mites. Entomologia exp. appl. 8 :305-308 .

140 4 Insect-host plant relations

Researcho nth ecause so fplan tinfestatio nb yinsect sha ssevera laspects .Ther ei sth e problemo fho windividua linsect srecogniz ecertai nplant sa sacceptabl ehosts ,analysi s ona populatio nleve lo fnutritiona lrelationship sbetwee na ninsec tspecie san dit shost , andpopulation-dynami c consequenceso fsuc hinteractions .Thes evariou s levelshav ebee n investigatedb ysevera lentomologist s inclos ecooperatio ni nth elaboratory ,unde rstand ­ ardizedcondition si nth efiel dan dunde rnatura lconditions .Thes estudie sinclud eanalysi s ofth esensor yphysiolog yo ffeedin gbehaviou r (4.1,4.2) ,effect so fvariation so fth e nutritionalstatu so fcro pplant so npopulatio ndevelopmen to finsect s (4.3)an dmite s(4.4 ) andth eeffec to ffoo dqualit ya sa consequenc eo fhos tplan t localityan dhost-plan tdens ­ ityo ninsec tfecundit yan dpes toutbreak s (4.5).

141 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980.

4.1 Host-plant selection in the Colorado potato beetle

J.H.Visse r& J .d eWild e

Departmento fEntomology ,Agricultura lUniversity ,Wageningen ,th eNetherlands .

Moretha na centur yago ,th eColorad opotat obeetl e Leptinotarsa decemlineata wasa n innocuous feedero nbuffal obu r Solanum rostratum, onth efoothill so fth eRock yMountain s inNort hAmerica .Th ecultivate dpotat o Solanum tuberosum wasthe nintroduce dint oit shab ­ itat.Thi sne wfoo dsourc eturne dou tt ob equit eacceptable ,initiatin ga nextensio no f thebeetle' sterritor yeastwards ,eve nacros sth eAtlanti cOcean ,t oEurop ewher eth eCo ­ loradopotat obeetl ewa sreporte da searl ya sth e1920 si nth eBordeau xregio no fFrance . Asth edispersa lo fthi sne winsec tpes tove rEurop ebrough tabou tsubstantia ldamag et o potatoproduction ,th ebeetle' sspecialize dfeedin ghabit ssoo nattracte dattention . Initiallya basi cquestio nwa swha tmake spotat ofoliag eacceptabl ean dwh yar enon - -solanaceousan dsevera lsolanaceou sspecie srejecte dfo rfeedin gan doviposition .Nowadays , inobservin gth ecomple x interactionso finsect san dplants ,i ti srealize dtha tan yattemp t togiv ea nunambiguou sanswe rt othi squestion ,woul doversimplif yth eproces so fhos tse ­ lection.Throug ha lon gperio do fassociatio no fth egenu s Leptinotarsa witha numbe ro f solanaceousspecies ,an dunde rth econstan tactio no fnatura lselection ,bot hth enutritio ­ nalrequirement san dfeedin ghabit so fth eColorad opotat obeetl ehav eadapte dt oth echem ­ icalcharacter so fit sfoo dplants .Th epotat oprove dt ofulfi lth ebeetle' sphysiologica l requirements- bein gsuitabl ean dacceptable- ,an da tpresen tpotat ocrop sar eth emai n foodresourc efo rmaintainin gthi sinsec tpes ti nmos to fit sterritory . Nevertheless,fro mtim et otim eth ebeetle slac kfood .Fo rinstanc ebecaus eo fcro pro ­ tation,post-diapaus ebeetle semerg ei nnon-hos tplan tcrop san dhav et osearc hfo rsuita ­ bleplants .Hencefort hthes ebeetle shav et orel yo nthei row nabilitie st ofin dthei r hostplants ,i ndirectin gthei rfeedin gan dovipositio nac ttoward sparticula rplan tspe ­ cies.Beside sbehaviora lcomponent so fexploratio ni nspac etim ei sa nessentia laspec ti n hostselection ,sinc ei nth ecours eo ftim eth eproportio nan dconstitutio no fsuccessiv e generationsar eaffecte db yth evariou sdegree st owhic hplant smee tth ephysiologica lre ­ quirementso fbot hlarva ean dadults . Thepresen tpape rfocuse sattentio no nth erestrictiv eelement si nspac ean dtime ,a s deducedfro ma serie so finvestigation s inth eNetherland sove rthirt yyears .Th esequenc e ofevent si nhos tselectio nfollow srathe rth ehistorica ltha nth efunctiona lline ,i nor ­ dert oexplai nth eprogres si nou runderstandin go fthi sinsect-hos trelationship .I nthi s way,th epape remphasize stha tever ysingl eeven ti sa decisiv eelemen ti nth eestablismen t ofth eColorad opotat obeetl eo na particula rplant .Th epape rdraw sou tsom eo fth eprin -

143 ciplesi nth eassociation so fphytophagou s insectswit hfoo dcrops .

LARVALFEEDIN GAN DGROWT H

Thelarva eo fth eColorad opotat obeetl eexhibi tremarkabl ediscriminativ epowers ,appar ­ entfro mth eextrem epreferenc efo ra fe wspecie so fsolanaceou splants .Th elarva estarv e todeat hi nth eabsenc eo fsuc hpalatabl efoo dplants .Fo ra prope runderstandin go fth e wordpalatable ,observation so nth ebehaviora lpattern sar ebriefl ysummarize d (Chin,1950 ; DeWilde ,1958) . Theodou ro fth eresistan tplan t Solanum demissum isa sattractiv e toth elarva ea sth e odouro fpotat ofoliage .Afte rcomin gint ocontac twit hth eleaves ,th elarva ebit ethi s newsubstratum ,thei rbitin grespons ebein ginitiate db yth eodour .However ,contrar yt o thefeedin gactio nperforme do npotat ofoliage ,th elarva ed ono tfee dcontinuousl yan d spendmos to fthei rtim erestin gan dwandering .Fo rfeeding , S. demissum isrejecte db y thelarvae .Beside s S. demissum, anumbe ro fothe rsolanaceou sspecie sd ono tposses son e ofth eessentia lqualitie so fth enorma l foodplants,a nacceptabl etaste .Th eselectiv e feedinghabit so fth elarva ear ecause db yavoidanc eo fdeterren tfactor si na rang eo f solanaceousspecies .Thes efactor shav ebee nattribute dt oa typica lclas so fsecondar y plantsubstance sdistribute di nSolanaceae ,i.e .alkaloid san dthei rparen talkaloid-gly - cosides. Petunia hybrida isa nexampl eo fth esolanaceou sspecie stha tcaus eadvers eeffect si n anotherway .Larva ear eattracte db yth eodou ro f Petunia leavesan do narriva lthe yea t arelativel ylarg eamoun to fth efoliage .Howeve r Petunia ispoisonou san dfeedin gkill s thelarvae .Unlik eth eavoidanc eo ffeedin go n S. demissum, feedingactio ni sno tprevented . Apparentlyth emai nadvantag efro mrejectio no funpalatabl especie si savoidanc eo ftoxi c principles.Th etoxi cnatur eo fsecondar yplan tsubstance sseem st ob eth eprincipa lrea ­ sonfo rth eselectiv efeedin ghabit so fth elarvae . Thenutritiv eingredient so fplant sar eessentia lfo rfeedin gan dgrowt ho fphytophagou s insects.Th enutritiona lrequirement so fth eColorad opotat obeetl einstar shav ebee nstud ­ iedwit hartificia ldiet s (Wardojo,1969) .Thes erequirement sd ono tdiffe ressentiall y fromth erequirement so fman yothe rphytophagou s insects,feedin go na diversit yo fplan t species.Howeve rth esuitabilit yo fth edie tt osuppor tgrowt hclosel ydepend so nth econ ­ centrationratio so fth eindividua lnutrients .Beside sthi smetaboli caspect ,th eac to f feedingha sa behaviora laspect .Th eamoun tconsume di saffecte db yth eproportion so fsev ­ eralnutrient s (Ritter,1967) . Throughperceptio no fbot hsecondar yplan tsubstance san dnutrients ,poisonin gan dmal ­ nutritiono fth elarva ear eprevented .I ngeneral ,youn glarva ehatc hfro mth eeg gpod ,de ­ positedb yth efemal eColorad obeetl eo nth eprope rfoo dplant .Eve nso ,ther ei sn oques ­ tionabou tth eadvantag eo fdiscriminativ epowers ,i fon eexamine sth eprobabl ecasualties , whenlarva efal lt oth egroun ddurin gheav yrain so rru nou to ffood .Larva eremove dfro m theirfoo dplan tsearc hi na rando mfashio nunti lthe yar eguide db yolfactor yan dopti c stimuli.The ybit eth esubstrat ean ds oar einforme do fit schemica lan dphysica lproper ­ ties.

144 ADULTFEEDING ,OVIPOSITIO NAN DEXPLORATIO N

Inth eacceptanc eo fsuitabl efeedin gan dovipositio nsite sth eadult sar eeve nmor ese ­ lectivetha nth elarvae .Th eprinciple sunderlyin g theacceptanc eo fthei rsolanaceou shost s seemt orequir ediscriminatio no fth esam echemica lcharacteristic sa srequire di nth ese ­ lectivefeedin ghabit so finstars .Th ebe-al lan dend-al lo fadul tlif ei sreproduction .Th e numbero fegg sdeposite do nplant ssuitabl efo rlarva lfeedin gan dgrowt hreflect sth ede ­ greet owhic hindividua lbeetle sovercom eth erestrictiv eelement s inspac ean dtime . Lacko falignmen to fadul tfeedin gan dovipositio nha sbee nobserve di nth eovipositio n preference for Solanum luteum (Bongers,1970) .Whe nfemal eColorad opotat obeetles ,pre ­ viously fedo npotat oplants ,ar egive nth echoic ebetwee nth efoliag eo fpotat oan dleave s of S. luteum, theysho wa marke dpreferenc e forovipositin go nth elatte rplant .However , inth ecours eo ftime ,th ebeetle' sfecundit yi ssuppresse dsinc efeedin go n S. luteum is avoided.Thoug h S. luteum ispreferre dt opotat oa sa novipositio nsubstratum ,reproductio n onthi sspecie s- successio ni ntim e- i simpeded . Explorationi nspac ei sthough tt ob eessentia lfo rfindin go fhos tplants .Th eodou r ofsolanaceou sspecie srelease sa nupwin glocomotor yrespons ei nColorad opotat obeetles , whichbring sth ebeetle s inth evicinit yo fthes eplant s (Visser& Avé , 1978). Inothe r words,throug holfactor ydiscriminatio nove ra lon grange ,exploratio n ist osom eexten t confinedt oa relevan tpar to fth evegetation .Chemica lanalysi so fpotat oplan todou rre ­ vealedth ecomple xo f 'generalgree nlea fvolatiles' ,lik ecis-3-hexen-1-ol ,cis-3-hexeny l acetate,trans-2-hexena lan dtrans-2-hexen-1-ol .Th econcentratio nratio so fthes evolatil e componentsar edecisiv e forth ereleas eo fa positiv eanemotacti crespons ei nth eColorad o potatobeetle .Whe nth eparticula rrati oi nthi scomple xi schange dartificially ,th ere ­ leaseo fth eupwin dlocomotor yrespons ei sprevented .Complexe so fth e 'generalgree nlea f volatiles'for ma predominan taspec to fal llea fodours ,discernabl ei nth edifferen tan d particularconcentratio nratios .I nmixe dvegetation ,interactio no fth edifferen tlea fo - doursmigh tpreven tth ereleas eo flong-rang eolfactor yorientation ,i nthi swa yhidin g plantsfro minsects .Thi sconceptio nmigh tgiv ea ne wdimensio nt oth eonse to fhost-plan t selection,a sth ebeetle' sabilit yt oexplor ei nspac ei sno taffecte db yth ehos tplant' s spatialdistribution ,bu tals ob yth eheterogeneit yo fplan todou ri nth evegetation .

CONCLUSIONS

Thesequentia lorde ri nth eproces so fhos tselectio ni sillustrate di nFigur e 1.Th e gapsbetwee nth eline ssymboliz eth einstan ta plan tcharacte rfulfil son eo fth ephysiolo ­ gicalrequirement so fa particula rinsect .A sdemonstrate d inth elarva lfeedin gac to n S. demissum and P. hybrida, andi nth eovipositio npreferenc e for S. luteum, non-hostspe ­ ciesoccasionall ymee tsom eo fth ephysiologica l requirementso fth eColorad opotat obeetl e butthes especie sar edevoi do fothe rcrucia lqualitie s (Fig. 1).Th eschem eindicate stha t bothnutrient san dsecondar yplan tsubstance s- antibiotic s- ar eth eprincipl ebarrier s forfeeding ,growt han dreproductio no finsect so nth emajorit yo fplan tspecies .I nth e Coloradopotat obeetle ,successiv ebehaviora lpatter shav ebee nevolve dt oevad enon-hos t species,whos elac ko ffitnes sbecome sapparen ti nth ecours eo ftime .Throug hthis ,th e

145 Host Selection

Insects

- Olfactory - Visual

-Tactile/proprioceptive - Gustatory

- Nutrients

-Tolerated antibiotica

Host Plant

5''

Fig. 1.Genera l scheme of host selection in phytophagous insects. Thewidt h of a gap between lines symbolizes the specificity of a particular plant character that meets one of the physio­ logical requirements of an insect.Host-plan t selection in the Colorado beetle is illustrated in the centre arrow, leading to reproduction on Solanum tuberosum; whereas the unfitness of non-host plants is shown by the other two situations, e.g. in the light arrow the 'unpalata- bility'o f S. demisswn.

selection process involves a secondmajo r aspect,exploratio n in space.Th e alignment of events inspac e and time,o f successive behavioral patterns andplan t characters favourable for reproduction, determines the process ofhos t selection.

REFERENCES

Bongers, W., 1970.Aspect s of host-plant relationship of the Colorado beetle.Meded . Landb- hogesch. Wageningen 70-10. 77 p. Chin, CT., 1950.Studie s on the physiological relations between the larvae of Leptinotarsa decemlineata Say and some solanaceous plants. Tijdschr. PIZiekt. 56 : 1-88. Ritter, F.J., 1967.Feedin g stimulants for the Colorado beetle.Meded . Rijksfac. Landbouw- wet. Gent 32 :291-305 . Visser, J.H. &D.A . Avé, 1978.Genera l green leaf volatiles in the olfactory orientation of the Colorado beetle,Leptinotars a decemlineata. Entomologia exp. appl. 24 :738-749 . Wardojo, S., 1969.Som e factors relating to the larval growth of the Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae) on artificial diets. Meded. Landbhogesch.Wageninge n 69-16. 75p . Wilde, J. de, 1958.Hos t plant selection in the Colorado beetle larva (Leptinotarsa decem­ lineata Say).Entomologi a exp. appl. 1 : 14-22.

146 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 4.2 Role of chemoreceptors in host-plant recognition by insects

L.M. Schoonhoven

Depto fAnima lPhysiology ,Agricultura lUniversity ,Wageningen ,th eNetherlands .

NOINSEC TATTACK SAL LPLANT S

Oneo fth ecrucia lfeature sabou tinfestation so fplant sb yinsec tpest s isth especi ­ ficityo fth erelation sbetwee ninsect san dthei rfoo dplants .Eve n 'polyphagous'specie s dono tfee do nal lplant san dsho wclea rpreference sfo rcertai nplan tspecie swithi nthei r hostspectrum .Thes egeneralists ,however ,ar efairl yrar ei nth einsec tworld . Morespecialize dinsects ,lik eth elarva eo fth elarg ewhit ebutterfl y (Vieris brassicae) andColorad opotat obeetles ,woul drathe rdi eo fstarvatio ntha nfee do nnon-hos tplants . Apparentlythei rhos tplant scontai nsomethin gtha tstimulate sfeedin gan di sabsen tfro m non-hostplants .Whe nsom echemical stypicall yoccurrin gi ncertai nplant s (likesinigri n incabbag ean dothe rcruciferou splants )becam eavailable ,abou t6 0year sago ,E .Verschaf ­ feltshowe dtha tvariou sinsec tspecie srecognize dthei rhos tplant sb ythes ecompounds . Meticulousbehaviora lobservation sb yV.G .Dethier ,G.S .Fraenke lan dother shav eextende d knowledgeabou ttypica lsecondar yplan tsubstances ,no tonl ya sattractant st osom einsect s livingo nth eplant scontainin gthem ,bu tals oa sdeterrent st oinsect sno tadapte dt othes e plants.Tha twa sth estag eo fknowledg ewhen ,abou t1 5year sago ,w estarte da nanalysi s ofth echemica lsense si nhost-plan trecognitio nb yelectrophysiologica lmethods .

WHATI STH ESENSOR YBASI SO FFEEDIN GBEHAVIOUR ?

Oncei tha dbee nestablishe dtha tcertai nke ychemical spla ya rol ei nfoo drecognition , thequestio naros ewha ti sth esensor ycapacit yo finsect si nterm so fsensitivit yan dspec ­ ificityo fthei rchemoreceptors .D oinsect sonl yperceiv eth eke ychemical stha ttypif y theirhos tplant so rd othe yobtai na mor ecomplet echemica limag eo fthei rfood ?D oinsec t speciesdiffe ri nthei rchemica lsenses ?An dd othe ytherefor ereac tdifferentl y todiffer ­ entplan tchemicals ?Ho wconsisten ti sth erelatio nbetwee nsensor yinpu tan dbehaviora l output? Theselectivit yshow nb ymos tinsect st othei rfoo di sundoubtedl y innate,bu tth epos ­ sibilityremaine dtha tsom eadaptatio noccure dwithi ninbor nlimits .I fso ,wher ean dt o whatexten ti ssuc hflexibilit ypresen tan dwha ti sit sphysiologica lbasis ? Isovipositio nbase dupo nth esam esensor y informationa sfoo dselection ? Ifnot ,wha t areth edifferences ?

147 Weaime dt osolv eman yquestion so fthi ssor ti nth ehop eo fextricatin gth esubtl e discriminatorybehaviou ro fphytophagou s insects.A nunderstandin go fth emechanism so f plantrecognitio nmigh tthe nhel pu st odisrup tsom eundesire d insect-plantrelationships . Therol eo fth eolfactor ysens ei nrecognizin gfoo dplant swil lb ediscusse db y Visser& D eWild e (Section4.1] .Th epresen tpape rwil l focuso nth egustator ysense .

HOWAR ESENSOR YRESPONSE ST OPLANT SMEASURED ?

Electrophysiologicalmethod senabl eu st orecor dth enerv eimpulse selicite di nth ere ­ ceptorcell safte rstimulatio nb ychemicals .Thes etrain so fimpulse scontai na code ,o n whichth ebrai nbase sa behaviora lreaction .Th echemica lsense sar eincorporate d inspe ­ cializedhair so rpapilla eo nth eexterna lmouthparts ,i nth ebucca lcavity ,o nth eantenna e ando nth efeet .Ofte neac hsensillu mi sequippe dwit h3- 4recepto rcells .Som einsects , sucha slocust san dflies ,hav ethousand so fsuc hsensilla ,wherea sother sposses sonl ya limitednumber .Lepidopterou s larvaehav ei ntota lonl yabou t3 0o fsuc hsensill acontainin g about 120chemosensor ycell so fwhic honl yabou t4 0serv eth egustator ysense .Thi sremark ­ ablysmal lnumbe ri son ereaso ntha tmos to fou rresearc hwa so nthes einsects .I fw eeve r hopet oobtai na complet epictur eo fth esensor ymessag esen tt oth ebrain ,i twil lb ei n thissimpl esystem .

FEEDINGBEHAVIOU RGUIDE DB YSENSOR YINPU T

Sensory reactions to general and to typical plant chemicals

Onth ebasi so fknow nbehaviora lreaction st ochemical stypica lo fcertai nplan ttax a (e.g.sinigrin) ,th epresenc eo fspecifi creceptor sfo rsuc hcompound smigh tb eexpected . Larvaeo fth elarg ewhit ebutterfl yd ohav e4 cell so nthei rmaxillar ytast ehair stha t reactt osinigri nan dsom eclosel yrelate dsubstances .I naddition ,however ,the yhav ecell s stimulatedb ysugars ,salt so ramin oacids .Fou rothe rcell sar especialize dt osens eth e presenceo ffeeding-inhibitor ysubstances ,includin gsevera lalkaloid san dterpenoid s(Ma , 1972).Thu sth egustator ysens eno tonl yreact st ocompound stha ttypicall yoccu ri ncer ­ tainplant sonl y (sinigrin,alkaloids) ,bu tals ot osubstance swit ha genera ldistribution . Apparently,quantitativ einformatio no nsuc hchemical s isals orelevan tt oth einsect .I t probablyhelp sthe mt ofin dth enutritionall yoptimu mplac eo na plant ,a sdoe sth epoly - phagous larvao fth egyps ymoth ,whic hcarefull yselect s leaveso falde rpicke dfro mth e southsid eo fth etre ean dhardl ytouche s leaves (ofth esam etree )collecte da tit snort h side,i fcondition sar eideal . Thoughther ear ecertainl yno tenoug hrecepto rtype st orecor dal lchemical spresen ti n acertai nplant ,insect sobtai na sufficientl ydetaile dindicatio no fit schemica lcomposi ­ tiont orecogniz eth eplan tspecies ,an dt osens emor esubtl echaracteristic s aboutplan t variety,physiologica lconditio nan dage .Al lsuc hdetail sar eencode di nth esubtl ean d complexpatter no fsensor ysignal stravellin gt oth ebrai n (Schoonhoven,1977) . Ina nele ­ gantan ddetaile dstudy ,th esensor yinpu tt oth ebrai nwa scompare dt oth ebehaviora lout ­ puti nquantitativ eterms .Relativel ysimpl erelationship sbetwee ninpu tan doutpu twer e

148 found,indicatin gtha tcentra lprocessin g involvesa fairl yuncomplicate dsyste m (Blom, 1978).

Sensory coding: species related differences

Probablyn otw oinsec tspecie sexis twit ha nidentica lse to fchemoreceptors .Althoug h somecompounds ,lik esucros ean dsalts ,ar eperceive db ymos tinsects ,ther ei sa remark ­ ablespecialization .Sometime sthes especialization shav ea nobviou sadaptiv evalue ,a sd o thesorbito lreceptor s insevera l insectspecie srestricte dt orosaceou splant so rth esi - nigrinreceptor si ncruciferae-feedin g insects.Othe rchemoreceptors ,lik eth efairl ygen ­ erallyoccurrin ginositol-recepto ro rth echlorogeni caci drecepto ri nColorad obeetl e larvaehav eles sobviou ssignificanc e (Schoonhoven, 1972). Thefindin gtha teve ni nsom ever yclosel yrelate dspecie sth ereceptor svar yconsider ­ ablyi nphysiologica lcharacteristic sma ygiv eu sclue sabou tth eevolutio no fth esensor y system.Fo rinstance ,som esmal lermin emoth s (Yponomeuta spp.),whic har etaxonomicall y veryclose ,fee do ndifferen tplants .Thei rgustator yreceptor sdiffe rmarkedly ,an dsee m adaptedt operceiv eth echemical stypica lo feac ho fthei rrespectiv ehos tplants .Thi s indicatestha tth ereceptors ,thoug hmorphologicall y conservative,posses sa hig hdegre e ofphysiologica lflexibilit y ina nevolutionar ysense .

WHEREDOE SLEARNIN GOCCUR ?

Thetobacc ohornwor m (Manduca sexta) feedsexclusivel yo nsolanaceou splants .I fi ti s rearedo ntomat oleaves ,th elast-insta rlarva esho wa preferenc efo rtomat oove rpotat o leaves.I freare do npotato ,it spreferenc ei sreversed .Stil lmor ecuriou si stha tlarva e rearedo na nartificia ldiet ,lackin gan ychemical sspecifi ct oa host-plant ,als oaccep t someplant soutsid ethei rnorma lhos tplan trange ,e.g .cabbage ,dandelio no rdogwood .Dur ­ inglarva ldevelopmen to na norma lhost ,som elearnin gapparentl ytake splace ,alterin g thefoo dpreferences .Undoubtedl ya majo rcomponen to fsuc hlearnin gprocesse si ssituate d inth ecentra lnervou ssystem .But ,interestingly ,th egustator yreceptor sals oaltere di n sensitivitywhe nth einsec twa sreare do ndifferen tdiets .Consequently ,par to fth e"learn ­ ing" processi sdu et ochange si nth eperiphery ,leadin gt oalteration s inth esensor yin ­ put. Thistyp eo fadaptatio no fchemoreceptor s ishithert ounknow nfo ranimal s (Schoonhoven, 1977).

OVIPOSITION

Theovipositin gfemale ,o fcourse ,largel ydetermine swha tplan the roffsprin gar eexpo ­ sedto .Sh ediscriminates ,als oo nth ebasi so fchemica linformation ,betwee nacceptabl e andunacceptabl eplants .Th elarg ewhit ebutterfl y (Vieris brassicae) hastarsa lreceptor s thatrespon dt osinigrin ,a selectrophysiologica l informationha srevealed .Befor eeg gdepo ­ sition,sh e"taps "wit hhe rfron t legs,makin ggoo dcontac tbetwee nthos ereceptor san dlea f chemicals. Althoughsh eneed sa cabbag eplan t foroviposition ,th ebutterfl ysearchin gfo ra plac e

149 tooviposi tavoid scabbag eleave stha talread ybea reggs .Togethe rwit heggs ,female spro ­ ducesom eunknow npheromone ,tha tdeter sothe rbutterflie s (Rothschild& Schoonhoven ,1977) . Thiswater-solubl epheromon ei ssense db yantenna l (olfactory)receptors ,a selectrophysio ­ logicalrecording shav eshown ,a swel la sb ycontac tchemoreceptor so nth etarsae . Apparently,ovipositio nbehaviou ri sals ogoverne db ya comple xan dsubtl estrea mo fsen ­ sorymessages .

APPLICABILITY

Thecombine dapproac ho felectrophysiologica lstudie san dbehaviora lanalysi sha scon ­ siderablyenlarge dou runderstandin go fth efactor sgovernin gfoo dselectio nb yinsect s (Beck& Schoonhoven ,1980) .Thes estudie smainl ylea dt oa theoretica lunderstanding ,al ­ thoughb yworkin gwit hpes tinsect son emigh tencounte rusefu linformation .Th eisolatio n ofa noviposition-deterrin gpheromon eo fth ecabbag elarg ewhit ebutterfly ,fo rexample , mayhav esom epromis ea sa cabbage-protectin gnatura lsubstance .Likewise ,feedin ginhibi ­ tors,whic har erelativel yeasil yassayabl eb yth emethod smentioned ,coul dpla ysom erol e incro pprotection .

REFERENCES

Beck,S.D . &L.M . Schoonhoven, 1980.Behaviora lfactor saffectin gexpressio nan dstabilit y ofresistance .In :F .Maxwel l &P .Jenning s (Editors),Breedin gplant sresistan t toin ­ sects.J .Wile y (inpress) . Blom,F. , 1978.Sensor yactivit yan dfoo d intake:a stud yo finput-outpu trelationship si n twophytophagou s insects.Neth .J .Zool .2 8 :277-340 . Ma,W.C. ,1972 .Dynamic so ffeedin gresponse s inPieri sbrassica eLinn ,a sa functio no f chemosensoryinput :a behavioral ,ultrastructura lan delectrophysiologica l study.Meded . Landbhogesch.Wageninge n 72-11. 162p . Rothschild,M . &L.M .Schoonhoven , 1977.Assessmen to feg gloa db yPieri sbrassica e(Lepi - doptera:Pieridae) .Natur e26 6 :352-355 . Schoonhoven,L.M. , 1972.Plan trecognitio nb ylepidopterou s larvae.Symposi ao fth eRoya l Entomological Society,Londo n6 ,p .87-99 . Schoonhoven,L.M . 1977.O nth eindividualit yo finsec tfeedin gbehaviour .Proc .K .ned . Akad.Wetensch .8 0C : 341-350 .

150 Integrated control of insect pests in the Netherlands. Fudoc, Wageningen, 1'c 4.3 Physiological condition of the potato plant and population development of Myzus persicae

P.Harrewij n

ResearchInstitut efo rPlan tProtectio n (IPO)Wageningen ,th eNetherlands .

DESCRIPTIONO FTH EPROBLE M

Aphidsar ea permanen tpes ti nou rpotat oculture .The ytransmi tdifferen tharmfu lvi ­ rusesan dar ea continuou smenac et ocrop so fsee dpotatoes .Eve n16 0year sago ,Friesia n seed-potatogrower slifte dcrop searl yt opreven t 'thecurl ' (potato leafroll).Insecti ­ cidesar eonl ypartl yeffectiv et opreven tsprea do fth epersisten tleafrol lvirus ,an d arealmos tineffectiv eagains tsprea do fnon-persisten tviruses ,lik epotat oviru sY . Theaphid sma ydie ,bu tto olate ,a sth eviru sha salread ybee ntransmitte dbefor eth ein ­ secticidedoe sit sjob . Theinfectio no fth etuber sha st ob eprevente db ykillin gth eleave so rliftin gshortl y aftera nintolerabl ehig himmigratio no fa numbe ro fvecto raphids . Theprecis edat eo fliftin gi so fgrea timportance .Eve non eday' sdifferenc ei nearl y liftingrun st oa differenc ei nyiel do fmillion so fdollar sove rth etota lare aunde r seedpotatoes .

AIMAN DMOTIVATIO NO FTH ERESEARC H

Asinsecticide sprovide donl ypartia lprotectio nagains tviru stransmission ,D rHill e RisLamber spropose da projec tt oinvestigat eway so finfluencin gdevelopmen tan dfligh t ofaphid si nsuc ha way ,tha tth ecro pcoul db elifte dlater .Th eresearc hstarte dwit h Myzus persicae, because iti sth eprincipl evecto ro fleafrol lan di ti sals oa nimportan t vectoro fnon-persisten tviruses .Als oquit ea lo ti sknow nabou tit slif ecycle ,anatom y andphysiology ,an dbehaviour . Thewinge demigrant scolonizin gth esumme rhost sproduc e individuals,whic hwil lmulti ­ plyparthenogeneticall y forsevera lgenerations .Interactio nbetwee nindividual sca nresul t inth eproductio no fth ewinge dmorph .Therefor ei tseeme dlogica lt oreduc epopulatio n densityb yinfluencin gth ephysiolog yo fth ehos tplan ti norde rt odela yo rreduc eth e productiono falatae .

151 WORKING METHODS

The available literature on field trials on the relationship betweenhost-plan t quality andpopulatio n development ofaphid s revealed anumbe ro fcontradictions . Itwa s deemed nec­ essary to investigatewhethe rw e could influence development and reproduction of M. persicae by theminera l nutrition of thepotat oplant . In 1966,Johnso n reliably demonstrated the direct influence ofth ehos tplan t on alary dimorphism in Aphis craccivora. As M. persicae mainly feeds onphloe m sap,whic h isdiffi ­ cult to analyse,i tseeme dwis e tous e artificial diets to study the significance of die­ tary factors inwin g dimorphism. Consequently, threemai n lineswer e followed inou rre ­ search. - The use ofsoilles s culture toestablis h the effect ofminera l nutrition ofth ehos tplan t onpopulatio n development of M. persicae. - The relationship between the composition of chemically defined diets andwin gproduction . - Field trials topu t thene wknowledg e intopractice . Special gravel culture systemswer e constructed to study the development of M. persicae on thepotat oplan t inrelatio n toN ,S ,K ,M g andC a levels ofth enutrien t solutions.Th e techniquewa s alsouse d to investigatewhethe rwin gproductio n and reproduction rate of M. persicae were similarly dependent onth enutritiona l status of thepotat oplant . Aphidswer e reared onartificia l dietsb y atechniqu e developedb yMittle r &Dad d (1962). Dietswer e modified to obtainoptimu m growth and reproduction, and acontinuous-flo warti ­ ficial-feeding devicewa s developed toallo w standardization ofcondition s fordisturbance . A newmetho dwa s developed tomeasur e dietuptak e and acceptance,b y isotope techniques. Thespecifi c effect ofa numbe r ofnutrient s onwin g dimorphism couldb e studiedwit h a specialmicro-injectio ndevice ,whic h eliminated gustatory effects ondevelopmenta lproces ­ ses. Infiel dtrial s different samplingmethod swer e compared to improve statistical treat­ ments.Assessmen t ofth equalit y ofth ehos tplan t included chemical analysis and reflection spectrophotometry.

RESULTSAN D DISCUSSION

Thenutritiona l value ofth epotat oplan t for M. persicae depended on the supply ofth e elements N,P , Kan dM g inparticular ,o fwhic hN ,P andM g stimulated growth and reproduc­ tion, and Kabov e acertai n level reduced them. Besides nutrition,ag e of theplan twa sde ­ terminative for thenutritiona l value ofth ephloe m sap.Althoug h only a fewnutrient s were essential ina biochemical way,abou t 20 amino acids and amides influenced growth andde ­ velopment of M. persicae. Growthwa s highly stimulatedb y amides,particularl y asparagine. The amino acidmethionin e also acted as aphagostimulan t andha d tob epresen t in thephloe m sap,togethe rwit h sucrose. Changes in thehos tplan t resulting inreduce d reproductionwer e also responsible fora smallerproportio n of alatae.Thi s result contradicted the generally accepted statement thatmor e alataewer e produced onhos tplant swit h asuboptima lnutritiona l value.Experi ­ mentswit h artificial diets demonstrated that these resultswer e just asvali d off the

152 plant.Aptera ewer eproduce dwhe nth eamin oaci drati oi nth efoo dwa sunfavourabl et onor ­ maldevelopmen to f M. persiaae. Theywer eals oproduced ,however ,o nver yyoun gplan tparts , especiallyo nseedlings ,whic hpermitte dnorma lgrowt han ddevelopment .Ye to na suboptima l diet,alata ewer eproduced ,i fth erestlessnes so fth eaphid swa sincreased . Host-plantsubstance sinfluencin gmorp hca nb edivide dint osevera lclasses ,wit hdif ­ ferentmode so faction .Som ehav ea twofol deffect ,a sthe yaffec tpopulatio ndevelopmen t (andcontac tbetwee nindividuals )an dth esyste mgovernin gwin gdimorphism .Thi si sespe ­ ciallytru efo rmethionine ,isoleucin ean dhistidine ,bu tals ofo rth erati oo fasparagin e toglutamin ean dt ounessentia l aminoacids .Fo ra fulle rrepor to fthes eresult sse eHar ­ rewijn (1977). Somecompound s (traceelements ,phytohormone san dgrowt hsubstances )hav ea nextrasen ­ soryeffec to nwin gdimorphism ,a swel la saffectin gth eactivit yo fneurosecretor ycell s thatregulat epolymorphism .Micro-injectio nexperiment sdemonstrate dtha tbiogeni camine s derivedfro mth earomati camin oacid stryptopha nan dtyrosin eha da mediatin g functioni n theregulatio no fwin gdimorphis mi n M. persiaae. A fewtrac eelements ,lik elithium ,in ­ terferedwit hth eactivit yo fthes ebiogeni camines ,thu sshiftin gth eregulator ymechanis m ofwin gdimorphis mtoward sth eapterou scours eo fdevelopment . Fieldtrial so nregulatio no fpopulatio ndevelopmen to f M. persicae byth eminera lnutri ­ tiono fth epotat oplan tconfirme dth eresult sobtaine di nth elaboratory .Bot hpopulatio n developmentan dproductio no falata eo fthi saphi dwer einfluence db ynitroge ndressin gan d byth eamoun to fpotassiu mavailabl et oth ecrop .Th emagnitud eo fth eeffect sobtaine di n soillnesscultur ean di nth efiel ddiffere dconsiderably ,althoug hth etren do fth eeffec t wasth esam ea slon ga sartificia lfertilizer sar eused .Thi scanno tb esai do forgani c manure,whic hreduce dpopulatio ndevelopmen ti nth efield .However ,whe npotat oplant s wereraise do nnutrien tsolution swit han dwithou textract so fstabl emanure ,bu twit ha n equalio nconcentratio nan drati oo fth emajo rnutrients ,th eperformanc eo f M. persiaae wasoptimu mi nal ltrial s (80-100larva epe rfemale) . Lowrate so fN fertilize rreduce dth etota lamin oaci dconten to fth eleaves .K reduce d glutamine,histidine ,methionin ean dtyrosine ,an dincrease dproline . Withresult so ffiel dtrial sfro m197 2t o1978 ,a fertilize rschem eha sbee ndevelope d (combinedtreatmen twit hN ,P an dK )tha tca nreduc epopulation so f M. persiaae and Maaro- siphum euphorbiae to20° so fnormal ,withou t lossi nyield .Win gproductio ni sreduce dfro m 70?O-30°Ó.Trial swit htrac eelement st odela ywin gdevelopmen ti nth efiel dar eno wunde r way.

SIGNIFICANCEFO RAGRICULTURA LPRACTIC E

Mackauer& Wa y (1976),i nthei rdiscussio no nalternativ emethod st ocontro laphids ,re ­ fert oth euniqu esensitivit yo f M. persiaae toth ephysiologica lconditio no fit shos t plants.The ystat etha tmanipulatio no fth ephysiolog yo fth eplan tcoul db einvaluabl ei n aprogra mo fintegrate dcontro lfo rthi saphid .Thi sprojec tha sprovide dsatisfactor y prooftha tmanipulatio no fth epotat oplan tca nmak ea majo rcontributio ntoward sa schem e ofintegrate dcontrol . Inth eNetherlands ,th eproportio no fwinge dmorph so f M. persiaae (althoughexception -

1S3 ally)ca nreac h30° 6i nth efiel db yth een do fJune .Ou rbasi cschem ewil lreduc ethi st o about 8%an di ti sexpecte dtha tprope rtimin go flithiu mtreatmen twil l furtherreduc e thisfigur et oles stha n To,o rproportionall y loweri fles swinge daphid sar enormall y produced.Thi sma yb esufficien tt oomi t 'cleaning'o fth ecro pwit h insecticidesbefor e selectionfo rth epresenc eo fnon-persisten tviruses ,an dfo rcontro lo fleafroll . Whenapplie dt oplot ssurrounde db yothe rcrops ,th eanti-aphi dtreatment swil lb emos t effectiveagains tpersisten tviruse san dwil lonl yreduc einfectio nb ya non-persisten tvi ­ rusi ns ofa ra si ti ssprea dwithi nth eplo tb ya developin gaphi dpopulation .Tha taspec t differsfro myea rt oyear ,a si tdepend so nfligh tactivit yo fnon-residents ,als oabl et o transmitnon-persisten tviruses .I tca nb ecalculate dtha ti nsom eyear sth etreatment s shouldreduc einfectio nwit hnon-persisten tviruse sb yles stha n50?. ,bu ti nthos eyear s insecticideswoul dgiv en obette rprotection ,woul db emor eexpensiv ean dhar mnatura lene ­ mies.

FUTUREOUTLOO K

VanHoo f (inprep. )recentl yfoun dtha twar epotatoe sma yb ea seriou ssourc eo fnon - -persistentviruse s (likePV Y ), thatca nsprea dint oa neighbourin gsee dpotat ofield . Theseresult sprovid ea ninterestin gbasi st oexten dou rtreatment st owar epotatoes .A furtherimprovemen ti ncontro lo faphi dfligh tma yb eobtaine db yapplicatio no ftrac eele ­ mentslik elithiu ma tth eprope rtime .I nsee dpotatoes ,a dela yi nwin gproductio nb yon e generationwil lb esufficient ;fo rwar epotatoes ,tim eschedule shav et ob eworke dout . Sprayingminera loil shelp st oreduc einfectio nwit hnon-persisten tviruses .Onc estart ­ ed,on eha st ocontinu esprayin ga tregula rintervals ,s oa yiel dreductio ni sinevitable . Ifou ranti-aphi dtreatment scoul db ecombine dwit hthi stechnique ,i twoul db epossibl e tosto poi lsprayin gafte rth ethrea tfo rearl yinfectio nwit hviru stransmitte db ynon - -hostaphid si sover .Thi styp eo fintegratio nwil lb estudie di nth enea rfuture .

REFERENCES

Harrewijn,P. , 1977.Nutritiona laspect so fdevelopmen tan dwin gdimorphis mi nth eaphi d Myzuspersicae .Thesis ,Univ .Amsterdam .9 8pp . Johnson,B. ,1966 .Win gpolymorphis m inaphids .III .Th einfluenc eo fth ehos tplant .Ento - mologiaexp .appl .9 :213-222 . Mackauer,M .& M.J .Way , 1976.Myzu spersica eSulz. ,a naphi do fworl d importance.In : V.L.Delucch i (Editor).Studie si nbiologica lcontrol .Cambridg eUniv .Press ,p .51-119 . Mittler,T.E .& R.H .Dadd , 1962.Artificia l feedingo fth eaphid ,Myzu spersica e (Sulzer) ona completel ydefine dsyntheti cdiet .Nature ,Lond . 195 :404 .

154 Integrated control of -insect pests in the Netherlands. Pudoc, Wageningen, 1980.

4.4 Nutritional relationship between host plants and phytophagous mites

J.J.H.Storm s

ResearchInstitut efo rPlan tProtectio n (IPO),Wageningen ,th eNetherlands .

DESCRIPTIONO FTH EPROBLE M

Atth ebeginnin go fth eninetee nsixties ,th eprospect so fintroducin ga schem eo fin ­ tegratedcontro li norchard swer eno tver yencouraging .Phytophagou smite sbecam ea seriou s problem,becaus eo fth ealarmin gdevelopmen to fresistanc et oth eusua linsecticide san d acaricides.Mor eo rles sselectiv eacaricide stha twoul dkee pnatura lenemie so fth epest s alivewer eno tavailabl ean dth estud yt ointroduc especifi cnatura lpredator swa si nit s infancy.Moreover ,ther ewa sa tendenc yt oenhanc enitroge ndressing si nappl eorchards . Thisle dKuene n (1962)t oquestio nwhethe rpredator scoul dcop ewit ha possibl yaccelerate d developmento fspide rmite sunde rthes ecircumstances . Therewas ,however ,som eevidenc etha tchange si nth echemica lcompositio no fappl elea f broughtabou tb ydifference si nmanurin gcoul db ea majo rfacto ri ncontrollin gth epopula ­ tiondevelopmen to fspide rmites .I nparticular ,Pos t (1962)foun dtha tth erat eo feg gpro ­ ductiono f Panonyehus ulmi wassignificantl y lowero nappl etree si nneglecte dorchard s thantha ti nwel lkep torchards .Th eleve lo flea fnitroge ni nneglecte dorchard swa slowe r thani nth ewel lkep tones . Incontrast ,populatio ndevelopmen to f P. ulmi inneglecte dpeac horchard si nCanad adi d notsee mt ob eretarded .Thi smad ei tdifficul tt odevelo pfertilize rscheme sfo rappl eor ­ chardstha twoul dfi tint oa schem eo fintegrate dcontrol .

AIMAN DMOTIVATIO NO FTH ERESEARC H

Theprojec twa sstarte dt oelucidat eth erol eo fminera lnutritio no fth eappl etre ei n populationdevelopmen to fspide rmite san dt oinvestigat eth einfluenc eo fa mit epopula ­ tiono nth ephysiolog yo fth ehos ti ndifferen tperiod so fth eyear .Mai nattentio nshoul d begive nt oapplicatio no ffertilizer swithi nth erang eexpecte di npractice .

WORKINGMETHOD S

Theresearc hdevelope dalon gtw omai nlines : - thereactio no fa mit epopulatio nt oalteratio ni nth echemica lcompositio no fth ehos t plant;

155 - thereactio no fa hos tt oth efeedin gactivitie so fa developin gmit epopulation . Theproble mwa sfirs tapproache di nlaborator yexperiments .One-yea rol dappl erootstock s weregrow ni ngrave lcultur eo ndifferen tnutrien tsolutions .I twa sthough ttha tknowledg e ofth enutritiona ldemand so fspide rmite swoul dhel pi nevaluatin gchemica lcompositio no f thehos tplants .S oth edevelopmen to fartificia ldiet swa sstarted .Preliminar yresult s showedtha t P. ulmi wasno ta suitabl emit efo rth echose nexperimenta l techniques.I nit s place, Tetranychus urticae wasuse dwit happl ean dbea na shos tplants . Phytophagousmite sdamag eth ecro pb ydecreasin gth eassimilator ycapacity .I observe d thatthe yma yals ointerfer ewit hsom echemica lprocesse s inth eplants .Wit hautoradio ­ graphy,th efat eo fsaliv ainjecte dint oth eplant ,an dauxi nrelationship swer einvesti ­ gated.Littl ewa sknow nabou tth emagnitud eo fth edamag ecause db ya developin gmit epo ­ pulation.Mor einformatio no nthi stopi cwa sthough tt ob eobtainabl eb ystudyin gtrans ­ porto fmineral s ina close dsystem .Thi styp eo fexperimen twa sse tu pa sbalanc estudies ; thati st osay ,th ewhol eo fnutrien tsolutio ntogethe rwit hplant san dmite swa sarrange d asa close dsyste mfo rcentai nnutrien telements .I nthi sway ,th eeffec to fmit eattac ko n thedistributio no fa certai nelemen tcoul db eevaluated . Fieldtrial swer ese tu pt oinduc ea differen tN conten t inth eleave so fappl etrees . Bothartificia lan dorgani cfertilizer swer eused .

RESULTSAN DDISCUSSIO N

Anincreas ei ntota lnitroge nconten to fleave so fappl erootstock sgrow ni ngrave l cultureincrease d longevityan deg gproductio no f P. ulmi and T. urticae. Differencei n theK /Mg2 ratioi nth enutrien tsolution swer eno tcorrelate dwit hmit ereproduction . Phosphoruspromote dmit edevelopment .I twa sdifficul tt ofin da clos erelationshi po f solubleN an dP i nth eleave swit hmit edevelopment .Dabrowsk i& Biela k (1978)arrive da t similarresult sfo rN an dP conten to fleave so fappl ecultivar san dth efecundit yo f P. ulmi. Balancestudie so n T. urticae onbea nplant sshowe dtha tmite scaus ea marke dchang ei n thedistributio no fP i nth eplant .Infestatio nincrease dtranspor to fP t oth egrowin g partso fth eplan tan dals ot oth epart soccupie db yth emites .Populatio ndensitie sbe ­ tween1 an d4 female spe rsquar ecentimetr eresulte di na growt hstimulation .I fth eden ­ sityexceede d 10cm -2 growthinhibitio noccurred . Mitesca ntransfor mth eamin oaci dtryptopha nint oa nindol ederivative .A sthe yinjec t salivaint oth eplant ,th eequilibriu mo fgrowt hsubstance sma ythu sb einfluence db ya miteinfestation .Ther ewa ssom eevidenc etha ta nauxin-lik esubstanc ean da gibberelli n playa rol ei ngrowt hregulatio no fth eplant ,afte rinfestatio nb ymites .Th efirs tthin g wastha tgrowt hwa sstimulate dand ,whe nth emit epopulatio ngrew ,i twa sreduced .S oa miteinfestatio ni na norchar dma yeve nb ebeneficial ,a slon ga si tdevelop sslowly .I n thisway ,predator sca nsta yaliv ean d 'standby 'fo raction .I twa s thoughttha ti nmos t summersth enutritiona lqualit yo fth eappl etree smus tb einfluence di nsom ewa yt oallo w slowpopulatio ngrowt ho fmites .Althoug hpopulatio ndevelopmen to fmite si nth egreenhous e wasfoun dt ob epositivel y influencedb ynitroge nfertilization ,fiel dtrial smainl yreveal ­ eda nincreas ei nlongevit yo fspide rmite s (upt o 2%% afternitroge ndressin ga tmor e

156 than30 0kg/ha )an donl ymino rdifference si nreproductio ncapacity .Va nd eVri e& Boersm a (1970)foun dtha tth edevelopmen to f Panonyahus ulmi onappl etree sreacte dpositivel yt o anincrease dconten to fN i nth ehos tplant ,bu tonl ys oi nth eabsenc eo fpredators ,es ­ pecially Typhlodromus potentillae. Thismean stha t T. potentillae isabl et oreduc eth e populationdensit yo fth epre y P. ulmi undervariou scondition so fth ehos tplant .I tcoul d alsoexplai nwh yStorm sfoun dtha tN a tmor etha n30 0kg/h ai norchard sincrease dlongevit y ofindividual so f P. ulmi, butha dlittl eeffec to npopulatio ndevelopment .A mor edetaile d knowledgeo fth echemica lrelationship sbetwee nfertilize ran dmit edevelopmen twa shar d toobtain ,a srearin go fmite so nartificia ldiet swa sno tver ysuccessful .Althoug h T. uvtiaae couldb ekep taliv efo rsom eweeks ,n odie tcoul db eformulate dtha tenable di tt o completeit slif ecycle .Th ebes tresult swer eachieve dwhe nenergy-ric hphosphates ,stear ­ ican dpalmiti caci dwer eadde dt oa die tcontainin gamin oacid sa ta mas sfractio no fn o moretha n9 0mg/kg .Thi sconcentratio ni slowe rb ya facto r7- 8tha nexpecte di nlea fjuic e ofbea n (0.5-0.6g/kg) . Glumaticaci dwa sno tquit eomitte dfro mth ediet ,althoug hit spresenc eseeme dt ohav e anegativ eeffec to nth eperformanc eo f T. uvtiaae (Storms,1971) .Dabrowsk i& Biela k (1978) ascribedth elo wsensitivit yo fth eros ecultiva rBaccar at o T. uvtiaae toit shig hconten t ofglumati cacid .

SIGNIFICANCEFO RHORTICULTUR EAN DFUTUR EOUTLOO K

Studieso fth enutritiona lrelationship sbetwee nhos tplant san dphytophagou smite shav e revealedman yfacts ,bu tonl ya narro wbasi sfo ra nintegrate dcontrol .I nth eNetherlands , Ndressing shav ebee nsubstantiall yreduce di nth elas tcoupl eo fyears .Thi sha sresulte d ina solutio no fth emit eproble mfo rmos tcultivars .Rabbing e (1976)constructe da numbe r ofsimulatio nmodel sfo rth erelationshi pbetwee n P. ulmi andth epredato r Amblyseiue po­ tentillae ona basi so ffiel dtrials .A slon ga slea fnitroge nwa sbetwee n2. 0an d3.0 %o f dryweight ,foo dqualit ycoul db eneglecte di nsimulatio nmodel so ffiel dsituations . Inyoun gorchard so nne wsites ,wher epredato ractivit yi slow ,i twil lb ewis et ous e fertilizerscarefully .Th esam ehold sfo rappl eorchard swher einsecticide sar euse dtha t harmth epredators .Fo rthes esituation sbeneficia leffect sma yb eobtaine db yspecia lcom ­ binationo fN ,M gan dK fertilizers .Anothe rpossibilit yi sth edevelopmen to fcultivar s with,fo rinstance ,a hig hconten to fglumati caci di nth eleaves .Thi sproject ,however , wasstoppe d in1971 .Sinc ethen ,onl ya littl eresearc hha sbee ndon eo nth edevelopmen t ofartificia ldiet sfo rmites .I ti st ob ehope dtha tsomewher e inth eworl d financialsup ­ portan dpatienc e isfoun dt oresum ethi susefu lan dinterestin gwork .

REFERENCES

Dabrowski,Z.T .& B .Bielak , 1978.Effec to fsom eplan tchemica lcompound so nth ebehaviou r andreproductio no fspide rmite s (Acarina:Tetranichidae) .Pape rpresente d atth e4t h Insect/HostPlan tSymp .Slough ,England .Entomologi aexp .appl .2 4 :117-126 . Kuenen,D.J. , 1962.Genera lconsideratio no nth esignificanc eo fpredator san dparasite si n orchards.Entomophag a7 :221-226 . Post,A. , 1962.Effec to fcultura lmeasure so nth epopulatio ndensit yo fth efrui ttre ere d spidermite ,Metatetranychu sulm i (Koch)(Acari ,Tetranychidae) .Thesis ,Univ .o fLeyden . 110p .

157 Rabbinge, R., 1976.Biologica l control of fruit-tree red spider mite. Simulation Monographs, Pudoc, Wageningen. 228 p. Storms, J.J.H., 1971.Voedingsfysiologisch e betrekkingen tussen waardplanten en spintmijten. Thesis (partly in English), Univ. of Leyden. 74 pp. Vrie,M . van de &A . Boersma, 1970.Th e influence of the predaceous mite Typhlodromus (A.) potentillae (German) on the development of Panonychus ulmi (Koch) on apple grown under various nitrogen conditions. Entomophaga 15 :291-304 .

1S8 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 4.5 Elements in the population dynamics of Euproctis chrysorrhoea on roadside trees

R.J.va nde rLind e ResearchInstitut efo rNatur eManagement ,Arnhem ,th eNetherlands .

INTRODUCTION

TheNetherland sha sonl ylittl efores tbu tman ytree salon groadside san dcanals .On e ofth epest sattackin gthes etree si sth ebrowntai lmoth , Euproctis chrysorrhoea, notorious notonl yfo rdefoliatin goak san dothe rtree sbu tals ofo rcausin gnuisanc eb yit shairs , whichirritat eth eski no fsusceptibl epeople . E. chrysorrhoea reachesth enorther nlimi to fit srang ei nth eNetherlands .I nth ein ­ terior,i ti srestricte dt oth eSout hpar to fth ecountry ,crossin gth eRive rWaal ,whic h isth esouther nmos tan dlarges tbranc ho fth eRhine ,flowin galmos teast-wes tthroug hth e middleo fth ecountry ,onl yoccasionally ,durin gsever eoutbreaks .I nth esan ddune so nth e coasto fth eNort hSea ,wher eth especie sdwell so nse abuckthor n (Hippophaë rhamnoides), itextend srigh tu pt oth enorthernmos ten do fth eNetherlands ,th eFriesia nIsles .Th e caterpillarssometime sinvad ecampin gsite safte rdefoliatin gthei rhos tplant san dar e dreadedb ytourist sa tth eseashore . Thewor kreporte di nthi spape raime da tunderstandin g thecause so fth eoutbreak so f E. chrysorrhoea inth einterio ro fth ecountry ,a sa basi sfo recologica lcontro lo fth e species.

LIFECYCL EAN DOUTBREAK S

E. chrysorrhoea hason egeneratio npe ryear .Th eadult sfl yi nJuly ,depositin gthei r eggmasse so nth eleave snea rth eti po fshoots .Afte rhatchin g inAugust ,th elarva ere ­ duceth eleave st oskeleto nan dspi na nes ta tth een do fa shoot .Th enest sbegi na srath ­ erloos eweb sbu tar egraduall ystrengthene dt obecom etoug hstructure si nwhic hth eca ­ terpillarshibernate .Al lth elarva ehatche dfro mon eeg gmass ,o rthos efro mtw oo rmor e masses,co-operat ei nbuildin gth enest .Earl yi nspring ,whe nth etemperatur erises ,th e caterpillars leavethei rnest san dstar tfeedin gwhe nth ebud sburst .I fth ecaterpillar s ares oabundan ta st odefoliat eth etrees ,the ydescen di nsearc ho fne wfoo dplants .Th e larvaear efull-grow ni nJun ean dpupat eo nth etree st ogiv eris et oadult si nJuly .Al ­ thoughsevera lspecie so ftre ean dshru bca nserv ea shosts ,th emai nfoo dplant sinlan d areoak ,hawthorn ,an dfrui ttrees . Outbreakso f E. chrysorrhoea inth eNetherland shav ebee nrecorde dsinc e 1902.Th eup s

159 1900 1910 1920 1930 1940 19S0 1960 1970 1980

Fig. I.Outbreak so f E. chrysorrhoea inth esout ho fth eNetherlands ; local severe.

anddown si nabundanc ear erathe rirregular ,an dth eduratio no foutbreak sshow sa nincreas e from3 year sinitiall yi n191 7t o1 0year sa tth epresen ttim e (Fig.1). From 1962t o1977 ,a surve yo fth edispersio nan dabundanc eo f E. chrysorrhoea wasmad e yearlyi nwinter ,whe nth enest sar econspicuous ,b yinspectin groadsid etree salon ga fixe d routei nth esouther npar to fth ecountr yfro ma car .I nperiod so flo wnumbers ,th epopu ­ lationo f E. chrysorrhoea maintainsa footin gi ncertai nplace s inth eregio nwher ei ti s indigenous,an dextend sit sare afro mthes ecentre swhe ncondition sfo rth especie sbecom e favourable.

OUTBREAKSAN DFOO DQUALIT Y

Theide atha tth equalit yo fth efoo dmigh tb ea ke yfacto ri noutbreak swa sprompte d byth eobservatio no fa fixe dorde ri nwhic hdifferen ttre especie swer eattacke db y E. chrysorrhoea inth ecours eo foutbreak s (Voûte& Va nde rLinde ,1963) .Rearin gexperiment s confirmedth esuppose ddifference si nsuitabilit yo fdifferen ttre especie sa sfoo dfo r thelarvae :hawthorn ,apple ,an doa ki ntha torde rprove ddecreasingl ysuitable .Moreover , larvaereare do nth esam etre especie si ndifferen tplace so fth ecountr ydiffere dstri ­ kinglyi nsucces so fcompletin gthei rdevelopment .Thos ereare dnort ho fth eRhin ewer eles s successfultha nthos ereare di nth esout h (Vande rLind e& Voûte ,1967) . Moredetaile drearin gexperiment si na ninsectariu mo ncut-of fbranches ,showe dtha t foliagefro mdifferen tpart so fa tre ediffere dwidel yi nsuitabilit y asfoo dfo rth elarva e inspring ,i.e .fro mhibernatio nt opupation .Female sfro mcaterpillar sreare do nfoliag e fromth eto po rth esout hsid eo foa ktree sproduce dsevera ltime sa sman yegg sa sfemale s fromlarva ereare do nbranche sfro mth enort hsid eo fth esam etrees .Again ,hawthor nprov ­ edmor esuitabl ea sfoo dtha noa k (Vande rLinde ,1968) . Inth eperio dfro mhatchin gt ohibernation ,th eorigi no fth efoo dals oinfluence dlar ­ valdevelopmen tan dhenc eth eeventua lfecundit yo fth epopulation .Thi swa sconclude dfro m experiments inwhic h larvaewer ereare di nsit uo ndifferen tpart so foa ktrees .Th etota l numbero fegg sproduce db yth egroup so flarva ewit hwhic hth eexperimen twa sstarte dwa s greatero nth eol dfoliag e (i.e.sprin gshoots )tha no nth eyoun g (i.e.summe rshoots )and , withinol dfoliage ,greate ro nth efoliag efro mth esout hsid etha nfro mth enort hsid eo f thetrees .Th emos tfavourabl etyp eo ffoo dshowe dth ehighes tconten to fprotei nan dsuga r (Vande rLinde ,i npreparation) . Thenatur eo fth efoo dha sa grea timpac to nth edevelopmen to fth elarva eo f E. chry­ sorrhoea and,presumably ,o nth efluctuation so fth epopulation .Th equalit yo fth efoliage , determinedb ytre especie san dsite ,an dinfluence db yweathe rconditions ,mus tb ea ke y factori nth eabundanc eo f E. chrysorrhoea. Itha sno tbee npossibl et opu tthi sassumptio nt oa complet etest ,whic hwoul dconsis to f

160 ascertainingth edevelopmen to f E. ahvysorrhoea nestsan dpopulations ,an danalysin gth e foliageo fth etrees ,o ndifferen tsite sdurin ga numbe ro fconsecutiv eyears .Som eprelim ­ inarywork ,althoug hi tdi dindicat eth emerit so fthi sapproach ,wa sno tsufficien tfo r conclusiveevidence .

NESTBUILDIN GA SA CRITICA LFACTO RFO RSURVIVA L

Ananalysi so fnest so ndifferen ttre especie si ncertai nlocalitie ssuggeste dtha t nestbuildin gi sa critica lfacto rfo rth esucces so fhibernatio no fth elarva einhabitin g thenest ,an dma yb edecisiv efo rsurviva lo floca lpopulations .Larva eo fsmal lgroups , whenbuildin gthei rhibernacula ,wer efoun dt ocontribut ea greate ramoun to fnes tmateria l perlarv atha ncaterpillar sfro mlarg egroups .Th eforme rweighe dles safte rhibernation , withsuggeste dlowe rvitality ,sinc eth epercentag esurviva lpe rnes twa spositivel ycorre ­ latedwit hth eweigh to fth elarva eafte rhibernation .Apparently ,nes tbuildin gi sheav y labourand ,i fi tha st ob eperforme dwit hto ofe wfello wcaterpillars ,i tdetract sfro m survivaldurin gwinter .Th eminimu mnumbe ro flarva epe rnes tsuccessfull ysurvivin gwa s 34.Foo dqualit yan damoun to ffoliag eavailabl eo na branc ha smateria lt oconstruc tth e nestar efactor sdeterminin gth esucces so fnes tbuilding .

E.CHRYSORRHOE AI NAN DCLOS ET OFOREST S

Singletree san droadsid etree sar emor epron et oheav yattac kb y E. ahrysovvhoea than treesi no rnea rforests ,a differenc eclea ra tmediu mdensitie sbu tbecomin g lesspro ­ nouncedi nyear so fsever eoutbreaks .Th enest si nth efores tlocalitie swer esmaller ,o n average,an dcontaine dfewe rlivin gcaterpillar si nsprin gtha nthos ei nope ncountry . Birddamage ,mainl yb ytitmice ,wa sgreate ri no rnea rforests ;bu tparasitization ,predom ­ inantlyb yth echalcid , Euçtevomaius pevegvinus, waslowe rtha ni nope nareas .

CONCLUDINGREMARK S

Thewor ko n E. ahvysorrhoea hasfocuse dattentio no na facto rto oofte nneglecte di n thepopulatio ndynamic so fphytophagou sinsect s: th equalit yo fthei rfood .Althoug hi t hasno tye ttrace da ful lan dcoheren tpictur eo fth erelationship sdeterminin gth epat ­ terno fris ean ddeclin es ocharacteristi cfo rthi sspecies ,i tsuggest sa napproac htha t mightimprov econtrol . Atpresent ,extensiv echemica lcontro lcampaign sb yaircraf to rpowerfu lsprayin gmachin ­ eryar einitiate dwhe noutbreak sdevelop .I twoul db ebette rt ofin dth efoothold so fth e populationdurin gperiod so fpopulatio ndepression ,carefull ymonito rthem ,an dtrea tthe n atth efirs tsig no fincrease . Recentlystarte dwor ki nth eNetherland sha sconcentrate do nlate-leafin goa ktype sa s apossibl emean so fcontrollin gth ebrowntai lmoth .Thi sapproac hmigh tb eparticularl y effectivei fthi styp eo foa kwer eplante da tth esite sno wpermittin g E. ahrysovvhoea to survivedurin ginclemen tperiods .

161 REFERENCES

Linde, R.J. van der, 1968.De r Einfluss der Nahrung auf die Populationsdichte des Goldaf­ ters (Euproctis chrysorrhoea L.). Z. angew. Ent. 62 :195-201 . Linde, R.J. van der &A.D . Voûte, 1967.Da s Auftreten des Goldafters (Euproctis chrysor­ rhoea L.) in den Niederlanden und der mögliche Einfluss der Nahrung auf die Schwankungen in der Populationsdichte. Z. angew. Ent. 60 :85-96 . Voûte, A.D. & R.J. van der Linde, 1963.Di e Reihenfolge der Wirtspflanzen beim Massenauf­ treten von Euproctis chrysorrhoea L. Z. angew. Ent. 51 :215-217 .

162 5 Host-plant resistance

Theimportanc eo fhost-plan tresistanc ea sa basi ccomponen to fintegrate dcontro lha s beeninsufficientl yrecognize dfo ra lon gtime .I nth eNetherlands ,relation so finsec tan d host-planthav ebee nextensivel y investigatedsinc eth een do fth efortie s (Chapter4 )bu t host-plantresistanc eonl yreceive dclos eattentio ni nth eearl yseventies .Despit ea relat ­ ivelyshor tperio do factivities ,result sar eencouraging . Mucheffor twa sdevote dt odevelopmen to freliabl ean defficien ttest s (5.1,5.4 ,5.5 , 5.6,5.7) .Simultaneousl ysource so fresistanc ewer etrace di neithe rcommercia lvarietie s (5.2,5.3) , varietiesfro mworl dcollection s (5.1,5.4 ,5.7 )o rrelate dspecie s (5.3,5.5 , 5.6).Resistanc ewa simprove db yrecurren tselectio n (5.2,5.3 )an dintercrossin go fpar ­ tiallyresistan tvarietie s (5.7).A star twa smad ewit htransferrin gresistanc efro mrelate d speciest ocommercia lvarietie s (5.5, 5.6). Breedingvarietie sbette rsuite dt oparasite san dpredator s (3.1,5.8 )i sanother ,rathe r peculiar,contributio no fplan tbreedin gt ointegrate dpes tcontrol . Someo fth enewl ybre dmateria lha salread ybee nrelease dt ocommercia lbreedin gfirm s (5.7,5.8) ,whic hwil lfurthe rdevelo pi tint ocommercia lvarieties .

163 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 5.1 Resistance to aphids in barley and wheat

G.A.M.va nMarrewij k (1)& F.L .Dielema n(2 )

1Institut eo fPlan tBreeding ,Agricultura lUniversity ,Wageningen ,th eNetherlands . 2Departmen to fEntomology ,Agricultura lUniversity ,Wageningen ,th eNetherlands .

DESCRIPTIONO FTH EPROBLE M

Cerealaphid suse dt opla ya mino rrol ea spest si nth eNetherlands .Ther ei ssom eevi ­ dencetha ti nth elas tdecade sth eaverag eleve lo finfestatio ni sgrowin ghighe ri nman y Europeancountries .Thre eaphi dspecie sar einvolved ,th ebird-cherr yoa taphid , Rhopalo- siphum padi, whichoccupie sth eculms ,th eros egrai naphid , Metopolophium dirhodum, which canb efoun dmainl yo nth elowe rleaves ,an dth eEnglis hgrai naphid , Sitobion avenue, whichinhabit sth eear san duppe rleaves .Sinc e S. avenae isth emos tnumerou saphi di nth e ripeningstage so fcereal san di sgenerall yassume dt ob eth emos tharmful ,investigation s werecentre do nthi sspecies .

MOTIVATIONAN DAI MO FTH EPROJEC T

Thoughth edat ao ndirec thar mcause db ycerea laphid sar erathe rlimited ,ther ei sa consensustha thig hpopulatio ndensitie sreduc egrai nyield .Th eeconomi cinjur yleve li s about20-3 0aphid spe rtiller ,o ra tleas t1 5aphid spe rear .Althoug hth eaphi dpopulatio n onlyseldo mexceed sth eeconomi cinjur yleve lan donl yi nrestricte dregion so fth ecountry , atendenc yca nb eobserve dt ospra ypreventively .Large-scal eapplicatio no finsecticide s wouldcaus ea sever eenvironmenta l load,takin gint oaccoun ttha tth etota lare ao fgrai n cerealsi sa tleas t2 0millio nhectare si nWester nEurope .Therefor ei ti so fimportanc e todevelo pmethod so fbiologica lcontro lt olowe rth egenera lleve lo finfestation .Geneti c resistancet ocerea laphid sseem st ob eth emos tappropriat ewa yt oattai nthi sgoal .Con ­ sequentlyth emai nobjectiv eo fth epresen tprojec ti st otrac esource so fhost-plan tresis ­ tancet ocerea laphids .Thi sca nonl yb eachieve dafte rth esecon dobjective ,th edevelop ­ mento fsimple ,efficien tan dreliabl escreenin gmethods .I nth efirs tphas eo fth eproject , muchattentio ni sgive nt otha taspect .

MATERIALS,METHOD SAN DCONSIDERATION S

Barleywa schose na sth emajo rtes tcrop .Betwee n197 3an d 1977,som e80 0accession s werescreened ,includin gcommercia lvarieties ,semi-wil dpopulation san dbotanica lspecies . In1977 ,hundre dwhea taccession sentere dth eprogra mtoo .

165 Screeningmethod swer edevelope da tthre elevels :natura linfestation ;artifica linocu ­ lationi nfiel dcage so rgreenhous ecompartment s;singl eplant sunde rcontrolle dconditions . Aconcis eoutlin eo fth epro san dcon so fth evariou stes tmethod sca nb efoun di nVa nMar - rewijk& D ePont i (1975). Naturalinfestatio ni sth emos tsimpl ewa yo ftesting .Thi smetho di suse dt oscree n largenumber so faccession s formajo rdifference si naphi dresistance .Accession sar eplant ­ edi nsmal lplots ,row so rtussock s ina randomize dbloc kdesig nan dassesse dfo raphi d densitya tfixe dintervals .Du et oth ehazardou sbuild-u po fepidemic san dth eirregula r distributiono faphid sa relativ elarg enumbe ro freplicate s isnecessar yt odetec tsignif ­ icantdifferences . Plantswer einfeste dartificiall yi nth efiel dwit hmodifie dReitze lcage sa sdescribe d inVa nMarrewij k& Dielema n (1977)a tabou tphas e7- 8o fth eFeeke sscal ewit ha rando m sampleo flaboratory-reare d S. avenae. Theinitia ldensit ywa sabou t 1aphi dpe rtiller . Highcost so fth etria lmad ethi skin do ftes tonl yfeasibl efo ra nunreplicate dchec ko n naturalinfestatio ntrial so rt otes tsmal lnumber so fselecte daccession sagain .Test sun ­ derabnorma lgrowin gconditions ,includin ggreenhous etests ,ar eonl ymeaningfu lalongsid e fieldtrials . Intest so nsingl eplants ,smal lnumber s (1-10)o ffourth-insta rlarva eo ryoun gadult s wereplace do nindividuall y cagedpo tplants .A seac hplan tca nb econsidere da separat e treatment,thes etest sca nb edon ei nman yreplicates .Th etest so nsingl eplant swer euse d forrenewe dtest so naccession sselecte di nth efield ,cag eo rgreenhous efo ra geneti c backgroundo fresistance ,t ofin dth emechanis mo fresistance ,an dt ofin doptimu mcondi ­ tionsfo rexpressio no fresistance .Th ecriteri ause dwer edirectl yo rindirectl yrelate d tofactor sdeterminin gth erat eo fincreas eo fa naphi dpopulation .

RESULTSAN DCONCLUSION S

Onlya genera loutlin eo fobservation san dresult si spresented . Naturalinfestatio ntrial sdi dno tyiel dan yvariet ycompletel yresistan tt o S. avenae nor M. dirhoditm. Noconclusion scoul db edraw nabou t Rh. pad-ibecaus eo fth ever ylo wden ­ sityi nal lyear so fobservation . Naturalinfestatio ntrial swer echaracterize db ya considerabl eamoun to fvariation , withinan dbetwee nblocks ,cause db yirregula rdistributio no faphids ,loca lactivit yo f predaciousinsects ,an dothe rexterna lfactors .Thi sseriousl yhandicappe dtracin gclear - -cutan dstatisticall ysignifican tdifference si nresistance .Nevertheles s therewa scon ­ siderableevidenc etha theritabl edifference si naphi dresistanc eoccurre dbetwee nth ebar ­ leyaccession stested . Bothi nfiel dan dgreenhous etests ,ther ewa sa retarde dpopulatio ngrowt ho f S. avenae onlat eo rnon-boltin gbarle yaccessions .I non eexperiment ,a significantl yhighe raphi d densitywa smeasure do nth etype stha tha dcom eint oear . Ahig hcorrelatio nwa sfoun dbetwee naphi ddensit ype rtille ran dth enumbe ro finfeste d culms,whe nth egenera lleve lo finfestatio nwa sno tto olow .Thi si si naccordanc ewit h observationsmad eb yBasedo w (1975)an dma y leadt oa simplifie dmetho do fassessment . Therewa sa conspiceou s lacko fconformit yi npopulatio ndevelopmen tbetwee naccession s

166 infiel dcage san di nnaturall yinfeste dplots .N oexplanatio ncoul db egive ns ofar . Two-rowbarle yaccession scontaine d lessaphid stha nfour-ro wo rsix-ro wtypes .I ti s doubtfulwhethe rthi sreflect sgrou pdifference s inaphi dresistance .A mor eobviou sex ­ planationi sth egreate raccessibilit yo ftwo-ro wbarle yt opredaceou s insects,especiall y coccinellids. Artificial inoculationi nth eope n (inorde rt oaccelerat epopulatio ndevelopment )prove d tob ea failure .Withi ntw oweeks ,aphi ddensit yfel lt oth eleve lo fnaturall yinfeste d plots. Differencesi nresistanc eobserve di nth efiel dwer egenerall yno tconfirme db ytest s inth egreenhous eo ro nsingl eplants .A nexceptio nwa sbarle yaccessio nCI-16145 ,whic h showeda lo waphi ddensit ya tnatura linfestatio nan dwa sles ssusceptibl etha nothe racces ­ sionsi na singl eplan ttest .Whe ninoculate da tFeeke sstage s5 o r6-7 ,th ereduce dsuscep ­ tibilitywa sexpresse db ya lo wreproduction ,a hig hlarva lan dadul tmortalit yan da rela ­ tivelylon ggeneratio ntime .

SIGNIFICANCEFO RFARMIN G

Introductiono fcerea lvarietie swit ha nincrease dleve lo fresistanc et oaphi dattac k willb ea valuabl econtributio nt ocro pfarming .I nth eNetherlands ,however ,commercia l varietieso fcultivate dcrop sar ebre dexclusivel yb yprivat ecompanies .Thes ewil lonl y bewillin gt oinclud eaphi dresistanc ei nthei rbreedin gprogram si fappropriat esource s ofresistance ,preferabl ya spartl ybre dmateria lan di fwel lestablishe dscreenin gmethod s areavailable .Therefor eth epresen tprojec ti sprerequisit efo rcommercia lbreedin go fre ­ sistancet oaphids .

FUTUREOUTLOO K

Theprojec tstarte di n197 3a sa join tactivit yo fth eDepartment so fEntomolog yan do f PlantBreedin go fth eAgricultura lUniversity ,Wageningen .Despit eth epromisin gresult s sofar ,i twil lno tb econtinue d init spresen tfor mafte r197 8becaus eo fit slaboriou s characteran dbecaus eo frestriction si nstaffing .

REFERENCES

Basedow,Th. ,1975 .Ein ezeitsparend eMethod ezu rzahlemässige nErfassun gvo nBlattläuse n (Homoptera,Aphididae )a nWeizenähren .Anz .Schädlingskd .Pflanz .Umweltschut z4 8 :8-10 . Marrewijk,G.A.M .va n& F.L .Dieleman , 1977.Screenin g techniquesfo rth edeterminatio no f aphidresistanc e inbarley .In :O.M.B .d ePont i& L .Brade r (Editors).Repor tEucarpia / IOBCWorkin gGrou pBreedin g forResistanc e toInsect san dMites ,Wageningen , 1976.Inter ­ nationalOrganizatio nfo rBiologica lControl .SROP/WPR SBull .No .77/3 ,p .37-43 . Marrewijk,G.A.M .va n& O.M.B .d ePonti ,1975 .Possibilitie san dlimitation so fbreedin g forpes tresistance .Meded .Fac .Landbouwwet .Rijksuniv .Gen t4 0 :229-247 .

167 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 5.2 Breeding of carrot (Daucus carota) for resistance to carrot fly (Psila rosae)

O.M.B.d ePont i (1)& J.C .Frerik s (2)

1Institut e forHorticultura lPlan tBreedin g (IVT),Wageningen ,th eNetherlands . 2Researc hInstitut efo rPlan tProtectio n (IPO),Wageningen ,th eNetherlands .

INTRODUCTION

Sinceth elarge-scal eintroductio no fsyntheti cpesticides ,insecticide shav ebee nuse d routinelyi nth eNetherland sagains tth ecarro tfl y (Psila rosae) incarrot s (Daucus carota), althoughi ti sdoubtfu lwhethe rthi si salway snecessary . Theus eo fthes einsecticide sals obecam ecommo npractic ei nselectio nfields ,s otha t susceptibleplant swer en olonge reradicate do rrecognized .Base do nothe ragronomi ccharac ­ terssom eo fthes eplant sma yhav ebee nselecte dan dparticipate d inth epollinatio nan d fertilizationprocesse so fthi scross-fertilize dcrop .Thi sprocedur ema yhav ecause da gradualshif tt oa lowe rresistanc ei nrecen tcarro tvarietie san dselections . Becauseo fth erapi dreductio ni ngerminatio no fcarro tseed ,i ti sno tpossibl et ocom ­ pareth eresistanc eo fol dvarietie san dselection swit htha to frecen tones .Fo rth esam e reason,ol dvarietie san dselection scanno tb euse da spossibl ereservoir so fresistance . Thisprojec taim sa ttracin gvariatio nfo rresistanc ebetwee nan dwithi nvarietie san d selections.B ycarefu lselection ,i ti sintende dt obree da carro tpopulatio nwit ha highe r resistance,whic hca nb euse da sgermplas mi ncommercia lbreeding .

WORKINGMETHOD S

Oversi xyears ,abou t 190varietie san dselection so fmainl yWes tEuropea norigi nhav e beenscreene dfo rresistanc ei nfiel dtrial si na nare awher eth ecarro tfl yi sgenerall y sufficientlyactive .Insecticide swer eno tuse dan dherbicide sonl ybefor eth eplant semerg ­ ed. InMay ,th evarietie swer esow ni n3- 8replicat erow s1.5 mlong ,accordin gt oth e amounto fsee davailable .Th efirst-generatio nattac ko fcarro tfly ,whic honl yrarel ykill ­ edplants ,wa sgenerall y lessimportan ttha nth esecond-generatio nattack ,whic hi nsom e yearswa sheavy .I nOctober ,th ecarrot swer eharvested ,washe dan dclassifie da sattacke d orunattacked .Fro mthos evarietie stha twer erepeatedl y leastattacked ,abou t2 0unattacke d carrotswer eselecte dfro mth emos theavil yattacke dreplicates ,wher eth eselectio npres ­ sureha dbee nth estrongest .Th eselectio ncriterio nwa saltere dfro myea rt oyear ,depend ­ ingo nth eaverag eleve lo fattack .B yselfing ,see dwa sgrow nfo reac hselecte dplan ti n thenex tyea ran da yea rlate rth eresultin ginbre d (Ii)line swer ecompare dwit hth epar -

169 entaimaterial .Fro mth ebes tI 2lines ,individua lplant swer eagai nselecte dan dselfe d andth eI 2line swer escreene dfo rresistanc etw oyear slater .

In1978 ,th efirs tserie so fI 2line soriginatin gfro m7 varietie swer etested .Test s included3 5varieties ,10 7I iline san d6 2I 2lines .

RESULTSAN DDISCUSSIO N

Thebehaviou ro fth ecarro tfl yresult si na ver yuneve ndistributio nove rth efield . Consequentlyth edifference si nattac kbetwee nreplicate sar ealway slarge .Th eyea r197 8 wassuitabl efo rselection ,becaus eincidenc eo nsusceptibl evarietie swa su pt o90% . Figure1 show sth eresult so fth e197 8trial .Th eline swer egenerall yteste di nfewe r replicatestha nth evarietie sbecaus eonl ylimite damoun to fsee dwer eharveste dfro m

Proportion of plots (%) 50-

40- 21 Susceptible" varieties n= 127 30

20

10

40 14 Resistant varieties 30 n=176 20

10- X=8 0 ^ 1 1 r "i 1 1 1 r

30- 16IiLine s n=76 20

10- J" X=7 2 T i 1 1 i i r

30-

20-

10-

"i 1 1 1 1 1 1 1 r 10 20 30 40 50 60 70 80 90 100 Proportion of carrots attacked (%) Fig. 1.Proportiona l frequencydistribution s ofreplicate d plotso f 'susceptible'an d 'resistant'varietie san do fselecte d Iian dI 2line sfro mth elatte rb yincidenc eo fcar ­ rotfly . n =numbe ro fplots ; X= mea nproportio n(% ) ofcarrot sattacked .

170 singleplants .Th evarietie swer edivide dint oa mor e"susceptible "an da mor e"resistant " group.Th efirs ttw ohistogram so fFig .1 demonstrat etha tth edifference si nresistanc e betweenvarietie sar esmall .Thi sagree swit hpreviou sexperienc e (Nieuwhof,1977) . Lineselectio ndurin gth efirs ttw ogeneration shav eresulte di na nincreas eo fabou t 20°6i nresistanc eo fth eselecte dline sove rth eparenta lgeneration .O fth eI ilines ,onl y afe w (16o f107 )me tth eselectio ncriterion .Thi sindicate stha tman ycarrot sselecte d

inth eparenta lmateria lwer eno tmor eresistant ,bu tmerel yescape dattack .O fth eI 2 lines,a large rproportio n (16o f62 )me tth eselectio ncriterion .Thi sshow stha tth ese ­ lectedI iline spossesse da highe rresistanc etha nth eparenta lmaterial .Th eeffectivenes s oflin eselectio nfo rcullin go fwrongl yselecte dmateria li sthu sdemonstrated .

Figure2 show stha twithi nsom evarietie sresistanc evaries .Improve dI 2line swer ese ­ lectedfro mth evarietie s 'Nantes','Pioneer' ,'Signal 'an d 'Vertou'.Othe rvarietie sar e stillunde rinvestigation . Althoughprolonge d lineselectio nmigh tresul ti na furthe rincreas ei nresistance ,thi s selectionprocedur ewil lno tb econtinue duninterruptedl ybecaus eo fth edeclin ei nfitness , quality,yield ,see dyiel dan dsee dquality ,wit hrepeate dinbreeding .Resistanc emigh tin ­ creaseb ybringin gtogethe rresistanc egene sfro mdifferen tvarieties .S oth eselecte dI 2 lineswil lb eintercrosse dan dth esee dharveste dfo reac hplan to rfo reac hline .Th efa ­ miliesthu sobtaine dwil lagai nb esubjecte dt olin eselectio nfo ron eo rtw ogenerations . Thisprocedur eca nb erepeate da slon ga sprogres si smade .Durin geac hintercros sgenera ­

tion,I 2line so fnewl ydiscovere dresistan tvarietie sca nb ecrosse dwit hth eexistin gre ­ sistantpopulation .Al lresistance sfoun dwil leventuall yb ebrough ttogethe ri non epopu ­ lationwit ha maximu mresistance .

Proportion of plots (%) 6O-1

50- Nantes n=23 6I2 Lines n = 27 40-

30- , r' 20 X= 8 8 10H , 1

40-1 25 30 5I2 Lines n= 30 1 I ' I 20 1 rt= 52 ! x = 78 10 !—L_J 1 1 1 1 1 1 1 1 r~i ' 70 80 90 100 Proportion of carrots attacked (% ) Fig.2 .Proportiona l frequencydistribution so freplicate dplot so fth evarietie s 'Nantes' and 'Pioneer'an do fselecte d I2line sfro mthe mb y incidenceo fcarro tfly . n =numbe ro f plots; X= mea nproportio n (%) ofcarrot sattacked .

171 FUTUREWOR K

Whenseed sar eharveste d inintercros sgeneration sfo reac hline ,large ramount so fsee d willbecom eavailable ,allowin gessentia lbackgroun dstudies .Th elimite damount so fsee d fromsingl eplant snecessitate dexperimenta ldesign swit hone-ro wplots .W emus tinvestigat e howfa rth edifference s inresistanc ehol di nlarge rplots ,whic hbette rrepresen tth esit ­ uationi ncrops .O nth eresistan tcarro tfamilies ,th epopulatio ndevelopmen to fth ecar ­ rotfl yca nb estudie di nterm so foviposition ,eg gviabilit yan dlarva ldevelopment .Als o chemicalan dbiophysica lcharacteristic so fth eleave san droot so fresistan tfamilie s shouldb ecompare dwit hthes eo fsusceptibl eone st odiscove ran yessentia lfactor srespon ­ siblefo rhos tselectio nan dutilizatio nb yth ecarro tfly .

SIGNIFICANCEFO RAGRICULTUR E

Theresult sindicat etha tresistanc eca nb eimprove dste pb yste pan dtha tth eultimat e levelo fresistanc ecanno tb epredicted .Possibl yadditiona lcontro lmeasure swil lremai n necessary,bu ttota ldependenc eo nchemica lcontro lwil lb eover .Partia lresistanc ea son e ofth ecomponent so fintegrate dcontro lo fcarro tfl ymigh timprov eth eeffectivenes so f otherfactors ,suc ha sope nwind yfields ,whic har eecologicall y lesssuitabl efo rth ecar ­ rotfly ,an dslow-releas einsecticides .

REFERENCE

Nieuwhof,M. , 1977.Som epreliminar y datao nresearc hint ocarro tfl yresistance .In : O.M.B.d ePont i& L .Brade r (Editors).Repor tEucarpia/IOB CWorkin gGrou pBreedin gfo r Resistancet oInsect san dMites ,Wageningen ,1976 .Internationa lOrganizatio nfo rBiol ­ ogicalControl .SROP/WPR SBull .No .77/3 ,p .13-16 .

172 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 5.3 Breeding onion (Allium cepa) for resistance to onion fly (Delia antiqua)

O.M.B.d ePont i

Institutefo rHorticultura lPlan tBreedin g (IVT),Wageningen ,th eNetherlands .

INTRODUCTION

Theaim ,motivatio nan dphilosoph yo fthi sresearc hprojec twer esimila rt othos eo fth e projecto ncarro tfl y (Section5.2) .

WORKINGMETHOD S

Over6 years ,abou t6 0varietie san dselection so f Allium cepa mainlyo fEuropea norigin , havebee nscreene dfo rresistanc et oth eonio nfl y (Delia antiqua). Themateria lals ocon ­ tained2 0breedin gpopulation so fth ePolis hvariet y 'Rawska',which ,accordin gt ofiel d observationsi nPoland ,wer eles spron et oonio nfly .Fro mbotani cgardens ,6 0accession s of Allium fistulosum werereceived ,a specie swhic hseeme dmor eresistan ttha n A. cepa. Thismateria lwa sscreene dfo rresistanc ei nfiel dtrial sa tWageningen ,wher eth eonio n flywa sgenerall ysufficientl yactive .Becaus eth etrial swer ealway sse tou ti nth esam e area,th epopulatio no fonio nfl yincrease dfro myea rt oyear ,s otha ti nsom eyear sth e selectionpressur etende dt ob eto oheavy .I n1978 ,however ,th eweathe rresulte di na ver y smallpopulatio no fonio nfl yan dconsequentl yth eselectio no fvaluabl einbre d (Iian dI 2) lineswa shindered .Thi sillustrate sth eshortcoming so ftestin gi nth efield .Thi smetho d is,however ,necessar yfo rcollectio no freliabl edat ao nth eresistanc e (VanMarrewij k& DePonti ,1975) . Theexperimenta ldesig nan dselectio nprocedure swer eidentica lt othos euse di nscreen ­ ingfo rcarro tfl yresistance ,wit hon eexception .Th efirs tgeneratio no fth eonio nfl y mostlycause dseriou sdamage .I tdestroye dth eyoun gseedlings ,whic hwer eno tdetectabl e atharvest .Therefor eal lplot sar ecounte dthre etimes :afte remergenc eo fth eseedling s (May),a tth een do fth efirs tgeneratio no fonio nfl y (July)an da tharves t (September). Atharvest ,th ebulb sar eclassifie da sattacke dan dunattacked .Thu sselectio nca nb ebase d (possiblystepwise )o nfirst-generatio nattac ko ro nall-seaso nattack .

RESULTSAN DDISCUSSIO N

In1976 ,th esusceptibl evarietie swer eattacke du pt o90°6 .Thi sleve lo fattac kprove d suitablefo rselection .Varietie so f Allium cepa werefoun dwit hsom edegre eo fresistanc e

173 Table 1.Proportio no fplant sattacke do fsom eonio nvarietie san d ofsom eaccession so f A. fistulosum asrecorde d ina fiel dtes ti n 1976.Value sar eaverage sfo ral lplot sfo rth ewhol egrowt hseason .

Material Origin Proportiono f plantsattacke d(% )

A. eepa 'Jumbo' Netherlands 90 A. eepa 'Hiberna' Czechoslovakia 54 A. aepa 'Wolska' Poland 58 A. aepa 'YellowMakoi ' Hungary 64 A. eepa 'Rawska sel. !' Poland 64 A. eepa 'Kastika' Hungary 65 A. fistulosum Hungary 32 A. fistulosum Czechoslovakia 34 A. fistulosum West Germany 34 A. fistulosum Sweden 35 A. fistulosum West Germany 71 A. fistulosum West Germany 73

toth eonio nfl y (Table 1).Withi nth erelate dspecie s A. fistulosum, markedlyhighe rre ­ sistancewa spresent ,althoug hno tal laccession so fth especie swer ehighl yresistant . Fromth emos tresistan t A. aepa varietiesan d A. fistulosum accessions,unattacke dplant s wereselecte dan dselfed .Th eI jline so fth evarietie swer eteste di n1978 ,whe nselectio n washindere db ya lo wfrequenc yo fattac k (susceptiblecontro lonl y35°s ). Nevertheles safte r selectioni non egeneration ,incidenc ei nth ebes tI iline swa sabou t 10percentag eunit s lesstha ntha to fth eparenta lvarieties .Th eI iline so f A. fistulosum willb eteste di n 1979. Resistancewa sfoun dmainl yi neaster nEuropea nvarieties ,perhap sbecaus einsecticide s wereintroduce dther elate ro rt oa lesse rextent ,a tleas ti nselectio nfields .

FUTUREWOR K

Selectionfo rresistanc ewil lb econtinue db yth esam eprocedure sa sfo rcarro tfly .A t first,th e A. aepa andth e A. fistulosum materialwil lb ebre dseparatel yan deve ni nalter ­ nateyears ,becaus eth eresistanc eo f A. fistulosum seemedt ob eunderestimated ,whe ntha t speciesgre wmixe dwit h A. aepa. Itseem stha tth eonio nflie sattracte db y A. aepa will readilyattac k A. fistulosum. Afteron eo rtw ocycle so fselection ,th etw okind so fpopu ­ lationwil lb ehybridize dan dfurthe rtreate da son ekin do fbreedin gpopulation .Whe nlarg ­ ersee dsample sbecom eavailabl eb yfamil yselection ,backgroun dstudie ssimila rt othos e describedfo rth ecarro tfl yca nb edone .

SIGNIFICANCEFO RAGRICULTURA LPRACTIC E

Iti sdifficul tt opredic twhic h levelo fresistanc et oth eonio nfl ywil lultimatel y bereached ,bu ti ti salmos tcertai ntha tadditiona lcontro lmeasure sremai nnecessary . Partialresistanc ea son eo fth ecomponent so fa nintegrate dcontro lsyste mo fth eonio n flymigh tpromot eothe rcomponent s liketh ereleas eo fsteril emales .Fo ri ti sexpecte d

174 thato nslowl y growing insectpopulation s the frequency and size of the releases canb e diminished, thus increasing theprofitabilit y ofthi s strategy.

REFERENCE

Marrewijk,G.A.M .va n &O.M.B .d e Ponti, 1975.Possibilitie s and limitations of breeding for pest resistance.Meded . Fac. Landbouwwet. Rijksuniv. Gent 40 :229-247 .

175 Integrated control of insect -pests in the Netherlands. Pudoc., Wageningen, 1980.

5.4 Resistance in lettuce (Lactuca sativa) to the green peach aphid (Myzus persicae)

A.H.Eenin k (1)& F.L .Dielema n (2)

1Institut efo rHorticultura lPlan tBreedin g (IVT),Wageningen ,th eNetherlands . 2Departmen to fEntomology ,Agricultura lUniversity ,Wageningen ,th eNetherlands .

INTRODUCTION

Thegree npeac haphid , Myzus persicae, causesproblem si ngreenhous elettuc ean dha st o becontrolle dwit hinsecticides .Othe rmethod so finsec tcontro lar eneede dbecaus eo fth e expenseo finsecticides ,adaptatio no faphid st osom einsecticide san dth eris ko fresidues , especially ina vegetabl ewit ha larg eare ao fconsumabl eleaf .Plan tresistanc ecoul doffe r aninexpensiv ean dsaf esolution .

MACROTESTFO RRESISTANC E

Fora rapi dscreenin g forresistanc eo fa larg ecollectio no fplan tgenotype so fth e IVT Lactuca genebank ,a macrotes twa sdevelope d (Eenink& Dieleman ,1977a) .Plan tgenotype s tob eteste dar egrow ni na greenhous e (15-25°C )i nfou rreplicate swit hfiv eplant spe r genotype ineac hreplicate .Individua lplant s (5-8leaves )ar einoculate dwit h 10-15aphid s rearedo nChines ecabbage .Afte r3- 4weeks ,th enumbe ro faphid spe rplan ti sestimate do n ascal efro m0 (absolut eresistant ,n oaphid sa tall )t o9 0 (verysusceptible ,man yaphids) . Bythi smethod ,mostl yrelativ edifference sbetwee nplant sca nb eobserved .Nevertheles s therei sa goo drelationshi pbetwee nestimate san dcount so fth enumbe ro faphid s (Eenink& Dieleman,1977a) . Byth emacrotest ,larg edifference swer efoun dbetwee nabou t80 0lettuc egenotype s (Fig.1). About 15selecte dpartiall yresistan tgenotype swer euse dfo rmor edetaile d investigations onth eaphid-lettuc erelationship ,fo rstudie so nth einheritanc eo fresistanc ean dfo rth e improvemento fth eleve lo fresistanc eb ybreeding . Ingeneral ,tes tprocedure sar edetermine db ycharacter so fth eplant ,th eaphi dan dth e plant-aphidrelationship .S orathe rdetaile dinformatio ni sneede dabou tfactor ssuc ha s plantage ,typ eo fleaf ,larva lgrowt h (weighto fth elarvae) ,fecundit yan dmortalit yo f larvaean dadults .Th einterdependenc eo fsom eo fthes ecriteri afo rresistance ,th egeneti c andenvironmenta l influenceso nth eexpressio nan dstabilit yo fresistanc eshoul dals ob e investigated.

177 Proportion of total accessions tested (%)

30-

20-

10-

—i 1 1 1 1 1 r— 0 10 20 30 40 50 60 70 80 90 Degreeo fresistanc e Fig. 1.Frequenc ydistributio no f26 6IV TLactuc aaccession sove ra scal efo rresistance . 0 =absolut eresistant ;9 0= susceptible .Value spe rgenotyp ear emean so f2 0plants .

INFLUENCEO FPLAN TAN DLEA FAG E

Colonizingaphid softe nchang ethei rpositio no na lea fan dove rdifferen tleave so f thesam eplant .Th eultimat eresul to fplan tdevelopmen tan dagein go fth eplant ,an dpopu ­ lationgrowt ho fth einsec ti sa distributio ndependen to nth eag eo fth eleaf .Fo rinstance , ona full ygrow nlettuc eplant ,mos taphid sar eo nth elower ,senescen tleaves . Thecharacteristi cdistributio no faphid sove ra plan tma yinfluenc eth eoutcom eo fre ­ sistancetests .Tabl e 1list ssom eresult so fth einfluenc eo fplan tag eo fa partiall y resistantan da susceptibl egenotyp eo naphi dbehaviou ran ddevelopment .Ther ewer elarg e differences forlarva lmortality ,insec tweigh tan dfecundit ybetwee nth eteste dgenotypes . Inbot hgenotypes ,insec tweigh tan dproductio no flarva ewer einfluence db yplan tage .Th e olderplant sseeme dt ob esomewha tmor esusceptibl etha nth eyounge rones .Th edifferenc e inresistanc ebetwee nth etw ogenotype smeasure db yweigh to finsec twa ssomewha tbigge r withyoun gplants .Th edifferenc ebetwee nresistan tan dsusceptibl eplant sfo rlarva epro ­ ductiondi dno tchang ewit hplan tage . Experimentswit ha partiall yresistan tan dsusceptibl egenotyp eals oshowe dth einfluenc e

178 Table 1.Influenc eo fplan tag eo nlarva lmortality ,insec tweigh tan d numbero flarva eproduce dpe raphi d (infou rdays )fo ra partiall y resistantan da susceptibl egenotype .Plan tag e2 2an d 15day sa tth etim e ofinfestation .

Quantity PIVT 313 PIVT 339 susceptibl e partially resistant

22 days 15

larvalmortalit y(% ) 23 23 50 58 insectweigh t (pg) 566 502 398 304 numbero flarva eproduce d 18.6 16.. 4 9.9 7.8 peraphi d in4 day s

oflea fag ean dlea fpart so nweigh to flarva ean dreproductio n (Eenink& Dieleman ,1977a) . Forthes eexperiments ,lea fcage swer euse d (2c mdiameter) .Weigh to finsec tan dreproduc ­ tionwer ehighe ro nol dleaves ,bot ho fth epartiall yresistan tan dth esusceptibl egenotype . Significantdifference sbetwee nlea fparts ,measure db yinsec tweigh tan dlarva eproduction , wereonl yobserve do nth epartiall yresistan tgenotype .Nea rth eti po fth eleaves ,th e highestvalue sfo rthes echaracter swer emeasured .Th edifference sbetwee nresistan tan d susceptibleplant sfo rweigh tan dproductio no flarva ehardl ychange dwit hlea fag eo rpar t ofth eleaf .

INFLUENCEO FAPHI DDENSIT Y

Someevidenc ei savailabl etha tth erat eo fincreas ei sdensity-dependent .Thi simplie s thatth ecriteri afo rresistanc ei nou rtest sar eals odensity-dependent .Th einfluenc eo f aphiddensit yo nfactor slik elarva lmortality ,productio no falatae ,insec tweigh tan d larvaeproductio nwa s investigatedwit h leafcag etests .Som eresult sfo rsusceptibl ean d partiallyresistan tgenotype sar egive ni nTabl e2 .Fo ral lcriteria ,larg edifference s existedbetwee nth etw ogenotypes .Th einfluenc eo faphi ddensit yo nmortalit yseeme dt o beabsen to rver yweak .O nbot hteste dgenotypes ,aphi ddensit ypositivel y influencedth e frequencyo fwinge daphid san dnegativel yinfluence dweigh to flarva ean dne tproduction .

Table2 .Influenc eo fnumbe ro faphid so nlarva lmortality ,proportio n ofwinge daphid s (%),insec tweigh tan dnumbe ro flarva eproduce dwit ha resistantan da susceptibl egenotype .

Quantity PIVT18 0 PIVT19 7 partiallyresistan t susceptible

larvaepe rcag e larvaepe rcag e 1 5 10 1 5 10

larvalmortalit y (%) 50 53 63 23 23 24 wingedaphid s (%) 13 19 32 4 9 14 weightpe raphi d (ug) 25 173 163 437 384 294 numbero flarva eproduce d 9.4 7.8 7.3 31.5 24.0 20.0 peraphi d in7 day s

179 Table 3.Compariso n ofbehaviou r of twobiotype s ofMyzu s persicae, (WM-1 and WM-2), on two lettucegenotypes .

Plant genotype Insectweigh t (ug) Larval mortality Proportions of adults after 7day s (%) after 7day s(% )

WM-1 WM-2 WM-1 WM-2 WM-I WM-

PIVT 313 637 268 4 48 84 24 PIVT 339 326 110 22 96 53 0

The differencebetwee n thesusceptibl e and resistant genotype forweigh t andproductio n of larvae seemed to decreasewit h increasing aphid density.

APHID BIOTYPES

The initialpopulatio n of M. persicae was collected from commercial crops oflettuce . Inth e laboratory,th e aphidswer e reared onChines e cabbage.Fro m thispopulation ,tw o biotypeswer e selected,WM- 1 andWM-2 .I nsevera l experiments,th ebehaviou rwa s compared of thesebiotype s on resistant andsusceptibl eplan t genotypes.Som e of the results are given inTabl e 3. Forbot h biotypes,larg e differenceswer e foundbetwee n the testedgeno ­ types for all criteria. Larvae ofWM- 2 developed slowero nbot hplan t genotypes andha d a lowerweigh t after 7day s and ahighe rmortality . Both the genotypes susceptible and resistant toWM- 1 were classed asba d foodplants forth eWM- 2biotype .Consequentl y all our tests for resistancewer ewit h theWM- 1 biotype.

ADAPTATION

Inaphi dpopulations ,physiologica l [short-term) adaptation (conditioning)ca n interfere with the results of resistance tests.Afte r transfer of M. persicae fromChines e cabbage to lettuce,th e strongest conditioningwa s found inalatae ,les s strong inapterou s aphids andnégligeabl e inyoun g larvae.S o first instar larvaewer e always used formicrotest s (Eenink &Dieleman , 1977a). Geneticvariatio nwithi n the aphidpopulatio nwa s already demonstratedb y the occurrence ofbiotypes .Thi s variationmigh t result ina genetic adaptation ofth e aphidpopulatio n to resistantplan t genotypes.Therefor e several experimentswer e donewit h susceptible and partially resistantplan t genotypes to investigate such an adaptation,resultin g in amor e or lessgradua lbreakdow n ofresistance .Preliminar y results suggest thatn o adaptation occurredwithi n 3generations . Similar resultswer e found forother plan t genotypes and aphidpopulation s over 12insec t generations. Further investigations have tob e carried out with aphidpopulation s originating from differentpart s of the country.

180 Degreeo fresistanc e 80-1

60-

40-

20-

0- 364 F1 550 197 F1 339 242 F 42 PIVTnumber san dF Fig.2 .Degre eo fresistanc eo fIV Taccession san do fF ifro mcrosses .0 = resistant ; 90= susceptible .

INHERITANCEO FRESISTANC E

Diallelecrosse swer emad ebetwee nsusceptibl ean dresistan tgenotypes .Th eparents ,

andFi ,F 2an dF 3population swer eevaluate dfo rresistance .A tleas tfo rsom egenotypes , resistancewa sinherite di nadditiv efashio n (Eenink& Dieleman ,1977b) .S oth eleve lo f resistanceo fth eF iwa sintermediat ebetwee ntha to fth eparent s (Figure2) .

Thegeneti cvariatio ni nF 2population sfro mcrosse sbetwee nsusceptibl ean dresistan t parentswa slarge rtha nth evariatio ni nth eF 2population s fromcrosse sbetwee ntw ore ­ sistantparents .S oprobabl ya tleas tsom egene sfo rresistanc ei nth etw oparent swer e thesame .A syet ,n otransgressio no fresistanc ecoul db eobtaine db ycrossin gresistan t parents.

CONCLUDINGREMARK S

Partiallyresistan tlettuc egenotype sobtaine ds ofa rcoul dcontribut et oaphi dcontro l inlettuce .Th eretarde dpopulatio ndevelopmen to fth eaphids ,fo rinstanc eb yhig hmortal ­ ityan dlo wfecundity ,allo wles sfrequen tapplicatio no finsecticides .Th eresistanc eleve l mayb eimprove di nth enea rfutur ewit htransgressio nb yintercrossin g resistantgenotypes .

REFERENCES

Eenink,A.H . &F.L .Dieleman ,1977a .Screenin gLactuc afo rresistanc et oMyzu spersicae . Neth.J .PI .Path .8 3 :139-151 . Eenink,A.H .& F.L .Dieleman ,1977b .Resistanc e inLactuc aL .t oMyzu spersica e (Sulzer). In:O.M.B .d ePont i SL .Brade r (Editors).Repor tEucarpia/IOB CWorkin gGrou pBreedin g forResistanc e toInsect san dMites ,Wageningen , 1976.Internationa lOrganizatio nfo r BiologicalControl .SROP/WRPS .Bull .No .77/3 ,p .61-66 .

181 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 5.5 Breeding lettuce (Lactuca sativa) for resistance to the aphid Nasonovia ribisnigri

F.L.Dielema n (1)S A.H .Eenin k(2 )

1Departmen to fEntomology ,Agricultura lUniversity ,Wageningen ,th eNetherlands . 2Institut efo rHorticultura lPlan tBreedin g (IVT),Wageningen ,th eNetherlands .

INTRODUCTION

Nasonovia ribisnigri isth emos tcommo naphi dcolonizin goutdoo rlettuce .Effectiv e controlo fthi saphi drequire sfrequen tapplicatio no finsecticide sbecaus eo frepeate d secondaryinfestatio nb ywinge daphids .Th eaphid sar emainl ypresen to nth eyounge rleav ­ es, insideth ehead so flettuce .Thi sbehaviou rmake spesticides ,especiall ycontac tones , lesseffective .S ous eo finsecticide sconfront sconsumer sbot hwit hinsecticida lresidue s anddea daphids .Resistan tlettuc evarietie scoul doffe ra solutio nt othes eproblems .

APHIDBEHAVIOU RAN DTES TPROCEDUR E

Testsfo rresistanc ehav et ob eadapte dt oaphi dbehaviou ran dcharacteristic so fth e hostplant .Th especifi cfeedin gbehaviou ran drapi ddisturbanc eo fsettle daphid smake s artificialinfestation ,manipulatio nan daphi dcountin gmor edifficul tthe nfo r Myzus per- sicae, anotherlettuce-infestin gaphid . N. ribisnigri isals osensitiv et ocrowding ,an d wingedaphid sar ealread yproduce da tlo wpopulatio ndensities .Thi sphenomeno nlimit sth e durationo ftests . Incertai ntests ,youn glettuc eplants(2 0day sold ,2 replicate san d5 plant spe rgeno ­ typepe rreplicate )wer einoculate dwit habou t 10aphid so fmixe dage san ddevelopment . Aftertw oweeks ,th epopulatio nincreas epe rplan tdiffere dwidel ybetwee nplan tgenotypes . Asa resul to fa larg escatter ,th esignificanc eo fthes edifference sfo rpartia lresis ­ tancewa sno talway sclear .Howeve ramon g30 0genotype stested ,som eaccession so fth e wildspecie s L. virosa couldb eclearl ydistinguishe dfro mal lothe rgenotype sbecaus eo f thever yhig hresistanc et oA' , ribisnigri (Dieleman& Eenink , 1977). Resistancewa sexpresse dquantitativel yb yth efollowin gmor edetaile dtes tprocedure . Tenfirst-insta rlarva ewer epu ti nth ecentr eo flettuc eseedling s (5plant spe rgenotype) . Theselarva ewer ebor nb yyoun galata et oavoi dth eproductio no fwinge daphid so nth e plantst ob etested .Afte r7-1 0days ,larva lmortalit ywa sassesse dan d5- 7day slate rth e totalnumbe ro faphid spe rplan twa scounted ,durin gth efirs tgeneratio no faphid sbor n onth eteste dplants .Tabl e 1illustrate sth edifferenc e inresistanc ebetwee na susceptibl e genotypean dth eresistan t L. virosa. Undernatura lan dartificia lconditions ,settlin go f N. ribisnigri onresistan t L. virosa wasobserved ,bu tcolonizatio nalway sfailed .

183 Table 1.Difference sbetwee na resistan tan da sus ­ ceptiblegenotyp eo f Lactuaa afterartificia linfes ­ tationwit h 10first-insta r larvaepe rplan t (5plant s per genotype).Survivin g larvaean d larvaeproduce d werecounte d 10an d 15day safte r infestation,respec ­ tively.

L. serriola (susceptible) L. virosa (resistant)

Numbero f Numbero f Numbero f Numbero f larvae larvae larvae larvae surviving produced surviving produced

5 70 0 0 7 78 0 0 8 70 0 0 9 70 0 0 10 140 0 0

TRANSFERO FRESISTANC E

Becauseresistanc ewa spresen ti naccession so fa wil d Laotuoa species,whic hwa srathe r distantfro mth ecultivate dspecie s L. sativa, greatbarrier sfo rtransfe ro fth eresistanc e tobutterhea dlettuc eha dt ob etaken .Anothe rsusceptibl ewil dspecies , L. serriola, was useda sa "bridg eparent "betwee n L. virosa (resistant)an d L. sativa (susceptible).Th e crossingschem ei soutline di nTabl e2 .Plant so fF jseeme dt ohav eth esam eresistanc e levela sth emal eparent ,s otha tresistanc ema yb egoverne db yon eo rmor edominan tchro ­ mosomalgenes .Onl ya fe wo fth eF iplant sshowe dsom efemal efertility ,an dal lplant s werecompletel ymale-sterile .Man yhundred so fbackcrosse st o L. serriola and L. sativa weremade ,resultin gi na fe wB ]seed .Afte rfurthe rbackcrossin gwit h L. serriola and L. sativa, andcultivatio no fsee do nnutrien tmediu mi ntes ttubes ,finall ysom eplant s wereobtaine dwit ha rathe rgoo dmal ean dfemal efertility .Afte rtesting ,som eo fthes e plantsseeme dt ohav eth esam eresistanc e levela sth eresistan tparenta lgenotyp e (Table3) .

Table2 .Crossin g schemefo rth e transfero fresistanc e from L. virosa to L. sativa.

L. serriola X L. virosa (susceptible) (resistant) Fi L. serriola (resistant) L. sativa L. Bi serriola L. sativa B L. serriola 2 L. sativa B3 X L. sativa (susceptible orresistant )

184 Table3 .A sampl eo fresistan t and susceptible selections(B 3 generation)obtaine db ybackcrossin g andcompare dwit hth e original susceptiblean dresisten tparents .Eac hplan twa s inoculatedwit h 10first-insta r larvae.Ther ewer e6 replicat e plants for Laotuaa serriola and5 fo r L. vivosa.

Genotype Numbero f Numbero f larvaesurvivin g larvaeproduce d (after 10days ) (after 15days )

L. serriola (susceptible) 85 L. vivosa (resistant) 0 Selectionsfro m backcrossing 3 0 resistant 0 2 100 susceptible 170 120

PROSPECTS

Iti sfeasibl et oinclud eth eresistanc efro mou rselection si nlettuc evarieties .Be ­ causeo fhig hresistance , N. ribisnigri cannotcoloniz eth eresistan tvarieties .S oth eus e ofinsecticide st ocontro lthi saphi dwil lb esuperfluous .Howeve rfurthe rinvestigation s areneede do nth einheritanc ean dstabilit yo fresistanc ean do nth echemica lbasi so f resistance.

REFERENCE

Dieleman,F.L .& A.H .Eenink , 1977.Resistanc e inlettuc e toNasonovi aribisnigri .In : O.M.B.d ePont i& L .Brade r (Editors).Repor tEucarpia/IOB CWorkin gGrou pBreedin gfo r Resistancet oInsect san dMites ,Wageningen , 1976.Internationa lOrganizatio nfo rBio ­ logicalControl .SROP/WPR SBull .No .77/3 ,p .67-68 .

185 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 5.6 Breeding tomato (Lycopersicon esculentum) for resistance to the greenhouse whitefly (Trialeurodes vaporariorum)

O.M.B.d ePont i& N.G .Hogenboo m

Institutefo rHorticultura lPlan tBreedin g (IVT),Wageningen ,th eNetherlands .

INTRODUCTION

Inth eNetherlands ,th egreenhous ewhitefl y (Trialeurodes vaporariorum) intomat oi s successfullycontrolle dwit hth eparasiti cwas p Encarsia formosa ona larg escal e(Va n Lenterene tal. , 1977).Environmenta lchange ssuc ha soccasiona lho tsumme rperiod so rin ­ tentionallowerin go ftemperature sfo rne wvarietie scan ,however ,distur b theequilibriu m betweenpes tan dparasite .Th ereliabilit yan dconsequentl yth eapplicabilit yo fth esyste m ofbiologica lcontro lca nb epromote db yus eo fvarietie sles ssusceptibl et oth egreen ­ housewhitefly ,s oretardin gdevelopmen to fth ewhitefly .Unlik eothe rcomponent so finte ­ gratedcontrol ,resistanc ei sgenerall yno tinfluence db yenvironmenta lchanges ,thu sben ­ efitingth eentir esystem . Thepresen tprojec twa saime da tfindin gsource so fresistanc ei ncultivate dan drelate d specieso ftomato .Simultaneousl yreliabl ean defficien ttes tmethod sha dt ob edeveloped .

SOURCESO FRESISTANC E

Thesearc hfo rsource so fresistanc ewa sstarte db yscreenin g8 3accession sbelongin g to8 specie so fth egenu s Lycopersicon and2 accession so f Solanum pennellii. Topreven t choiceb yth ewhitefly ,th eaccession swer eteste dseparatel y ina greenhous e inlarg ecag ­ esmad eo fcheesecloth .I neac hcage ,thre eplant swer e infestedwit h 75whitefl yemerge d frompupa eth eda ybefore .Afte rsi xweeks ,reproductio no fth efirs tgeneratio ndevelopin g incage swa sassesse db yestimatin gth enumbe ro fadults ,th enumbe ro fempt ypupa ean dth e numbero fne weggs .Withi nth ecultivate dspecie s L. esculentum, nousuabl elevel so fresis ­ tancewer etraced .Onl yth erelate dspecie s S. pennellii and L. hirsutum wereselecte da s partiallyresistan t (DePont ie tal. , 1975).

TESTMETHOD S

Totransfe rth eresistanc e fromth ewil dt oth ecultivate dspecies , S. pennellii and L. hirsutum var. glabratum werecrosse dwit hsusceptibl ecommercia lvarieties .Fo rth e

screeningo fth esegregatin gF 2an dfollowin ggenerations ,plant swer egrow ni npots .A t thestag ewit h2- 3tru eleaves ,eac hplan twa scovere dwit ha transparan tplasti ccylinde r

187 andinfeste dwit h 15femal ewhitefl y emergedth eda ybefore .Afte rS days ,livin gwhiteflie s werecounte dan dthe nkille dwit hsulfote pfumigant .Thre eweek s later,pupa ewer ecounted . Theresistanc eo fselecte dline so fFi ,an dfurthe rgeneration swa schecke di npractica l testsunde rnorma lgrowin gconditions .Fo rtha tpurpose ,1 8plant so feac hlin ean do fth e susceptiblean dth eresistan tparen twer eseparatel yplante di nsmal lisolate dcompartment s ofa greenhouse .Eac hplan twa sinfeste dwit h3 0femal ewhiteflie san dth edevelopmen to f thepopulation swa sfollowe db yestimatin gth enumbe ro fadul twhiteflie si nth esecon d andthir dgeneratio nafte rinfestation .I nthes etests ,man yline sfro mplant sselecte d inpo ttest swer ea ssusceptibl ea sth esusceptibl econtrol ,s oth ereliabilit yo fth epo t testwa sdoubtful . In1978 ,3 0line swer eextensivel yteste db ybot hmeans .I nadditio nt oth evisua lesti ­ mationo fth enumber so fadul twhiteflie s inth econsecutiv egenerations ,anothe rmethod , developedb ya guest-worker ,D rM.J .Berlinge r (RegionalExperimen tStation ,Gilat ,Israel ) was introduced.I neac hcompartmen twer eplace d5 yello wPetr itrap s (yellow-paintedplas ­ ticPetr idishes ,grease dwit hTanglefoot) .Afte r4 8h th enumbe ro ftrappe dwhiteflie s waselectronicall ycounte dwit ha Biotra nI IColon yCounter .I ngenera lthes esample so f thepopulation sagree dwit hth evisua lestimate .A sth ecorrelatio nbetwee nth epo ttes t andth epractica ltes twas ,indeed ,ver ypoor ,th epo ttest ,i nit sorigina lform ,wa s judgedinadequate . Inth emeantime ,Berlinge rstarte da detaile dstud yo fth erelationshi pbetwee nth e whiteflyan dit shost s L. esculentum, L. hirsutum var. glabratum and S. pennellii. Heuse d materialwhos esusceptibilit yo rresistanc eha dbee ndetermine dwit hcertaint yi npractica l tests.Unde rcontrolle dconditions ,th efollowin gcharacteristic swer eassessed :adul t survival,ovipositio nrate ,eg gan dlarva lmortality ,se xrati oan dduratio no fdevelopment . Thesedat awer ecompare dwit hthos eo npopulatio ndevelopmen ti na greenhous efo rthre ege ­ nerations.Th epreliminar yresult sindicate dtha tth edifference s insurviva lan doviposi ­ tionrat eo ntomat oan dit swil drelative swer esmal ldurin gth efirs tday so fth ewhite - fly'sadul tlife ,wherea s laterth edifference s increased.Thi sagree swit hth eexperience s ofWoet s& Va nLentere n (1976),wh ostudie dth esuitabilit yo fdifferen tvegetabl ecrop s ashost sfo rth ewhitefly .Th estud yo fpopulatio ndevelopmen tshowe dals otha tth eresis ­ tanceo f S. pennellii dependedo nit sgrowt hstage :th efirs tleave swer erathe rsusceptibl e whereasth elater-develope d leaveswer ecompletel yresistant .Bot hfinding smigh texplai n thefailur eo fth epo ttest .A nimprove dtes ti sbein gdeveloped .

RESULTSAN DDISCUSSIO N

Theshortcoming so fth epo ttes thav eretarde dth edevelopmen to fresistan tbreedin g lines.Afte rsevera lpractica ltests ,man ylines ,unjustl yselecte di npo ttests ,ha dt o bediscarded .Fro m L. esculentum x L. hirsutum var. gläbratum crosses,onl yon eresistan t

F7 linean dsom eF 3 lineswer e left.Tabl e 1show sth eresistanc eo fthi sF 7lin ean dth e

resistanceo f S. pennellii. Insegregatin gF 3 linesfro mcrosse sbetwee n L. esculentum and S. pennellii, resistantplant swer eselected .I nTabl e 1,th eresistanc eo f S. pennellii isunderestimated ,becaus edevelopmen to fth ewhitefl ypopulatio no n L. esculentum wasre ­ tardedb yheav ycontaminatio nwit hparasiti cwasps .Contaminatio nwit h E. formosa isa majo r

188 Table 1.Number so fgreenhous ewhiteflie s collected in5 Petr i dish traps over4 8h i nth ethir d generation after inoculation intw o different practical testso nth etomat o cultivar 'Heinz 1370',tw o related speciesan da breedin g line. Material Numbero f whiteflies trapped Test 1 Test2 L. esoulentum cv.Hein z 1370 3215 605 L. hivsutum var. glabvatwn 44 F7 (Heinz 1370x L. hirsutism var. glabvatwn) 166 S. pennellii - 112

problemi nth epractica l tests,becaus e thatwas p cannotb eselectivel y controlled. To investigatewhethe r resistantplant s canb erecognize dwhe n they are grownbetwee n

susceptibleplants , L. esoulentum, L. hivsutum var. glabvatum, theresistan tF 7 linean d one susceptibleF 7 linewer eplante d randomlyi na greenhouse .Afte r inoculating each plant with3 0femal ewhiteflies ,th eplant swer e judgeda si nth epractica l test.I ntha tsitua ­ tiontoo ,th edifference s between resistantan dsusceptibl e plantswer e clear.S otha tmeth ­ od too seems suitablefo r selecting segregating populations.

SIGNIFICANCE FORHORTICULTUR E PRACTICEAN D FORFUTUR EWOR K

Invie wo fth e levelso fresistanc e found,i tma yb epossibl et obree d varieties that dono t needan y additional controlmeasures . The sticky exudateo fth eglandula rhair so fS. pennellii isth emos t striking mechanism ofresistanc eo ftha tspecies .Howeve r fromcrosse sbetwee n this speciesan dth etomato , someF 3plant swer e selectedwit h the same levelo fresistanc ea s S. pennellii, butwit h markedly less sticky exudate.S oothe r factors,suc ha scomponent so fth e leafsap ,mus t alsocontribut et oth eresistance .I nbreedin g resistant lines,w ewil l avoid incorporation ofth e characteristic sticky exudate,i nwhic h theparasiti cwasp sar eals o trapped.I fnot , resistancewoul dbecom e incompatiblewit h theus eo fE. formosa. As soona sth epo t testha sbee n improved,th ebreedin go fresistan t lines canb eenhanc ­ ed. Large amountso fF 2 seedso fcrosse s between the resistantwil d speciesan dth eculti ­ vated tomatoar estil l available.Th e search forne w sourceso fresistanc ewithi n therelat ­ ed specieso ftomat owil l alsob erepeated .

REFERENCES

Lenteren,J.C . van,J .Woets ,N .va nde rPoel ,W .va nBoxtel ,S .va nd eMerendonk ,R . van der Kamp,H .Nel l& L .Sevenster-va nde rLelie , 1977.Biologica l controlo fth e green­ housewhitefl y Trialeurodes vaporariorum (Westwood) (Homoptera:Aleyrodidae )b yEncarsi a formosa Gahan (Hymenoptera:Aphelinidae )i nHolland ,a nexampl eo fsuccessfu l applied ecological research.Med . Fac. Landbouwwet. Rijksuniv. Gent4 2(2 ): 1333-1342 . Ponti,O.M.B . de,G .Pe t& N.G .Hogenboom , 1975.Resistanc et oth eglasshous e whitefly (Trialeurodes vaporariorumWestw. )i ntomat o (Lycopersicon esculentum Mill.)an drelate d species.Euphytic a2 4: 645-649 . 189 Woets, J. &J.C . van Lenteren, 1976.Th e parasite-host relationship between Encarsia for- mosa (Hymenoptera: Aphelinidae) and Trialeurodes vaporariorum (Homoptera: Aleyrodidae). 6. The influence of the host plant on the greenhouse whitefly and its parasite Encarsia formosa. In:L . Brader (Editor), Progress in Integrated Control in Glasshouses, Report Working Group Integrated Control in Glasshouses,Antibe s 1976. SROP/WPRS Bull. 77/4 : 151-164.

190 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 5.7 Breeding cucumber (Cucumis sativus) for resistance to the two-spotted spider mite (Tetranychus urticae)

O.M.B.d ePont i

Institutefo rHorticultura lPlan tBreedin g (IVT),Wageningen ,th eNetherlands .

INTRODUCTION

Inth eNetherlands ,abou t 1000h ao fcucumber sar egrow ni ngreenhouses .Th econtro lo f thetwo-spotte dspide rmit e (Tetranychus urticae) requirespermanen tattentio nan deffor t byth egrowe rt opreven teconomi c loss.Afte ra nenthusiasti cstar ti nth eearl yseventies , biologicalcontro lwit hth epredator ymite , Phytoseiulus persimilis hascease dt oexpan d (Section 3.1).Althoug hthi scontro lsyste mgenerall yfunction swell ,i ti ssensitiv et o environmentalchange ,incur scost san drequire smuc hcar eb yth egrower . Thetwo-spotte dspide rmit ethrive sles so nresistan tvarieties ,whic hmigh tpromot e biologicalcontro lan ddiminis hth efrequenc yan ddos eo facaricid esprays .S obreedin g andus eo fresistan tvarietie spromot eintegrate dcontro l (DePonti ,1977a) .Th epresen t projectinvestigate dth ebreedin go fcucumbe rvarietie shighl yresistan tt oth etwo-spotte d spidermite .

WORKINGMETHOD S

Kooistra (1971)selecte d 12partiall yresistan tvarietie safte rthre egreenhous etrial s inwhic h40 0varietie so fth eIV Tcucumbe rcollectio nwer escreene dfo rresistanc eb ya simpledamag erating .Wit hth eselecte dvarieties ,th ebreedin go fresistan tline so fgreen ­ housecucumbe rwa sstarted ,bu tth escreenin gtechnique ssoo nprove dinadequat efo rth epur ­ pose.S oa thoroug hstud yo fth ehost-parasit erelationshi pwa sstarted ,wit hcucumbe rva ­ rietiesdifferen ti nresistance .Th eintentio nwa st otrac ethos easpect so fpopulatio n developmento fth etwo-spotte dspide rmit etha twer einfluence db yresistance .Accordin g toit slevel ,resistanc ereduce dadul tlifetime ,oviposition ,eg gviability ,an dlarva lan d nymphalsurviva l (DePonti ,1977b) . Basedo nthi sstudy ,tw oresistanc etest swer edeveloped . - Inth elaborator ytes t (DePonti ,1977b) ,th edegre eo facceptanc ean dreproductio nwa s scoredo npotte dplant san dlea fdiscs ,respectively .Afte rgreasin gth epetiol eo fth e firsttru elea fwit h 'Tanglefoot',2 0femal edeutonymph swer eplace do ntha tleaf .Afte r 10days ,th emite slef twer ecounte da sa measur eo facceptance .Fro mthes emite s (adults abouteigh tday sold) ,fiv ewer eplace do nseparat e leafdisc so fth esecon dlea fan dafte r threedays ,ovipositio nwa sobserve da sa measur eo freproduction .Thes etest sar ecarrie d

191 outunde rcontrolle dcondition s inclimat erooms . - Inth epractica ltes t (DePonti ,1978a )unde rnorma lgrowin gcondition si na greenhouse , 10adul tfemal emite swer eplace do nth ethir dlea fo feac hplan tt ob eteste di nth e third—leafstage .Ove rabou teigh tweeks ,th edevelopmen to fth espide rmit epopulatio n wasrate do na damag escal efro m0 t o5 . Aftera nadditiona lscreenin go f40 0varieties ,altogethe r80 0varietie swer etested .Th e 50leas tdamage done swer eextensivel y retestedi nlaborator yan dpractica ltests .There ­ afterth eresearc hwa scontinue db yinvestigatin gth egenuinenes so fresistanc ean dway so f increasingit .Durin gal lphase so fth eproject ,th erol ewa sconsidere do fth ebitte rprin ­ ciplecucurbitacin- ci nthi sresistance .Va nKeule n (1980)develope da nefficien tmetho d ofestimatin gthi scompound .

RESULTSAN DDISCUSSIO N

Ofth e5 0selecte dvarieties ,onl y9 (outo f8001 )wer esignificantl y differentfro mth e susceptiblecontro l foracceptance ,reproductio nan ddamag einde x (DePonti ,1978b) .Tabl e1 showsth edifference s inacceptanc ean dreproductio nbetwee nsom eo fthes evarietie san d thesusceptibl econtrol .Th eimplication so fthes epartia lresistance s fordevelopmen tan d controlo fth etwo-spotte dspide rmit ear ebes tshow ni nth epractica ltest .Th eslo win ­ creasei ndamag eo fth epartiall yresistan tvarietie si sdemonstrate di nFigur e 1.Th ehor ­ izontallin ea ta damag einde xo f1. 9represent sth eeconomi cinjur y level,whic hfo rth e mostresistan tvarietie swa spasse dabou t3 week slate rtha nfo rth esusceptibl econtrol . Thereductio ni nreproductio nafte rmovin gth emite sfro ma susceptibl evariety ,o nwhic h theyar enormall yreared ,t oothe r (resistant)varietie smigh tonl yb etempory .I fso ,th e resistanceo fth eselecte dvarietie swoul dno tb egenuine .T oinvestigat ethis ,bot hresis ­ tancetest swer erepeate dafte rth emite sha dbee nreare do nth eselecte dvarietie sfo r 10-20generations .Th edegre eo facceptanc ean dreproductio nan dth edamag einde xdecrease d rathertha nincreased ,providin gevidenc e forth egenuinenes so fth eresistanc e (DePonti , 1978b). Attemptingt oincreas eth eleve lo fresistanc efoun di nth epartiall y resistantvarieties , Iintercrosse dthes evarietie san dsubjecte dth esuccessiv egeneration st oselectio ni nlabo ­ ratoryan dpractica ltests .Tabl e2 an dFigur e2 clearl ydemonstrat etha tthi sbreedin gpro -

Table 1.Degre eo facceptanc ean dfecundit yo fth etwo-spotte d spider miteo n5 partiall yresistan tcucumbe rvarietie san d thesusceptibl e control. Variety Geographic Accep tance Numbero fegg spe r origin (%) femalei n3 day s PI22086 0 Korea 24 11.6 HybridLG P UnitedState s 36 18.5 Taipein o1 Taiwan 39 21.1 PI17888 5 Turkey 35 11.5 OhioM R20 0 UnitedState s 37 18.3 Susceptible control Netherlands 76 26.5

192 Damage index (arbitrary unit) 5

Economie injuryleve l

4 5 6~ # Time after infestation (weeks) Fig. 1.Increas eo fdamag eo nth esusceptibl econtro l (o)an do n5 partiall yresistan t cucumbervarietie safte rinfestatio nwit h 10femal etwo-spotte d spidermite spe rplant . Theeconomi c injuryleve li sa tdamag einde x1.9 .

cedurewa ssuccessful . Some F5 lines were selectedwit h amarkedl y lower reproduction than theparenta l varieties.Th e1 5mos t resistant lineswer e released in197 8t oprivat e breed­ ing firms inth eNetherlands ,whic h will tryt ocombin e this resistancewit h other useful agronomic characteristics todevelo p varieties resistant totwo-spotte d spider mite. All resistant varieties arebitter ,a swoul db eexpecte d since theworl d assortmento f cucumber contains 991bitte r varieties.Althoug h resistant andbitte r varieties generally didno tcontai nmor e cucurbitacin-c than susceptible andbitte r ones, therewa sa nunintend ­ ed increase inth eamoun to fcucurbitacin- c inth eselecte d F5 lines overth eparenta l varieties.Howeve r many bitter-free andresistan t plants were found inF 2 andbackcros s generations after crossing resistant andbitte rwit h susceptible andbitter-fre e lines.

Table2 .Degre eo facceptanc ean dfecundit yo fth etwo-spotte d spidermit eo na susceptibl econtrol ,o n2 partiall yresistan t cucumbervarietie san do n2 line sderive d fromcrosse sbetwee n thesevarieties .

Varietyo rlin e Acceptance Numbero fegg spe r (%) femalei n3 day s HybridLG P 36 14.1 Robin5 0 45 15.1 F5 (HLGPx Robi n50 ) 45 8.4 F5 (HLGPx Robi n50 ) 34 9.4 Susceptiblecontro l 72 21.0

193 Damage index (arbitrary unit) 5T

Economie injuryleve l

4 5 . 6 7 Time after infestation (weeks v ) Fig. 2.Increas e of damage on the susceptible control (o),o n twopartiall y resistantva ­ rieties (•) and on twoF 5 lines derived from crosses between thevarietie s(x) .

SIGNIFICANCE FORHORTICULTUR E AND FOR FUTUREWOR K

Control of the two-spotted spidermit e canb e advancedb y the introduction of resistant varieties. Figure 2show s that a combination of resistancewit h acaricidal controlwil l cause areductio n in frequency ofsprayin g tohal fo r a third.Biologica l controlwil l also be favouredb y retarded development of themites ,althoug h theexac tquantitativ e effect hasno tye tbee n investigated.Accordin g to the extent of spontaneous infections, resistance might oftenb e enough foru s to abandon any additional control. The inheritance of the resistance is still understudy ,bu t appears tob epolygenic .S o thebitte rprincipl e cucurbitacin-c,whos e presence is governedb y one dominant gene,can ­ notb e entirely responsible for resistance. Further analysis ofth e genetics of theresis ­ tance inrelatio n to that ofcucurbitacin- c should clarify the role of that substance.Th e influence of resistance on the efficiency of chemical andbiologica l controlwil l alsob e investigated and attempswil lb emad e to tracebiochemica l orbiophysica l factors responsi­ ble forth e resistance. Since the release ofresistan t lines tobreedin g firms,thes e firms havebee n andwil l be supported inthei r efforts tobree d cucumbervarietie s resistant to two-spotted spidermite .

REFERENCES

Keulen, H.A. van, 1980. Fluorodensimetric estimation of cucurbitacin-c content in leaves of Cucumis sativus L.(i n preparation). Kooistra,E. , 1971.Re d spider mite tolerance in cucumber.Euphytic a 20 :47-50 .

194 Ponti, O.M.B, de, 1977a,b ; 1978a,b Resistance in Cucumis sativus L. to Tetranychus urticae Koch. 1.Th e role of plant breeding in integrated control. 2.Designin g areli ­ able laboratory test for resistance based on aspects of the host-parasite relationship. 3. Search for sources of resistance. 4. The genuineness of the resistance. Euphytica 26 :633-640 ;641-654 ;2 7 : 167-176;435-439 .

195 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980.

5.8 Breeding glabrous cucumber (Cucumis sativus) varieties to improve the biological control of the greenhouse whitefly (Trialeurodes vaporariorum)

O.M.B.d ePont i

Institutefo rHorticultura lPlan tBreedin g (IVT),Wageningen ,th eNetherland s

INTRODUCTION

Inth eearl y 1970s,th egreenhous ewhitefl y (Trialeurodes vaporariorum) becamea majo r pesto fgreenhous ecucumber s (Cucumis sativus) inth eNetherlands .I n1976 ,20 0varietie s ofth eIV Tcucumbe rcollectio nwer escreene dfo rresistanc et oth ewhitefly .Technique s developedt oscree ntomat ofo rresistanc et oth esam einsec t (DePont ie tal. ,1975 )wer e used.Significan tdifference sbetwee nvarietie swer eno tfound .Thi sma yb edu et oa lac k ofdifference si nresistanc eor ,mor elikely ,t oinadequacie s inth escreenin gtechniques . Alsoi nth etomat oproject ,thes etechnique sraise ddoubt s (Section 5.6).Unti limprove d techniquesbecom eavailable ,screenin go fth ecucumbe rcollectio nha sbee npostponed . Contraryt oth esituatio nwit htomato ,sufficien tcontro lo fth egreenhous ewhitefl y byth eparasiti cwas p Encarsia formosa israrel yachieve di ngreenhous ecucumbers ,despit e repeatedlarg eintroduction so fth ewasp .Va nLentere ne tal . (1977)ascribe dthi sfailur e ofcontro lt oth eman ylarg ehair so nth ecucumbe rlea fan dth ehoneyde wo nth ehairs . Thesefactor swoul dreduc eth emobilit yan dconsequentl yth eparasitis mb yth ewasp .There ­ forevarietie swer esough twit ha lea fmorpholog ytha twoul dhinde rth ewas pt oa lesse r extent.

WORKINGMETHOD S

Witha stereomicroscope ,th e20 0varietie smentione dabov ewer ejudge dfo rth elengt h anddensit yo fth ehair so nth eleave san dth ethicknes san ddensit yo fth eveins .Differ ­ enceswer etrace db ycompariso nwit ha standar dvariety .O naberran tvarietie sth enumbe r ofhair swer ecounte dan ddivide db ylea farea .

RESULTSAN DDISCUSSIO N

Ofth e20 0varieties ,onl y7 showe dclearl ydeviatin g leafcharacteristic s (Table1) . Towha texten tthes echaracteristic smigh tfavou rth emobilit yo fth eparasiti cwas pwa s notstudied ,becaus ew ethe ncam eacros sa publicatio no fStrelnikov a& Mashtakov a (1973) abouttw oglabrou scucumbe rmutant s thatsounde dpromisin g forth epurpose .Afte rreceiv ­ ingsee do fthes emutant sfro mth eVavilo vAil-Unio nInstitut eo fPlan tIndustr yi nLenin -

197 Table 1.Descriptio no flea f characteristics inwhic hsom e cucumbervarietie sdeviat efro mth estandard .

Variety Origin Description

PI16722 3 Turkey 40%fewe rhair san d shorterhair s PI17160 9 ii 50%fewe rhair s PI17367 4 H 40%fewe rhair s PI17967 6 India 40%fewe rhair s PI17695 0 Turkey shorterhair s PI13784 6 Iran lowervei ndensit y ZiaStetg aS i Vietnam thinnervein s

grad,I multiplie di tan dgav ei tt oVa nLentere nan dWoets ,wh ofoun dtha to nth eglabrou s leavesth ewas pwa sn olonge rhampere db yth ehair san dtravelle da ta spee d3. 5time sa s greata so nnorma lhair yleave s (Hulspas-Jordaan& Va nLenteren ,1978) .Th eexpecte dposi ­ tiveinfluenc eo fthi senhance dmobilit yo nparasitis mwil lb einvestigate di ngreenhous e andlaborator ytests . Anticipating theresult so fthes etests ,I hav estarte dbreedin gglabrou scucumbe rva ­ rietiesb ycrossin gth emutant swit hgreenhous ecucumbe rbreedin g lineso fIVT .Recentl y 8advance dbreedin g lineswit hth eglabrou scharacteristi chav ebee nrelease dt obreedin g firmsi nth eNetherlands .Becaus eo fth esimpl einheritanc e (1recessiv egene )an dselect - abilityo fth echaracter ,releas eo fglabrou svarietie sma ysoo nb eexpected .

FUTUREWOR K

Althoughparasitis mb yth ewas pmigh tb eenhance db yglabrousness ,th ereproductio nrat e ofth egreenhous ewhitefl y isstil lrathe rhig han dabou tth esam ea so nnorma lhair yva ­ rieties.Biologica lcontro lo fthi sinsec tca nb efurthe rimprove db ybreedin gvarietie s resistantt oth egreenhous ewhitefly ,s otha tth ereproductio nrat ei sreduced .A ssoo na s efficientscreenin gtechnique sar edeveloped ,investigation s intoresistanc et oth ewhitefl y willb eresumed .

SIGNIFICANCEFO RHORTICULTUR E

Withglabrou scucumbe rvarieties ,biologica lcontro lo fth egreenhous ewhitefl ywit hth e parasiticwas p Encarsia fovmosa willb epossible .Th econsequen tdeclin ei nus eo finsecti ­ cideswil lals opromot ebiologica lcontro lo fth etwo-spotte dspide rmit e (Tetranychus uvtieae) withth epredator ymit e Phytoseiulus -pevsimilis. A forthcomingreleas eo fvarietie s resistentt opowder ymilde w Sphaerotheca fuliginea willals ofacilitat eth ebiologica lcon ­ trolo fbot hpests . Sofar ,n ounfavourabl echaracteristic so fglabrousnes shav ebee nfound .O nth econtrary , iti sexpecte dtha tgrower swil lwelcom ethes evarietie sbecaus ethe ycaus eles sski nirri ­ tation. REFERENCES

Hulspas-Jordaan, P.M. &J.C . van Lentereii, 1978.Th e relationship between host-plant leaf structure and parasitization efficiency of the parasitic wasp Encarsia formosa Gahan (Hymenoptera: Aphelinidae). Med. Fac. Landbouwwet. Rijksuniv. Gent: 43 (2) :431-440 . Lenteren, J.C.va n et al., 1977.Biologica l control of the greenhouse whitefly Trialeurodes vaporariorum (Westwood) (Homoptera:Aleyrodidae ) by Encarsia formosa Gahan (Hymenoptera: Aphelinidae) inHolland , an example of successful applied ecological research. Med. Fac. Landbouwwet. Rijksuniv. Gent 42 (2) :1333-1342 . Ponti, O.M.B. de, G. Pet &N.G . Hogenboom, 1975.Resistanc e to the glasshouse whitefly (Trialeurodes vaporariorum Westw.) in tomato (Lycopersicon esculentumMill. ) and related species. Euphytica 24 :645-649 . Strelnikova, T.R. &A.K . Mashtakova 1973.A new non-pubescent cucumber form (Russian). Selektsiya i semenovodstvo ovoshchnykh, Kishinev. 1973 :3-6 .

199 6 Pheromones and attractants

Since 1967,Dutc hresearc hha splaye da leadin grol ei nth efiel do finsec tpheromones . Inspiredb yth esuccesse so fD rW.L .Roelof si nth eUnite dStates ,i twa sdecide dt ocon ­ centrateal leffort sfirs to norchar dpests ,i nparticula ro nth etortrici d (orleaf-roller ) moths.Th eInstitut efo rPesticid eResearc ha tWagenir.gen ,an dth eDivisio no fTechnolog y forSociet yTN Oa tDelf tcooperate dclosely .Th elatte rinstitut edi dth echemica lanalysis , namelyisolatio nan didentificatio n (6.1).Th eforme rinstitut eteste dth epheromone si nth e fieldand ,afte rpositiv eresults ,worke dou tmethod sfo rpractica lus eo fth epheromone s eitherfo rmonitorin go rfo rcontro lb ydisruptio no fmatin g (6.3). Mosto fth epheromon ecompound swer esynthesize dan dpurifie di nWageninge nan da larg e collectiono fsuc hcompound swa sbuil tup .Thi scollectio nha smad ei tpossibl et ofin da numbero fse xattractan tmixture sfo rsevera lmot hspecie sb yempirica lscreenin g (6.2). Atpresent ,th eresearc hprogra m isn olonge rexclusivel ydevote dt opest so ffrui t orchards.Muc hattentio ni sno wals obein gpai dt opest si nvegetabl ean dflowe rcrops .

201 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 6.1 Isolation and identification of pheromones

F.J.Ritte r &C.J .Persoon s

Divisiono fTechnolog yfo rSociet yTNO ,Delft ,th eNetherlands .

DESCRIPTIONO FTH EPROBLE M (INCLUDINGHISTORY )

In1959 ,A .Butenand te tal .isolate dan didentifie dth efirs tinsec tpheromone :bomby - kol,th ese xpheromon eo fth esilkwor mmoth .Soo nafte rthi spioneerin gwork ,attempt swer e made,mainl yi nth eUnite dStates ,t oidentif ypheromone so fpes tinsect st ofin dway so f selectivecontrol .Wit hth etechnique sthe navailable ,tha twa sa trick yjo ban dsevera l chemicalstructure spublishe di ntha tperio dha dt ob ewithdraw nlater . Concurrentlywit hth echemica lresearch ,fiel dwor kwa sdon ewit h 'sextraps 'containin g lifevirgi nfemale st ofin dou twhethe rse xpheromone scould ,i nprinciple ,b euse di npes t control.I nth eNetherlands ,Mink sdi dtha ti n196 7fo rth esummerfrui ttortri xmot h Adoxophyes orana and,i nlate ryears ,h edemonstrate dth epotentia lus eo fse xpheromone s formonitorin gpurpose si nsupervise do rintegrate dcontro lo ftha tinsec ti norchards .Bu t asth etrap swer eno tsufficientl yeffectiv et oreplac eligh ttraps ,i twa sdecide dt otr y toisolat ean didentif yth ese xpheromone ,i nth ehop etha tth esyntheti cpheromon ewoul d yieldbette rresults . Thisjoin tprojec twa sstarte di n197 0b yth eLaborator y forInsecticid eResearc h(no w Institutefo rPesticid eResearch) ,whic hdi dth ebiologica lwork ,an dth eCentra lLaborator y TNO (nowDivisio no fTechnolog yfo rSociety) ,whic hdi dth eisolatio nan didentification . Thelatte rha dalread ygaine dsom eexperienc ei nthi sfiel dwit hwor ko ncockroache san d termites,an dha didentifie d (Z)-3, (Z)-6,(E)-8-dodecatrieno l asa trail-followin gcompoun d forth eFrenc htermit e Reticulitermes santonensis in1969 ,a yea rafte rth ecompoun dha d beenidentifie d inth eUnite dState si nAmerica n Reticulitermes spp.Afte ridentificatio n ofth ese xpheromon eo f A. orana in1971 ,th eprojec twa sextende dt oth eidentificatio no f these xpheromone so fothe rlepidopter aan do fth eAmerica ncockroach ,th ealar mpheromon e ofgrai naphid san dth etrai lpheromon eo fth ePharaoh' sant .

AIMAN DMOTIVATIO N

Theai mo fth eprojec ti sth eidentificatio no fpheromone sfo rsynthesi san dus ei nse ­ lectivepes tcontrol . Itsmotivatio ni sdifferen tfo rdifferen tinsects .Th etortricid s Adoxophyes orana, Archips podanus and Pandemis heparana, forexample ,ar ethre emajo rleaf-rolle rpest si n

203 Dutchorchards ,a sals oi nothe rEuropea ncountries .Th ecabbag eleaf-rolle r Clepsis speatrana isa seriou spes ti noutdoo ran dgreenhous erose si nth eNetherlands . Thepotat otuberwor mmot h Phthorimaea operaulella isno ta commo npes ti nth eNether ­ lands,bu tit sse xpheromon ewa sidentifie da sa par to fa progra mt odevelo pa metho do f detectingimporte dinfestations .Th einsec tis ,however ,a majo rpes to fpotatoe si nMedi ­ terraneancountrie si nEurop ean dals oi ntropica lan dsubtropica lregion sthroughou tth e world. Aphidsar emajo rpest sal love rth eworld .I nth eNetherland sthe yar ea significan t pesto fyoun gcerea lplant san dthe yar eseriou svector so fviru sdisease so fpotatoe san d sugar-beet. Thereason sfo rth eisolatio nan didentificatio no fpheromone so fnon-agricultura lpes t insectsar edifferent .Termites ,fo rexample ,ar eeconomicall yamon gth emos tseriou spest s inth eworld ,particularl ythos eo fth egenu s Reticulitermes. Inth eNetherlands ,the ysel ­ dompos ea problem ,bu tthei rpheromon ecoul db euse dt odetec tinfestation si nimporte d timber.Cockroaches ,i nparticula r Blattella germanica, butt oa lesse rdegre eals o Periplaneta americana, andth epharaoh' san t Monomorium pharaonis, areserieu surba npest s inman ycountries ,includin gth eNetherlands .

WORKINGMETHOD S

Usuallywhol einsects ,abdomens ,gland so rothe rtissue sar eextracte dfro ma fe whundre d upt oabou t3 000 0insects .Th eisolatio nan didentificatio nstep sar emonitore db ya be ­ havioralassa yan dofte nals ob yelectro-antennography .Th emai ntechnique so fseparatio n andpurificatio nar ehigh-pressur e liquidchromatograph yan dga schromatography .Th echem ­ icalstructure so fth epheromone sar edetermine db ysevera lchemica lan dphysica lmicro ­ techniquessuc ha shydrogénation ,ozonolysis ,reactio nchromatography ,mas sspectrometry , infraredspectroscop yan dnuclea rmagneti cresonnance .Th estructur emus tultimatel yb e confirmedb ysynthesi san db ytestin gth eactivit yo fth esyntheti cpheromone .

RESULTSAN DDISCUSSIO N

These xpheromon eo f A. orana wassoo nisolate dan dit sstructur ewa sreporte di n1971 . Itwa sth efirs ttim ea se xpheromon ewa sfound ,i nwhic hth epresenc eo ftw oisomers ,(Z)- 9 and (Z)-11 tetradecenylacetate ,wa sprerequisit efo rbiologica l activity.Th erati oo fth e twocompound swa scrucial :i nse xtrap sth elarges tnumbe ro fmale swer etrappe dwit ha ratioo f9:1 .Othe rratio sgav emuc hsmalle rcatches .No wthes efact sar ehardl ysurprisin g forpheromon escientist sbu tthe ywer ever ymuc hs oi n1971 . Thetw ocomponent smentione dar e isomers, differingonl yi nth epositio no fthei rdoubl e bond.Togethe rwit hRoelof s (CornellUniversity) ,w e foundth esam etw oisomer si nanothe r tortricidmoth , Clepsis speatrana, whichi ssympatri cwit h A. orana andha sit sflight si n thesam eperiods .Th erati oo fth etw ose xpheromon ecomponent s in C. spectrana wasth ere ­ verseo ftha to f A. orana. Thedifferenc eseem st oensur ethei rreproductiv eisolation . Thejoin teffort so fth eteam sa tWageninge nan dDelf tyielde d anothersurpris ewhe nth e structureo fth ese xpheromon eo fa thir dtortrici dmoth , Arahips podanus, waselucidate d

204 andreporte di n1973 :agai na binar ypheromone .Th ecomponent swer ecis-tran sisomers : CZ)-11an d (E)-11tetradeceny lacetate ,i na rati oo fabou t 1:1.Thi swa squit eunexpecte d attha ttim ea si twa sgenerall ybelieve damon gpheromon escientist stha tcis-tran sisomer s ofse xpheromone swer einhibitor srathe rtha nsynergists .I ti sno wknow nfro mexperiment s inman ycountrie stha tsuc ha synergis mbetwee ncis-tran sisomer si sa ver ycommo nphenom ­ enon,no tonl yi nmono-unsaturate dpheromone sbu tals oi nthos econtainin gtw odoubl e bonds.A nexampl eo fth elatte ri sgossyplure ,a 1: 1mixtur eo f (Z,Z)an d (Z,E)7,11-hexa - decadienylacetates .Thi sgossyplur e isth efirs tsuccessfu lcommercia ldisruptiv eo fa n agriculturalpes t (thepin kbollworm) ;i twa sregistere db yth eUnite dState sEnvironmenta l ProtectionAgenc yi n1978 . Eventh efirs tse xpheromon eeve ridentifie d (Butenandt'sbombykol )recentl yprove dt o bea componen to fa mor ecomple xsecretion ,whic hals ocontain son eo fit scis-tran siso ­ mers.Th ebiologica l functiono fth elatte ri sno tye tknown . Anexampl eo fsynergis mbetwee nse xpheromone sonl ydifferin gi nth enumbe ro fdoubl e bondswa sfoun di nth epotat otuberwor mmot h Phthorimaea operoulella. Itsstructur ewa s againelucidate db ya join teffor to fth eteam sa tDelf tan dWageningen .Th ecomponents , (E)-4,(Z)-7-tridecadieny l acetatean d (E)-4, (Z)-7,(Z)-IO-tridecatrieny lacetate ,ar e rareexample so fse xpheromone swit ha nuneve nnumbe ro fcarbo natoms .Th ethre edoubl e bondsi nth esecon dcomponen twer eals ounprecedente damon gse xpheromones . Inth eUnite dStates ,th ealar mpheromon eo fth erose ,pea ,greenbu gan dcotto naphid s wasreporte dt ob e (E)-ß-farnesenei n1972 ,an dit spresenc ei n Myzus persioae wasreport ­ edi n1973 ,bein gconfirme di nth esam eyea rb yWientje se tal .i nou rlaboratory .I ncol ­ laborationwit hHill eRi sLambers ,th egrai naphid s Macrosiphum (Sitobion) avenae, Rhopa- losiphum padi and Metopolophium dirkodum weremass-culture dan d (E)-g-farnesenewa sfoun d tob eth ealar mpheromon eo fthes eaphid stoo . Althoughno trelevan tt oagriculture ,th eresult so fresearc ho ntermites ,cockroache s andant swer eals oregularl ydiscusse dan dreporte dt oth eWorkin gPart yo nIntegrate dPes t Control.Persoon san dRitte rwer eawarde dth eRoya lDutch/Shel lPriz e197 8fo rthei rwor k onth eAmerica ncockroac han do npharaoh' sant .Tw ose xpheromone so f Veviplaneta ameriaana havebee nisolated :periplanon eA (C15H20O2)an dperiplanon eB (Ci5H2o03).Th estructur eo f thelatte rprove dt ob e (1Z,5E)-1,10(14)-diepoxy-4(15) ,S-germacradiene-9-one ,whic hwa s confirmedb ysynthesi sb yStil li nth eUnite dStates .Th eodou rtrai lo fth epharaoh' san t wasfoun dt ocontai ntw obiologicall yactiv eheterocycli ccompounds ,monomorin eI an dIII , and,i naddition ,a ver ypoten ttrai lpheromone ,calle dfaranal .A ninterestin gfeatur eo f itsstructure ,(6E,10Z)-3,4,7,11-tetramethyl-6,10-tridecadienal-1 ,i sit sresemblanc et o juvenilehormon eII .

SIGNIFICANCEFO RAGRICULTUR E

These xpheromone so f Adoxophyes ovana and Arohips podanus areno wuse droutinel yb yth e HorticulturalAdvisor yServic ei nth eNetherland sa sa monitorin gagen ti nse xtraps .Prom ­ isingfiel dresult sfo rdirec tcontro lo f A. ovana byth econfusio ntechniqu ear eabou tt o bepu tint opractice .Th eothe rpheromone sdescribe dar estil lbein gevaluate d forthei r practicalus ei nmonitorin gdevice so rdirec tcontrol ,fo rexampl eb ydisruptin gmatin g throughpermeatio no fth eai rwit hse xpheromones . 205 lOTUREOUTLOO K

Inth epast ,attempt st ous epheromone si npes tcontro lhav eofte nstarte dprematurely : laterth estructure softe nappeare dt ob eincorrec to rincomplete .I nparticular ,th esig ­ nificanceo fisomer so fth emai npheromon ean do fothe rmino rcomponent swa sneglected .W e nowkno wman yexample so fbinar yan dmulticomponen tpheromones .Som eo fth esecondar yo r minorcomponent sar eessentia lfo rbiologica lactivit yunde rfiel dconditions ;other senhanc e theefficienc yconsiderabl yo rhav ea vita lfunctio ni nth etota lsyste mo fattraction ,ex ­ citationan dmating .Fo rsevera lspecies ,w ehav eevidenc ethat ,althoug hth emai ncompo ­ nentso fth etota lpheromon eblen dar eknown ,som emino rbu thighl yimportan tcomponent s arestil lt ob eidentified .Furthe ranalytica lwor k isthe nnecessary .Se xtrap scontainin g pheromoneswil lprobabl yfin dman ymor euse si nth enea rfuture .Bu tals oth eus eo fphero ­ monesi ndirec tcontro lseem st ob ewithi nreach .Th eresult sobtaine di nth eUnite dState s withth edirec tcontro lo fth epin kbollworm ,ar eparticularl yencouraging .A crucia lmat ­ terfo rth esucces so fthes eapproache si sth edevelopmen to fsuitabl econtrolled-releas e formulationsan dtechniques . Thepractica lus eo fpheromone s islaggin gfa rbehin dscientifi cknowledge ,largel ybe ­ causeo feconomi cfactors .Th especificit yo fthes eagent si sa grea tadvantag efo rth e environmentbu tmake sthe monl yattractiv e forindustr ywhe nthe yca nb euse do npest so f greateconomi cimportance .Th eexpens eincurre di nobtainin ggovernmen tapprova lfo rregis ­ trationo fa produc ti sa mai nreaso nfo rth ereluctanc eo fth epesticid eindustr yt oente r thisfield .Fo rfurthe rprogress ,clos ecollaboratio nbetwee ngovernment ,industr yan duni ­ versitieso rothe rnon-profi torganization s istherefor enecessary .

REFERENCES

Persoons,C.J. , 1977.Structur eelucidatio no fsom einsec tpheromones :a contributio nt o thedevelopmen to fselectiv epes tcontro lagents .Thesis ,Wageningen . Ritter,F.J. , 1979.Chemica lecology :odou rcommunicatio n inanimals .Genera l introduction andoverview .In :F.J ,Ritte r (Editor).Chemica lecology :odou rcommunicatio n inanimals . Elsevier/NorthHollan dBiomedica lPress ,Amsterdam . 1-15. Ritter,F.J . &C.J .Persoons ,1975 ,Recen tdevelopment s ininsec tpheromon eresearch ,i n particular inTh eNetherlands .Neth .J . Zool.2 5 :261-275 . Ritter,F.J . &C.J .Persoons ,1976 .Insec tpheromone sa sa basi sfo rth edevelopmen to fmor e effectiveselectiv epes tcontro lagents .In :E.J .Arien s (Editor).Dru gdesign .7 .Acade ­ micPress ,Ne wYor kp .59-114 .

206 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 6.2 Synthesis and investigation of potential sex pheromones of insects

S.Voerma n

Institutefo rPesticid eResearch ,Wageningen ,th eNetherlands .

INTRODUCTION

Forenvironmenta lan deconomi creasons ,researc han dextensio no npes tcontro li saime d atreducin gamount so finsecticides ,fo rinstanc eb yapplyin gthe monl ywhe nnecessar yan d atth erigh ttime .A nexac tknowledg eo fth epresenc eo rabsenc eo fth enoxiou sinsec tspe ­ ciesi sindispensable .Se xpheromone san dattractant so finsect sca nb euse di ncollectin g thisinformatio nan destimatin gfligh tactivities .Stick ytraps ,baite dwit h 1m go rles s ofth epheromone ,usuall yattrac tonl yon einsec tspecies .S oth estar to fth efligh tperio d ofa ninsec tspecie sca nb eeasil yestablished .I fn oinsect sar etrapped ,n ocontro lmeas ­ uresar enecessary .I fso ,trappin gdat aca nb ehelpfu lt ose tu pa nefficien tan deconomi c programo fcontrol . Alsochemica lcommunicatio nbetwee nmale san dfemale so fa ninsec tspecie sca nb edis ­ ruptedb yevaporatin g largeamount so fthei rse xpheromon e intoth eair .Thi smetho dcoul d becomea ver yselectiv ewa yo fcontrollin ginsect san di sbein gstudie di nsevera lpart so f theworld .

RESULTSAN DDISCUSSIO N

Ourattentio nwa sinitiall yconcentrate do nleaf-roller s (Lepidoptera:Tortricidae )i n applean dpea rorchards ;late rothe rinsec tspecie swer estudie dtoo .Man yunsaturate d straight-chainacetate swer esynthesize dt osuppor tcurren tidentificatio nprogram san dt o screenthes ecompound si norchards ,singl yo rmixe di nsevera lcombination so nthei rattrac - tivity.Figur e 1show sa typica lreactio nschem et oobtai n (Z)-9-tetradecen-1-olacetat e (Z-9-TDA).Wit hsligh tmodifications ,mos tpositiona lan dgeometrica lisomer sca nb epre ­ pared (Voerman,1979a) . A9: 1mixtur eo fZ-9-TD Aan dZ-11-TD Ai sth ese xpheromon eo f Adoxophyes orana (Lepido­ ptera:Tortricidae) .Later ,w efoun dtha ta 1: 1mixtur eo fE-11-TD Aan dZ-11-TD Ai sth ese x pheromoneo fth emot h Archips podanus. TheE compoun dca nb eobtaine db yreductio no f 2-(11-tetradecynyloxy)tetrahydropyra nwit hsodiu mi na mixtur eo fliqui dammoni aan dtetra - hydrofuran. Nowabou t10 0mono-unsaturate dacetate sar eavailabl ewit hvaryin gchai nlengt h (10-18 carbonatoms )an dpositio no fth edoubl ebon di nth echain .The yar euse di nfiel dscreenin g

207 HOCjjOH H Ct HOC8Cf ^IQJ.HCE L^O-CgCt

HCECC4 LJ-0-C8CECC4 ^- '-' BuLi/HMPT

1.HAc,Ac 2Q AcOC8clcC4

2.H2> P-2 Ni

Fig. 1.Reactio nschem efo robtainin g (Z)-9-tetradecen-l-olacetate .

anda smode lcompound si nidentificatio nprograms .Durin gfiel dscreenin gMink se tal . (1976)discovere dtha ta 1: 1mixtur eo f (E)-9an d (Z)-9dodecen-1-o lacetat ewa sattractiv e formal e Enarmonia formosana moths (Lepidoptera:Olethreutinae) . Highisomeri cpurit yi sessential .Smal lamount so fE- 9o rE-1 1TD Amuc hdecreas eth e attractivityo fth ese xpheromon eo f Adoxophyes ovana. Becausei ti salmos timpossibl et o synthesizegeometricall ypur ecompounds ,syntheti ccompound smus tultimatel yb epurifie d toremov esmal lamount so fth eunwante disomer .Thi sca nb eachieve db yargentatio nchro ­ matography:a liquid-chromatographi cmetho di nwhic hwea kinteraction sar euse dbetwee n silverion san dethyleni cbonds .Th eE compound sfor ma weake rcomple xwit hsilve rion s thanth eZ compound san dtherefor epas squicke rthroug ha colum ncontainin gsilve rion s thanth eZ compound swit ha suitabl emobil ephase .Thi sprincipl eca nals ob euse dt oesti ­ mateth eisomeri cpurit yo fa sample .Gas—liqui dchromatograph y isals oindispensabl e (Voerman,1979a) . Moresophisticate dmethod sar eneede dt oproduc epoly-unsaturate dstraight-chai nace ­ tates.Al l4 geometrica lisomer so f3,13-octadecadien-1-o lacetat eca nb emad eb ychemica l conversiono f9-tetradecen-1-o l acetatesa si sshow ni nFigur e2 (Voerman ,1979b) . TheZ ,Z isome ri sa nattractan tfo rth emal eclearwin gmot h Synanthedon myopaeformzs (Lepidoptera:Sesiidae) .Additio no fa smal lamoun to fon eo fth estereoisomer sprobabl y resultsi na mixtur etha ti smor eattractiv etha nth esingl ecompound . Thepotat otuberwor mmoth , Phthorimaea opevoulella (Lepidoptera:Gelechiidae )i sa se ­ riouspes ti ntropica lan dsubtropica lareas .It sse xpheromon ewa sidentifie dan dconsist s

1. KOH/MeOH

C4C = CC8OAc 2. CBr4,03P/THF C4C= CC8Br

LiCECH C4C= CC8C = CH ^—^ »- »•

1. Reduction C4C= CC8CECC2OH 2.AcetylQtion

C4C=CC8C = CC2OAc Fig.2 .Chemica lconversio no f9-tetradecen-l-o lacetate st o3 ,13-octadecadien-l-o l acetates.Th esymbo l i standsfo rpheny lgroup .

208 oBB Q O Q Q

< O c co 00 00 e e

en + P B-5 eu C i 0 u T-t eu u CO .O.r-c 1 3 X M eu CU CO U

ö « a fi ^K s K c^ ö -fi CS ö ,o i 1 1 « a 8 ö i-s co \0 kJ Qi-J 't-, rH i-i c S K r-> C3 c» i 1 O 0 CU All i §?« S) ö e» K ö c c 1 1 •H S Si co CD CU O c--i O S fi Cü l IS «•« ca « 4J u •o T) X co co ö +> -^ co \--S t-i a E Ö «"§ CU CU o O CU CS M '^ -^ Cü siM W E O ö, -w ca 4J 4J •o T> Si CO ?H S M^ S) O 0 V 0 Ä e V ÄO O O 3j 6 O E ton E •» II il II II II CU CU co ca g rC rif CS) O o <0 OÄ« Q S .-I p. EX, EX, £ ü o o r-i 8 B= X .O co » » ö s-g-s* •w aj+» V S O o

209 oftw ocompounds : (E)-4,(Z)-7-tridecadien-1-o lacetat e (PTM1 )an d (E)-4, (Z)-7,(Z)-10 - tridecatrien-1-ol acetate (PTM 2).Mixture so fPT M 1an dPT M2 ar ever yattractive .Th e ratioo fth etw ocomponent sdoe sno tsee mcritica l (Voerman& Rothschild , 1978).

CONCLUDINGREMARK S

Sofar ,ou rwor kha dle dt oth ecommercia lavailabilit yo fsevera lse xpheromone san d attractants.Som eo fthe mar euse di npes tcontro lo ri nentomologica lresearch .Tabl e1 givesa surve yo finsect sspecie sfo rwhic hattractiv ecap sar eproduce do na fairl yregula r basis.Som eformulation sca ncertainl yb eimproved .Identificatio nprogram sar eunde rwa y forsom eimportan tinsects .A listha sbee ncompile do finsec tspecie s forwhic hth eisola ­ tion,identification ,an dsynthesi so fth ese xpheromone si sregarde da suseful .Muc hwor k remainst ob edon eo nfiel dscreenin go fsevera lpotentia lattractants .

REFERENCES

Minks,A.K. ,S .Voerma n& M .va nd eVrie ,1976 .A se xattractan tfo rth echerry-bar ktortri x moth,Enarmoni aformosana .Entomologi aexp .appl . 19 :301-302 . Voerman,S. ,1979a .Synthesis ,purification ,an dfiel dscreenin go fpotentia linsec tse x pheromones.In :F.J .Ritte r (Editor).Chemica lecology :odou rcommunicatio n inanimals . Elsevier/North-HollandBiomedica lPress ,Amsterdam ,p .353-364 . Voerman,S. , 1979b.Chemica lconversio no f9-tetradecen-l-o lacetate s to3 ,13-octadecadien - l-olacetates ,se xattractant sfo rmal eclearwin gmoth s (Lepidoptera,Sesiidae) .J . Chem.Ecol .5 :759-766 . Voerman,S .& G.H.L .Rothschild , 1978.Synthesi so fth etw ocomponent so fth ese xpheromon e systemo fth epotat otuberwor mmoth ,Phthorimae aoperculell a (Zeiler)(Lepidoptera : Gelechiidae)an dfiel dexperienc ewit h them.J .Chem .Ecol .4 :531-542 .

210 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 6.3 Use of sex pheromones for the control of leaf-rollers in orchards

C.va nde rKraa n (1),P .va nDevente r (1) &A.K .Mink s (2)

1Institut efo rPesticid eResearch ,Wageningen ,th eNetherland s 2Researc h Institutefo rPlan tProtectio n (IPO),Wageningen ,th eNetherland s

INTRODUCTION

Inth eNetherlands ,severa lleaf-rolle rmot hspecie s (Tortricidae)ar eimportan tpests , particularly infrui tcrops ,becaus ethe yca nseriousl yaffec tth equalit yo ffruit . Themoth sar epredominantl ynocturnal .Sexuall ymatur efemal emoth sreleas ea nodou r signalb ymean so fse xpheromones ,tha tdra wmale st ofemale si nth edar kfo rmating ,eve n whenth epopulatio no fmoth si sver ylow .Thi sodou rrelationshi pwork sefficiently .Extreme ­ lylo wconcentration so fse xpheromon eca nalread ystimulat eth emal emoth san dguid ethe m overlon gdistance st othei rdestination ,th e 'calling'female .

THESEARC HFO RPHEROMONE SAN DATTRACTANT S

Thestron glong-distanc eattractio no flepidopterou spheromone sha sevoke dmuc hresearc h onpossibl eapplication s (Sections6. 1 and6.2) . Inth eNetherlands ,investigation so nse x pheromoneso fnoxiou sinsect swer estarte di n1967 .A smai nexperimenta linsec twa schosen : thesumme rfrui ttortri xmoth , Adoxophyes orana, themajo rlepidopterou spes ti nDutc happl e andpea rorchard ssinc esevera ldecades . Soonth eproductio no fa neffectiv epheromon eb yth efemale so fthi sspecie scoul db e established.Thi spheromon ewa s isolatedan dpurifie dfro mth eextrac to fth eabdomina l tipso fmass-reare dfemal emoths .I n1971 ,i twa sidentifie di ncooperatio nwit hth eCentra l LaboratoryTN Oa tDelft .Thi swa sth efirs tlepidopterou sse xpheromon etha tturne dou tt o consisto fmor etha non ecomponent ,th epositiona lisomer scis- 9an dcis-1 1 tetradecenyl acetate.The ywer eattractiv eonl yi neac hother' spresenc ean dals oonl yi nproportion s closet o9:1 . Sincetha ttim eeffectiv ese xattractant shav ebee nfoun dfo ra numbe ro fothe rleaf - rollerspecies ,i nmos tcase sals oo fimportanc e infrui torchards .The ywer efoun deithe r byidentificatio no fth enatura lse xpheromone so rb yscreenin go fappropriat ecompound s orblend si nth efield .Suc hinvestigation s forothe rspecie sar estil li nful lprogress .

211 EFFECTIVECONTRO LO FADOXOPHYE SORAN AB YMONITORIN GWIT HSEX-PHEROMON ETRAP S

Fromth ebeginnin go fth einvestigation sattentio nwa sconcentrate do nho wth epheromon e of A. orana couldb euse dfo rcontro lo fthi simportan tpes t (Minks 1975;Mink s 1977). Thelarva eo f A. orana mostlyhid ever ywel li nthei rhos tplants ,eithe ri nleave so r inleave san dfruit sspu ntogether .Contro l isno teas yan dsprayin gi sonl yeffectiv e againstnewl yhatche dlarva ewhil ethe yar esearchin g forfres hleaves .A ssoo na sfres h leavesar efound ,th elarva estar tspinning ,an dthe nbecom edifficul tt oreac hwit hsprays . Thereforecorrec ttimin go fth espray si sessentia lt ob eeffective . Thenewl yhatche dlarvae ,however ,ar es otin yan dinconspiciou s thata sufficientl y accuratedeterminatio no fth efirs tmomen to feg ghatchin go nth ebasi so fvisua lobserva ­ tionsi nth eorchar di simpossible . Ametho dwa sdevelope dt oforecas tho wlon gafte rth ebeginnin go fa mot hfligh tth e firstegg so fth ene wgeneratio nwoul dhatch ,base do nth erelatio nbetwee ntemperatur e andtim eo fdevelopmen to fth eeggs :hea tsummation .Fo rpractica lapplicatio no fthi s method,onl ymot hflight san dtemperatur enee db erecorded . Atfirst ,ligh ttrap swer euse dt odetermin eth estar tan dtren do fth efligh to f A. orana. Since 1968,stick ytrap shav ebee ntrie dtoo ,baite da tfirs twit hlivin gvirgi n femalemoth so rcrud eabdomina lextracts ,bu tafte relucidatio no fth echemica lstructur e ofth epheromone ,th esyntheti cmixtur ewa suse d (Section6.2) .Thes esex-pheromon etrap s provedeas yt ohandl ean dt oregiste rth efligh tperiod sreliably .I ncombinatio nwit hth e forecastingmethod ,the ymad ei tsimpl et odetermin eth erigh tsprayin gtime s (Minks& D e Jong,1975) .Fo rsevera lyears ,th esyste mha sbee nuse db yth eHorticultura lAdvisor yServ ­ ice (PlantProtection )al love rth ecountr ywit hexcellen tresults ,thu sincreasin gth e effectivenesso finsecticida lspray san ddecreasin gth enumbe ro fthem .

PHEROMONEATTRACTIO NAN DINHIBITIO N

Strongattractio ni nth efiel dwit hsyntheti cpheromone sca nonl yb eachieve di fth e proportionso fth epheromon ecomponent sb ea sclos ea spossibl et oth enatura lpheromon e blendan di fchemica lpurit yb eextremel yhigh .A contaminatio no fth epheromon eprepara ­ tionwit ha fe wpe rcen to frelate dchemical sa spositiona lo rgeometrica lisomer sma y destroyth eattraction .Fo r A. orana, additiono f2-6° so fth eopposit egeometrica lisomer s trans-9an dtrans-11-Cii.OA Ci n9: 1 mixtureso ralon ereduce dcatche sb ymor etha nhal f (Minks,1975) .

DIRECTCONTRO LWIT HSE XPHEROMONE S

Thesynthesi so fpheromone san davailabilit yi nrelativel ylarg eamount shav eopene dne w prospectsfo rdirec tcontro lo finsec tpests .Th ese xpheromon ecommunicatio nsyste mo fa tortricidspecie si sessentia lfo rsuccessfu lreproductio nan dtherefor econstitute sa prom ­ isingpoin to fattack ,b ypreventin gfertilizatio no fth efemal eb yth emal emoths . Forthi spurpose ,se xpheromone sca nb eapplie di ntw oways .Th efirs twa yi smas strap ­ ping:usin gth estron glong-distanc eattractio nt olur ea sman ymale sa spossibl eint o

212 stickytraps ,thu seliminatin gthe mfro mth ereproductio nprocess .Th esecon dwa yi sconfu ­ siono rmating-disruption :interruptin gth epheromon ecommunicatio nsyste mo fth epes tin ­ sectb ypermeatio no fth eair ,whic hmigh taffec tth emate-findin g abilityo fth emale san d thusth ereproductiv ecapacit yo fth epopulation . Threedifferen teffect so fai rpermeatio nwit hpheromon ear epossible : -Disorientation :male sca nn olonge rfin dth e 'calling'femal emoths . -Adaptation :th erelativel ywea ksignal so fth efemal emoth sca nn olonge rb esmelled ,be ­ causeo fa nincreas ei nth esensitivit y thresholdo fth emale' srecepto rcells ,whic hper ­ ceiveth epheromone . -Habituation :natura lpheromon esignal sn olonge relici tth eadequat ebehaviora lreactions , becauseo fa nincreas ei nth ethreshol do fth ecerebra lneura lsystem . Howfa rshoul dmate-findin g abilityo fth eleaf-roller sb esuppresse dbefor esatisfactor y controlo fth einsect sca nb eachieved ?Experienc efro mexperiment swit hth esterile-mal e techniqueindicat etha ti fonl y 10%o fth efemale sca nmate ,effectiv econtro lo fth epopu ­ lationi spossible .S ofo rmass-trapping ,a tleas t90 %o fth emale sshoul db etrappe di n thefirs tnight so fth eflight ,preferabl ybefor eth efirs tmating .Fo rmating-disruptio n experimentsa neve nhighe refficienc yo fcatchin g isneeded ,becaus eal lmal emoth so fth e populationsremai npresen tcontinuousl ydurin gth efligh tperio dan dar epotentiall yabl e tomat edurin geac hnigh to fth efligh tperiod .

EXPERIENCEWIT HMATING-DISRUPTIO NEXPERIMENT S

Minkse tal . (1976)obtaine dpromisin gresult si na firs tmating-disruptio nexperimen t on A. orana bysprayin go fmicro-encapsulate dantipheromone s (trans-9an dtrans-1 1tetra - decenylacetate ,rati o9:1) .However ,thes eresult swer eno tconfirme di nlate ryears ,whe n resultswer evariabl ean dsometime seve ncontradictory .Onl yon ethin gcoul db econclude d fromthi sfirs tserie so fexperiments :namel ytha tfo r A. orana thebes tprospect so feffec ­ tivedisruptio no fmatin gar eno tb yus eo fantipheromone sbu tb yus eo fth epheromon eit ­ selfi na blen dtha tshoul dmimi cth enatura lpheromon ea sclosel ya spossible . In1978 ,stron gevidenc ewa s foundtha tmating-disruptio nfo r A. orana wastechnicall y feasible.I nou rexperimenta lorchards ,pheromon eevaporate dfro mwidel yseparate ddispen ­ sers,evenl ydistribute da ta densit yo fabou t40 0pe rhectar ean d5 metre sapart .Les s than1 g o fpheromon epe rhectar epe rfligh tperio dsuppresse dcatche so fth emoth sb y 95-981.Somewha thighe rdose sgav ea suppressio no f99-100°& .A dos eo fno tmor etha n1 0g pheromonepe rhectar epe rseaso nseem ssufficien tt oachiev esatisfactor ycontro lo fth e matingactivitie so fth e A. orana populations.

MOREFUNDAMENTA LRESEARC HI SNEEDE D

Morefundamenta lunderstandin go fth ebehaviour ,th ecommunicatio nsyste man dpopulatio n dynamicso fth einsect si sneede dbefor ew eca nmanipulat epheromones .S osinc e 1976,mor e attentionha sbee npai dt oth estud yo fbehaviora lresponse so fth einsect safte rth eappli ­ cationo fpheromones .

213 PLANSFO RTH EFUTUR E

Forth ecomin gyears ,a large-scal epheromon eexperimen tha sbee nplanne d ina larg e parto fth eExperimenta lOrchar d 'DeSchuilenburg 'a tLienden .A nattemp twil lb emad et o control Adoxophyes orana andals oth ecodlin gmot h Laspeyresia pomonella, exclusivelywit h syntheticse xpheromone .Dat aabou tmatin gsucces so ffemal emoth san dlong-ter meffect s inth edevelopmen to fth epopulatio no fth eleaf-rolle rmoth swil lb ecollected . Ifth eresult so fthes eexperiment sar efavourable ,ther ewil lb egoo dprospect sfo r futureapplication so fpheromone sa scontro lagents ,no tonl yi nfrui tgrowing ,bu tals o inothe rarea so fhorticulture ,particularl y insituation swit hon eo rtw omajo rpests . Greenhousessee midea lfo rmating-disruptio nexperiments .Howeve rth echemica lstructur e ofth epheromone so fsom elepidopterou spest si nglasshouse si sno tye tknown . Side-effectso nth eenvironmen tar ehardl yconceivabl ea sa consequenc eo fspecifi cac ­ tion,th elo wtoxicit yan dth eextremel ylo wdosages .I ncontras tt omos tinsecticides , pheromonesmigh tallo wrecover yo rmigh tno teve naffec tnatura l controlagent so fpests . Thissor to fagent sca npla ya nimportan trol ei nth etransitio nfro mintensiv echemica l treatmentst ointegrate do rbiologica lcontrol .

REFERENCES

Minks,A.K. ,1977 .Trappin gwit hbehavior-modifyin g chemicals:feasibilit yan dlimitations . In:H.H .Shore y &J.J .McKelve yJ r (Editors),Joh nWiley ,Chemica lContro lo finsec tbe ­ havior:Theor yan dApplication sNe wYork .p .385-394 . Minks,A.K. , 1975.Biologica laspect so fth eus eo fpheromone s inintegrate d controlwit h particular referencet oth esummerfrui ttortri xmoth ,Adoxophye sorana .In :L .Brade r (Editor)CR . 5e Symp.Lutt eIntégré ee nvergers .Internationa lUnio nOILB/SRO Pp . 295-302. Minks,A.K .& D.J . deJong ,1975 .Determinatio no fsprayin gdate sfo rAdoxophye soran ab y sexpheromon e trapsan d temperaturerecordings .J .econ .Ent .6 8 :729-732 . Minks,A.K. ,S .Voerma n& J.A .Klun , 1976.Disruptio no fpheromon ecommunicatio nwit h micro-encapsulated antipheromonesagains tAdoxophye sorana .Entomologi aexp .appl . 20 :163-169 .

214 7 Selective insecticides

Therear etw okind so fselectivit yo fpesticides ,tha tbetwee nlarg eclasse so forganisms , likearthropods ,fungi ,highe rplants ,vertebrates ,an dtha tbetwee nmuc hmor eclosel yre ­ latedspecies . Manypesticide ssho wa considerabl edegre eo fth eforme rtype ,bu tgenerall ylittl eat ­ tentioni spai dt oth eselectivit ybetwee nrelate dspecies ,whic hi so fparticula rimpor ­ tancei nintegrate dcontrol . Inth estudie spresente dhere ,severa laspect so fselectivit yo fbot hkind shav ebee n investigated.Thes estudie srelat et osuc hvarie daspect sa sth egenera lbasi so fselec ­ tivity (7.1),th emod eo factio no fth eselectiv einsecticid ediflubenzuro n (7.3)an dpos ­ sibleside-effec to fthi scompoun do nnestlin gbird s (7.4),th emod eo factio no fsom e selectivefungicide s (7.2)an dstudie so nth eeffec to fvariou spesticide so nbeneficia l mitespecie s (7.5). Suchstudie sar eessentia li npromotin gdevelopmen tan dus eo fselectiv epesticide san d consequentlyo fintegrate dcontrol ,whic hi sstrongl ydependen to nth eavailabilit yo fcom ­ poundswit ha slittl edisturbin ginfluenc ea spossibl ei nth ebiologica lsystem si nwhic h theyhav et ob eemployed .

215 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 7.1 Processes in selective toxicity of insecticides to insects

F.J.Oppenoort h& W .Wellin g

Institutefo rPesticid eResearch ,Wageningen ,th eNetherlands .

GENERALPRINCIPLE S

Oneca ndistinguis htw okind so fselectivity ,tha tbetwee nbroa dclasse so fanimals , sucha sarthropod san dvertebrates ,an dtha tbetwee nmuc hmor eclosel yrelate dspecies . Thelatte ri so fparticula rimportanc ei nintegrate dcontrol .I fth eus eo finsecticide s ist ob eintegrate dwit hothe rimportan tmean so frestrainin ginsects ,notabl ypredator s andparasites ,insecticide sshoul db eavailabl etha tenabl eu st okil lth epes twithou t eradicatingit snatura lenemies . Whenlookin gfo rsuc hselectiv ecompounds ,a nalternativ et olarge-scal escreenin g couldb efundamenta lresearc ho nthos eprocesse stha tdetermin eth esusceptibilit yo fin ­ sectspecie st oinsecticides ,an dapplicatio no fit sresult st oth edevelopmen to fne w compoundso rth eus eo fexistin gones . Onewa yt ose tabou tsuc hresearc hi st ostud ywha tmechanism sar einvolve di non eo f themos tobviou scase so fselectiv etoxicity :tha to fdifference si nsusceptibilit ybetwee n strainso fon ean dth esam especies .I nsuc ha case ,onl ya singl eo rver yfe wfactor s usuallycaus eth edifferenc ean dthei reffec tca nb erelativel yeasil yassesse db ycompar ­ isono fappropriat estrains .Anothe rwa yi st oinvestigat eth emajo rprocesse scontribut ­ ingi non ewa yo ranothe rt oth etoxi ceffec to fa ninsecticid ean dt odescrib equantita ­ tivelyho wthe yinterac tan dho wth ecomple xdynami csyste mthe yrepresen tfunction sa sa whole. Forth efirs tapproach ,strain sar euse dtha thav edevelope dresistanc ei nth efiel dt o insecticides.Thi sseem si nparticula rjustifiabl esinc ei tha sbee nshow ni nsom ecase s thatdifference sbetwee nstrain sresembl ethos eresponsibl efo rdifference sbetwee nspecie s (Dyte,1969) . Thestud yo fresistanc emechanism so fcours eprovide sinformatio no nothe raspect so f insecttoxicolog ytha njus tselectivity .W ehop etha ti tshoul dcontribut et oth epreven ­ tiono rovercomin go fresistanc et oinsecticides .

EXAMPLES

A fewexample so fthi skin do fapproach ,th enatur eo fth eresults ,an dit spossibl e usefulnessi npractica lproblem swil lb egive nhere .

217 Combinedgeneti can dbiochemica lresearc hha sshow ntha tsingl egene sar eofte nrespon ­ siblefo rdifference s insusceptibilit yb ya profoun dinfluenc eo non eo fth etoxicologica l parameters,suc ha sdetoxicatio nan dsit eo faction .Simpl egeneti ctechnique sallo wo rfa ­ cilitateseparation ,combinatio nan dcharacterizatio no fth evariou s factors.A sa nexample , resistancet oDD Ti nhouseflie sca nb edu et othre edifferen tcauses ,eac hdependen to na singlegene :tw okind so fdetoxicatio nan don ekin do fchang ei nsensitivit ya tth esit e ofaction .Thes ethre ekind so fresistanc ehav edivers echaracteristics :th etw odependen t ondetoxicatio nca nb esynergize db ydifferen tsynergist s (overcomeb ymean so fnon-toxi c detoxication-blockers),th eon ecause db ychange dsensitivit yo fth esit eo factio nals o causesresistanc et opyrethroids ,a nexampl eo fcross-resistance . Interactiono ffactor si ssometime squit emarked .A nacetylcholinesteras ewit ha 20-fol d decreasedsensitivit y toorganophosphoru s inhibitorscause slittl eresistanc ewhe nintro ­ ducedint oa strai ni nwhic hdetoxicatio nt oth einhibitio n (tetrachlorvinphos inthi scase ) isvirtuall yabsent .T oanothe rinsecticide ,paraoxon ,ther ei smuc hmor eresistance ,be ­ causethi scompoun di sdetoxicate db yoxidation .I foxidatio ni sblocked ,resistanc ei s greatlyreduce d (Table1) . Aninterestin gquestio ni swhethe rthes eresistanc estudie sindicat ewha tfactor sar e importantfo rtoxicity .Detoxicatio nan dsit eo factio nofte ncaus eresistance ,wherea s penetrationan dbindin gd ono tfigur ea simportan tresistanc efactors .Ar eth elatte run ­ importantals oi ndifference sbetwee nspecies ,o rar ethe yabsen tbecaus ethe ycanno tread ­ ilyb echange dwit h theavailabl egeneti cvariation ? Theeffec to fpenetratio no ntoxicit yfollow sfro mth esimpl eobservatio ntha tresistanc e factorsar eusuall ymuc hsmalle rafte rinjectio ntha nafte rtopica lapplicatio no fa ninsec ­ ticide.I ntopica ltreatment ,ther ei sals oa wel lknow neffec to fth esolven t ,whic h showsth epractica limportanc eo fth erat eo fentr yi nth eus eo fpesticides .Rat eo fentry , however,i sonl yon eo fman yprocesse stha tcontribut et otoxicity .Interna ltransport , reversiblebinding ,distribution ,detoxicatio nan dreactio nwit hth etarge tar eals orele ­ vant.The ycan ,moreover ,b ehighl yinteractiv e (Table1) . Sucha syste mca nb erepresente d insimplifie dfor ma sa deterministi ccompartmenta l model.A numbe ro fprocesse stha tsee mtoxicologicall yrelevan tar eselecte dan drepresent -

Table 1.Interactio no fdetoxicatio nan dreduce d sensitivityo fsit eo faction .

Strain Synergist Tetrachlorvinphos Paraoxon

S - 0.025 0.036 + 0.013 (2 x) 0.004 (9 x) R - 0.098 1.890 + 0.081 (1 x) 0.010 (189 x) Thefigure srepresen t themedia nletha ldos e (LD )i nU gpe rfl yo ftopicall yapplie din ­ secticideo ftw ostrain so fhousefly ,S an dR ,tha tdiffe ronl yi nth esensitivit y ofthei r acetylcholinesterases.Th erat eo finhibitio no fthi senzym ei sreduce d 18an d2 3fol dfo r tetrachlorvinphos andparaoxon ,respectively .Th einsecticide sar eapplie d inth epresenc e orabsenc eo fth esynergis t sesamex,whic hblock soxidativ edetoxication .Synergisti cfac ­ tor'sar egive ni nparenthesis . Tetrachlorvinphos ishardl ydegrade db yoxidation ,s oneithe r synergistno rreduce dsen ­ sitivityo facetylcholinesteras ehav emuc heffect .Paraoxo ni sactivel ydegrade doxidatively , whichha sa larg eeffec twhe nth eacetylcholinesteras ewit hreduce d sensitivity ispresent .

218 edb ydifferentia lequations .B ysolvin gthe mnumerically ,th efat ean dactio no ftoxi c compoundsca nb esimulated .Man yexperimenta lmeasurement sar erequire dt oobtai nth epara ­ metersneede di nth eequations .Th eexpertis ean dinsigh tobtaine dearlie ri nresistanc e studiesi so fgrea thel pfo rsuc ha complet edescriptio nbu tth edevelopmen to fmodel sals o showswher eessentia lknowledg ei sstil llacking . Thisapproac ht oinsecticida lactio ni srathe rne wan di tha sstil lt oprov eit suse ­ fulness.Preliminar yresult ssugges ttha tth erat eo fcuticula rpenetratio nan dth eexten t ofadsorptio no flipophili ccompound sb ytissu econstituent sar efactor so fsimila rweigh t todetoxication .

PRACTICALRESULT S

Fundamentalstudie so fthi snatur ed ono tgenerall ylea dt odirec tpractica lresults . A fewexample sca nnevertheles sb epresented . Inman ystrain so forganophosphorus-resistan t houseflies,organophosphate sca nb ehydrol - ysed.Thi sonl yapplie st omethy lan dethy lcompounds ,n-propy lcompound sblockin gth e hydrolyticenzyme .Suc hcompound sca ntherefor eac ta ssynergists .I nth ehousefly ,thi s isunfortunatel yo flittl ehelp ,sinc edetoxicatio nb yoxidatio nals odeveloped ,an ddi d nothav eth erestricte dscop eo fth ehydrolyti cdefenc emechanism .Ou rfindin gle dhoweve r toth edevelopmen tb ya Japanes efir mo fth ene winsecticid epropaphos ,use dfo rcontrol ­ lingvariou sric einsect s (Sakai,1978) .Curiousl yenough ,i tprove dusefu lagains tresis ­ tantinsect swit ha completel ydifferen tmechanism ,dependin go na naltere dacetylcholin ­ esterase.Th ecompoun dwa smor etoxi ct ogree nric eleafhopper sresistan tt omethyl-carbamat e thant oth esusceptibl eone ! Duringa stud yo foxidativ edetoxicatio no forganophosphates ,w efoun dtha tminut eamount s oftoxi co rnon-toxi cthionophosphate sblocke ddetoxication .Suc hcompound swer eextremel y powerfulsynergist s forth estrain so fhouseflie sinvolved . Wefee ltha tth escarc eexample so fdirec tpractica lapplicabilit yd ono tconstitut e themai noutpu to fou rapproach .Th emai noutpu tshoul db eth econtributio nt oth egenera l knowledgeo finsec ttoxicology ,whic hi nman ysubtl eway sshoul dallo wu st odevelo pan d refineth econtro lo finsects .

REFERENCES

Dyte,C.E. ,1969 .Evolutionar yaspect so finsecticid eselectivity .Proc .5th .Britis hIn - sectic.Fungic .Conf .Britis hCro pProtectio nCouncil ,Cradley ,Malvern ,Worcestershire . p.393-397 . Oppenoorth,F.J. , 1976.Developmen to fresistanc e toinsecticides .In :R.L .Metcal f& J.J . McKelveyJ r (Editors),Th efutur efo rinsecticides .Wile y &Sons ,Ne wYork .p .41-63 . Oppenoorth,F.J . &W .Welling , 1976.Biochemistr y andphysiolog yo fresistance .In :C.F . Wilkinson (Editor),Insecticid ebiochemistr yan dphysiology ,Plenu mPress ,Ne wYork . p.507-551 . Sakai,M. , 1978.Mode so factio no finsecticide sdevelope d inJapan .Japa nPesticid eInf . 34 :5-13 . Welling,W. , 1977.Dynami caspect so finsect-insecticid e interactions.A .Rev .Ent . 22 :53-78 .

219 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 7.2 Fungitoxic mechanism of organophosphorus compounds

M.A.d eWaar d

Laboratoryo fPhytopathology ,Agricultura lUniversity ,Wageningen .

INTRODUCTION

Incro pprotection ,organophosphoru scompound sar euse dmainl ya sinsecticide san dgen ­ erallyhav ea lo wfunga ltoxicity .Howeve rsinc e 1960,organophosphoru scompound shav e alsobee ndevelope da sfungicides ,th efirs ton ebein gtriamiphos .Th echemica li ssystemi c andselectivel yactiv eagains tpowder ymilde wfung io nsevera lornamenta lplants .Sinc e thattime ,man yothe rorganophosphoru s fungicideshav ebee nintroduce dsuc ha sKitazi nan d edinfenphos,selectivel yactiv eagains t Vyricularia oryzae onrice ,an dpyrazopho sactiv e againstsevera lpowder ymilde wfungi .Som eo fthes echemical sha da usefu lside-effec t againstaphid san dspide rmites .Th emechanis mo ffungicida lactio no forganophosphoru s fungicideswa sunknown .W esuppose dtha tknowledg eo nth emechanis mo finsecticida lactivit y mightprovid eclue sfo rth eelucidatio no fthei rfungicida laction ,an ds oth esubjec twa s investigatedfro m196 8u pt o197 4a tth eLaborator yo fPhytopatholog yi nWageningen ,i nco - -operationwit hth eWorkin gPart yo nIntegrate dContro lo fPest si nth eNetherlands .

RESULTSAN DDISCUSSIO N

Attentionwa sconcentrate do npyrazopho s (0,0-diethyl0-(5-methyl-6-ethoxycarbonylpyra - zolo(1,5-a)pyrimidin-2-ylphosphorothioate) .Thi schemica ldisplaye dbot ha protectiv ean d curativeactio nagains tth epowder ymilde wfungu s Sphaerotheca -fuliginea oncucumber ;toxi ­ cityt o P. oryzae onbarle ywa sdemonstrate dtoo . Bothpyrazopho san dit sphosphat eanalogu e (PO-pyrazophos)inhibite dcarboxylesterase s of S. fuliginea. Butsinc en ocorrelatio ncoul db eestablishe do finhibitio no fth eactiv ­ ityo fthes eenzyme s inviv ob ypyrazopho san dPO-pyrazopho swit hfungitoxicity ,thi sef ­ fectprobabl ydoe sno taccoun tfo rth eactio no fpyrazophos .I nfurthe rexperiment swit h P. oryzae, Kitazin (0,0-diethyl 5-benzylphosphorothioate )an dedinfenpho s (o-ethyl S,S- diphenylphosphorodithioate )influence dth epermeabilit yo fcel lmembranes .A tfungitoxi c concentrations,thes etw osubstance scause da leakag eo f( 32P) orthophosphate frommyceliu m intoth ecultur emedium .Effect so nchiti nsynthesi swer esuppose dt ob esecondary ,sinc e fungitha td ono tsynthesiz echiti nlik e Pythium debaryanum areals osensitiv et othes e chemicals.Pyrazopho sha dn oeffec to ncel lmembran epermeabilit yno rchiti nsynthesis . Pyrazophosals ohardl yaffecte dnuclei caci dan dprotei nsynthesi so fP . oryzae, while

221 oxygenuptak ewa sonl yslightl yinhibited .S opyrazopho sdi dno thav ea pronounce dshort - -termeffec to nan yo fth emetaboli cprocesse stested . Inshor tter mexperiment swit ha nincubatio ntim eo f2 h ,pyrazopho swa s lesstoxi ct o fungalgrowt hb ya facto r10 0t o100 0a si nexperiment si nwhic hgrowt hwa sassaye dafte r incubationfo ron eweek .Thes eresult sca nb ea tleas tpartl yexplaine db yth emetaboli c conversiono fpyrazopho si nth elonge rter mint otw ofungitoxi cbreakdow nproducts ,PO - pyrazophosan d2-hydroxy-S-methyl-6-ethoxycarbonylpyrazolo(1,5-1)pyrimidin e (PP).I nshor t termexperiments ,P Peve nprove dt ob econsiderabl ymor etoxi cfo rmycelia lgrowt hi nsus ­ pensionsbuffere da tp H4. 0tha npyrazopho san dPO-pyrazopho s ands omigh tb eth eactua l fungitoxicprincipl eo fpyrazophos .Thi svie wi ssupporte db yth efindin gtha tPP ,i ncon ­ trastt opyrazophos ,als oinhibite dsynthesi so fnuclei cacid san dprotein san duptak eo f oxygenb yth efungus .Th ewea keffect so fpyrazopho so nthes eprocesse san do nmycelia l growthi nshor tter mexperiment swer eprobabl ydu et oa ninsufficien tconversio no fpyra ­ zophosint oP Punde rthes econditions . Pythium debaryanum and Saccharomyees oevevisiae are insensitivet opyrazophos .Upo nincubatio no fthes efung iwit hth efungicide ,n obreakdow n productscoul db edetected .S osensitivit yo ffung it opyrazopho sseem st oresul tfro mse ­ lectiveuptak eo fpyrazopho so rfro mit sconversio nint oPO-pyrazopho san dPP ,a sha sbee n demonstrated for P. oryzae. In P. oryzae, PPcoul dac ti non eo ftw oways .I tcoul dspecificall y inhibitoxyge nup ­ takean ds oindirectl yinhibi tcellula rsyntheti cprocesse s likenuclei caci dan dprotei n synthesiso ri tcoul dreac taspecificall ywit hcellula rcomponent san ds odirectl yaffec t bothoxyge nuptak ean dbiosyntheti cprocesses . Thediethylthionophosphat e groupo fpyrazopho si so flittl eimportanc ei nth eintrinsi c fungitoxicaction ,i ncontras tt oorganophosphoru s insecticides.I npyrazophos ,th ediethyl ­ thionophosphatesubstituen tma y acta sa ninbuil tformulatio nfactor ,whic hfacilitate s theuptak eo fpyrazophos .Th efungicid eha st ob ehydrolyse d intracellularlybefor ei tca n exertit stoxi caction .

REFERENCE

Waard,M.A .de ,1974 .Mechanism so factio no fth eorganophosphoru s fungicidepyrazophos . Meded.Landbhogesch .Wageninge n74-14 .

222 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 7.3 Mode of action of diflubenzuron

W.H.va nEc k& F.J .Oppenoort h

Institutefo rPesticid eResearch ,Wageningen ,th eNetherlands .

DESCRIPTIONO FTH EPROBLE M

Muchwa salread yknow nabou tth eactio no fdiflubenzuro no ninsect swhe nw estarte d ourstudy .Insect streate dwit hdiflubenzuro nhav ea wea kcuticl etha tdisrupt seasily , causingdeat hdurin gmoulting .Th eamoun to fchiti ni naffecte dcuticle si sgreatl yreduce d indicatingtha tchiti nsynthesi si simpaired .Diflubenzuro ninhibit schiti nsynthesi ssoo n afterapplication ,suggestin gtha ti tinterfere sdirectly .Th edetail so fth emod eo faction , however,ha dstil lt ob eresolved .Althoug hi twa sgenerall yassume dtha tchiti nsynthetas e (thepolymerizatio nenzyme )wa sth erecepto ro fdiflubenzuron ,evidenc ewa sno tconvincing . Ifon eo fth ereaction si sblocke di na step-by-ste pproces s likechiti nsynthesi s thepre ­ cursoro ftha treactio nshoul daccumulate .S owhe nchiti nsynthetas ei sblocked ,it ssub ­ strateuridinediphosphat eff-acetylglucosamine (UDPGIcNAc )shoul daccumulate .Indeed ,Mark s &Sow a (1976)foun da build-u po fUDPGIcNA ci ninsec ttissu etreate dwit hdiflubenzuron , thoughDeu le tal . (1978)di dno tfin da nincreas ei nUDPGIcNA ci ntreate dlarva eo f Vieris brassicae.

AIMAN DMOTIVATIO NO FTH ERESEARC H

Mostinsecticide shav eidentica lsite so factio ni nvertebrate san dinsects .The nse ­ lectivityo fa ninsecticid ema yb eascribe dt odifference si npenetration ,distribution , metabolisman drat eo freactio na tth esit eo factio no fth ecompoun di ninsect san dverte ­ brates.Thi sselectivit ydepend so nquantitativ edifference sbetwee non eo rmor eo fthes e toxicologicalparameters . Selectivityo fdiflubenzuro nseem st ob eon eo fth efe wexample so fqualitativ eselec ­ tivity,a sdiflubenzuro ninterfere swit hsynthesi so fchitin ,a proces stha ti smainl yfoun d inarthropod san dfung ibu ti sabsen tfro mothe rorganisms . Astud yo fth emod eo factio no fdiflubenzuro ncoul dtel lu smor eabou tth ecomple xpro ­ cessesi nchiti nsynthesi san dcuticl eformatio ni ninsects .Moreove ri fw ecoul dfin dou t wherei tacts ,w ecoul destablis hwhethe ra nenzym ewer einvolve dtha ti suniqu et oinsect s andfungi ,a si schiti nsynthetase .Tha twoul dindicat eth enatur eo fth eselectivit yo f thecompoun dan dpossibl etoxicologica lhazard st oothe rorganisms .

223 Table 1.Accumulatio no furidinediphosphat eA?-acetyl - glucosamine (UDPGlcNAc)i nbod ywall so fhousefl ylarva e treatedwit hinhibitor so fchiti nsynthesis .

Control Diflubenzuron PolyoxinD

UDGPlcNAc 0.72 1.28 1.27 Chitin 0.63 0.03 0.03

Datarepresen tamoun to flabelle dprecurso rconverte d intoUDPGlcNA can dchiti n (pmol)i na tes tsyste mwit h bodywall sfro mquadruplicat esample so f4 maggots .

METHODS

Sincei tha sbee nimpossibl es ofa rt ostud ychiti nsynthesi so finsect si na cell-fre e system,an dstudie so nwhol einsect shav esevera ldisadvantages ,a nattemp twa smad et o studychiti nsynthesi san dit sinhibitio ni nisolate dorgans .Thi scompromis eavoid sman y ofth ecomplexitie so fstudie so nwhol eorganisms ,bu tma yno tprovid ecomplet eanswer so n themolecula rnatur eo fth etoxi caction . Soa syste mwa sdevelope dconsistin go fbod ywall so factivel ygrowin g larvaeo fth e housefly Musaa domestioa. Duringincubatio no fth ebod ywall swit ha radioactivel ylabelle d precursor,radioactivit ywa sreadil yincorporate dint ochiti nan dth eeffect so fdifluben ­ zurono nchiti nsynthesi scoul db estudied . PolyoxinD ha sbee nshow nt ob ea competitiv einhibito ro fchiti nsynthetas ei nfungi . Whenproperl yadministered ,i tals oinhibit schiti nsynthesi si ninsects .Sinc eit smod e ofactio ni smos tlikel yth esam ei ninsect sa si nfungi ,th ecompoun dwa sinclude di nou r studiesfo rcomparison .

RESULTSAN DDISCUSSIO N

Theeffect so fdiflubenzuro nan dpolyoxi nD o nsynthesi so fchiti ni nbod ywall so f houseflylarva ear esummarize di nTabl e1 .Wit heithe rcompound ,exactl yth esam eeffec t wasobtained :chiti nsynthesi swa sinhibite dalmos tcompletely ,an dUDPGlcNA cincreased . Theincreas ecorresponde dt oth edecreas ei nincorporatio ni nchitin .Th eaccumulatio no f UDPGlcNAcindicate stha tchiti nsynthetas ei sth erecepto rno tonl yfo rpolyoxi nD bu tals o fordiflubenzuron ,thoug hfina lproo fo fthi sstil lha st oawai tstudie so fth einsec t enzymei na cell-fre esystem .Sinc efunga lchiti nsynthetas e isno tinhibite db ydifluben ­ zuron,a consequenc eo fthi sconclusio nwoul db etha tther ei sa differenc ei nsusceptibil ­ ityo fth echiti nsynthetase st odiflubenzuro nbetwee nfung ian dinsects .

REFERENCES

Deul,D.H. ,B.J .d eJon g& J.A.M .Kortenbach ,1978 .Inhibitio no fchiti nsynthesi sb ytw o l-(2,6-disubstituted benzoyl)-3-phenylureainsecticide s2 .Pestic .Biochem .Physiol . 8 :98-105 . Eek,W.H .van ,1979 .Mod eo factio no ftw obenzoylpheny lurea sa sinhibitor so fchiti nsyn ­ thesisi ninsects .Insec tBiochem .9 :295-300 . Marks,E.P .& B.A .Sowa ,1976 .Cuticl eformatio ni nvitro .In :H.R .Hepbur n (Editor).Th e insectintegument .Elsevie rScientifi cPublishin gCompany ,Amsterdam ,p .339-357 . 224 Integrated control of insect pests in the Netherlands. Pudoe, Vlageningen, 1980. 7.4 Impact of the insecticide diflubenzuron on insectivorous birds

R.H.d eReed e

Laboratory forEntomology ,Agricultura lUniversity ,Wageningen ,th eNetherlands .

INTRODUCTION

Diflubenzuron,a recentl ydevelope dinsecticide ,i sa stomac hpoiso nwhic hinterfere s withth edepositio no fchiti ni nth einsect' sskin ,thu scausin gdeat hdurin gth emoultin g process. Insectssensitiv et odiflubenzuro nar eno timmediatel ykille db ythi scompound ,bu t onlyafte ra longe ro rshorte rtim ei nth efollowin gmoul t (VanDaale ne tal. ,1972) . Diflubenzuronma ywel lb einclude di nintegrate dcontro lprograms ,becaus ei tsave scer ­ taincategorie so fbeneficia larthropods . However,a sa consequenc eo fit sdelaye daction ,insectivorou sbird scoul dpossibl ytak e inan dfee dthei rnestling swit hs omuc hdiflubenzuron ,tha tpoisonin gmigh tensue .Thi s wasconsidere dpossibl efo rth ecucko o (Cuaulus canorus), theoriol e (Oriolus oriolus) and thered-backe dshrik e (Lantus colluvio), whichconsum eth ecaterpillar so fth ebrowntai l moth (Euproctis chrysorrhoea). Insom eregion so fth eNetherlands ,thes ecaterpillar sar e asever epes ti nshad etrees ,whic hca nb econtrolle db ydiflubenzuron .

METHOD

Cuckoos,oriole san dred-backe dshrikes ,however ,canno tb esubjecte dt oexperiment . Therefore,bird si na comparabl esituatio nhav ebee nselected ,namel ygrea tti t (Parus major) inorchard san dcoppice .Tit susin gnestboxe sca neasil yb estudie dan dthei rfoo d consists largelyo fcaterpillars .Tre esparrow s (Passer montanus) wereals oinclude di nth e researchbecaus eo fthei rgrea tnumbe ri nth estud yorchards .

RESULTSAN DCONCLUSIO N

Nosignifican teffec to fdiflubenzuro no nbreedin gan do ngrowt ho fnestling so fth e examinedbird swa sfoun di ncompariso nwit hbird si nnearb yunspraye dexperimenta lfields . Onth ebasi so fmeasurement so fth ecompositio no fth efoo do fth enestling san dth e contentso fdiflubenzuro ni nth eleaf-eatin ginsect si nth efood ,th eactua lan dmaximu m possibledail yintak eo fdiflubenzuro nb ynestling swer eestimate d (Table1) . Themaximu mpossibl edail yintak eb ynestling so fth egrea tti twa sabou ta hundredt h

225 Table 1.Actua ldail yintak eo fdiflubenzuro ni nterm so fbodyweigh t (mg/kg)b ynestling s estimated inth eexperimenta l fieldsan dmaximu mpossibl edail y intake (mg/kg)calculate d fornestling so fth egrea ttit ,tre esparro wan d thered-backe dshrike .

Ageo f Actual intake Maximum possible intake nestlings (days) orchard ashc c 'PPic e orchard shadetree s

great tree great great tree redbacked - tit sparrow tit tit sparrow shrike

1-2 4 0.5 4 15 5 3 3-7 3 0.9 2 13 10 4 8-12 3 0.9 0.6 11 10 3 13-.. 2 0.6 0.3 10 7 2

ofth ehighes tdail yintak eb ybobwhit equai lan dmallar dduc ki neight-da ydietar ytoxi ­ citytest s (PhilipsDuphar ,1975 )whic hreveale dn oobservabl esign so ftoxicity .Poisonin g ofinsectivorou sbird swit hdiflubenzuro ni norchard san dshad etree si stherefor eunlikely .

REFERENCES

Daalen,J.J .van ,J .Meltzer ,R .Mulde r &K .Wellinga ,1972 .A ne winsecticid ewit ha nove l modeo faction .Naturwissenschafte n5 9 :312-313 . PhilipsDuphar ,1975 .Dimilin ,a ne winsecticid e interferingwit hchiti ndeposition .Tech ­ nicalinformation . Reede,R.H .de .A fiel dstud yo nth epossibl eimpac to f theinsecticid ediflubenzuro no n insectivorousbird s (inprep.) .

226 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 7.5 Effect of pesticides on predacious mites

A.Q.va nZo n& L.P.S .va nde rGees t

Laboratoryo fExperimenta lEntomology ,Universit yo fAmsterdam ,th eNetherlands .

INTRODUCTION

Inintegrate dsystem sfo rcontro lo fpest san ddiseases ,chemica lpesticide smus tb e carefullyselected .Th epesticide sshoul db eselectiv ewit hlittl eo rn oadvers eeffec t onbeneficia l arthropods,suc ha sparasitoids ,predator san dpollinators .Broad-spectru m pesticidesshoul db eavoide di nan ycase . Amongth ebeneficia larthropods ,phytosei dmite spla ya importan trol ea spredator so f spidermites .A wel lknow nexampl ei s Phytoseiulus persimilis, alreadyuse dfo rsevera l yearsi ncontro lo fspide rmite si ngreenhouses .It ssuccess ,however ,entirel ydepend s onprope rselectio no fpesticide ssimultaneousl yuse dwit hth epredator ,e.g .fungicide s againstmilde wan dothe rfungu sdiseases .I norchards ,phytosei dmite so fth egener a Amblyseius and Typhlodromus areprobabl yo fgrea timportanc ei nth eregulatio no fspide r mitepopulations .Thes emite sca nonl yac ta scontro lagents ,i fthe yar eno tseriousl y affectedb ypesticides . Thepresen tstud ywa sse tu pi norde rt ogathe rinformatio nabou tadvers eeffect so f pesticideso npredaciou smites ,a sa nai di na bette rselectio no fpesticide so ncrop s wherephytosei dmite shel pt oregulat ephytophagou smit epopulations . Parto fth ewor ki si ncollaboratio nwit hth eWorkin gGrou p 'Pesticidesan dBeneficia l Arthropods'o fth eInternationa lOrganizatio no fBiologica lControl .Thi sworkin ggrou pi s attemptingt ostandardiz eprocedure sfo rth eassa yo fpesticide sagains ta larg enumbe ro f differentspecie so fbeneficia larthropods .

WORKINGMETHOD S

Ofth epredaciou smites , Phytoseiulus persimilis waschosen ,becaus ei ti salread ycom ­ merciallyuse dfo rcontro lo fspide rmites . Amblyseius bibens, amit efro mMadagasca r (Blommers,1973) ,wa suse da sa representativ eo fth egenu s Amblyseius andth eclosel yre ­ latedgenu s Typhlodromus, botho fimportanc ei norchards .I twa schose nrathe rtha non eo f thewes tEuropea n Amblyseius or Typhlodromus species,becaus ei twa savailabl ei nou rlab ­ oratoryan dbecaus eo fit sbehaviora lcharacteristics ,whic hmak ei tmor esuitabl ea s testobjec ttha nth eothe rspecies . Thesusceptibilit yo fth emite stoward sth echemical sar eonl yteste di nth elaborator y.

227 Besidespesticides ,othe rcompound swer etested :phytoauxins ,folia rfertilizer san dcos ­ metics,use dfo rimprovin gth eappearanc eo ffruits .Tes tprocedure sar ea sfollows . Predatormite sar eplace do nculture so fdetache d Phaseolus vulgaris leafo nmois tcot ­ tonwool .Th eleave sar eheavil yinfeste dwit hth espide rmit e Tetranyahus urtiaae, which servesa spre yfo rth epredator .Th epredato rmit ei sallowe dt oadap titsel ft oth elea f foron eday ,an dth elea fi sthe ntreate dwit hth epesticid eb ymean so fa Potte rprecisio n spraytower .Fo r P. persimilis^, thechemical sar eteste di n3 concentrations :th econcen ­ trationrecommende db yth emanufacture ran ddoubl ean dhal ftha tconcentration .I ntest s with A. bibens, onlyth erecommende dconcentratio ni stested .Mortality ,eg gproductio nan d hatchingar eobserve dove r8 days .Fo rsom epesticides ,regressio nline so flo gdos eagains t mortalitywer edetermine db yey ean dmedia nletha lconcentration swer eestimate d (5concen ­ trationswit h3 0adult spe rconcentration ) (Table 1). Whenadult sar etested ,5 individual sar eplace do neac hlea fculture ,1 0juvenile so r 20egg sfo reac hlea far etake nfo rassa yo fothe rstages .Condition sdurin gth etest swer e seta t2 5°C ,70 %relativ ehumidit yan da ligh tphas eo f1 8h i na perio do f2 4h . Pesticidesmentione di nth etex tan dtabl econtai nth efollowin gactiv eingredient s: PallinalM (BASF):a mixtur eo f44 %metiram ,15 %maneb ,an d 12|%nitrothaldiisopropyl ; Nimrod (ICI):25 1buprimate ; Plondrel50 W (DowChemical) :20« .ditalimphos ; Funginex (Asepta):20 1triforine ; Morestan (Bayer):25 %quinomethionate ; Fungaflor(Philip sDuphar) : 20%imazalil ; Karathane (Aagrunol):22j Idinocap ; SM5 5 (Ligtermoet):45 %sulphu ran d20 %captan ; Goldion (PhilipsDuphar) :60 %sulphu ran d20 %mancozeb ; Malonoben(Philip sDuphar) : 50%3, 5 di-tert-butyl-4-hydroxybenzylidenemalonitrile; Benlate (PhilipsDuphar) :50 %benomyl ; Curamil (Hoechst):30 %pyrazophos ; Pirimor (ICI):50 %pirimicarb ;

Table 1.Recommende dconcentration s forapplicatio no fa numbe ro fpesticide san dthei r medianletha lconcentratio n (LC50)toward sadult so f Amblyseius bibens atdifferen ttime s aftertreatment .Th econcentration sar eexpresse d traditionally in'%' ,meanin gher egram s ofactiv eingredien tpe rlitr eo fdilute dpreparation .

Pesticide RecommendedI LC50 (%) after preparation concentration ('%' =0. 1 g/D 1da y 4day s 7day s 10day s Pirimor 0.05 0.1 0.1 0.1 Plictran 0.1 0.2 0.15 0.1 Benilate 0.05 >1.0 >1.0 0.1 Karathane 0.06-0.I 1 0.15 0.1 0.1 Torque 0.05 >1.0 1.0 0.5 Thiodan 0.1 0.15 0.15 0.15 LuxanMane b 80 0.2 0.4 0.3 0.2 LuxanZ ine b (70%) 0.05 >0.8 >0.8 0.5

1.Concentratio ndependen to ninterval sbetwee napplication s

228 Plictran (PhilipsDuphar) :25 1cyhexatine ; Karathane (Aagrunol): 12\%dinocap ; Torque (Shell):50 %phenbutaninoxide ; Thiodan (Hoechst): 50%endosulfan ; LuxanMane b 80:80 1maneb .

RESULTSAN DDISCUSSIO N

Elevenfungicide shav es ofa rbee nteste dfo rthei ractio no n P. persimilis (VanZo n& Wysoki, 1978).Th efungicide sPallina lM ,Nimrod ,Plondrel ,Funginex ,Moresta nan dFunga - florcause dn odamag et oan yo fth estage so fth epredator .Karathan eaffecte djuvenil e stagesan degg st osom edegree .S M55 ,Golde nSs pan dMalonobe nha dlittl eeffec to nadults , butkille dmos tegg san djuveniles . About40-5 0chemical shav ea sye tbee nteste dfo rthei ractio no n A. bibens, including mosto fth epesticide suse di norchard si nth eNetherlands .Mos to fth epesticide swer e fungicides.Onl yadulticid ean dovicid eactio nwer edetermined .Chemical sknow nt ohav ea hightoxicit yfo ra broa dspectru mo finsect s (e.g.parathion )wer eno tinclude di nth e study. Fungicidescontainin gmanganes ei ngenera lsho wa nunacceptabl eeffec to n A. bibens, especially ifon etake sint oaccoun tth efrequen tapplicatio no ffungicide si norchards . Onlya fe wacaricide swer etested ,a si twa sfel ttha tthes epesticide sar eno tneede di n integratedcontrol ,wher espide rmite sar econtrolle db ypredaciou smites .Tw oinsecticide s weretested :endosulfa nan dpirimor .Bot hcompound sshowe da moderat eeffec ta tth erecom ­ mendeddose ,bu ta sligh texces sma ycaus econsiderabl edamage . Noneo fth efolia rfertilizers ,cosmetic san dphytoauxin sshowe dan yadvers eeffec to n thepredators . Thedat ao nmedia nletha lconcentration sar estil ltentative ,a sth etest shav eno t beenreplicated .Th econcentratio nrecommende dfo rapplicatio ni sals ogiven .Som echemicals , sucha sBenomy lan dZine bca nb esafel yused .Fo rothers ,however ,cautio ni sneeded . Thetes tmetho ddoe sno tclosel yfollo wth especification so ftes tcondition sprepare d byth eIOB CWorkin gGrou pdurin ga meetin gi nColmar ,Franc ei n1974 .W eha dt odeviat e forsevera lreasons . TheWorkin gGrou pspecifie dtha ttes tanimal sb eplace do nsurface salread ycontainin g aresidu eo fth echemica lt ob etested .I nou rmethod ,th echemica li sapplie dt oleave s withth epredato rmit ealread yo nit .Thi si sdon ebecaus ea nadaptatio nperio di srequire d forth emite :th emite swil lotherwis e leaveth elea fan dbecom etrappe di nth ecotto nwool . Alsocontrar yt oth especificatio ni stha tegg sar eteste dan dth ehatchabilit yo fegg s laidb ytreate dfemale si scalculated .Fo rsom epesticides ,specifi cactio nwa sfoun do n eggso ro noffspring .I fth e 'Colmar'specification swer efollowed ,suc heffect swoul dno t beobserved .Th eWorkin gGrou pals opreferre dth eus eo finer tsubstrates ,suc ha sglas so r plasticsinstea dof ,fo rinstance ,leaves .Th eus eo finer tsubstrate sgav econsiderabl e difficulties:mite sten dt oleav eth etreate dsurface .Efficien t isolationbarrier swer e needed,a sw eha dt owor kwit hope ncell si norde rt oavou dvapou ractio no fth echemicals . Itwa spossibl et ous etalcu mpowde ra sisolatio nbarrie rfo radult so f P. persimilis, but

229 thissyste mfaile dfo rth ejuvenil estage so fthi ssam especie san dfo rth esmalle r Ambly- seius species.

SIGNIFICANCEFO RAGRICULTUR E

Datao nth eactio no fpesticide so nbeneficia larthropod sar estil lfe wbu tar eessen ­ tiali nintegrate dcontrol .I fpesticide sar eneede di nsuc hschemes ,the yshoul db eselec ­ tivean dharmles st oparasitoid san dpredators . Knowledgeo nth eeffec to fagricultura lchemical so na larg enumbe ro fbeneficia larthro ­ podso fdifferen ttaxonomi egroup si sver ywelcome .Th eIOB Cworkin ggrou pwa sforme dfo r thispurpose .Informatio no nth eeffec to fpesticide so nbeneficia larthropod sshoul db e addedt oth elabe lo fan ypesticid epreparation .

FUTUREOUTLOO K

Mosto fth eresult swer eobtaine db yusin gth etropica lpredato rmit especie s A. bibens. Researchwil lb eneede dt odetermin ewhethe rthi sparticula rmit especie sreact si nth e samewa ya sth epredato rmite stha toccu rnaturall yi nth eorchard .Th esusceptibilit yo f A. bibens mayb edifferen tfro mtha to fwes tEuropea nspecies .Comparativ estudie sar e planned. Manypesticide san dothe ragricultura lchemical sstil lnee dt ob eteste do npredato r mites.

REFERENCES

Blommers,L.H.M. ,1973 .Fiv ene wspecie so fphytoseii dmite s (Acarina:Mesostigmata )fro m SouthWe. ='Madagascar .Bull .zool .Museu mAmsterda m3 (16 ): 109-113 . Zon,A.Q .van ,& M .Wysoki , 1978.Th eeffec to fsom efungicide so nPhytoseiulu spersimilis . Entomophaga2 3 :371-378 .

230 8 Insect hormones

Indifferen tinstitution s forfundamenta lan dapplie dentomology ,i twa srealize dtha t insecthormone scoul db eexploite da spossibl esubstitute sfo rconventiona linsecticides . Thischapte rdescribe sth emultidisciplinar ystud yo finsec thormones .Th efirs tsectio n (8.1)deal swit hth edelineatio no fendocrin eprocesse si nth eColorad opotat obeetle . Environmentalsignal sinfluenc eth ebehaviou ro fadult so fthi smode linsec tthroug hth e interventiono fth ehormona lsyste man di nparticula rth ejuvenil ehormone .Severa lo fth e principlesfoun dwer eo fus efo rth eplannin gan dinterpretatio no fth eothe rexperiment s withhormones .Juvenil ehormon ei sals oth eke yhormon ei ncast edifferentiatio nan dadul t behaviouro fth ehone ybee .Yet ,du et oth eselectiv eactio no fcertai nanalogues ,be ecol ­ onieswil lprobabl ytolerat eth epresenc ei nth eorchard so fth epowerfu lanalogu eepofeno - nane (8.2).Laborator ystudie swer econducte dt odetermin eho winsect sreac tan dunde rwha t conditionsanalogue sca nb euse dt ocontro lth esumme rfrui ttortri xmoth ,a seriou spes t inappl eorchard s (8.3).Th elas tsectio n (8.4)report so nth eus eo fepofenonan ea sa pest ­ icidet ocontro lthi smot han da variet yo fothe rspecie sunde rfiel dconditions .Th ecompat ­ ibilitywit hothe rmethod so fbiologica lcontro li sdiscussed .

231 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980 8.1 Endocrine regulation of seasonal states in the Colorado potato beetle, Leptinotarsa decemlineata

C.A.D.d eKort ,H .Schoonevel d &J .d eWilde .

Departmento fEntomology ,Agricultura lUniversity ,Wageningen ,th eNetherlands .

INTRODUCTION

Inth eSectio n 'InsectHormone san dPheromones 'o fth eWorkin gPart yo nIntegrate dCon ­ trol,on eo fth etopic sregularl ydiscusse dwa sendocrin eregulatio no fadul tdiapaus ei n theColorad opotat obeetl estudie db yth eDepartmen to fEntomolog yi nWageningen .Thi swor k wasgraduall yextende dt oinclud eth eendocrin eregulatio no freproduction ,phas eformatio n inlocusts ,cast eformatio ni nth ehoney-bee ,an dendocrin easpect so fhost-parasit esyn ­ chronization.Th epresen tchapte rgive sa naccoun to fth eresult so fthes efundamenta lstud ­ ies.Whe nth eWorkin gPart yo nIntegrate dContro lwa sstarted ,researc ho nth eidentifi ­ cationo fjuvenil ehormon ean decdyson eha dbee nundertake nb ysevera lgroups ,becaus eo f thepotentia lus eo fthes esubstance sa sselectiv einsecticides .Littl ewa sthe nknow no f theinvolvemen to fth etw oinsec thormone si necologica lrelations ,an dou rinvestigation s haveprovide da nunderstandin go fth ecomplexit yo fthei reffects .The yhav eals oprompte d suggestionsfo rhormona linsec tcontro lb yrevealin gspecifi csite so faction .Example sar e giveni nth efollowin gparagraphs .

SEASONALADAPTATIO N INTH ECOLORAD OPOTAT OBEETL E- ROL EO FJUVENIL EHORMON E

Insectsar eregularl yface dwit hcondition sunsuitabl efo rbreeding .T osurviv esuc h unfavourablecondition sthe yhav edevelope dbehavioura l andphysiologica lmechanism sfo r adaptation,includin gmigratio nan ddiapause .Thes emechanism sca nb econsidere da sintegra l partso fth elif ehistor yo fth einsect ,an denabl eth einsect st osurvive ,eithe rb yescap e inspac e (migration)o ri ntim e (diapause).Bot hmechanism sar eusuall yfacultative ,whic h meanstha tthe yca neithe roccu ro rb eomitte dfro mth elif ehistory .The yenabl eth ein ­ sectt osynchroniz eit sdevelopmenta lan dbreedin gactivit yt oth emos tfavourabl eseasona l stateo fth eenvironment . Asbot hreproductio nan dadul tdiapaus eca nb einfluence db yth ecorpor aallata ,whic har e controlledb yth ebrain ,th eneuroendocrin esyste mwa sconsidere da sth ecentr egovernin g theseprocesses .Thi slinke decophysiologica lan dendocrinologica lwor ko nth elife-histor y ofinsect si nou rlaboratory . In1946 ,D eWild efoun dtha ti nth eNetherland sth eadul tColorad opotat obeetl ema yen ­ tera reproductiv ediapaus ea tth een do fJuly .H esubsequentl ystarte da serie so fobser -

233 vationsan dexperiment st ofin dth eenvironmenta lfactor sinvolve dan dth einterna lneuro ­ endocrineprocesse srespondin gt othes esignals .Photoperio dprove dt ob eth emai nfacto r governingdiapause .Unde rlong-da ycondition s (e.g.1 8h ligh tan d6 h dark) ,mor etha n70 % ofth ebeetle s feedan dreproduce ,bu tshor tday sinvariabl yinduc ediapause ,th ecritica l photoperiodbein gabou t 15h .Ol dpotat oleave sinduce ddiapaus eunde rlong-da yconditions . SomeRussia nresearc hshowe dtha ttemperature sabov e3 0° Cantagonize dth eshort-da yeffect . Thewor kprogresse di ntw odirections :ecophysiolog yan dendocrinology .

Eoophysiologiaal work

Thiswor kshowe dwhic hexterna lfactor sinfluence dth ephenolog yo fth ebeetl ean di t showedtha tgeographi cdispersa lmodifie dth ephotoperiodi crespons ethroughou tth eEuropea n area.Ou rlaborator ypopulatio nshowe dconsiderabl eadaptability .Relativel yquic kchange s wereobserve di nphotoperiodi cresponse ,fecundity ,an dth eduratio no fsom elaten tperiods . Thiswor kha sgrow nou tint oa ninternationa lnetwor ko fobservation so nseasona ldevelop ­ mento fpopulation s insom ecritica larea si nEurop ean dNea rAsia ,t ostud yth eadaptivit y ofth ebeetle sstrateg yo fphenologica ldevelopmen ti nrelatio nt osurviva lan dpes tout ­ breaks.W eals onee dmor einformatio no nwhethe rmigratio ni sa nintegra lpar to fth elife - -historyo fth ebeetl ean do nfactor spromotin gthi sbehaviour .Alongsid eth efiel dobser ­ vations,wor ki sdon ea tth elaborator yi nWageninge no nphotoperiodi crespons ei na larg e numbero fgeographi cstrains . Thelaborator ystrai nkep tfo r2 0year si nth eDepartmen to fEntomolog yi nWageninge n hasdouble dit srat eo freproductio nan dha sshortene dit scritica lphotoperio db yabou t 2h .Also ,th eincidenc eo fpre-diapaus eovipositio nha sincreased . Insevera lnatura lEuropea npopulations ,especiall y inthos eo fsouther norigin ,th eeffec t ofshort-da yi ninducin gdiapaus ei sconsiderabl y lesstha ni nth eorigina lFrenc hpopula ­ tion.I nsom eTurkis hpopulations ,lon gday s (16h )n olonge rpreven tdiapause .Mos tmarked , however,i sth econsiderabl eindividua lvariatio ni nadul tresponse st ophotoperio di neac h population,a sexpresse dfo rinstanc ei nth efina leffec t (diapauseo rreproduction) ,an d inth eduratio no ftransien tphase ssuc ha spre-diapaus ean dpre-oviposition .Thi svaria ­ bilityassure ssurviva leve nunde runfavourabl esumme rconditions .A reasonabl yquic kadap ­ tationoccur sunde rchange dpattern so fselectio npressure ,bot hi nth efiel dan di nth e laboratory (DeWild ee tal. , 1978).

Endocrine basis of diapause and reproduction

Thecorpu sallatum ,whic hproduce sJH-II I (Ci6 juvenilehormone) ,ha semerge da sa maste r glandcontrollin gdiapaus ean doogenesis .Abou t 1960,w efoun dtha tallatectom yan dshort - -dayha dsimila reffects ,an di nsubsequen twor kw eclearl yestablishe dtha tcorpu sallatu m activitywa sunde rphotoperiodi ccontrol .Biologica lassa yo fth econcentration so fjuvenil e hprmonewit hth eGalleri awax-tes tshowe dtha tunde rlong-da ycondition shig hconcentration s ofJ Hwer epresen ti nth ehaemolymph ,whil eunde rshort-da ycondition sonl yminut eamount s ofJ Hwer edetecte dsoo nafte radul temergence .Thereafte rth etitr erapidl ydecrease san d duringdiapaus eth etitr eo fhormon ei sbelo wth edetectio nlimi to fth ebioassa y (DeWild e

234 etal. , 1968).Chemica lanalysi sconfirme dtha thig hconcentration s ofJH-II Iwer ecirculat ­ ingi nth ehaemolymp hunde rlong-da yconditions ,whil eonl yminut econcentration swer epre ­ senti nshort-da ybeetles.(Fig.1 .) .

NEUROENDOCRINE INTEGRATION:JUVENIL EHORMON ETITR E

Ourinvestigation so nth erol eo fth ecorpu sallatu mi nth eadul tbeetl edea lprinci ­ pallywit htw oaspect s:ho wth eenvironmenta lstimul iar etranslate dint oa neuro-endocrin e response;ho wth ecorpu sallatu m (CA)affect sth etarge ttissues . Theneurosecretor ycell so fth ebrai nrepresen tth efina lcommo npathwa yo fneuro-endo ­ crineintegration .Th ephotoperiodi c information,afte rbein greceive db yth ebrain ,i s passedo nt oth eneuro-endocrin esystem ,togethe rwit hinformatio nfro ma variet yo fothe r sources.Afte rintegratio no fthes esignals ,th ecerebra lneurosecretor ycell sinfluenc e theactivit yo fth eCA ,whic hneed sconstan tstimulatio nt oproduc ejuvenil ehormone .Thi s conclusioni sbase do ndetaile dstudie so nfactor sinvolve di nregulatio no fth ehormon e titrei nhaemolymph . Thestead ystat econcentratio no fhormon ei smaintaine db yequilibriu mbetwee nsynthesi s byth eC Aan ddegradatio ni nhaemolymp han dtissues .Degradatio no fth ehormon eseem sver y rapid.Afte rinjectin g( 3H) JH-I,w efoun da half-lif eo fonl y2 5min .Juvenil ehormon e

3 ymol /ml.h GU/mlxlO" 30

10.0-

-I T ' I r 12 54 0 3 Diapause Postdiapause Fig. 1.Juvenil ehormon e titrean dhormon ecarboxy l esteraseactivit y inhaemolymp ho f Coloradobeetle sreare dunde rdifferen tligh tregimes .Broke nline ,lon gday ;soli dline , shortday ;shor tday ;• titr edata ;x activit yo festerases .GU ,Galleri aassa yunits .Af ­ terD eKor te tal . (1978).

235 canb edegrade db yesteras e attack atth emethy l ester functiono rb yhydratio no fth e epoxide groupb yth eenzym e epoxide hydratase.Studie so nmetabolis mo fth ehormon e showed that degradationb yesterase swa sth emajo rpathwa y inth eColorado potat obeetl ean dtha t thehormon ebreak s downmos t rapidly inth ehaemolymph ,whic h contains anactiv eJ Hspecifi c carboxyl esterase.Th ephysiologica l significance isindicate db yth eobservatio n thatth e esterase activity shows drastic changes closely correlatedwit h hormone titre (Fig. 1). ApparentlyJ Hesteras e activity isunder strict control.Hig h titreso fth ehormon e coin-

CA volume (x10"6mm3) 800

600-

400-

200-

-l 1 1 1 1 r "1 1 r 0 2 4 8 12 54 0 3 7 -•— Days Diapause Postdiapause p mol/pair CA.h 3-1

T 12 54 0 3 7 Diapause Postdiapause Fig. 2.Volume so fcorpor a allata (CA)(A )an drate so fsynthesi s invitr oo fjuvenil ehor ­ monepe rpai ro fcorpor a allata (B)fro mbeetle s reared under different light cycles. Bro­ ken line,lon gday ;soli d line,shor tday .Afte r Schooneveld etal . (1977)an dKrame r (1978).

236 cidewit hrelativel y lowJ Hesteras eactivit yan dlo wtitre so fhormon ewit hhig hesteras e activity,e.g .i nth elas tlarva linsta ran dunde rshort-da yconditions .However ,eve nunde r long-dayconditions ,th eJ Hesteras eactivit yi shighe rtha ni nth ehaemolymp ho fothe rin ­ sectspecie sstudie d (DeKor te tal. , 1978).Th eproble mremain so fho whormon etitre sca n risei nth epresenc eo fsuc hhig hesteras eactivity .W einvestigate dwhethe ra carrie rpro ­ teintha tprotecte dth ehormon eagains tbreakdow nwa spresen ti nhaemolymph .Indeed ,a high-molecularlipoprotei nha sbee nshow nt obin dth ehormon ewit ha lo wdissociatio ncon ­ stant (X ~10 5mol/1) ,bu ti tprotect sth ehormon eonl ypartl yagains tth eesterase s (De Korte tal. ,1978) . Undercondition so frapi ddegradatio nan dlittl eprotection ,th eoccurrenc eo fhig hti ­ treso fjuvenil ehormon eca nb eexplaine donl yi fsynthesi sb yth eC Ai srapid .Indeed ,b y ashort-ter mradiochemica lassa yi nvitro ,Krame r (1978)showe drapi dsynthesi sb yCA .Th e rateo fsynthesi si nvitr ochange ddrasticall yi nbeetle so fdifferen tag ean ddifferen t photoperiodictreatmen t (Fig.2) .Th eC Aactivit ywa smuc hhighe ri nlong-da ybeetle stha n inshort-da ybeetles .I ndiapause ,th erat eo fsynthesi swa sver ylow ,a swoul db eexpect ­ ed.Rate so fsynthesi sfoun db ythi sassa yi nvitr ocorrelate dnicel ywit htitre so fhor ­ monei nth ehaemolymph .S oth ephotoperiodi ceffec to nth ehormon etitr ei nhaemolymp hi s primarilycause db ydifference si nth erat eo fsynthesi sb yth eC A (Kramer,1978) .Th e changesi nth eactivit yo fth eesteras ei nhaemolymp har ea consequenc eo flo wtitre so f hormonerathe rtha nth ecause .Th ehig hesteras eactivit yfoun ddurin gpre-diapaus ei s probablyrequire dt oeliminat eth elas ttrace so fth ehormone ,thu senablin gth ebeetle s toente rdiapaus e (DeKor te tal. , 1978).

CONTROLO FCORPU SALLATU MACTIVIT Y

Ifa lo wactivit yo fcorpor aallat a (CA)i sth emai ncaus eo fdiapause ,th equestio n arisesho wtha tactivit yi sregulate db yth ebrain .Ar ecorpor aallat acontrolle db yneura l pathwayso rb yhumora lstimuli ?Severin go fth enerve st oth eC Adoe sno tchang eglan dac ­ tivitycompare dt ocontrol si neithe rlong-da yo rshort-da ybeetles ,whe nth egland sar e examinedwit hth eassa ysyste mi nvitr o2 4h afte rcuttin gnerve s (Schoonevelde tal. , 1979). Soprobabl ydenervate dcorpor aallat aremai nactiv eunde rlon gdays ,an dd ono tbecom eacti ­ vatedb yremovin gthe mfro mth ebrai nunde rshor tdays .Thu sn oneura linhibitio nfro mth e braini seviden ti nth eColorad opotat obeetle .Indeed ,D eWild eshowe dtha tseverin go f thenerv icorpor iallat ineve rprevente dth eonse to fdiapaus e ifcarrie dou ti nshort-da y animals.S ohumora lstimuli ,mos tprobabl yfro mth ebrain ,see mprimaril y involvedi nregu ­ lationo fth ecorpor aallata . Wear ejus tbeginnin gt ounderstan dwha tth efunctio no fneurohormone sma yb ei nth e Coloradopotat obeetle .I ti slikel ytha ta tleas ton eo fth eneurosecretor y factorsplay s arol ei nth econtro lo fth eCA .Indeed ,diathermi ccauterizatio no fth epar s intercerebralis ofth eprotocerebru minactivate sth eglands .Moreover ,D eWilde.showe dtha tdiapaus eafte r allatectomyca neasil yb eprevente db yimplantatio no fon epai ro fcorpor aallat afro mac ­ tivereproducin g females.Thi sdoe sno thappe ni nbeetle si nshort-da ydiapause .I ttake s manymor epair so fcorpor aallat at opreven tonse to fdiapause .Thi sca neasil yb eexplaine d ifw eassum etha tcorpor aallat aimplante dint oa short-da ybeetl erapidl ylos ethei rac -

237 tivity,whil ei nlong-da yallatectomize dbeetle sth eimplante dgland sretai nthei ractivity . Thus,th ebrai nproduce sa substanc estimulatin gC A (allatotropin)unde rlong-da yconditions , butno twit hshor tdays .Alternativel ywit hshor tdays ,a ninhibitin gsubstanc ei sproduce d (allatohibin),whic hprevent sth eactivatio no fcorpor aallat aunde rshort-da yconditions . Thesearc hfo reithe rtyp eo fhumora lfactor sfro mth ebrai nwil lb econtinued . Ifth etitr eo fhormon e inhaemolymp hi shomoeostaticall y regulatedb ychange si nth e activityo fth ecorpor aallat agoverne db yth ebrain ,ther eshoul dals ob ea feedbac kmech ­ anismt okee pth etitr ea ta desire dlevel .T ofin dou twhethe rsuc ha feedbac kmechanis m operates,th efollowin gexperiment swer edesigned .Unilatera lallatectom ywa sperforme di n long-daybeetle san dth etitr eo fhormon emeasure dseve nday safte rth eoperation ,an dth e activityo fth eremainin gglan dwa s testedi nth eassa ysyste mi nvitro .Th esingl ecorpu s allatumha dincrease dit sactivit ysignificantl yan dth ehormon econcentratio nremaine dth e samea si nth econtrols .S oth eneuroendocrin esyste maccuratel y compensatesfo rth elos s ofon eC Ab yincreasin gth eactivit yo fth eother .O nth eothe rhand ,whe nextr acorpor a allataar eimplante di nlong-da yanimal sth evolum eo fth eC Ao fth erecipien tbeetle sre ­ mained low.Moreover ,topica lapplicatio no fjuvenil ehormon et olong-da ybeetle sdepresse d thevolum eo fth eCA ,an dth eassa yi nvitr oo fC Aactivit yclearl yshowe da decreas ei n synthesis.

JUVENILEHORMON EAN DFLIGH TMUSCL EDEVELOPMEN T

Diapausei scharacterize db ya dramati creductio ni nmetaboli crate .Th emai ncaus epro ­ vedt ob eth edegeneratio no fth efligh tmuscles .Th equestio narise swhethe rjuvenil ehor ­ monedirectl yaffect sfligh tmuscles .A temergence ,th efligh tmuscle shav esmal lmyofibril s andonl yfe wmitochondria .Rapi ddevelopmen ttake splac edurin gth efirs t8 day sunde rlong - -dayconditions .Durin gpre-diapause ,developmen ti sincomplet ean dth emuscle sdegenerat e afterth eonse to fdiapause .Terminatio no fdiapaus elead st orapi dregeneratio no fth e flightmuscles .Thes edevelopmenta lchange si nth efligh tmuscle scorrelate dnicel ywit h thetitr eo fhormon ei nhaemolymph .Hig htitre sresul ti ncomplet efligh tmuscl edevelop ­ ment;lo wtitre si nincomplet edevelopment ;extremel ylo wtitre si ncomplet efligh tmuscl e atrophy.Th einterpretatio ntha tJ Hregulate sfligh tmuscl edevelopmen tdirectl yi sunsatis ­ factory.Fligh tmuscl edegeneratio nals ooccur si nothe rinsec tspecie sbu tmostl ydurin g reproductionwhe nth ecorpor aallat aar epresume dt ob eactive .Indeed ,allatectom yinhib ­ itsdegeneratio ni nthos especies ,whil etreatmen twit hhormon estimulate sbreakdow no f flightmuscle .Thes eexample sdemonstrat etha tfligh tmuscl edevelopmen tan ddegeneratio n arecorrelate dwit hth eactivit yo fth ecorpor aallata ,bu tth erespons eo fthes emuscle s tohormon eca nb edifferen ti ndifferen tinsects .Thi spresent sa seriou sdifficult yi n correlatingfligh tmuscl edevelopmen tan ddegeneratio nwit hhormon etitre .Perhap sther e israthe ra correlatio nwit h locomotoryactivity . Inmigrator yinsects ,fligh toccur sbefor ereproduction ;fligh tmuscle sdegenerat ewhe n migrationha sended .I nth eColorad opotat obeetle ,degeneratio noccur swit hdiapause ,a stateo falmos tcomplet eimmobilit yi nth esoi la ta dept ho f40-6 0cm .Th eeffec to fth e hormoneca nwel lb emediate db yth enervou ssystem .Indeed ,diapaus ei saccompanie db ya drasticdecreas ei nacetylcholinesteras e activityi nth ebrain .Moreover ,severanc eo fth e

238 nervet oth efligh tmuscl e leadst oa failur eo fnorma lfligh tmuscl edevelopment .Appar ­ entlyfligh tmuscl edevelopmen tan ddegeneratio nha sbee ns ocorrelate dwit hdiapaus etha t itfit sint oth ephenologica lstrateg yo fth eColorad opotat obeetle .

ENDOCRINEREGULATIO NO FREPRODUCTIO N

Reproductioni nth eColorad opotat obeetl eoccur sunde rlong-da yconditions .Tw oday s afteremergenc eth eadul tbeetl estart sproducin gyolk .Matin gstart so nDa y 2o r3 an dfro m Day5 onward sovipositio noccur sdail yi nbatche so fmor etha n6 0egg spe rfemale .Th emajor ­ ityo fth eyol kprotein sconsist so f2 proteins ,vitellins ,whic har eimmunologicall yidenti ­ calwit h2 protein si nth ehaemolymp h(vitellogenins) .Th evitellogenin s aresynthesize da t ahig hrat ei nth efatbod yo flong-da yfemale safte rDa y 2,transporte dt oth eovaries ,an d specificallytake nu pb ypinocytosis . Undershort-da yconditions ,vitellogeni nsynthesi sb yth efa tbod yi sver yslo wan dyol k isn olonge rproduced .However ,th efa tbod ythe nsynthesize sa larg enumbe ro fothe rpro ­ teins.Amon gthese ,ther ear ethre eprotein sstore di nlarg eamount safte rDa y6 i n'pro ­ teingranules' .Larg edifference sexis ti nth efa tbod ybetwee nlong-da yan dshort-da ybee ­ tles,bot hfunctionall y andstructurally .Thes edifference si nfunctio nar eunde rth econ ­ trolo fhormones ,especiall yjuvenil ehormone .Allatectom yo flong-da ybeetle slead st oa decreasei nsynthesi so fvitellogenins .Treatmen to fshort-da ybeetle swit hjuvenil ehor ­ monelead st oincrease dsynthesi so fvitellogenin sb yth efa tbody .Howeve rth ehormon ealon e isno tth eonl yfacto rresponsibl efo rprotei nmetabolis mi nth efa tbody .Increas ei npro ­ teinsynthesi sals ooccur si nallatectomize ddiapausin ganimal si fthe yar etransferre dt o long-day. Moreover,whe n 1-day-diapausingbeetle swer etreate dtopicall ywit ha larg edos eo fju ­ venilehormone ,the yentere dth esoi lagai nimmediately .Severa lday slater ,som ebeetle s emergedagai nbu tal lreturne dt oth esoi lafte ra fe wday st osevera lweeks .Ver yfe wfe ­ malesoviposite ddurin gtha tperiod ,eve nwhe nJ Hdose swer eincrease dt oletha lamounts . Mimeticstha twer eknow nt ob emor epoten ttha nnatura ljuvenil ehormon ei nothe rtest s alsodemonstrate dhig hactivit yi nthei rpotenc yt obrea kdiapause .Bu tal lcompound sonl y inducedtemporar yactivatio nan dlimite dreproductiv eactivity . Theothe rfacto rrequire dt obrea kdiapaus epermanentl yprove dt ob ea long-da yregime . Longdays ,i ncombinatio nwit hjuvenil ehormon ei na dos enormall yactivatin g 75%o fth e diapausingbeetle sterminate ddiapaus ean dgav epersistin greproductiv eactivit yi n1001 . ofth ebeetles .Th ebeetle' scorpor aallat ahardl ypla ya rol eunde rthes econdition san d mayb eremove dwithou tan ynoticeabl eeffec tove r2 months .Sinc eexogenou shormon ei srap ­ idlydegrade donc ei tarrive si nth eblood ,reproductio nunde rthes econdition smus tcon ­ tinuei nspit eo fver ylo wtitre so fhormone .Thi sfindin grequire sclarification .

OUTLOOK

In1967 ,th echemica lstructure so fbot hth ejuvenil ehormon ean decdyson ewer eeluci ­ dated,an dworld-wid einvestigation s onth epractica lus eo fth ehormone san dthei ranalo ­ gueswer eunde rway .Abou t6 year s later,th eresponsibl eauthoritie swer econfronte dwit h

239 requestsfo radmissio no fth efirs thormona linsecticides .Wor kdon eb you rWorkin gPart y onIntegrate dContro lha scontribute dt othes edevelopments . Ourinvestigation shav ehelpe dt oprovid ebackgroun dinformatio nt ojudg eth econsequen ­ cesfo rinsec tlif ei ngenera lo fsprayin go rdustin gwit hinsec thormones .Brea ko fdia ­ pause,interferenc ewit hoecomorp hdevelopmen tar ematter si npoint .Ou rfindin gtha tqueen ­ likecharacteristic s developwhe nhone ybe elarva ear etreate dwit hsmal ldose so fjuvenil e hormonecam ejus ti ntim efo rth eplan tprotectio nauthoritie st ob ealerted .W ewer efirs t inelucidatin gtha ttitre so fjuvenil ehormon ear eresponsibl efo rseasona lstate san doeco - morphs (DeWilde , 1978). Nowtha tth eendocrin ebasi sha sbee nelucidated ,th ewhol econceptio no fseasona lstrat ­ egiesi ninsect san dth eimpac to ftoke nstimul ii so nmuc hfirme rfooting .

REFERENCES

Kort,C.A.D .de ,1969 .Hormone san d thestructura lan dbiochemica lpropertie so fth efligh t musclesi nth eColorad obeetle .Meded .LandbHogesch .Wageninge n69-2 .6 3p . Kort,C.A.D .de ,S.J .Krame r& M .Wieten ,1978 .Regulatio no fjuvenil ehormon etitre si n theadul tColorad obeetle :interactio nwit hcarboxylesterase s andcarrie rproteins .In : P.J. Gaillard &H.H .Boe r (Editors).Comparativ eendocrinology .Elsevier/North-Hollan d BiochemicalPress ,Amsterdam ,p .507-510 . Kramer,S.J. , 1978.Age-dependen t changesi ncorpu sallatu mactivit y invitr oi nth eadul t Coloradopotat obeetle ,Leptinotars adecemlineata .J .Insect .Physiol .2 4 :461-464 . Loof,A .d e &J .d eWilde ,1970 .Hormona lcontro lo fsynthesi so fvitellogeni c femalepro ­ teini nth eColorad obeetle .J .Insec tPhysiol . 16: 1455-1466 . Schooneveld,H. ,S.J .Kramer ,H .Privé e &A .va nHuis , 1979.Evidenc eo fcontrolle dcorpu s allatumactivit y inth eadul tColorad opotat obeetle .J .Insec tPhysiol .2 5 :449-453 . Schooneveld,H. ,A .Otaz oSanche s& J .d eWilde ,1977 .Juvenil ehormone-induce dbrea kan d terminationo fdiapaus ei nth eColorad opotat obeetle .J .Insec tPhysiol .2 3 :689-696 . Wilde,J .de ,1978 .Seasona lstate san dendocrin elevel si ninsects .In :I .Assenmache r& D.S.Farne r (Editors).Environmenta lendocrinology .Springe rVerlag ,Berlin ,p .10-19 . Wilde,J .de ,E .Boersma ,A .Brouwer ,R .va nGen t &A .va nd eWielen ,1978 .Laborator yan d fieldobservation so nseasonalit yepidemiolog yan dhost-plan trelationship s ingeograph ­ icpopulation so fth eColorad obeetle .Unpublishe d report,Departmen to fEntomology , AgriculturalUniversity ,Wageningen ,th eNetherlands .8 1p . Wilde,J .de ,G.B .Staal ,C.A.D .d eKort ,A .d eLoof ,& G .Baard , 1968.Juvenil ehormon e titeri nth ehaemolymp ha sa functio no fphotoperiodi c treatment inth eadul tColorad o beetle.Proc .K .Ned .Acad .Wet .C .7 1 :321-326 .

240 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980.

8.2 Effects of juvenile hormone and some analogues on caste differentiation and adult behaviour in the honey bee, Apis mellifera

J.Beetsm a

Laboratoryo fEntomology ,Agricultura lUniversity ,Wageningen ,th eNetherlands .

INTRODUCTION

Thedevelopmen to fa femal elarv aint oa quee no rworke rbe edepend scompletel yo nth e conditionsprevailin gi nth ecell si nwhic hthe yar ereared .Fro mexperiment so nrearin g oflarva ei nvitro ,th efollowin ghypothese shav ebee npu tforwar di nth eliterature . Theproces so fquee ndifferentiatio ni sregulate db y - thepresenc eo fa determinin gprincipl ei nth efoo do fquee nlarvae ; - thehighe rmoistur econten to fth efoo do fyoun gquee nlarvae ,resultin g ina highe rfoo d intaketha nb yworke rlarvae ; - thehighe rconten to fsugar si nth efoo do fyoun gquee nlarvae ,inducin ga highe rfoo d intaketha nb yworke rlarvae ; -a differenc ei nhormon ebalanc ei nth eearl ystage so flarva ldevelopmen tbetwee nquee n andworke rlarvae . Theai mo fou rresearc hi nth elaborator yo fEntomolog ywa st oattai na bette runder ­ standingo fth eproces so fcast edifferentiatio nb ytestin gsom eo fthes ehypothese si n vivo.Th elaborator yinteres tdirecte dresearc ht oth eeffect so fhormona linsecticide so n colonydevelopment .

ROLEO FJUVENIL EHORMON EI NCAST EDIFFERENTIATIO N

Ina comparativ eanatomica lstudy ,Wirt z (1973)demonstrate dtha tth ecorpor aallat a inquee nlarva ewer elarge rtha ni nworke rlarvae .A nincreas ei nsiz ean dactivit yo fth e corporaallat aoccurre dafte rtransferrin g 2-day-oldworke rlarva eint oquee ncells .Th e Galleriawax-tes tshowe dtha tth etitr eo fth ejuvenil ehormon ei nth ehaemolymp ho f 3-day-oldlarva ewa sabou t 10time sa shig ha si nworke rlarva eo fth esam eage . Toprov etha tth ehormon eplay sa rol ei ncast edifferentiation ,i twa sapplie dtopicall y toworke rlarva e (Wirtz,1973) .Applicatio no f1 y go fJH- It o3.5-day-ol dlarva eresulte d inth edevelopmen to fworker-size dindividual swit hobviou squee ncharacteristics ,eve n thoughtreate dlarva ereceive dnorma lamount so fworke rjell yfro mth enurs ebee san dgre w innarro wcells .I nthi sproject ,J .Naiss edemonstrate dtha tth edegeneratio no fovariole s inyoun gworke rlarva ewa sinhibite db yartificiall yincreasin gth etitr eo fth ehormon ei n

241 haemolymph. Queendifferentiatio nwa sals oobtaine dafte rtopica lapplicatio no fsevera ljuvenil e hormoneanalogue s (JHA).Copij ne tal . (1979)foun dtha tapplicatio no f1 y go fJH- Io r ZR-512t oworke rlarva e3.2 5 -3.5 0day sol dresulte di nth ehighes tdegre eo fexpressio n ofqueenlik echaracteristics . Afteri tbecam eknow ntha tJH-II Iwa sth eonl ynatura ljuvenil ehormon ei nth eadult , theeffec twa sstudie do fapplicatio no fthi ssubstanc eo ncast edifferentiatio ni nth e larvae.Rathe rtha naffectin gal lmeasure dcharacteristic sb yJH- Iapplication ,on edos e of3-1 4u go fJH-II Icause donl ysom efeature swithi na nindividua lt obecom equeenlike . Howeverthric erepeate dapplication so f4 u go fJH-II I improvedth edifferentiatio nint o aqueenlik eindividual .Th edifferen teffect so fJH- Ian dJH-II Io ncast edifferentiatio n andth eextremel ylo wmortalit yafte rapplicatio no fJH-II Isugges ttha tJH-II Iplay sa rolebot hi nth eadul tbe ean di nlarva ldevelopment . DeKor te tal .(1977 )demonstrate dtha tJH- Iwa sno tdegrade db yspecifi cesterase si n thehaemolymp ho flarva eo fth elas tthre einstars ;a ver ylo wactivit yo fJH-II Iesteras e wasfoun donl yi nth e5t hinstar .A si ti sver yunlikel ytha tenzym eactivitie sdiffe rto ­ wardsJH- Ian dJH-III ,w eassum etha tth edifferen tresult sobtaine dafte rapplicatio no f thesetw ohormone sma yb edu et oa differen trat eo freleas efro mth ecuticl et oth ehae ­ molymph.Afte rapplicatio no fJH-I ,th etitr eremaine dhig htw oday safte rapplicatio n (Copijne tal. , 1979).A neffectiv eJH-II Ititr ewa sprobabl ymaintaine donl ybriefly .Th e inductiono fquee ncharacteristic sshoul dthe ndepen do nth ecoincidenc eo fa hig htitr e inth ehaemolymp h anda sensitiv eperio do fseparat eimagina idiscs . Finalevidenc eo fth esignificanc eo fth ehormon ei nth eproces so fqueen-worke rdiffer ­ entiationwa sobtaine db yadministratio no fth ecorpu sallatu minhibito rPrecocene-II , acompoun dextracte dfro mth eher b Ageratum houstonianum. Goewiee tal . (1978)foun dtha t thecorpor aallat apartiall yo rcompletel ydisappeare dafte rtopica lapplicatio no fPreco ­ cene-IIt oquee nlarvae .Althoug hal llarva eha dconsume dlarg eamount so froya ljelly , whichshoul denhanc equee ndifferentiation ,th eresultin gadult sdevelope dworker-lik e characteristics.

FUNCTIONO FTH EBRAI N

Iti sstil lunknow nho wth eperceptio no ffoo dqualit yo rdifference s infoo dintak e regulateth eproductio no fjuvenil ehormon ei nth ecorpor aallata .Recen tstudie sb yGoewi e (1978)reveale dtha tth emedia lneurosecretor ycell si nth ebrai nar eno tinvolved .Thes e cellsar ehardl ydifferentiate di nlarva eu pt o6 0h .However ,a tth een do fth e4t han d 5thlarva linstar ,differentiatio no fthes ecell si scomplete dan da considerabl enumbe r ofneurosecretor ygranule sar etransporte di nth eaxon srunnin gfro mth eneurosecretor y cellst oth ecorpor acardiac aan dt oth ecorpor aallata .Th eappearanc eo fneurosecretor y materiali nth ecorpor aallat acoincide swit ha decreas ei nactivit yo fthes eglands .S o duringthes estage so flarva ldevelopment ,th emedia nneurosecretor ycell smus tinhibi t productiono fjuvenil ehormone .

242 PERCEPTIONO FFOO DQUALIT Y

Withscannin gelectron-microscopy ,Goewi e (1976)describe dth edevelopmen to fth esens e organso nth elarva lmout hparts .Afte rpreliminar yexperiment sb yWirt z (1973),Goewi e (1978)studie dth ehistolog yan dfunctio no fthes esens eorgans .Al lchemoreceptor sprove d sensitivet osugar san dsalts .Howeve rn oothe rteste dcomponen to flarva lfood ,includin g Rembold'sdeterminin gprincipl estimulate dth esens eorgans .Thi sresul twa sconfirme dwhe n comparingrecepto rresponse sgenerate db ydilute droya ljell yan dworke rjelly .A wate rre ­ ceptorcoul dno tb efound .S osugar sma yfunctio na sphagostimulant san dn odeterminin g principleo rothe rfoo dcomponen ti sinvolve di ncast edifferentiatio na tth estag eo fper ­ ception.

FURTHERRESEARC HO NCAST EDIFFERENTIATIO N

Themai nproble mt ob esolve di sth edifferen tbehaviou ro fth enurs ebee swhe nfeedin g larvaei nquee no rworke rcells .

OTHEREFFECT SO FJUVENIL EHORMON EAN DIT SANALOGUE S

Copijne tal . (1979)demonstrate dtha tsevera lanalogue stopicall yadministere di nvar ­ iousdose st oyoun gworke rlarva ecause da hig hmortality ,bot hi nth elarva lan dpupa l stages.Th eadul tbee sinterfere dwit hth edevelopmen to fth etreate dbroo dafte rth ecell s hadbee nseale db ythem .Thoug hseale dcell scontainin gtreate dan duntreate dworke rlarva e appearidentica lt oth ehuma neye ,th ebee sdiscriminate dbetwee nth etw osituations .Soon , allhormon etreate dlarva ean dpupa ewer eremove dfro mthei rcell sb yth ebee s (Wirtz,1973) . Thicknesso fth ecocoon ,ultimat eorientatio no fth epupatin g larvao rcontac tpheromone s mayinfor mth ebee so fth epresenc eo fth etreate dbrood .Colonie srepeatedl yuse dt orea r treatedlarva eneglecte dth ebroo dan dsom etime sth equee ndisappeare d (Wirtz,1973) . Becauseo fthes eobservations ,ou rgrou passume dtha tth ebehaviou ro fth enurs ebee sha d beenaffecte da swell .

EFFECTO FJUVENIL EHORMON EANALOGUE SO NCOLON YDEVELOPMEN T

Byfeedin gsmal lcolonie so nanalogue so rb ysprayin ganalogue sont oa cro pvisite db y bees,Beetsm a& Te nHoute n (1975)foun da considerabl emortalit yi nth ebroo dnests .No t onlyth ebroo dwa saffecte dbu tals oth eadul tbees .Foo dgland sdegenerate dcompletel y andwa xgland swer esmall . Treatmento fcolonie swit hsom eanalogue sresulte di nth edeat ho rlos so fth equeen . Sincequeen sar enormall y fedb yth ebees ,th eobserve deffec ti spresumabl ycause db yde ­ generationo ffoo dgland so fth eworkers .Queen-rearin gbehaviou rwa saffecte da swell . Dequeeninga colon ynormall yresult si ntransformatio no fsom eworke rcell sint oquee ncell s byth eworkers .However ,n oquee ncell swer ebuil twhe nth equee ndisappeare dfro manalogu e treatedcolonies .

242 CONCLUSION

Ifjuvenil ehormon eanalogue sar et ob euse di npes tcontrol ,th eeffect so nth edevel ­ opmento fusefu linsect smus tb eteste dfirst .Th eanalogu eepofenonane ,whic hhardl yaf ­ fectedparasiti chymenoptera ,seem sals oinactiv eagains tth ehone ybee .Sinc en oincreas e inmortalit yo fadul thone ybee scoul db edemonstrate dafte rcontac twit hanalogue s(Beets - ma& Te nHouten ,1975) ,th ecurren tmetho do fscreenin gpesticide s fortoxicit yt ohone y beesshoul db euse dwit hcaution .Effect so nbroo ddevelopmen tan dadul tbehaviou rshoul d certainlyb estudie dtoo .

REFERENCES

Beetsma,J. , 1979.Th eproces so fqueen-worke rdifferentiatio ni nth ehoneybee .Be eWl d 60(1): 24-39 . Beetsma,J .& A .te nHouten ,1975 .Effect so fjuvenil ehormon eanalogue s inth efoo do f honey-beecolonie s (Apismellifer a L.). Z.angew .Ent .77(3 ): 292-300 . Copijn,G.M. ,J .Beetsm a& P .Wirtz , 1979.Quee ndifferentiatio nan dmortalit yafte r applicationo fdifferen t juvenilehormon eanalogue s toworke rlarva eo fth ehone ybe e (Apismellifer a L.). Proc.K .ned .Akad .Wet .C 82(1 ): 29-42 . Goewie,E.A. , 1978.Regulatio no fcast edifferentiatio ni nth ehoneybe e (Apismellifer a L.). Meded.LandbHogesch .Wageninge n78-15:1-75 . Goewie,E.A. ,J .Beetsm a& J .d eWilde ,1978 .Effect so fPrecocene-I Io ncast edifferentia ­ tioni nth ehone ybe e (Apismellifer a L.).Mitteilunge nde rdeutsche nGesellschaf tfü r allgemeineun dangewandt eEntomologi e (1)304-305 . Kort,C.A.D .de ,M .Wieten ,S.J .Krame r& E.A .Goewie ,1977 .Juvenil ehormon edegradatio n andcarrie rprotein si nhoney-be elarvae .Proc .K .ned .Akad .Wet .C 80(4 ): 297-301 . Wilde,J .de ,1976 .Juvenil ehormon ean dcast edifferentiatio ni nth ehone ybe e (Apismel ­ liferaL.) . In:M .Lüsche r (Editor),Phas ean dcast edeterminatio n ininsects .Pergamon , Oxford,p .5-20 . Wirtz,P . 1973.Differentiatio ni nth ehoneybe elarva .Meded .LandbHogesch .Wageninge n 73-5:1-155.

244 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 8.3 Use of insect growth regulators with juvenile hormone activity to control Adoxophyes orana: laboratory studies

H.Schoonevel d

Departmento fEntomology ,Agricultura lUniversity ,Wageningen ,th eNetherlands .

Theendocrin esyste mi ninsect scontrol ssevera lprocesse sassociate dwit hembryogene - sis,growt han ddevelopment ,reproduction ,diapause ,an dvariou saspect so fbehaviour .Ex ­ perimentalchange si nhormon ebalance ,brough tabou ta tspecifi cstage so fth elif ecycl e arelikel yt oinduc epermanen tdisturbanc eo fthes eprocesses ,whic hma yreduc eth echan ­ ceso fnorma ldevelopmen to fth eindividua lo rit sfitnes sfo rsurvival . Studieso nhormona linsec tcontro lar efocuse do nth efindin go fwea kspot sdurin gdevel ­ opment,i nwhic hhormona lbalanc ema yb eupset .Thi spape rconsider sth eus eo fsyntheti c compoundswit hjuvenil ehormon eactivity ,ofte ncalle dinsec tgrowt hregulator s (IGR),i n controlo fsumme rfrui ttortri xmot h Adoxophyes orana, whichi sa pes ti nappl eorchard s inth eNetherland san dwhic h ishar dt ocontro lwit hselectiv einsecticide s (Sections1.3 , 1.8an d8.4) .Introductor y laboratoryresearc hwa sconducte dt odetermin eth ebiologica l activityo fdifferen tcompounds .Thi spape rstresse sth eevaluatio no ffactor so fspecia l importancet oIG Ractio ni nth efield .

MATERIALSAN DMETHOD S

Adoxophyes orana larvaewer emass-reare do nartificia ldie ta t2 0 C,unles sotherwis e specified.Freshl ymoulte d5th-insta rlarva ewer ecollecte d fromth ecultur eboxes ,kep t isolated,an dtreate dtopicall ywit hon eo fth efollowin gcompounds :methy l10,11-epoxy - -7-ethyl-3,11-dimethyl-2,6-tridecadienoate (IGR-1); 6,7-epoxy-3,7-dimethyl-1-3,^(methy ­ lenedioxy)phenoxy-2-nonen e (IGR-2); 6,7-epoxy-3-ethyl-1-(p-ethylphenoxy)-7-methylnonane (IGR-3).Al lcompound swer euse da smixture so fisomer sdissolve di nacetone ,an dwer esup ­ pliedb yD rR .Maa gA.G . (Dielsdorf,Switzerland) .Pupa ean dadult swer einspecte dfo ref ­ fectsb ycriteri aoutline di nth etext .

RESULTSAN DDISCUSSIO N

Dose-response relationship

Oneneed smethod st odetermin ean dcompar eth ebiologica lactivit yo fdifferen tcompound s inorde rt oselec tth emos tsuitabl eone . For A. orana, thecompound swer eapplie dtopicall ywithi non eda yo fth emoul tt oth e5t h

245 (last)larva linstar .Th eeffec twa sassesse dafte rpupation .Smal ldose syielde dpupa e withmino reffects ,suc ha sretentio no flarva lproleg so rpalp i (score 1);large rdose s resultedi nth eretentio no fmor elarva lcharacteristic s includinggree ncoloration .Th e strongesteffec twa sth eformatio no fa supernumerar yperfec t6th-insta rlarv a (score7 ) (Abdallah,1972) .Whe nsufficientl y largenumber so flarva ewer etreated ,th eaverag eef ­ fecto fa give ndos ewa spredictable .Plottin gth elo go fth edos eagains tth eaverag enu ­ mericalrespons eresulte di na sigmoi dcurve ,whic hmad ei teas yt orea dth edos etha t gavea scor eof ,say ,3 .Th erathe rpoten tcompound sselecte d forfurthe revaluation , IGR2 an d3 ,wer ea hundre dtime smor eactiv etha nIGR- 1an dth ecritica ldos ewa sabou t 0.1 ygpe rlarva . Thelarva esho wa noptimu msensitivit y (criticalperiod )abou tth emiddl eo fth e5t h intermoultperiod .Earlie rapplicatio nresult s inpartia lbreakdow no fth ecompoun dbefor e thesensitiv eperiod ;late rapplicatio ni sineffectua lsinc eth esensitiv eperio dha slarge ­ lyelapsed .Sprayin g inth efiel dmus tb eprecisel ysynchronize dt oth edevelopmen to fth e population;alternativel ya deposi tmus tb eapplie do nth esubstrate ,suc htha tever yindi ­ viduali na mixe dpopulatio nreceive ssufficien to fth ecompoun da tit ssensitiv estage .

Effect of temperature

Temperatures inth efiel dvar yconsiderably .A si twa sunknow nwhethe rth eactio no f compoundswa smodifie db y lowo rhig htemperature ,treate dlarva ewer ekep ta ttemperature s inth erang efro m1 3t o3 2° Can dpupa lscore swer ecompare d (Schooneveld& Wiebenga ,1974) . Lowtemperatur egav eclearl y lesspronounce deffec tbu tgreatl yextende dth esensitiv epe ­ riod.Hig htemperature sgav edramaticall ydecrease deffect san dreduce dth esensitiv estag e toonl y2 days ,eve ni fhig htemperature s lastedonl ya fe whour seac hda yi na regula r day/nighttemperatur eregime ,a sobtaine di nth efield .Th eresult sar ea sye tunexplaine d buton ewoul dexpec ttha tho tperiod si nth efiel dwoul db ea disadvantag e forsuc hcontrol .

Effect on adult emergence

Todetermin eth esignificanc eo fjuvenil ehormon eanalogue so npupation ,th efurthe r lifehistor yo ftreate danimal swa sfollowed .Ther ewa sa clea rrelatio nbetwee nth eef ­ fectso fcompound so npupatio nan dth econditio no fth eadult semergin g fromsuc hpupae . Pupaewit hscore so f1 an d2 usuall ygav eris et oexternall ynorma ladults .Adult sfro m pupaewit hscore so f3 ha dcrumple dwing san dmove dmuc h less.Thos efro mpupa ewit ha scoreo f4 neve remerged . 'Pupae'score d5 o rhighe rsometime smoulte donc eo rtwic emor e butneve rreache dadulthood . Adultemergenc ewa sreduce ddramaticall ywhe ntreatmen twa spostpone dunti lth esecon d halfo fth efift hinstar ,i.e .whe nn ovisibl eeffect so npupatio nwer eobtained .Treat ­ ment 1t o2 day sbefor epupatio nprevente dalmos tal lmoth sfro memergenc e (Fig.1) . The 'criticalperiod 'wa sthu sextende dconsiderably .

246 Mortality ( %) 100-1 __—* O O IGR-1 IGR-2

80-

1 1 T T 6 8 10 12 ,14 Time after last larval moult (days) Fig. 1.Mortalit ybefor eo rdurin gadul tecdysi safte rtreatin glast-insta rlarva eo rpupa e aton eo fth eindicate d intervalswit h5 U go fIGR- 1o r0.0 5u go fIGR-2 .Arro windicate s pupation.

Effect on behaviour

Preliminaryexperiment sindicate dtha ttreatmen tinfluence dtw oaspect so fbehaviour . Fifth-instarlarva efeedin go nbea nplant sspraye dwit ha hig hconcentratio no fIGR- 3fel l fromth eplan tmor eofte ntha nlarva eo nplant sspraye dwit hlowe rdoses .Whe nthes efalle n larvaewer ecollecte dan dfe do nuntreate dartificia ldiet ,a positiv ecorrelatio nwa sfoun d betweenth emorphogeneti ceffec ta tpupatio nan dth eincidenc eo ffalling .S olocomotio ni n larvamigh tb eimpede db yth ecompounds . Spontaneousmovemen to fmoth swa svisibl y lesswhe nth epupa efro mwhic hthe yemerge d showedonl ymino rjuvenil echaracteristics .Normall ymal emoth sreacte dt osyntheti cse x pheromonewit ha displa yo fwin gmovement .Pheromon ea ta concentratio ntha twoul dnormall y activatenearl yal lmale sactivate dfewe rmale sth emor eo fa compoun dha dbee napplie dt o thelarvae .Onl ya fe wmale sfro mpupa eo fscore s 1o r2 reacted ,wherea sth eduratio no f theactivit ywa sless . Eacho fthes eeffect so nbehaviou rma yreduc echance so fsurviva lan dreproduction .

Effect on reproduction

Mothsfro mtreate dpupa ewer e lessfecund ;severa linduce dabnormalitie saccentuate d thateffec t (Schooneveld& Abdallah ,1975) . Insom eindividuals ,th eovarie slooke dabnor ­ mala tecdysis . Insom efemales ,nurs ecell san doocyte sdevelope dirregularl yan doocyte sdegenerate d earlyo rlate rdurin googenesis .I nothers ,eg gmaturatio nwa sslowe ddow nan dovipositio n wasretarde dbu tmatin gwit hnorma lmale sremaine dpossible ,althoug hth efrequenc ywa sre ­ duced.Treatmen to fth eadult sdi dno tdistur breproductio no rfertilit yo fth eeggs .Non e

247 Table 1.Relationshi pbetwee ndegre eo fpupa l juvenilization (scores)an dnumbe r ofoff ­ springsfro mth eresultin gmoths .

Pupal scores Relative number of offspi ring <{ ? IGR-1 IGR-2

untreated untreated 1001 1001 0 0 99 1 1 4 16 2 2 0 0 untreated 0 51 103 untreated 1 26 14 untreated 2 0 8 0 untreated 90 138 1 untreated 21 56 2 untreated 7 20

1.Referenc evalu e 100%fo runtreate dse x partnerskep ta sisolate dpairs .

ofth ecompound steste dha da hig hovicida lactio nwhe napplie ddirectl yt obatche so feggs . Factorscontributin gt oth enumbe ro foffsprin gar emating ,fertilizatio no feggs ,an d numbero fegg smature dan ddeposite d (Table 1).Eac ho fthes efactor swa saffecte dafte r larvaewer etreate dwit hth ecompounds .Mal esexua lbehaviou rwa smor einhibite dtha n femaleresponsiveness .Analyse swer emad eb ystudyin gseparat ecouple si nwhic hnone , oneo rbot hpartner swer etreated .Th enumbe ro foffsprin gwa sreduce dt o16 4o fnorma l ifbot hpartner so ronl yth emal eoriginate d frompupa escore d 1,i.e .showe dbarel y visibleaberration .Adult s frompupa escore d2 o rmor edi dno treproduc ea tall .I nth e field,the ywoul dno tcontribut et opopulatio nincreases . Thesefinding sindicat etha tvisibl esign so fjuvenilizatio nreflec tdevelopmenta lanom ­ alieso fmuc hgreate rimpac ttha nha dbee nrealized .

Conclusions and prospects

Thedevelopmenta lstag edurin gwhic h A. orana inth efiel dma yb ereache dan daffecte d byjuvenil ehormon eanalogue si srestricte dt oth e5th-insta rlarva .Younge rlarva ear e notaffected ;pupa ear ewel lhidde nan ddifficul tt oreac hwit hsprays ;adult sar einsen ­ sitivean dpossibl yto omobile ;egg sar ehardl yaffected .Hormona ldisturbance scaus evisi ­ bleaberration si nth epupa lo rimagina iinstar ,dependin go nth etimin go fth eapplication . Larvaei nth efiel dar eno tstrictl ysynchronized ,s ofo rcontro lw enee da compoun dtha t issufficientl ypersisten to nth etre et odisrup tdevelopmen to fbot hfas tan dslowl ydevel ­ opingindividuals ,a sdoe s IGR-3.Smal loutdoo rtrial swit hIGR- 3hav edemonstrate dit s potentialfo rcontro lo f A. orana (Schoonevelde tal. , 1976).

248 REFERENCES

Abdallah M.D., 1972.Juvenil e hormone morphogenetic activity of sesquiterpenoids and non- -sesquiterpenoids in last stage larvae of Adoxophyes orana (Lepidoptera: Tortricidae). Entomologia exp. appl. 15 :411-416 . Schooneveld H. &M.D .Abdallah , 1975.Effect s of insect growth regulators with juvenile hormone activity on metamorphosis, reproduction, and egg fertility of Adoxophyes orana. J. econ. Ent. 68 :529-533 . Schooneveld H., J.P.va n der Molen &J . Wiebenga, 1976.Potentia l use of insect growth reg­ ulators for controlling Adoxophyes orana: laboratory and small-plot field studies.En ­ tomologia exp. appl. 19 :227-234 . Schooneveld H. & J. Wiebenga, 1974.Temperature-dependen t juvenile hormone effects on pu­ pation of Adoxophyes orana.J . econ.Ent . 67 :711-715 .

249 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 8.4 Use of the insect growth regulator, epofenonane, in integrated control in orchards

J.P.va nde rMole n &P .Gruys 1

DeSchuilenbur g experimentalorchard ,Lienden ,th eNetherlands .

INTRODUCTION

Inorchard si nth eNetherlands , Adoxophyes orana isfeare da sa pes tbecaus eth eexten t ofoutbreak si sunpredictable .Th elarvae ,hidin gagains tleave sattache db ya we bt o fruits,ma ydamag esevera ltenth so fa nappl ecro pi nJul yand ,t oa lesse rdegree ,agai n duringth esecon dgeneratio no fth etortrici d inSeptember .Wit hroutin echemica lcontrol , outbreakso f A. orana canb esevere .Althoug hbeneficia linsect ssee mt osuppres sthes e outbreakst osom eextent ,directe dchemica lcontro lseem sindispensabl e (Sections 1.3an d 1.8). Theinsecticide stha thav eprove nhighl ysuccessfu lagains t A. orana, sucha sazinfos - -methyl,methidathion ,an drecentl ycertai nsyntheti cpyrethroids ,ar eunselectiv ean dno t suitedt ointegrate dcontrol .O fth eapprove dselectiv ecaterpilla r insecticides,diflu - benzuroni sno teffectiv eagains t A. orana, and Bacillus thuringiensis notsufficientl y reliable (Sections 1.1 and9.1) .Sinc elaborator yan dsmal lfiel dtrial sshowe dth eeffec ­ tivenesso fcertai ninsec tgrowt hregulators ,juvenil ehormon eanalogues ,i ncontro lo f A. orana (Section8.3) ,th eusefulnes s forintegrate dcontro lo fth emos tpromisin go fthese , epofenonane,wa steste do na larg escale . Threequestion swer eraised : -Give nth efac ttha tonl yfifth-insta rlarva ear esusceptibl et othi sinsecticide ,ca n sufficientcontro lb eachieved ? -Wil lothe rnoxiou sinsect sb econtrolle da tth esam etime ? - Isth eus eo fepofenonan ecompatibl ewit hbiologica lcontro lo fothe rpests ,i nparticu ­ lar Panonychus ulmi'? Thoughi ti sth efift hinsta rtha ti ssusceptibl et oepofenonane ,i.e .a perio di nth e lifecycl eafte rth ecaterpilla rha sdamage dth eplant ,thi sinsecticid ema ysuccee di n controllingcaterpillars .Howeve rth erational eo fcontro li sdifferen tfro mtha tfo rcon ­ ventionalinsecticides . Afterhibernatio ni nthei rsecon do rthir dinstar ,th elarva eo f A. orana feedo nth e youngfoliag ei nApri lan dMa ywithou tcausin geconomi cdamag ea tth edensitie soccurrin g atthi stime .I fth epopulatio ncoul db ereduce dt osuc ha degre ebefor eth enex tharmfu l

1.Presen taddress :Researc hInstitut efo rNatur eManagement ,Arnhem ,th eNetherlands .

251 generationtha ti tcoul dno tris et oa harmfu l levelwithi nth esam eyear ,an di fimmigra ­ tiono fmoth swer eunimportant ,acceptabl econtro lwoul db eachieved .Thi swa sth eapproac h inou rtrials .Conventiona lcontac tinsecticide sar eno tparticularl ysuccessfu lagains t A. ovana whenapplie di nspring ;the yare ,however ,effectiv ewhe nuse da thatchin go fth e eggso fth efirs tan dsecon dgeneratio no fth eyea ri nJun ean dAugust .

METHOD

Wecompare dth edevelopmen to f A. ovana andothe rinsect si nentir eappl eorchard streat ­ edwit hAC R201 9E an duntreate dorchards .Swis scolleague sorganize dparalle ltrials . ACR201 9E contain sa mixtur eo f 6,7-epoxy-3-ethyl-1-(p-ethyl-phenoxy)-7-methylnonane and6,7-epoxy-1-(p-ethylphenoxy)-3,4,7-trimethylnonane(epofenonane) .I fdirecte dagains t A. ovana, itwa sapplie dtwic ebetwee nearl yan dful lbloom ,whe nabou t3 0an d90 1o fth e larvaewer ei nthei r5t hinstar .I faime dagains tothe rtortricids ,aphid san d Lepidosaphes ulnri, sprayingdate swer eadapte dt oth ephenolog yo fthes einsects .Dosage srange dfro m 0.6 to1. 5k ga.i .pe rhectare . Theeffec to fth espray swa sassesse dwit hindividua l A. ovana aswel la sb ydevelopmen t ofth epopulation .Larva eo f A. ovana wereeithe rcollecte dafte rsprayin gan dreare di n thelaborator yo nuntreate dartificia ldie to rtreate dfoliag eo rkep ti ngauz ebag si n theirnatura lpositio no nth etree san dexamine dabou ttw oweek safte rspraying .Th emorpho - geneticeffect swer escore da si nlaborator ytest s (Section8.3) . Toascertai nth einfluenc eo fth espray so nth epopulatio no f A. ovana, relativedensi ­ tieso fth elarva ewer edetermined ,i nsample so fblosso mi nsprin gan do fshoot si nsum ­ mer.Absolut edensities ,expresse da slarva epe rtree ,wer esometime sassesse di norde r toestimat eth emultiplicatio nfacto rfro mth etreate dgeneratio nt oth enex tone . Inon eo fth eorchard si nwhic hbiologica lcontro lo f Panonyahus ulmi wasfunctioning , theeffec to fth eepofenonan espray so nth espide rmite-predato rrelationshi pwa sassessed .

EFFECTO NADOXOPHYE SORAN A

Thedelaye dactio no fepofenonan emad ei tdifficul tt oasses sit seffec ti nth efield , onth eindividua linsect san do nth epopulation . Whenlarva ecollecte di nth efiel d 1-3week safte rtreatmen twer ereare do nuntreate d artificialdiet ,th eeffec twa sunderestimated ;bu twhe nthe ywer ekep to ntreate dfoliage , itwa ssometime soverestimated .Larva eenclose di ngauz ebag so nth etree safte rtreatmen t presumablygiv eth emos treliabl eresults . Twospraying scause dmorphogeneti ceffects ,a sfoun di nth elaborator yi nal lo ralmos t allenclose dspecimens .The ydie deithe ra slarva eo rpupa eor ,i fthe ydi ddevelo pint o adults,the ydeposite dfe wviabl eeggs ,i fany .Th efina leffec to fpreventin ga nex tgener ­ ationwa sestimate da salmos tcomplete ;an dth egreate rpar to fth eeffec tseeme dt ob e duet oth efirs tspraying .Th esecon dsprayin gma yb esuperfluou sunde rcertai nweathe r conditionso rwhe nth edensit yo fth ehibernate d larvaei slow . Trapsbaite dwit hsyntheti cfemal epheromon eshowe dconsiderabl ysmalle rcatche si nsuf ­ ficientlyisolate dtes torchard stha ni nuntreate dareas .Catche si ntrap so nth eborder s

252 oftes tplot sneighbourin guntreate dcontrols ,however ,sugges ttha tre-immigratio nma y rapidlyneutraliz e theeffec ti fa sourc eo f A. orana isnearby . Insufficientl y isolatedorchards ,th eeffec to nth epopulation so ftreatment si nsprin g lastedthroughou tth esumme ran da satisfactor y levelo fcontro lwa sachieved ;damag eb y A. orana toth efruit sremaine dbelo wth eacceptabl elimit . Thetrial sar ebein gcontinue di nsom eorchard sseparate db yu pt o80 0m fromth enex t orchard,t oestimat eth edegre eo fisolatio nrequire dfo rthi scontro ltechniqu et ofunc ­ tionproperly .Th efirs tresult ssugges ttha tabou t10 0m ma yb esufficient .

EFFECTO NOTHE RTORTRICID S

Ptyaholoma lecheana, Hedya nubiferana, Archips podanus, Archips rosanus, Spilonota ooellana and Pandemis heparana mayincreas ei nnumber swit ha nintegrate dprogramm e insteado fcon ­ ventionalchemica lcontrol .Th efift hlarva linsta ro fth eforme rtw ospecies ,whic har e hardlyharmful ,coincide swit htha to f A. orana, andthe yar eabou ta ssusceptible .Hence , theyar econtrolle dwit hth espraying sdirecte dagains t A. orana. Thefift hinstar so fth e othertortricid smentioned ,whic har einjurious ,ar emor edisperse dove rMa yan dJune .Epo - fenonanespray sten dt oinduc ea normall yfunctionin gsupernumerar y larvalinsta ri nthes e species,thu sprotractin g thenoxiou sstage .Therefore ,th eusefulnes so fepofenonan et o controlothe rspecie so forchar dtortricid stha n A. orana isa sye tquestionable .

EFFECTO NOTHE RINSECT S

Aphidssuc ha s Rhopalosiphum insertion, Dysaphis plantaginea and Eriosoma lanigerum, and thecocci d Lepidosaphis ulmi arecontrolle dt oa larg ean dpossibl ysatisfactor ydegre ei f spraysar eproperl ytimed :earl ysprin gfo rth eaphid san dMay ,partiall ycoinciden twit h thespray sagains t A. orana, for L. ulmi. Thelate rsprayin gma yals oac tagains tth egeom - etrids Operophtera brumata and Chloroolystis rectangulata.

COMPATIBILITYWIT HBIOLOGICA LCONTRO L

Sprayso fepofenonan eapplie dfo rthre econsecutiv eyear st oa norchar di nwhic h Pano- nychus ulmi waskep ta ta lo wleve lb ypredator ymites ,mainl y Typhlodromus pyri, haveno t upsetth erelationshi po fspide rmit ean dpredator .Thi scorroborate sth eresult so flabo ­ ratorytest si nwhic hepofenonan ewa sno ttoxi ct opredator ymites .

CONCLUSIONAN DPROSPECT S

Theevidenc es ofa rsuggest stha tcontro lo f A. orana bysufficientl ypersisten tjuvenil e hormoneanalogue si spractical ,i fth eare atreate di ssufficientl y isolatedo rlarge .Al ­ thoughsevera linsect sfro mdifferen torder sar esusceptibl et oepofenonane ,separat espray ­ ingswoul dprobabl yb eneede dt oachiev esatisfactor ycontro lbecaus etimin gi ss ocritica l withthi sinsecticide . Sincecontro lo f A. orana andcertai nothe rinsect scoul db eincrease do rmaintaine d

253 aftersevera lyear sa ta hig hleve lwit hles singredient ,th etrial swit hepofenonan ear e beingcontinue da spar to flarge-scal etest so nintegrate dcontrol . Regrettably,epofenonan ewil lno tb emarkete da sa ninsecticid ebecaus eth eeconomi c prospectsar eno tfavourabl efo rthi sexpensiv echemical .Nevertheles sw econside ri tuse ­ fult ocontinu ethes etest sbecaus eeconomicall ymor epromisin gchemical swit ha nidentica l modeo factio nar ebein gdeveloped ,an dsimila rcomplication swil lb eassociate dwit hothe r controlagent sactin gwit hdelaye deffects ,a shav epheromone suse dfo rmal edisruption .

REFERENCE

Schmid,A. ,J.P .va nde rMolen ,W .Jucker ,M .Baggiolin i& Ph .Antonin , 1978.Th eus eo f insectgrowt hregulators ,analogue so fth ejuvenil ehormone ,agains tsumme rfrui ttor - trixmoth ,Adoxophye soran aan dothe rpests .Entomologi aexp .appl .2 4 :65-82 .

254 9 Micro-organisms, viruses and nematodes

Nematodes,fungi ,viruse san dth espore-formin gbacteriu m Bacillus thuringiensis were studieda spotentia lorganis mi nth ebiologica lan dintegrate dcontro lo fsom einsec tpests . Preparationso f B. thuringiensis gaveinsufficien tan dvariabl eresult sagains tth esumme r generationo f Adoxophyes orana, whereaspromisin gresult swer eobtaine di nth elaborator y (9.1). Infiel dtrials ,a nattractiv ereductio ni nfrui tdamag ewa sobserve dafte rapplica ­ tiono fth egranulosi san dnuclea rpolyhedrosi sviru so f Laspeyresia pomonella and A. orana. Thenuclea rpolyhedrosi sviruse so f A. orana and Mamestra brassicae wereno tcross - -infectives otha t M. brassicae couldno tb euse dt oproduc e A. orana nucleopolyhedrosis virus (9.2)a searlie rwor kha dsuggested .T odemonstrat eth edifference sbetwee nthes e virusesa ne wtoo li nth efor mo fa nanalysi so fth evira lDN Aafte rdigestio nb yrestric ­ tionenzyme swa sused .Thi smetho dwil lb ereliabl ea sa techniqu et oidentif yviruse san d virusisolate s (9.3). Studieso nth eus eo fth enematod e Neoaplectana carpocapsae are inprogres swit hemphasi s onth econtro lo f Synanthedon myopaeformis and Soiapteron tabaniformes (9.5).Th esignifi ­ canceo fsom ene wisolate so frhabditid swil lb estudied .A feasibilit ystud yha sstarte d onus eo f Entomophthora spp.i nth econtro lo faphid s (9.4).

255 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 9.1 Trials with Bacillus thuringiensis against lepidopterous pests

L.P.S.va nde rGees t& H.J.M .Wassink 1

Laboratoryo fExperimenta lEntomology ,Universit yo fAmsterdam ,th eNetherlands .

DESCRIPTIONAN DAI MO FTH ERESEARC H

Oneo fth emos teffectiv einsec tpathogen suse dfo rcontro lo finsec tpest si sundoub ­ tedlyth espore-formin gbacteriu m Bacillus thuringiensis. Itact smainl yb ymean so fth e S'-endotoxin, containedi na cellula rinclusio n (crystalo rparaspora lbody )forme dsimul ­ taneouslywit hth espore .Th e6'-endotoxi ni shighl yselectiv ean di sactiv eagains tlar ­ vaeo flepidopterou sinsects . Researcho nthi spathoge nstarte di nou rlaborator yi nth elat e1950 san dwa sa ttha t timepartl yi ncollaboratio nwit hth ePar kDepartmen to fth eMunicipalit yo fAmsterdam . Thiswor ksolve dth eregula rproble mo fth eten tcaterpilla r Malacosoma neustria inel m treesi npark san dalon gth estreet so fAmsterdam :commercia l B. thuringiensis formulations werea neffectiv emean so fcontro lan dhav ebee nuse di nth ecit ysinc eth eearl y1960 s (Vande rLaa n& Wassink ,1962) .Thes eformulation sreplac eothe rinsecticides ,i nparticu ­ larDerri spowder ,whic hofte ngav edifficulties ,fo rinstanc eb ykillin gfis hi nprivat e ponds. Laterresearc ho n B. thuringiensis inou rlaborator yha sbee nconcerne dwit hintegrate d controli norchard so rwit hmethod so fbiologica lassa yfo rstandardizatio no f B. thurin­ giensis preparations anddeterminatio no fthei reffectiveness . Thewor ko n B. thuringiensis withorchar dpest swa sconcentrate do nth eleaf-rolle r Adoxophyes orana, oneo fth eke ypest si norchards .I nfiel dtests ,tree s3- 4year sol d weretreate dwit hth efollowin gcommercia lpreparation so f B. thuringiensis: Dipel,Thuri - cideH Pan dBiotro l183 .Th efirs ttw oproduct scontai nth epoten tHD- 1 strain(Dulmage , 1970),Biotro l 183i sa nolde rproduc tan dmuc hles seffective .Som etreatment swit h B. thuringiensis werecombine dwit h lowdose so finsecticide s (azinphosmethy lan dtetrachlor - vinphos)t odetec tan ypossibl esynergisti caction .Th etreatment swer ei nsprin gagains t theoverwinterin ggeneratio nan dagains tth efirs tsumme rgeneratio no fth eyear . Inth elaboratory ,severa lfactor swer estudied ,suc ha stemperatur ean dultraviole t light.I naddition ,th eeffec to fchitinas ewa sstudied ,a si twa sreporte dtha tthi sen ­ zymeenhance sth eactio no f B. thuringiensis (Smirnoff& Valero ,1972) .Th ereactio no f

1.Presen taddress :Institut ed eZoologi aagricola ,Universida d Centrald eVenezuela ,Mara - cay,Venezuela .

2S7 A. orana wasals ostudie dafte ringestio no fth espore-crysta lcomple xb yfeedin glarva e onsuspension so fpur espores ,crystal so rcombinations ,a sther ewa ssom eevidenc etha t thisspecie scoul donl yb ekille db yth ecombine dactio no fspore san dcrystals ,a relati ­ velyrar ephenomeno ncalle dtyp eII Ireactio n (Heimpel& Angus ,19S9 ). Spore san dcrystal s wereobtaine dfro mth ecommercia lpreparatio nDipel .The ywer eseparate db ya flotatio n method,b ydensity-gradien tcentrifugatio no rb ykillin gth espore swit hradiatio no rlyso - zymetreatment . Anotheraspec to fth eresearc ho nthi spathoge nwa sth edevelopmen to fmethod so fbio ­ logicalassa yt otes tth eeffectivenes so fdifferen tpreparation so f B. thuringiensis. Thesetest swer emainl yo n Pieris brassioae (Vande rGees t& Wassink , 1972).B ya modifi ­ cationo ftha tmethod ,man yisolate so f B. thuringiensis ofsevera lserotype swer eteste d asa contributio nt oa ninternationa lprogra mo nth espectru mo factivit yo fdifferen t B. thuringiensis serotypesorganize db yth eUnite dState sDepartmen to fAgriculture .Severa l otherlaboratorie si nNort hAmerica ,Japa nan dEurop eparticipated .Th eprogra mallowe d studyo fth eactivit yo fman yisolate stoward sman yinsec tspecies ,includin g lepidopterous anddipterou s larvae.Mosquit olarva ewer estudied ,sinc erecen tinvestigation s showedac ­ tivityo fcertai nstrain so f B. thuringiensis. Iti sno tye tknown ,whethe rtha tactivit y wascause db yth eactio no fth e< 5'-endotoxi no rb yothe ractions .Othe rDipter awer ein ­ cludedi nth eprogra mt odetec tpossibl epresenc eo fothe rtoxin si nth epreparations ,suc h asß'-exotoxin .

RESULTSAN DDISCUSSIO N

Inth efirs tyea ro ffiel dtrials ,acceptabl econtro lwa sobtaine dagains tth esumme r generationo f A. orana insevera ltest swit hformulation sbase do nth eHD- 1strai no f B. thuringiensis. Itwa sno tpossibl et oobtai nsatisfactor ycontro l inth esprin go fover ­ winteringlarvae .N osynergisti ceffec twa sdetecte do f B. thuringiensis andlo wdose so f azinphosmethy lo rtetrachlorvinphos . Laterresult sagains tth efirs tsumme rgeneratio nwer equit evariabl ean di ncertai n yearsinsufficient ,eve nwhe ntreatment sar erepeate dever y 7-10days .Th elarva ewer e quitesusceptibl et o B. thuringiensis inlaborator yexperiments .Th edisappointin gresult s inth efiel dar eattribute dt oth ebehaviou ro flarvae ,whic har efo rmos to fthei rlif e hiddenunderneat hweb so rbetwee nfolde dleaves .The yca nonl yb ereache db yinsecticides , whenthe ymov et oothe rshelter .Insecticide swit ha contac tactio nar emor eeffectiv e againstthes emigratin g larvaetha ninsecticide swit ha stomac haction ,suc ha s B. thuring­ iensis. Controlo flarva ema yb eimprove db yincreasin gpersistenc eo fth einsecticides , forinstanc eb yaddin gsticker so rultraviole tprotectants ,suc ha sbenzy lcinnamate ,whic h provedeffectiv ei nth elaborator ya ta concentratio no f1 0g/1 .Th eactio no f B. thuring­ iensis couldno tb eimprove db yaddin gth eenzym echitinase . Anotherfacto ri nth eactio no f B. thuringiensis istemperature .A ttemperature so f1 5 C orless ,contro lwa smuc hpoorer ,unles ssi xtime sa smuc hwa sapplie da sa t2 2 C.How ­ everi nsprin gth einsecticid ehav ebee ndilute db yth erapi dgrowt ho ffoliag enotwith ­ standingth elo wtemperature sprevailin gi nth eNetherland s intha ttime . Inlaborator ytests , A. orana provedt obelon gt oth egrou po finsect swit hth etyp eI I

258 reaction (Heimpel& Angus ,1959 )afte ringestio no fth espore-crysta lcomplex .Th ecrystal s causedparalysi so fth ealimentar ytrac tsoo nafte ruptake .Deat hensue dafte rabou t4- 5 days.N ospore swer eneede dt okil lth einsect .Th emedia nletha ldos eo fcrystal sfo r 2nd-instarlarva ewa sabou t250 . Forth eInternationa lCooperativ eProgra mo nth espectru mo factivit ystudie so f B. thuringiensis serotypes,mor etha n30 0differen tisolate swer etested .Result s fromal l participantswil lb epublishe da sa Technica lBulleti no fth eUnite dState sDepartmen to f Agriculture.Subgroup swithi nserotype sdiffere di nreactio ntoward sdifferen tspecie so f insects,probabl yb ydifference si nth e6'-endotoxi ncomposition .Agains t P. brassicae, thehighes tproportio no factiv eisolate swer efoun di nth evariet y kurstaki (serotype 3a,b).A moderat eproportio no factiv eisolate swa sfoun dals oi nth evarietie s thuringien­ sis (serotype1 )an d alesti (serotype 3a).Mos to fth eothe rvarietie scomprise disolate s with lowtoxicity ,e.g . galleriae (serotype 5a,b), kenyae (serotype4a,c )an d aizawai (se­ rotype 7).Som eo fth eisolate steste di nth eprogra mwer efoun dt ob emor eeffectiv etha n theHD- 1strai npresentl y includedi nmos to fth epresen tcommercia lformulation san dwil l undoubtedlyb eexploite di nth efuture . Poorperformanc eo f B. thuringiensis, especiallyi nth espring ,ca nsometime sb eattri ­ butedt oth elo wtemperatures .I ti sno tknow nwhethe ran yo fth eisolate steste di nth e internationalprogra mperforme dbette ra tlo wtemperature stha nth eHD- 1strain . Bacillus thuringiensis isstil llittl euse di nth eNetherlands .I tha sbee nsuccessfull y usedagains t Malaoosoma neustria, Euproctis chrysorrhoea and Stilpnotia Salicis. Inexperi ­ mentalfields ,result shav ebee nvariabl eagains t A. orana and Operophthera brumata. Prepa­ rationsbase do nthi spathoge nhav ea potentia lus eagains tcabbag epests ,suc ha sth e highlysusceptibl eP . brassicae andth eles ssusceptibl e Mamestra brassicae. Undercertai n circumstances,the yca nals ob euse dfo rth econtro lo finsect ssuc ha s Ephestia spp.i n storedproducts .

SIGNIFICANCEFO RAGRICULTURA LPRACTIC E

Theselectivit yo finsecticide swit h B. thuringiensis asagen tmake sthi styp eo fprod ­ uctattractiv eagains tinsec tpests ,especiall yi nintegrate dcontro lan dwher eus eo f chemicaltoxin sshoul db eavoided ,a si nrecreationa lareas .I ti sdisappointin g thatgoo d controli sno tpossibl e forth emai nlepidopterou spest so fhorticultur ean dagricultur e bymean so f B. thuringiensis. Asa resul to fth einternationa lprogram ,mor eactiv eformu ­ lationso fthi sbacteriu mma yb emarkete di nth efuture .Ne wformulation sactiv ea tlowe r temperaturesar eneede dfo rsom epest si nth eNetherlands .

REFERENCES

Dulmage,H.T. ,1970 .Insecticida l activityo fHD-1 ,a ne wisolat eo fBacillu sthuringiensi s var. alesti.J .Invertebr .Pathol . 15: 232-239 . Geest,L.P.S .va nde r& H.J.M .Wassink , 1972.Standardizatio no fBacillu s thuringiensispre ­ parations:a ne wbioassa ymetho dwit hPieri sbrassica ea stes tinsect .J .Invertebr . Pathol. 19: 361-365 . Heimpel,A.M . &T.A .Angus ,1959 .Th esit eo factio no fcrystalliferou sbacteri ai nLepidop - teralarvae .J . Insect.Pathol . 1: 152-170 .

259 Laan, P.A. van der &H.J.M .Wassink , 1962. Control of tent caterpillars (Malacosoma neutria) with Bacillus thuringiensis in the city of Amsterdam. Tijdschr. PIZiekt. 68 :143-146 . Smirnoff,W.A . & J.R. Valero, 1972.Pertubation s métaboliques chez Choristoneura fumiferana Clemens au cours de l'infection par Bacillus thuringiensis seul ou en présence de chitinase. Revue can. Biol. 31 :163-169 .

260 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 9.2 Baculoviruses as agents in biological control

D.Peter s

Departmento fVirology ,Agricultura lUniversity ,Wageningen ,th eNetherlands .

Viruses,especiall yth ebaculoviruses ,whic hinfec tofte na smal lrang eo fspecies ,ma y offera mean so fselectiv epes tcontro li nagricultur ean dforestry .

ACTIVATIONO FLATEN TINFECTION SI NMAMESTR ABRASSICA EAN DADOXOPHYE SORAN A

Tous ebaculoviruse s incontro lo finsec tpests ,larg eamount so fviru sha st ob epro ­ ducedo na commercia lscal ean da tcost scomparabl ewit hthos eo finsecticides .Muc hre ­ searchi sdirecte dt odevelopin gtechnique st ogro winsect so na larg escal eo nchea par ­ tificialdiets .Th eus eo flarg einsect st oproduc ethes eviruse si son eapproach .Ponse n &D eJon g (1964)trie dt ous elarva eo fth ecabbag emot h Mamestra brassicae toproduc eth e nuclearpolyhedrosi sviru so fth esumme rfrui ttortri xmot h Adoxophyes orana. Larvaeinocu ­ latedwit hth eviru swen tdow nwit hnuclea rpolyhedrosis .Nuclea rpolyhedrosi sviruse scon ­ tainon e (single-embedded)o rmor e (multiple-embedded)nucleocapsid spe renvelope .Th eviru s of A. orana isa single-embedde dvirus .Howeve rn osingle-embedde dviruse swer efoun di nth e cross-inoculated M. brassicae butonl ya multiple-embedde don elik ethos eusuall yencounter ­ edi nnaturall ypolyhedrosis-disease d larvaeo f M. brassicae . Inback-inoculation so fthi s viruso f M. brassicae to A. orana larvae,single-embedde dviruse swer edetecte di nth edis ­ easedlarvae .Thes eobservation swer ereaso nfo ra mor ethoroug hstud yo nth erelation s ofth enuclea rpolyhedrosi sviruse soccurrin gi n M. brassicae and A. orana. Theresult so f Ponsen& D eJon gcoul db einterprete deithe ra sactivatio no flaten tinfection soccurrin g inbot hspecie so ra son eviru sdifferentl yenvelope db yth etw ohosts . Furtherstudie s (Jurkovicovä,1979 )confirme dtha tth etw oviruse swer esingl yan dmul ­ tiplyembedde dviruses .Th epolyhedr ao fthes eviruse sdiffere di nsiz ean dshape .Mos to f thepolyhedr ai n A. orana wereglobula ran drange di ndiamete rfro m1 t o2 um .Thos ei n M. brassicae havea hexagona lo rpentagona loutlin ean drange di ndiamete rfro m1. 5t o4 um . Oncompariso no fth epolyhedra lan dvira lprotein sb yPolyacrylamid e gelelectrophoresis , nocharacteristi cdifference swer edetected .Thes ecomparativ estudie sdi dno trevea lan y distinctionothe rtha nth ewa yth enucleocapsid swer eenveloped .T olear nmor eabou tth e virusesuse dan dproduce d inth ecross-inoculatio nexperiment sth eattentio nwa sno wdirect ­ edtoward sth enuclei cacid so fthes eviruses . Themolecula rweigh to fth ecircula rdouble-strande dnuclei cacid s (DNA)o fth eviruse s from A. orana and M. brassicae wasestimate dt ob e67x10 6 and89x10 6 fromlengt hmeasure -

261 mentso nelectro nmicrograph san dfro mreassociatio nkinetics .B yth elatte rtechnique ,n o homologywa sfoun dbetwee nth eDN Ao fthes eviruse swhe nassaye db ycompetitio nhybridiza ­ tion.Thes eDN Amolecule swer eals odifferentiate db yanalysi so fth efragment sobtaine db y digestiono fthes emolecule swit hrestrictio nendonucleas eEc oRI .Thi senzym egive sa frag ­ mentationpatter nspecifi cfo reac hDNA .N ofragment swit hth esam esiz ewer edetecte di n theDN Adigest so fth etw oviruses .Th eDN Ao fth etw oviruse sdiffere dals oi nthei rbuoyan t densityi nCsC 1 solution,indicativ eo fdifference si nbas ecomposition .Th econten to f guanineplu scytosin ecalculate dfro mbuoyan tdensit yo fth eDN Ao fth etw oviruse swa s consistentwit htha tderive dfro mtherma ldenaturation .Al lthes eresult sindicat etha tth e twoviruse sar edifferen tentitie stha tca neasil yb edistinguishe db yth epropertie so f theirgenomes . Inparticular ,analysi so fth eDN Afragment sfro mdigestio nwit hrestrictio nenzyme s givesirrefutabl eanswers .Thi stechniqu ewa suse dt oanalys eth eviru sfro mcross-inocula ­ tionexperiments .Larva eo f A. orana and M. brassiaae wereeac hinoculate dwit hviru sfro m theothe rspecies .Th enumbe ro flarva econtainin gpolyhedr awa ssignificantl yhighe rfo r thecross-inoculate dgrou ptha nfo rth euninoculate dgroup .DN Awa sisolate dfro mth epoly ­ hedrao fcross-inoculate dlarva ean dcompare dwit hDN Afro mviru suse da sinoculum .Th e DNAfragmentatio npatter no fth eviru sisolate dfro mcross-inoculate dlarva ewa sidentica l withtha to fth eviru snaturall yoccurrin gi ntha thost .S oth eviru so f A. orana andM. brassiaae areno tcross-infective . Latentinfection swer edemonstrate db yth epresenc eo fvira lDN Ai nseemingl yhealth y larvae.DN Awa sextracte dfro mlarva egrow nfro msurface-sterilize degg san dwa sanalyse d byreassociatio nwit hvira lDNA .Abou t 2.5vira lDN Acopie swer edetecte dpe rdiploi dhos t genomeo f M. brassiaae. Theamoun to fvira lDN Ai n A. orana wasmuc hless .Ever ycop yo f hostgenom econtaine d0.0 4cop yo fvira lDNA . Themortalit yrat eo flarva ewa smuc hlowe ri nthes eexperiment stha nfoun db yPonse n &D eJong ,wh onotice dtha t8 0t o90° so fth epopulatio ndie dafte rcross-inoculation .Thi s differencei nmortalit ywoul db edu et oth emor esteril econdition sw euse di nou rlabora ­ toryfo rth erearin go fth einsects . Toexplai nlaten tinfections ,th eviru sha st ob etransmitte dt oth eprogeny .Thi strans ­ missionfro mgeneratio nt ogeneratio nma ytak eplac ei ntw oways .Th eviru sma yb etrans ­ mitteda tth esurfac eo fth eeg gan dwithi nth eeg gitself .Polyhedr awer edetecte di nlar ­ vaegrow nfro msurface-sterilize degg sa swel la sfro muntreate deggs .Mor elarva ewit h polyhedrawer efoun di nth esecon dgroup ,indicatin gtha tbot hmode so ftransmissio noccur . Asshown ,th eviruse so f A. orana and M. brassiaae aredifferen ttype stha tcanno tin ­ fectth eothe rhost .Symptom sobserve dafte rcross-inoculatio nar eprobabl ydu et oactiva ­ tiono flaten tinfections ,whic hpresumabl yoccu rmor ei nfiel dtha ni npopulation smain ­ tainedfo ra lon gtim ei nth elaboratory .Uncontrolle doutbreak so fpolyhedrosi s infiel d andlaborator ypopulation sca nb eexplaine db yth espontaneou sactivatio no flaten tinfec ­ tions.

262 BIOLOGICALCONTRO LWIT HVIRUSE S

Recentlya smal lprogra mwa sinitiate dt ostud yth eeffect so ftw obaculoviruse s inth e controlo ftw omoth si nDutc horchards .Experiment swer ewit hth egranulosi sviru so fth e codlingmoth , Laspeyresia pomonella in197 7an d1978 ,an dwit hth enuclea rpolyhedrosi s viruso fth esumme rfrui ttortri xmot h Adoxophyes ovana in1978 .I nth esumme ro f1977 ,2 and3 spray so f L. pomonella viruswer eapplie di ndifferen tplot sa tdose so fabou t5.10 10 granulespe rtree .Bot hschedule so fsprayin greduce ddamag eb yth ecodlin gmot hb yabou t 75%,wit hmos to fth eapple shavin ga stoppe dentry .Insecticid etreatment sgav ea reductio n by95% . Inth econtro lplots ,19 %o fth eapple swer edamage deithe rb ysuperficia lo rdee p bores.Bette rresult swer eobtaine di nth esumme ro f1978 .Th enumbe ro fmoth swa slow ,prob ­ ablybecaus eo fth ecoo lseason .Onl y 2.5-3.8%o fth eapple si nth econtro lplot swer eaf ­ fectedb yth ecodlin gmot han d7 %b yth efrui ttortrix . Attempswer emad ei n197 8t oestimat eth epopulatio no fth ecodlin gmot han dth efrui t tortrixb ysamplin gdiapausin g larvae.Th efe wspecimen s foundan dthei rdistributio ndi d notallo wan yconclusion .Th eactivit yo fth etw oviruse swa schecke db ybiologica lassay s duringbot hseasons .I n197 7th eviru sfro m L. pomonella wascompletel yinactivate di n abouttw oweeks .I n1978 ,th einactivatio nwa smuc hslower ,bot hviruse sshowin ga dro pi n activityb yhal fove rthre eweeks .Thi sdifferenc ei nrat eo finactivatio nwa sprobabl y duet oth edifferenc ei nduratio no fsunshin ei n197 7an d1978 . Theresult sencourag econtinuanc eo fth estudies .Th eeffect so fth emixtur eo fviruse s onth ecodlin gmot hwil lreceiv eattention .

REFERENCES

Jurkovicovä,II. ,1980 .Activatio no flaten tviru sinfection s inlarva eo fAdoxophye soran a (Lepidoptera:Tortricidae )an do fBarathr abrassica e (Lepidoptera:Noctuidae )b yforeig n polyhedra.J .Invertebr .Pathol , (inpress) . Jurkovicovä,11 .& J.H.va nTouw , 1979.Som epropertie so f thegenom eo fAdoxophye soran a (Lepidoptera:Tortricidae )an do fBarathr abrassica e (Lepidotera:Noctuidae) .Insec t Biochem.9 :425-428 . Jurkovicovä,M. ,J.H .va nTouw ,J.S .Sussenbac h 8. J. terSchegget ,1979 .Characterizatio no f thenuclea rpolyhedrosi sviru sDN Ao fAdoxophye soran aan do fBarathr abrassicae .Viro ­ logy93 :8-19 . Ponsen,M.B .& D.J . deJong ,1964 .O na nuclea ran dcytoplasmi cpolyhedrosi so fAdoxophye s orana.Entomophag a9 : 253-255 .

263 Integrated control of insect -pests in the Netherlands. Pudoc, Wageningen, 1980. 9.3 Restriction endonucleases: a new tool in baculovirus identification

J.M.Vla k

Departmento fVirology ,Agricultura lUniversity ,Wageningen ,th eNetherlands .

INTRODUCTION

Nuclearpolyhedrosi sviruse s (NPV)an dgranulosi sviruse sfor ma grou po fviruse s (baculoviruses)tha tar epathogeni c forinvertebrates ,mainl yinsects .Thes eviruse sar e naturalenemie so finsect san dthe yca nreduc eth epopulatio ndensit yo finsect sb yepi ­ zootics.Amon ginsects ,hos trange so fbaculoviruse sar eofte nlimite di norders ,familie s oreve nspecies .Th ehig hspecificit yan dnatura loccurrenc emak ethes eviruse ssuitabl e forcontro lo finsec tpest swithou tcreatin gheav yburde no nth eenvironment .Th ebaculo ­ viruseshav ebee npromote db yth eWorl dHealt hOrganizatio n (WHO)an dFoo dan dAgricultur e Organization (FAO)a sgoo dalternative st ochemica lpesticide s inbiologica lpes tcontro l (WHO/FAO,1973) .

AIMO FINVESTIGATION S

Inusin gthes ebaculoviruse s innature ,i ti sa prerequisit et oestablis hunequivocall y theidentit yo fth eviru sbefor ean dafte rfiel duse .Fo rexample ,i nstudie st odetermin e hostranges ,on emus tsho wwhethe rth eviru suse dha dcause dvirosi s ina targe thos to r hadprovoke da hithert olaten tinfectio ngivin gris et odisease .Severa ltechnique sar e availablefo rviru sidentification ,bu tthe yal lar ei nthemselve sunsatisfactor yfo rune ­ quivocalidentification .I ti sdifficul tt oidentif yth eviru so nth ebasi so fit shos t range,sinc edifferen tviruse sca nhav esimila rhos tranges .Moreover ,th ebiologica lassay s areparticularl y laboriousan dtime-consuming .Serologica l techniquesgiv eonl yindication s ast oth enatur eo fth evirus ,becaus eman yviruse sreac tpositivel ywit hheterologou san - tisera.Howeve rserolog y isno won eo fth emos trapi dan dsensitiv etechnique s forviru s identification.Analysi so fvira lprotein so nPolyacrylamid e gelsi semergin ga sa too lfo r identificationbut ,becaus eo fth epresenc eo fproteolyti cactivit yi nvira lpreparations , isles sattractive .Therefore ,a nurgen tnee dremain sfo ra reliabl ean dsensitiv emetho d toidentif ybaculoviruse sb ystabl echaracteristics .W ehop et omee tthes erequirement sb y usingrestrictio nendonucleas eanalysi so fvira lnuclei cacids .

265 TOOLS

Baculovirusesar erod-shape dan dconsis to fenvelope dnucleocapsid scontainin g deoxyribonucleicaci d (DNA)a sgeneti celement .Man yviru sparticles ,singl yo ri nbundles , aresurrounde db ya protei nmatri xgivin ga fina lstructur eo f0. 3 to1 5y mdiamete rtha t ispolyhedra lo rgranula ri nshape .Baculoviruse scontai na circular ,double-strande dDN A moleculei nth efor mo fa superhelix .Recently ,bacteria lenzyme shav ebee nfoun dtha tre ­ cognizean dcleav edouble-strande dDN Aa tspecifi cnucleotid esequence s (Roberts,1976) . Eacho fthes e 'restrictionendonucleases 'will ,therefore ,generat ea se to fDN Afragment s thati suniqu efo ra give nvirus .Restrictio nendonuclease sEc oR I (from Escherichia coli BS5),Ba mH I (from Bacillus amyloliquefaciens H)an dSm aI (fro m Serratia marcescens S,) havebee nuse di nthi sstud yo nth eidentificatio no fth enuclea rpolyhedrosi sviruse so f thealfalf aloope r Autographa californica (AcNPV), th ecabbag emot h Marriestra (Barathra) brassicae (MbNPV)an dth efal larmywor m Spodoptera frugiperda (SfNPV).Fragment so fDNA , generatedafte rcleavag eo fvira lDNA ,wer eanalyse db yelectrophoresi so nagaros egel s andwer enumbere dalphabeticall ystartin gwit hA forth elarges tfragment .Th emolecula r weighto fth efragment si sexpresse di nmegadalton s (10G daltons).

BACULOVIRUSIDENTIFICATIO N

Thefragmentatio npatter no fSfNP VDN Adigeste dwit hEc oR Iwa suniqu efo rSfNPV ,an d wascompletel ydifferen tfro mth eEc oR Icleavag epatter no fMbNP VDN Aan dAcNP VDN A(Fig . 1). Fragmentswit hcommo nelectrophoreti cmobilitie swer erarel yfound ,suggestin gtha t therei sonl ylimite dhomolog ybetwee nthes ebaculoviruses .Simila rresult swer eobtaine d whenthes evira lDNA swer etreate dwit hothe rrestrictio nendonuclease ssuc ha sSm aI an d BamHI .Th eDN Afragment sgenerate db yth eenzymati cdegradatio nirrefutabl yidentif yeac h ofth ethre eviruses .Th eapparen tdifferen tmake-u po fnucleotid esequence si sals ore ­ flectedb yth elarg enumbe ro fbiologica ldifference sbetwee nthes eviruses ,fo rinstanc e inmorphology ,hos trang ean dbiologica lactivity . Fromth ecabbag emot h M. brassicae, twoNP Visolate swer eobtaine dan dcompared .On e isolatewa sfoun dnea rRhene ni nth eNetherland s (MbNPV ),th eothe rnea rDarmstad ti n Germany (MbNPV ). Theirbiologica lan dbiochemica lpropertie sappeare dt ob esimilar ,i f notidentical .Afte ranalysi so fthei rDN Awit hrestrictio nendonucleas eBa mHI ,Ec oR Ian d SmaI th etw oviru sisolate swer edifferentiate db yth epresenc eo funiqu eDN Afragment s (Fig. 2).Howeve rth etw otype so fDN Aals oshar eman yfragment swit hth esam eelectropho ­ reticmobilit yi ngel ssuggestin ga larg edegre eo fsequenc ehomology .Th esimilarit yi n biologicalpropertie so fth eNP Vi sa reflexio no fthi shomolog yan dthes etw oviruse s shouldb econsidere da sstrain srathe rtha ndifferen ttype so fvirus .Sinc eMbNP Vappear s tob ea facto rlimitin gth epopulatio no f M. brassicae inth efield ,th eDepartmen to f Virologyplan st orelat eth eregiona ldistributio no fothe risolate so fMbNP Vwit hth edi ­ vergenceo fDN Asequenc ean dbiologica lpropertie s (Vlak& Gröner ,1980) .

266 Sf Mb Ac Mol.wt/106

•2 0 •10

DC E

P Q

EcoR I EcoR I EcoR I

Fig. 1.Schem eo fdeoxyribonuclei c acid (DNA)fro m Spodoptera frugiperda (Sf)nuclea r polyhedrosisvirus (NPV), Mamestva brassicae (Mb)NP VDN Aan d Autographa californioa (Ac)NP V DNAdigeste dwit hendonucleas eEc oRI .Th eDN Afragment swer eseparate db y sizeelectropho - retically inagaros ege lo fconcentratio n inwate r 10g/ 1an dwer estaine dwit hethidiu m bromide.

FURTHERCHARACTERIZATIO NO FBACULOVIRU SDN A

DNAo fth eNP Vfro mth ealfalf aloope r A. californica, alepidoptera nendogenou si nAme ­ rica,wa sstudie di nmor edetail .Thi sAcNP Vca nb emultiplie di nestablishe dinsec tcel l lineso fsevera lspecies ,an dit sbiolog yi sth ebes tstudie do fal lbaculoviruses .Th eDN A was isolatedfro mextracellula rvirion sa scovalentl yclosed ,double-strande dmolecules . Thesubstanc e (mole)fractio no fguanin eplu scytosin ei nAcNP VDN Awa sestimate d fromit s buoyantdensit yi nCsC lan dit smeltin gpoin tt ob eabou t0.427 .Fro mvelocit ysedimentatio n inalkalin ean dneutra lsucros egradients ,a molecula rweigh to fabou t8 0x TO6wa scalcu ­ latedfo rAcNP VDN A (Vlak& Odink ,1979) .

267 3 ^•o Q -D 3

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268 Afterdigestio no fAcNP VDN Awit hBa mHI ,seve nfragment swer egenerate dan dseparate d byelectrophoresi s (Fig. 3).Th emolecula rweigh to fth efragment srange dfro m5 5x 10 6fo r BamHI- At o0.6 9x 106dalton sfo rBa mHI-G .AcNP VDN Awa scleave db ySm aI int ofou rfrag ­ mentsrangin gi nsiz efro m4 7x 10 6fo rfragmen tSm aI- At o9 x 10G forSm aI-D .Twenty-on e fragmentswer egenerate db ydigestio no fAcNPV-DN Awit hEc oRI ,wit hmolecula rweight srang ­ ingfro m9. 3x 10 6fo rEc oRI- At o0.6 5x 106fo rEc oRI- R (Fig. 3).Mos tfragment swer e presenti nequimola ramounts .I nsom ecases ,however ,tw o (EcoRI-B ,Ec oRI- Kan dEc oRI-P ) orthre e (EcoRI-E )fragment so fsimila rsize ,bu twit hdifferen tnucleotid esequence swer e detected (indicatedb ythicke rlines) .B ysummatio no fth emolecula rweight so fth efragments , generatedb yeac ho fthes erestrictio nendonucleases ,a molecula rweigh to fabou t8 2x 10 6 wasdeduce dfo rAcNP VDNA .A tpresent ,I a mconstructin ga ma pwit hth ephysica lorde ro f theBa mHI ,Ec oR Ian dSm aI fragments .

Autographa californica NPV-DNA

Mol.wt/106

20 10

Bam HI Sma I EcoR I Fig.3 .Schem eo fdeoxyribonuclei c acid (DNA)fro m Autographa californica nuclearpolyhe - drosisviru s (NPV)digeste dwit hBa mHI ,Sm aI an dEc oRI .Th eDN Afragment swer eseparate d bysiz eelectrophoreticall y inagaros ege lo fconcentratio n 10g/ 1an dwer estaine dwit h ethidiumbromide .

269 Analysiso fAcNP VDN Awit hEc oR I (Fig.3 )als oreveale dth epresenc eo ftw omino rfrag ­ ments (EcoRI- Han dEc oRI-J ,dotte d lines).Vira lDN Ao fclone so fAcNP Vtha twer eselecte d byplaqu eassay so ninsec tcells ,lacke dthes etw omino rfragments .Thi sresul tma yindicat e thatth eorigina lisolat eo fAcNP Vcoul db econsidere da sa populatio no fdifferen tbu tre ­ latedviruses .Thi sheterogeneit yha sno tye tbee ncorrelate dwit hbiologica lproperties .I f heterogeneity isa mor egenera lphenomenon ,i tma ypla ya rol ei nth emaintenanc eo fthes e baculoviruses innatur ean dthei radaptatio nt onon-targe tinsects .Thi sshoul db ea matte r ofconcer nwhe nunclone dviru si sapplie dt ocontro linsec tpests .

CONCLUDINGREMARK S

Restrictionendonucleas eanalysi so fDN Ai sa usefu lprocedur et odiscriminat ebetwee n nuclearpolyhedrosi sviruse san dprobabl yals ogranulosi sviruse soccurrin gi nnature ,an d addsa ne wtechniqu efo ridentifyin gbaculoviruses .Th esensitivit yo fth emetho dbase do n recognitiono fnucleotid esequence si shig han dmeet sth erequirement sfo ra nunequivoca l identificationo fbaculoviruses .Eve nsubtl edifference sbetwee nstrain sca nb edetected . Geneticchange si nth eviru swhe nexpose dt onatur eca nno wb eaccuratel ymonitore dwit h thisenzymi canalysi so fDNA .Othe rrestrictio nendonuclease stha nthos ementione dma yb e usefulto oi nbaculoviru sidentification .Studie so nth emolecula rbiolog yo fbaculoviruse s aspresente dher ema ycontribut et oth esafe rus eo fthes eviruse si ncontro lo finsec t pests.

REFERENCES

Roberts,R.J . 1976.Restrictio nendonucleases .Critica lReview s inBiochemistr y (Chemical RubberCompany )4 :123-164 . Vlak,J.M . &A .Gröner , 1980.Identificatio no ftw onuclea rpolyhedrosi sviruse sfro mth e cabbagemoth ,Mamestr abrassica e (L.)(Lepidoptera :Noctuidae) .J . Invertebr.Pathol .3 5 (inpress ). Vlak,J.M . &K.G .Odink ,1979 .Th estructur eo fAutograph acalifornic anuclea rpolyhedrosi s virusdeoxyribonuclei c acid.J .gen .Virol .4 4 :333-347 . WHO/FAO, 1973.Th eus eo fviruse sfo rth econtro lo finsec tpest san ddiseas evectors . TechnicalRepor tSerie sNo .531/FA OAgricultura l StudiesNo .91 .WHO ,Geneva .4 8p .

270 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980.

9.4 Control of aphids with insect pathogens

L.P.S.va nde rGees t (1),R.A .Samso n (2) &H.J.M .Wassink 1 (1)

1Laborator yo fExperimenta lEntomology ,Universit y ofAmsterdam ,th eNetherland s 2Centra lBurea uo fFunga lCultures ,Baarn ,th eNetherlands .

DESCRIPTIONO FTH EPROBLE M

Aphidsar eseriou spest si na variet yo fagricultura lcrops ,eithe rb ythei rmer epres ­ encei nvas tnumber so rb ythei rabilit yt otransmi tplan tviruses .Ther ei sconsiderabl e economiclos si ncrop ssuc ha spotat oan dsugar-beet ,wher e Myzus persicae actsa sth e vectort osevera lviru sdiseases .Eve na ver ylo wpopulatio ndensit yo f M. persicae early inth eyea rma ycaus egrea teconomi clos st oa sugar-bee tcro pb yviru stransmission . Aphidshav ebee ncontrolle dfo rman yyear swit hchemica linsecticides .Recentl yth eus e ofchemical sagains taphid sha sincrease dtremendously ,a scontro lo faphid si ncereal sha s beenfoun dt oincreas eyields .Thi sincrease dus eo fchemical s isundesirabl efo rth eenvi ­ ronment,especiall ysinc ecereal sar egrow nove rwid eareas .Resistanc et ochemica linsec ­ ticideshav ebee nreporte dfro msevera lplaces .Contro lmethod sothe rtha nchemica lshoul d thereforeb estudie dmor eclosely .

AIMAN DMOTIVATIO N

Fieldstudie shav eshow ntha taphi dpopulation sar esometime s infectedb yentomogenou s fungi,especiall y fungio fth egenu s Entomophthora, mainlyth especie s E. aphidis, E. fresenii and E. thaxteriana. Underfavourabl econditions ,aphi dpopulation sma yb ewipe d outove rlarg eareas .I nBrittany , Aphis fabae populationsar econtrolle dever yyea rnatu ­ rallyb y Entomophthora species (Missoniere tal. , 1970). Itwa salway sfel ttha tth eoccurrenc eo fepidemic so f Entomophthora inaphi dpopulation s dependedonl yupo nth eprope rclimati ccondition san dtha tth eamoun to finfectiv emateria l presentwa sneve ra limitin gfactor .However ,i ti spossibl etha tinsufficien tinfectiv e materiali savailabl et ocaus eepidemic si naphi dpopulations .Introductio no finfectiv e material,i nth efor mo fspore so ra sinfecte ddea do rlivin gaphid sunde rfavourabl ecli ­ maticcondition sma ythu scontro lth eaphids . Thepresen tresearc hwa sse tu pi norde rt ostud ywhethe r Entomophthora spp.coul dcon ­ trolaphid si nannua lcrops .Complet econtro lo faphid si sno talway srequired :a dela yi n thebuildin gu po faphi dpopulation s inpotatoe san dsugar-bee twoul dalread yb evaluable .

1.Presen tadlress :Institut od eZoologi aagricola ,Universida d Centrald eVenezuela , Maracay,Venezuela .

271 WORKINGMETHOD S

Several Entomophthora speciesreceive dfro mothe rlaboratorie s (InstitutPasteur ,Paris , Francean dRothamste dExperimen tStation ,Harpenden ,Herts ,England )wer eavailable : E. aphidis, E. fresenii, E. phalloides, E. thaxteriana and E. virulenta. Allthes especie s except E. fresenii growo nartificia lmedia . Fourphase sar eplanne dfo rth eresearch . 1.Laborator ystudies ,t oobtai ninformatio nabou tclimati ccondition sfavourabl efo r Entomophthora infectioni naphids .Experiment swer estarte dt ostud ygerminatio no fspore s atdifferen ttemperature san drelativ ehumidities .Preliminar yexperiment swer eals ocon ­ ductedt ofollo wth esprea do fth efung ii n Aphis fabae populationsi nsmal lcage sunde r differentrelativ ehumiditie sa ta temperatur eo f2 1 C.Infectiv emateria lwa sintroduce d inth efor mo fdea dinfecte daphids . 2.Mas scultivatio no fpromisin g Entomophthora species. 3.Listin go f Entomophthora specieso ninsect si nth eNetherlands ,i nparticula ro naphids . 4.Smal lexperiment so ngreenhous ean doutdoo rcrops ,o nwhic hthes efung iwil lb euse da s controlagent sfo raphids . Phases 1an d2 hav estarted .

RESULTSAN DDISCUSSIO N

Sporegerminatio nwa sstudie di nmor edetai lfo r E. virulenta. At2 1 Can d100 1relativ e humidity,germinatio nstarte dafte r3- 4h bu ta reasonabl e level (40-50*)o fgerminatio nwa s onlyreache dafte r2 0h .Germinatio na tlowe rrelativ ehumidities ,eve na t981 ,wa sconside ­ rably less.Fo rth eothe rspecie so ffungi ,n odetaile ddat aar eye tavailable . Forth ecag eexperiments ,dea daphid sinfecte dwit h E. aphidis wereuse da sinfectiv e material.Eve na thig hhumidities ,onl ya fe waphid sbecam einfecte di nthi sway .Perhap s thespore swer eno tsufficientl ysprea dthroughou tth ecag ei nthi smanner .Sprayin go fth e plantsi nth ecage swit ha suspensio no fspore sma ygiv ea muc hhighe rinfectio no fth e aphids.Suc htest sar eplanned . In1978 ,onl ya fe winfecte daphid swer eobserve di nth eNetherlands .Mos to fthes e aphidscollecte dappeare dt ohav ebee nkille db y E. aphidis. Soa hig hrelativ ehumidit yi sneede dfo rsatisfactor ygerminatio no fspores .W eshould , however,interpre tthes edat acarefully :t oobtai na nepidemi ci na naphi dpopulation ,a highproportio no fgerminate dspore sma yno tb eneeded .Onl ya fe wgerminate dspore si s neededt oinfec tan dkil la naphid .B ytreatin ga cro pwit ha hig hdosag eo fspores ,suffi ­ cientgerminatin gspore sma yb eobtaine deve nunde rcondition stha tar esuboptima lfo rth e fungus.

FUTUREOUTLOO K

Whenenoug hdat aabou tclimati ccondition s favourable for Entomophthora infectionsar e obtained,attentio nwil lb epai dt oth emas srearin go fth efung ii norde rt ostar tfiel d application.Mos to fth efung iunde rstud yca nb eculture do nartificia lmedia :th egrowth ,

272 however,i sslo wfo rmos tspecies ;onl y E. virulenta growseasily .Thi scharacteristi c makesthi sspecie ssee mmor esuitabl ea sa biologica l insecticide.Whic hfungu swil lb e chosenfo rth efiel dwor k is,o fcourse ,dependen tals oo nothe rcharacteristic so fth e species.

REFERENCE

Missonier,J. ,Y .Rober t& G .Thoizon ,1970 .Circonstance sépidémiologique ssemblan tfavo ­ riserl edéveloppemen tde smycose sà Entomophthorale sche ztroi saphides ,Aphi sfaba e Scop.,Capitophoru shorn iBorne re tMyzu spersica e (Sulz.).Entomophag a 15 :169-190 .

273

Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 9.5 Control of insects with nematodes

W.R.Simon s Laboratoryo fNematology ,Agricultura lUniversity ,Wageningen ,th eNetherland s Friesland Collegeo fAgriculture ,Leeuwarden ,th eNetherlands .

INTRODUCTION

Nematodesassociate dwit hinsect shav ebee nknow nsinc eth eEighteent hCentur yan da t presentove rthre ethousan drelationship shav ebee ndescribe d (Poinar,1975) .O fthese ,a fairnumbe rca nb efata lt oth einsec thost ;other sma ycaus esterility ;ofte nn oapparen t harmi sdon et oth einsect .Abou tth enatura lregulator yrol eo fparasiti cnematode si n insectpopulations ,knowledg ei sstil llimited .Parasitis mha sbee nshow nt orang efro m lesstha n1 1t o100 %fo rspecifi cgroup slik emermithids .Ofte nth eoccurrenc eo fa hig h levelo fparasitis mha sle dt ospeculatio nwhethe rth enematod econcerne dma ypla ya majo r role.I nthei rrevie wo fthi ssubject ,Gordo n& Webste r (1974)sa y"Biologica lcontro lo f insectpest san ddiseas evector sb ynematode si son eo fth emor epromisin galternative st o over-relianceupo npersistan tchemica linsecticides" . Successfulinsec tcontro lha sbee nachieve dwit h Romanomermis culicivorax againstvariou s mosquitolarva ean dwit h Deladenus siricidicola againstth ewood-wasp , Sirex noctilio in Australia. Neoaplectana specieshav ebee nuse di nman yexperiment swit hvaryin gsuccess . Inth eNetherlands ,studie so nth eus eo fentomophagou snematode sstarte di n197 5o na lim ­ itedscale .

METHODS

Staringfro minsec tproblems ,tw oapproache sca nb econsidered . 1.Searchin gfo rparasiti cnematode s ininsec tpopulation s ineithe routbrea karea so ri n naturalhabitats .Whe nfound ,investigatin g theirusefulnes sa scontro lagents .Thi smean s studyingthei rbiology ,testin gthei rusefulnes sfo rpractica lcontrol ,includin gecologi ­ calstudies ,an destablishin g aprocedur efo rmas sculture . 2.Tryin gt ous eknow naggressiv e (orles sspecific )parasiti cnematodes ,fo rinstanc e memberso fth eSteinernematida e (Rhabditida),tha thav eprove dpromisin gelsewhere . Anidea lworkin gmetho dwoul dinclud eboth ,bu tlimite dresource shav edirecte dou r choicet oApproac h 2i nth efirs tinstanc ean d Neoaplectana carpocapsae isbein gtested . Thisnematod ema yb eregarde da sa vecto ro fit sow ndeadl ysymbioti cbacterium . Recentlyth esearc hfo rindigenou sparasite sha sbee ninclude di nth eprogra mo na lim ­ itedscale .

275 Neoapleotana carpocapsae

Attemperature sbelo w 15 C,th epathogenicit yo f N. carpocapsae decreasesrapidly .Sinc e Dutchsoi lcondition sca nvar yconsiderabl y thenematode' ssuitabilit y forus eunde rfiel d conditionsha dt ob eestablished .Fo rtha tpurpose ,soi lwa sspraye dwit hnematode sagains t thesusceptibl ebeetl e larvaeo frape , Psylliodes chrysocephala, inlat esumme ran dautumn . Asa rule ,laborator ytest s— treatin g larvaewit hnematode si na Petr idis h- preceded fieldo rpo ttrials . Allexperiment swer econducte di nmois thabitat si nsoi lan di ninsec ttunnel si ntrees , andpreferabl yo narthropod swhos echemica lcontro lha dprove ddifficul to rface dobjections . Susceptibleinsect swit hpromisin grate so fmortalit y infiel do rpo ttrial swil lb e furtherteste dfo rth eeffec to fsoil ,nematode ,insec tan dapplicatio nfactor s(Simons , 1978),i norde rt odetermin ewhethe rth enematod eca nsuppres sth einsec tpopulatio nt oa n economicallyacceptabl elevel . Inal linitia ltrial si nsoil ,dosage so fnematode swer estandardize d at10 0pe rsquar e centimetrean dwer eapplie db ysprayin gth esoi lsurfac ewit ha naqueou snematod esuspension .

Indigenous rhabditids and pest-specific nematodes

Soilsample so fon elitr ewer etake nfro muncultivate dligh tsoil swit ha natura lvege ­ tation.I nth elaboratory ,fiv eo rsi xwa xmot hlarvae , Galleria mellonella, werepu tint o eachsoi lsampl e (Bedding'strap )and ,afte ron eweek ,dea dlarva ewer eexamine dan dpu t ontoa Whit etra pfo rfurthe rcultur ean dstudie so fth erhabditi dparasite sfound .Befor e undertakingmorphologica lstudies ,a mutua lcrossbreedin gschedul ewa scarrie dou tt ode ­ terminerelationship so fth edifferen tnematod epopulations .Alon gwit hmorphologica lan d taxonomiestudies ,th enematodes 'pathogenicit y tovariou sinsec tlarva ewil lb einvestigated . Thesearc hfo rpest-specifi cparasiti cnematode sb ycollectin g livean ddea dinsect si n croppingarea ssufferin g fromth einsec tha sreceive dlittl eattentio ns ofar .On efortuito s discoverywil lb ementioned .

RESULTSAN DDISCUSSIO N

Neoapleotana carpocapsae (as insect-control agent)

Infectivestage so f N. carpocapsae canb estore da thig hdensitie s (100millio npe rlitre ) informali na ta concentratio n 1ml/ 1a t5 t o8 ° Cwit hcontinuou saeration .Th enumbe ro f livenematode sdecrease sslowly .Afte rthre emonths ,mos tnematode sar estil laliv ean di n goodcondition .Aeratio na troo mtemperatur efo ra fe wday sbefor estorag eincrease ssurviv ­ alsAfte rtw oyears ,storag elosse sar econsiderabl ean dals ovirulenc edecrease swhe nap ­ pliedt osoil . Survivali nsoi la tdetectabl edensitie sseem st ob ea matte ro fweek s (8t o 15),depend ­ ingo ntemperatur ean dsoi ltype ,i.e .biologica lactivit yi nth esoil .Detaile dstudie s willb enecessar yt odetermin e 'residual'effect so npopulation so fpes tan dothe rinsects . Psylliodas chrysocephala (Coleoptera:Chrysomelidae) .Number so fyoun glarva ei nrap e

276 plantswer ereduce db yu pt o60 %b ySeptembe rspraying swit hnematodes .Sprayin gi nNovem ­ bergav epoo rcontrol .Simila rfiel dtrial sth efollowin gyea ryielde dn opositiv eresults , becausemajo rlarva linvasio nbega ni nNovember ,whe nsoi ltemperature swer eto olo wfo r thenematode .Furthe rtrial swit hthi sinsec twer econsidere duseless ,a si tha dbecom e cleartha t N. eavpocapsea mightb eusefu lonl ya tsoi ltemperature sprevailin gi nDutc h summers.

Agrotis segetum (Lepidoptera:Noctuidae) ,a universa lpolyphagou spes tinsect .Po texper ­ imentsgav eu pt o80° 6contro lo f3r d- 5 t hinsta rlarvae ,whe nth enematode swer espraye d onth esoi lo rapplie di na mois tbra nmixture .Th ereductio ni ndamag et oyoun glettuc e plantswa sstatisticall ysignifican tbu teconomicall yinsufficient .Furthe rwor ki sgoin g ont oimprov econtrol . Otiorrhynahus sulaatus (Coleoptera:Curculionidae) ,a pes ti ncrop ssuc ha sstrawberrie s andornamentals .Resistanc et ochemica linsecticide sha sbecom ea rea lproble man di nstraw ­ berriesaldri ni sth eonl yalternativ efo rth emoment ,until ,it sus ei sprohibite dcomplete ­ ly.Successfu llaborator ytest swit h N. aarpooapsae werefollowe db yfiel dtrial si ntw o successiveyears ,bu tth eresult swer eunpromisin g (Seeals ounde r 'Indigenousrhabditid s andpest-specifi cnematodes') . Hoplocampa testudinea (Hymenoptera:Tenthredinidae) .Last-insta rlarva eo fthi sinsec t dropou to fyoun gapple sont oth esoi lt ofor ma cocoo nan doverwinte ra ta dept ho f1 0t o 20cm .I fnematode sar epresen twhe nth elarva earriv ea tth esoi lsurface ,the ymigh tb e ablet openetrate .Po tan dfiel dtrial shav eprove dthi st ob epossibl ebu tsoi lcondition s maystrongl yinfluenc econtrol .Thi sstud yi sbein gcontinued . Sciapteron tabaniformis (Lepidoptera:Sesiidae) .Injectio no fnematode sint otunnel si n youngpoplar skille dal lcaterpillar s inth etree sexamine d (testsb yL .Wouters ,Lelystad) . Thisoffer sgoo dcontro lfo rsmall-scal eapplication ,a si nfiel dtrial so ri ntre enurser ­ ies,bu ti sotherwis efa rto olaborious .Simpl ysprayin gth esurfac eo fth eaffecte darea s ona tre eha sn oeffect ,sinc eth enematode scanno tpenetrat eth emas so fbore-mea li nth e tunnels. Synanthedon myopaeformis (Lepidoptera:Sesiidae) .Spray so nappl etrunk sallowe dnematode s topenetrat eth erathe rsuperficia ltunnel san dkil lth elarvae .Test sar ebein gcontinued . Scolytus multistriatus (Coleoptera: Ipidae),a vecto ro fDutc hel mdisease .Eve nunde r favourable laboratoryconditions ,th enematode scoul dno tpenetrat eth ebore-mea li nth e tunnelsunderneat hth ebark . Delia brassiaae (Diptera:Muscidae )maggots , Atomaria linearis (Coleoptera:Cryptophagidae ) imagos, Onyahiums armatus (Collembola:Onychiuridae )nymphs ,Scutigerella immaculata (Symphila:Scutigerellidae )nymphs .I nal lcases ,bot hlaborator yan dfiel do rpo ttest s haveshow nth elac ko fsusceptibilit yo fthes eorganism st o N. aarpooapsae. Closeexaminatio n hasshow ntha tpenetratio no fth enematode sthroug hth esmal lnatura lopening so f S. imma­ culata isimpossible .I nth ecas eo f 0. armatus itha sbee nobserve dtha tth enematode sscar e thespringtail sa ssoo na sthe ycom ei ncontact . Ina pathogenicit y test,youn gChines egrass-car p (Ctenopharyngodon idella) werekep t inwate ra tabou t2 2 Cwit ha maximu mo f1 000 0 N. aarpooapsae perlitr efo r1 8days .N o injuriouseffec tcoul db edetected .

277 Indigenous rhabditids and pest-specific nematodes

Fourteennematod epopulation shav ebee nisolate dfro msoi lsample san dculture so n Gallepia mellonella. Allpopulation sconsis to f fleoaplectana species.A cross-breedin g schedulei sbein gcarrie dou tan dth efirs tresult shav eindicate dsom erelationships . Taxonomiestudie san dpathogenicit ytest swil lfollow . Recentlya fe wre ddea dlarva eo f Otiorrhynchus sulcatus, containinga Heterorhabditis species,wer efoun do nstrawberr yplant si npots .Thi snematod eals ocarrie sa symbioti c bacteriumi nit sintestinum .Th eutilit yfo rbiologica lcontro lo f 0. sulcatus andothe r insectswil lb einvestigated .A preliminar y testi nth elaborator yan dwit hpot shav e indicateda hig hdegre eo fsusceptibilit yo f 0. sulcatus larvae.

FUTUREOUTLOO K

Knowledgeo fth eusefulnes so fnematode si ninsec tcontro li sstil lscanty ,bu teve nth e hithertoacquire dinsigh twil lallo wdevelopmen to fgoo dmethods .T ocompet ewit hchemica l insecticides,th emetho dmus tb ereliable .I freliabilit ycanno tb eachieve dwit hon enema ­ todespecie salone ,combine dus ewit hothe rpathogen so rlo wdosage so fnon-persisten t selectiveinsecticide sshoul db econsidered . Practicalcontro lo finsect scanno tb eachieve db yon emean salone .Neithe rwil lnem ­ atodesbrin gth eultimat esolution .Thes elong-neglecte dorganism sca nb eexpecte dt otak e ona usefu lrol ei nth econtro lo finsect si nth eNetherlands .

REFERENCES

Gordon,R .& J.M .Webster , 1974.Biologica lcontro lo finsect sb ynematodes .Helminth . Abstr.Ser .A 4 3 :327-349 . Poinar,G.O. ,Jr. ,1975 .Entomogenou snematodes .E.J .Brill ,Leiden .31 7p . Simons,W.R. , 1978.Preliminar y researcho nentomophagou snematodes ,i nparticula ro n Neoaplectanaspecies ,i nth eNetherlands .Meded .Fac .Landbouwwet .Rijksuniv .Gen t 43 :765-768 .

278 10 Supporting techniques

Manytechnique shav ebee nuse di nresearc ho nintegrate dcontrol ,an dthre emerite d descriptioni nsom edetail . Systemsanalysi san dcompute rsimulation ,technique sholdin gmuc hpromis ea stool si n basicresearc han dpossibl yi nth epractic eo fintegrate dpes tmanagemen ta swell ,hav e beensuccessfull yuse da sa nai dfo ranalysin gprey-predato rsystem so fmite san dth e epidemiologyo fcerea laphid s (10.1,10.2) . Detailedmeteorologica lassessment si nsuppor to fstudie swer eindispensabl e (10.3). Finally,experience swit hradiobiologica ltechnique sar esummarized .The ywer efoun d indispensablei na narra yo fproblem sencountere di nphysiologica lan decologica lstudie s bymember so fth eWorkin gPart y (10.4).

279 Integrated control of insect pests in the Netherlands. Pudoo, Wageningen, 1980. 10.1 Systems analysis and simulation as an aid to the understanding of acarine predator-prey systems

R.Rabbing e& M.W .Sabeli s

Departmento fTheoretica lProductio nEcology ,Agricultura lUniversity ,Wageningen ,th e Netherlands.

INTRODUCTION

Duringth elas tdecad esystem sanalysi san dsimulatio nhav egaine dincrease dinteres t incro pprotection .I nth eWorkin gPart yo nIntegrate dContro lo fPests ,thes etechnique s weres ofa ruse dmainl yt oanalys ean dunderstan dbiologica lcontro lwit hmites . Theexperienc ewit hintroductio no fendemi cpredator ymite san dmodifie dsprayin gsche ­ mesan dproduct s indicatetha tthes epredator ymite sca nreduc ean dmaintai npopulation s offruit-tre ere dspide rmit ebelo wth eeconomi cthreshold .A tpresent ,predator ymite sar e comingint owid eus ei nth econtro lo fspide rmite si nappl eorchards ,an da larg epropor ­ tiono fth egrower so fvegetable si ngreenhouse sar eusin gpredator ymite sfo rcontro lo f spidermite si ncucumbe ran dswee tpeppers .Fo rswee tpepper sth epredator ymite sca nb e useda sa nacaricide .A permanen tcontro lsyste mi sdesirabl efo ral lcrop sbu ti ti sques ­ tionablewhethe ri tca nb eachieved .Thi sstud yinvestigate sth epossibilitie s forsuc h controli nrelatio nt opre yan dpredator ymit especies ,thei rspatia ldistribution ,webbin g activityan dbehaviour .I nth etw ocrops ,th echange swit hintroductio no fpredator ymite s havebee nmeasured ,bu tth emod eo fcontro li sstil lpoorl yunderstood .Thi sunderstandin g shouldb ebase do nintegratio no fth eknowledg eo fth eunderlyin gecologica lprocesses .Ou r studywit hsimulatio nmodel saime da tsuc ha nintegratio nan da tclose rinsigh ti nth eaca ­ rinesystem san dthei rsensitivit yt odisturbance .I tma ythu spav eth ewa yfo rsimpl epres ­ criptionso nho wt omanag eth eprey-predato rsyste mi nth ecours eo ftim ei nrelatio nt o cropstatu san dclimate .Simplifie dmodel sca nthu slea dt oadvic ei nspraying san dinter ­ ventionswit hpredator ymite so ralternat eprey ;the yma yals ohel pi nplannin gobservation s duringth emonitorin gphase .

MODELLINGTECHNIQU E

Themodel suse di nthi sstud yar eo fth estate-variabl etype ,an dcontai nstat evariables , thatcharacteriz equantitativ epropertie so fth esystem ,suc ha sth enumbe ro fegg san dfe ­ males,th eamoun to fbiomas so rth econten to fth epredator' sgut ,rat evariable stha tex ­ pressth erat eo fchang eo fth estat evariables ,suc ha sdevelopmen trate ,ovipositio nrat e orth epredator' sdigestio nrate ,an ddrivin gvariable stha tcharacteriz eth einfluenc efro m outside,suc ha smacrometeorologica lvariables .

281 Oftena hierarchica lapproac hi sused .I ti sbase do nth eide atha tonl ytw olevel so f causaldept hshoul db edistinguishe di na model .Fo rexampl eth erat eo fassimilatio nma y beexplaine d fromknowledg eo fth estomata lbehaviour ,th ephysiolog yo fcell sma yb eex ­ plained fromth eunderlyin gbiochemica lprocesses .However ,a proble m inusin gthi sprincipl e istha ti ncomplicate dsystem sth ecausa lrelation sar es omanifol dtha ta relationa ldia ­ gramlook slik ea spider' swe b rathertha na pyramid .Usuall yth ecausa lconnection sar e morenumerou si nsom eplace stha ni nothers ,s otha ti ti ssometime spossibl ewit hsom e skillan deffor ti nmodelling ,t odistinguis h regionswit hrelativel yman yrelation sinsid e andonl ya fe woutside .Thes eregion sar ecalle dsubmodels . Oftensimplifie dan dshor tmathematica lrelation sbase do ncalculation swit hthes esub ­ modelsar euse di nth ehigher-ordere dmodel so fth ewhol esystem .Model so nwalkin gbehav ­ iouro fa predator ymit emay ,fo rexample ,constitut eon eo fth emodel so nsubprocesse so f theprédatio nprocess ,whic hi nit stur ni son eo fth eelement so fa mode lo nth epopula ­ tiondynamic so fpredaciou san dpre ymite s ina cro psystem .

POPULATIONMODEL S

Forbot hpre yan dpredator ,populatio nmodel sar ebase do nknowledg eo fth eeffec to f humidity,temperature ,daylengt han dfoo dquality .Relation sbetwee nrate so fdevelopment , mortality,oviposition ,ageing ,diapausin go non ehan dan dtemperatur eo rothe rphysica l factorso nth eothe rhan dar eintroduce dbase do ndat afro mth eliterature ,o nestimate s ando nlaborator yexperiments .T oaccoun tfo rth edifferen tmorphologica lstages ,ag eclass ­ esar edistinguished .Th eresidenc etim ei neac hage-clas sdepend so nth elengt ho ftha t developmentstag eo fth eanimals .Dispersio ni ntim edurin gdevelopmen tan dagein gi sals o takenint oaccount .Fo rexampl eegg so fon ebatc hlai da tth esam emomen thatc ha tdiffer ­ enttimes .T od oso ,a specia l 'boxcar'routin ei sdevelope dwit hwhic hdevelopmen tthroug h differentstage si ssimulated .Thi ssubroutin emimic sth edispersio ni ntim edurin gdevelop ­ mentan dagein gan dadapt sth emimicke ddispersio nt oexterna lconditions .Basicall ythi s isdon eb ydistinguishin gartificia lage-classe swithi nth emorphologica lage-classes ,whic h arepasse da tdifferen trates .

PREY-PREDATOR INTERACTIONS

Thecor eo fth epopulatio nmodel so fpre yan dpredator ymite sconsist so fth einteraction s betweenth etw opopulations .Thes einteraction s includefunctiona lresponse so fth epredato r topre ydensit yan dquantitativ eresponse so fth epredato rt oincreasin go rdecreasin gpre y densities.T ogras pth ecomplicate dprey-predato rrelation ,Frans z (1974)unravelle dbehav ­ ioralcomponent so fth eprédatio nproces si ndetail .H efoun dtha tth epredator' sbehaviou r wasgoverne db yth esatiatio nleve lo fth egu tan dtha tthi sinduce schange si npre yprefer ­ encean dpre yutilization .Fransz' sstudie swer edon ewit hth etwo-spotte dspide rmit ean d thepredator ymit e Metaseiulus occidentalis. Theadul tfemal epredato r (themos tvoraciou s stage)show sa stron gpreferenc e forth eyounge rstage so fth eprey ,bu tthi spreferenc e decreaseswhe nth epredator sar e"hungry" .T omeasur epre ypreferenc ean dpre yutilizatio n inrelatio nt osatiatio nleve lo fth epredator ,th eprédatio nproces swa sanalyse di ndetail .

282 Atim eserie so fth eprédatio nproces swit hal lit selement swa smade .A searchin gpredato r encountersa pre yan dthi sma yresul ti na killing .Wha thappen sdepend so nth esatiatio n levelo fth epredator .I nhungr ypredators ,th esucces srati o (numbero fsuccessfu lencoun ­ tersdivide db yth etota lnumbe ro fencounters )i shig han di nsatiate dpredator slow .Th e handlingo rkillin go fth epredato rtake ssom etim e (handlingtime) ,afte rwhic hth epreda ­ torma ystar tfeeding .Th elengt ho fth efeedin gperio ddepend sagai no nth esatiatio nleve l ofth epredato rsinc ehungr ypredator sma ysta ylon gwit hthei rprey ,eve nafte rth eprey' s bodyconten ti scompletel yconsumed ,wherea ssatiate dpredator sma yleav ethei rpre ybefor e theyar ecompletel yconsumed .

SATIATIONLEVE LO FTH EPREDATO R

Apparentlyth esatiatio nleve l (gutcontent )i son eo fth emos timportan tstat evariable s inth esystem .Severa lway st omeasur eth esatiatio nleve lar epossible .Fo rfruit-tre ere d spidermit ean dth epredator ymit e Amblyseius potentillae, gutconten tca nb escore dvisu ­ allybecaus ewell-fe dpredator sar edar kan dreddish ,whil ehungr ypredator sar ewhitis h andtransparent .A colou rscal ewa stherefor edevelope dtha trelate dth eamoun to flea fan d animalpigment s inth epredator ,whic htogethe rconstitut eth ecolour ,t oth erelativ epréda ­ tionrat ean dpre yutilization .Thes erelation swer eintroduce dint oth epopulatio nmodels . Ovipositionrat ean ddevelopmen trat eo fth epredato r (quantitativeresponse )als odepende d onth esatiatio nleve lan dtemperatur ean dwer esimilarl yintroduce d intoth epopulatio n model.I fa visua lcharacterizatio no fth esatiatio nleve li simpossible ,th eweigh to fth e predatorsma yb euse da sa stat evariabl etha tgovern spredator ybehaviour .

STOCHASTICCHARACTE RO FTH EPREDATIO NPROCES S

Twoevent si nth eprédatio nproces ssho wa clea rstochasti ccharacter .Thes ear eth e encountering andabandonin go fth eprey .Frans z (1974)showe dtha tbecaus eo fth ecurvili ­ nearrelationship so fth eencounterin grat ean dabandonin grat ewit hth epredator' ssatia ­ tionlevel ,stochasti cmodel shav et ob eused .Wit hlinea rrelationships ,th edifference s betweendeterministi can dstochasti cmodel swer eabsent .Sinc eth erelation smentione dwer e non-linear,a stochasti cmode lwa snecessary .Thi stediou saffai rrequire dmuc hcompute r timean ds oth edevelopmen to fothe rtechnique swa snecessary .Especiall y forpopulatio n modelso fprey-predato rinteractions ,simplifie dmodel sar eurgentl yneeded . Fransz (1974)therefor eintroduce da ne wsimulatio nmetho dcalle dcompoun dsimulation . Thiswa sbasicall ya deterministi csimulatio nmode lfo rclasse so findividual swit ha cer ­ tainsatiatio nlevel ,whic har eiterativel y reclassed ineac htim einterval .Whe nth enum ­ bero fclasse si sproperl ychosen ,th eresult so fthi smode lscarcel ydeviat efro mth esto - chasticalmode lan dth ecompute rtim ei sconsiderabl y less. Anotherwa yt oaccoun tfo rth estochasti ccharacte ro fsom eelement so fth eprédatio n processi st oappl yqueuin gtheory ,a spropose db yTaylo r (1976).I nthi sapproach ,th e predatori sconsidere dt ob ea servic efacility ,fo rexampl ea dentist ,an dth epre yt ob e aclient .Thi sclien tma yente rth ewaitin groo m (gut)a ta certai nrat ei nexpectanc eo f theservic e (digestion).T oevaluat eth ementione dprédatio nmodels ,i.e .deterministic ,

283 stochastic,compoun dan dqueuing ,thei routcome swer ecompare dwit hth eresult so fexperi ­ mentso nth eprédatio nrat eo f M. occidental-is onegg so ftwo-spotte dspide rmite .Th edeter ­ ministicmode lgive serroneou s resultsan dth eoutcome so fth ethre eothe rmodel sfal lwithi n theconfidenc einterval so fth emeasurements . Themode lcalculation sfurthe rshowe dtha ti fth enumbe ro ftwo-spotte dspide rmite swa s keptconstan twit hon estandardized 1 M. occidentalis predatoro na lea fdisc ,a nequilibriu m wasreache dwithi na fe whours .I ntha tsituation ,th edegre eo fsatiatio no fth epredator y miteoscillate swit ha smal lamplitud ea ta leve ltha tdepend smainl yo npredato ran dpre y densityan do nth etemperatur eo fth esystem .I nthi sstead ystate ,uniqu erelation sexis t betweenth eprédatio nrat ean dth edensit yo fpre yan dpredator ,s otha tsimplifie drela ­ tionsma yb eintroduce di nth epopulatio nmodels .I nth esituatio no fth efruit-tre ere d spidermit eth erelativ eprédatio nrat e [prédationrat edivide db ypre ydensit yi nth e steadystate) ,an dpre yutilizatio nexpressin gth edegre eo fconsumptio no fa pre yar ein ­ troduceda sfunction so fth esatiatio nlevel .Temperatur eaffect sbot hthes erelation san d evidentlyals oth erat eo fdigestio nan dthu sth edecreas ei nsatiatio nlevel .

MICROWEATHER

Sinceth emite soperat ei nth esmal llamina rlaye raroun dth eleaf ,the yar eexpose dt o themicroweathe rthere .T oevaluat eth eeffec to fmicroweathe ro nth ebiologica lparameters , amicroweathe rsimulato rwa scouple dt oth epopulatio nmodels .Fo rth efruit-tre ere dspi ­ dermit e— predatorymit esystem ,th eresul to fthi scombine dmode lcalculatio ndoe sno t differfro mth epopulatio nmode lcalculation si nwhic hai rtemperatur ewa suse da sa drivin g force.Thu sth ewid evariet yo flea ftemperature si ssuc htha tth efe wplace swit htempera ­ turesmuc hhighe rtha nth eai rtemperatur emus tb ecancelle dou tb ya hig hnumbe ro fleave s withtemperature sslightl ylowe rtha nth eai rtemperature .

VALIDATIONO FTH EPOPULATIO NMODEL S

Evaluationprocedure sshoul db eperforme db ycomparin gmode loutpu twit hth eresult so f independentexperiment so nth epopulatio nlevel .Th esimples tevaluatio no fth epopulatio n modelso fpre yan dpredato rmite si sb ymeasuremen to fth epopulatio ngrowt ho fpre yan d predatori nth ecours eo ftim ei nsmal lecosystem sunde rcontrolle dcondition s insituation s withan dwithou tpredators .Th eresult sfo rth efruit-tre ere dspide rmit ear eshow ni n Figure 1an dar ereache dwit ha mode li nwhic hth edifferenc ei nsiz eo fth esyste mi sin ­ troducedb ysimpl eextrapolatio no fth esurfac eo nwhic hth eprédatio nproces sexperiment s aredon e (5.6cm 2)t oth esurfac eo fth eecosystem .Althoug h theresult so fthi sevaluatio n werereasonable ,i twa squestionabl ewhethe rsuc ha simpl eextrapolatio ni spermissible , sincei nman ycase serror sdu et oth eheterogenou sdistributio no fth epre yan dth especifi c walkingpatter no fth epredato rma ycounterbalanc ebu tals ocaus econsiderabl edeviation s fromth esimulate dpattern .Fo rth etwo-spotte dspide rmite ,thi squestio nwa sexamined .I n

I.Th epredator ymite suse di nth eprédatio nexperiment swer ereare dunde rconstan tcondi ­ tionsan dar eo fa wel ldefine dage ,gu tconten tan dfoo dhistory .

284 thatsystem ,pre yar edistribute d incluster san dinterfer ewit hth emobilit yo fth epreda ­ torb yth eproductio no fa dens eweb .Withi nthes ewebbe dcolonies ,ver yhig hdensitie so f prey,20-10 0c m2 ,ar ereached .Outsid ean dinsid eth ecolony ,behaviou ri squit edifferent . Outsideth ecolonies ,th epredator swal k infixe dpatterns ,guide db yleav efringe san d veins,insid eth ecolonie sthei rwalkin gpatter ni smor erandom .No tal lmorphologica l stageso fpre yan dpredato rparticipat ei nth edispersa lprocess .I nth etwo-spotte dspide r mite,dispersa li smainl yb yth eadul tfemale sbefor eovipositio nwherea si nth epredator y mitesbot hadul tfemale san dmale sma yb eactiv ei ndispersa ldurin gthei rwhol eimagina i life,dependin go nfoo dconditions .Therefor et oevaluat eth epopulatio nmodel si nthes e situations,a provisio nwa sintroduce dt oaccoun tfo rth edispersal .Th edispersa lsubmodel s ofth epredato ran dpre ywer edevelope dfro mdetaile dstudie so fwalkin gbehaviou ro fboth . Dispersalb ywin dwa sno tconsidere d forthes esituations ,sinc eth ewin dspee di sto olo w toinduc etak eof fo fth epredator y (Johnson& Croft ,1977 )an dpre ymite sunde rgreenhous e conditions.Basicall ythes emodel swer es oconstructe dtha tpopulatio nmodel swer eapplie d todifferen tspatia lunitie scouple db ydifferen tdispersa lrates .Thes esimulatio nmodel s includedth eclea rpreferenc eo fth epredator ymite s M. oooidentalis and P. persimilis for thewebbe dareas .Thei reffectivenes s insearchin gbehaviou routsid eth ecolonie sguide db y leavefringe san dleav evein smak ethei rresidenc etim eoutsid eth ecolonie snegligible . Thisdoe sno thol dfo rothe rpredator ymit especie ssuc ha s Amblyseius potentillae that cannotmov earoun di nth ewebbe darea san dshow sa clea rpreferenc efo rth ethickes tpart s ofth eribs ,a sa restin gplace .

Modelcalculation swit hpopulatio nmodel si nwhic hthes easpect so fdispersio nwer e consideredshowe dthat ,i nsystem so flimite dsize ,regulatio no fth epopulatio no fpre y waspossible ,a si nth eexperiment sshow ni nFigur e2 .

EVALUATIONFO RTH EFIEL DSITUATIO N

Toevaluat eth esimulatio nmodel sunde rfiel dconditions ,th esimulate dfluctuation s inpopulatio no ffruit-tre ere dspide rmit ean dth epredator ymite swa scompare dwit hth e averagedresult so fsom eappl eorchards .Figur e3 give sth eobserve daverag edensitie san d thesimulate ddensitie sfo radul tfemale so fth epre yan dpredator .Th esimulate dfunction s arebase do na ninitia lnumbe rpe r 100leave so f4 pre yfemale stha thav ejus tmatured ,1 predatorfemal eo n1 June ,th eobserve dsurfac eo fth eleave san dth eweathe rdat ao f197 4 inth eorchards .Ther ewa sa goo doveral lagreemen tbetwee nth esimulate dan dmeasure dre ­ sults,especiall yfo rth emaximu mnumber so fpre yan dpredator ,th etim ela gbetwee nthes e maximaan dth edensit yo fpre yan dpredato rwit hrespec tt oeac hother .Als oth eobserve d andsimulate dcolou rvalue s (theindicato ro fsatiatio nlevel )o fth eadul tpredato rwer e ingoo dagreement . Fromth esimulations ,th enumbe ro fgeneration sca neasil yb ededuce dand ,b ychangin g parametersan dstructura lelement s inth emodel ,thei rcontributio nt oth ebehaviou ro fth e systemma yb edetermined .Non eo fth echange sha da majo reffec to nth ebehaviou ro fth e acarinesyste mi norchards .A wid erang eo fprey-predato rratio sma yb etolerate d insprin g withoutleadin gt oto ohig hpre ydensitie s inth esummer .Th eprédatio nactivit yo fth e youngerstage san dth eadul tmale so fth epredator ymit ewa srelativel yinsignifican tan d

285 Panonychus ulmi

Number of eggs uuo- 500- ^r^^ 200- ' 100- [ ' 50- 20- I 10- 5- I

2-

I —I— i i i •• • r 1 -i 1 r i i 36 39 Time (d) Number of larvae 500

30 33 36 39 Time(d )

Fig. 1.Simulatio n of popula­ Number of protochrysalis tion dynamics of fruit-tree red 100 spider mite and the predatory mite Amblyseius potentillae in a small apple ecosystem in com­ parisonwit h the experimental outcomes (Rabbinge, 1976). Simulated numbers of the spider mite are given as drawn lines and measured figures as confi­ dence intervals (a=0.05) (p. 286).Simulate d numbers of the spider mite are given as dotted lines and measured fig­ ures as confidence intervals (a=0.05) (p.287) .

286 Amblyseius potentillae

Number of eggs 10-

/ 2 , / / """•*- 1- / / / 0.5 r i/

/ / J 0.2-

-i ( 1 1 1 1 1 1 1 1 r- 1 1 3 6 9 12 15 18 21 24 27 30 33 36 39 Time(d)

Number of larvae 10-1

5-

2 •r - / 1- r ' 1

0.5

0.2-

—\ 1 1 1 1 1 1 1 1 1 1 1 I 3 6 9 12 15 18 1 24 27 30 33 36 39 Time(d)

Number of protonymphs 10-

5-

/ 2- __ S ~ 1- / i

/ J 0.5- / /] >• 0.2- / 1 1 J 6 9 12 15 18 21 24 27 30 33 36 39 Time(d) Fig. 1 continued.

287 Metaseiulus occidentafis Tetranychus urticae

Number of eggs, larvae, nymphs, Number of ovjposition females adult males and preoviposition females 103 103

16 24 32 40 48 Time(d) Time(d)

Tetranychus urticae

Webbed leaf area (cm2) 10r

56 Time(d) Fig.2 .Simulatio no fth epopulatio ndynamic so f two-spotted spidermit e Metaseiulus ooei- dentalis inrose s in8 lea fecosystem s (Sabelis,1980) . aA twi gwit h8 spide rmit ecolonie swit heffect so fmutua l interferenceo nprédation , bA twi gconsidere d ason ecolony ,withou tmutua l interferenceeffect san dneglectin gdis ­ persal.

theadul tfemal epredator ymit ewa sth emajo rregulato rbecaus eo fit shig hprédatio ncapa ­ city,it slon glif ean dit snumerica lrespons et oincreasin gpre ydensities .Th esyste mwa s rathersensitiv et olengt ho fth ejuvenil eperio do fth epre yan dth edela yi ndevelopmen t ofth epredato ri fi twa sno tsufficientl y fed.Th elatte reffect sma yb eprevente di f alternatepre ylik egal lmidge s (Eryiophidae)o rmilde wspore san dhoneyde war epresent . Forth eacarin esyste mi nroses ,dispersa lo fth etwo-spotte dspide rmite san dth epre ­ datorymite si nth ecro pwa so fmajo rimportance .Th esimulation sshowe dtha tdispersa lo f Panonychus ulmi

Number of oo 200-1

1 1 1 1 1 1 1 1 1 50 100 150 Time (h)

Amblyseius potentiltae

Number of o.g 200

Amblyseius potentillae

Colour value go 7-\

-\ 1 150 Time(h) Fig.3. Simulated (dotted lines) and experimental results (drawn lines) of the population dynamics of fruit-tree red spider mite and the predatory mite A. potentillae in apple orchards (Rabbinge, 1976). Data are number of mites per 100 leaves.

289 thepredator s caused a considerable delay in thepredator-pre y interactions.Thi s delaywa s partly due to thepredator y mite frequently entering and leaving the colonies at lowpre y densities and alsoperhap s to the relatively highpredato r densities.A s a consequence of thisbehaviou r thevariabilit y inpre y numbers increases considerably (Fig.2) .

MANAGEMENTAN D PROSPECTS

Formanagement ,th emodel s are too complicated and too time-consuming.Therefor e other simplified relations areneeded . This hasbee nme t for the fruit-tree red spidermit e sys­ temb y sensitivity analysis.Thu s prescriptions were developedwhic h show acceptableprey - -predator ratios.Th e acceptable ratio ofpre y females topredato r femalewa s 10o n 25May , and decreased to 3o n 15August .Prescription s of this typema yb e usedb y the extension services and themonitorin g growers. Themode l calculations with the two-spotted spidermit e system showed that dispersal behaviour of thepre y andpredator y mitesha d agrea t effect on thebehaviou r of the system. So faronl y the dispersal ofwalkin gpre y andpredator ymite s hasbee n considered and it seemsnecessar y to investigate the dispersal ofpre y andpredator y mites bywind . Some knowledge ofthes e effects is available (Johnson &Croft , 1977),bu t this information is still insufficient togai nmor e understanding of the dispersal ofmites . Inrose s ingreen ­ houses, dispersal bywin d seems negligible sincewin d velocities areneve r high enough for departure.Othe r aspects thatnee dmor e research are thepossibilitie s forothe r foodre ­ sources for thepredator y mites to surviveperiod s of food scarcity.Th e models showed that these alternate food sourceswer enecessar y inth e orchard system sincepre y densities may reachver y low levels.Thi s is evenmor e needed forclustere dprey ,fo r instance two-spotted spidermite s inroses .Th emodel swer e ahel p informulatin g the conditions thatha d tob e fulfilled to reach a reliable control system.

REFERENCES

Fransz,H.G. , 1974.Th e functional response topre y density ina n acarine system. Simulation Monographs,Pudoc ,Wageningen . 149p . Goudriaan,J. , 1977.Cro pmicrometeorology : a simulation study. Simulation Monographs,Pudoc , Wageningen. 257p . Johnson, B.W. &B.A . Croft, 1977.Laborator y study of thedispersa l behaviour of Amblyseius fallacis. Ann.ent .Soc . Am. 69 :1019-1023 . Rabbinge,R. , 1976:Biologica l control of fruit tree red spider mite.Simulatio nMonographs , Pudoc,Wageningen . 234p . Sabelis,M.W. , 1980.Toward s an evaluation of predatory mites for the control of spidermi ­ tes. SimulationMonographs ,Pudoc ,Wageningen , (in prep.). Taylor,R.J. , 1976.Valu e of clumping to prey and the evolutionary response of ambush pre­ dators. Am. Nat. 110 :13-29 . Wit, CT. de &J . Goudriaan, 1978.Simulatio n of ecological processes. Simulation Mono­ graphs,Pudoc ,Wageningen . 175p .

290 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 10.2 Epidemiology of the cereal aphid, Sitobion avenae

G.W.Ankersmi t (1)& R .Rabbing e (2)

1Departmen to fEntomology ,Agricultura lUniversity ,Wageningen ,th eNetherlands . 2Departmen to fTheoretica lProductio nEcology ,Agricultura lUniversity ,Wageningen ,th e Netherlands.

Inth epas tdecennium ,cerea laphid sbecam ea seriou sproble mt owhea tgrowin gi nth e Netherlands.Thre especie sar eofte nnumerous ,on eo fthem , Sitobion avenae, wasconsidere d themos tseriou spes tan dwa sstudie di nmor edetail .Thi sspecie sca nrapidl yincreas ei n thefe wweek sbetwee nth eonse to fflowerin gan dth emilky-rip estage .I tfeed smainl yo n theear .I tdamage sno tonl yb ysuckin gnutrient sfro mth eplan tbu ti tals oproduce slarg e amountso fhone yde wtha tdistur bth ephysiolog yo fth eplan tan dstimulat eth egrowt ho f saprophytican dpathogeni cfungi . Theexplosiv echaracte ro fpopulatio ngrowt hmake sforecastin gdifficult .Therefor egrow ­ ersten dt ospra ythei rfield spreventivel ywit hpirimicar bo rorganopohsphoru scompound s earlyi nth eflowerin gperiod .I nvie wo fth evas tare aunde rwheat ,thi smean sa consider ­ ableincreas ei nth eus eo fenvironmentall yhazardou stoxicants . Theai mo fthi sstud ywa st odevelo psimulatio nmodel stha tca nhel pt oexplai npopula ­ tiondevelopmen tan dtha tca nb euse dfo rforecastin gove rperiod so f3- 5week s (Rabbinge etal. , 1979).Possibl ythes emodel sca npav eth ewa yfo rdevelopmen to fsimple rrule sfo r prognosisan do fa reliabl ecro pprotectio nsystem .Moreove rthe yma yhel pt oexplai npopu ­ lationdevelopmen tan dguid eresearc ht oth emor esignifican trelationship sbetwee naphids , theirhos tplant san dth enatura lenemies .Th estud yi sbase do nanalysi so fphysiologica l andecologica lphenomen aa tth eindividua l level.A nexistin gmode ldescribin gth egrowt h ofwhea ti ssimplifie dan dcouple dt oth eaphi dpopulatio ngrowt hmode lt ocalculat eth e effecto fth eaphid so nth eplan tmakin gus eo fdetaile dstudie so nth eaphi d- hos tplan t relations (Vereijken, 1979).

MODELOUTPU T

Figure 1show soutpu tfro mth epopulatio nmode li ncompariso nwit hfiel dobservation si n 1976. Thecorrespondenc e seemsreasonable .Th eperio do frapi dgrowt ha swel la sth epea k arewel ldescribe da sconfirme db ysimulation so fth eepidemic so f197 5an d1977 . Somewhatles scorrespondenc eexist sfo rth ecollaps eo fth epopulation .A ttha tphase ,mor ­ talityb yprédatio nan d Entomophthora spp.seem simportan ta swel la semigratio no falates . Theactio no f Entomophthora spp.i sno tincorporate di nth emode lbecaus eo flac ko fexper ­ imentaldata .

291 Number per tiller

100- 1976

50-

0.5-

15 JUNE Fig. 1.Simulate dan dcounte d totalnumbe ro f S. avenae in 1976.Th econtro lnumber sar e giveni nterm so f 957.confidenc eintervals .

AGE-DISTRIBUTION

Fromfiel dobservations ,w ema ydeduc etha talate simmigrat eunti laroun dflowerin go f wheat.Afterwards ,th enumbe ro fimmigrate dalate so nth eplant sn olonge rincreases . Asth eoffsprin go fthes ealate sconsist so fapterae ,thes econstitut eth emai ndrivin g forceo fpopulatio ngrowth .Thei rnumbe rlargel yexplain s futuregrowth .Th eoffsprin go f apteraear emainl yalate stha tar eassume dt oemigrate .Simulatio nwit hth eabov eassump ­ tionso nimmigratio nan demigratio nincorporate di nth emode lgive sa reasonabl ecorrespond ­ encebetwee nsimulate dan dobserve dag edistributio na sexpresse db yth eLi ,insta r(Fig . 2). Themode linclude sparameter sfo rdevelopmen tan dreproductio nfro mliteratur edat a andlaborator ystudies .Th ecorrespondenc eindicate stha tou rlaborator ydat ao ndevelop ­ mentan dreproductio nsuffic et ounderstan dth epopulatio ngrowt hi nth efield .

292 Number per tiller 10- Simulated L4APT. Simulated L4AL.

Measured L4 APT,

Measured L4AL.

0.5

0.1

0.05-

0.01

Fig. 2.Simulate d andcounte d number ofalat ean dapterou s Li^.Th ecounte d numbers aregive n in terms of95 %confidenc e intervals (Figure from Neth. J.PI . Path.).

SENSITIVITY ANALYSIS

The modelling effortma yhel p topin-poin t black spots inou rknowledg e andt oevaluat e the relative significance forth epopulatio n dynamics ofdifferen t phenomena.T odetermin e the contribution ofdifferen t processes, sensitivitywa sanalysed .Th ecompute r modelwa s runwit h some ofth erelation s changed orwit h subprocesses omitted andreplace db ysimpl e algorithms. This sensitivity analysis gives thefollowin g results.

Immigration

Ignoring immigration inth esimulatio n after theen do fMa yha dlittl e effect onultimat e growth in197 6bu ta distinc t onei n197 5an d1977 .I n197 6immigratio n before theen do f May determined later population level.

293 Emigration

Theoffsprin go falate sar egenerall yapterou slik ethos eo fnon-crowde daptera ebu t thelatte rsituatio nrarel yoccur si nth eepidemic .Crowdin gL icause simmediat ewin gdevel ­ opmenti nsom especimens .Crowdin go fLi ,an dapterou sadult sresult si nman yalat eoff ­ spring.Th efat eo fthes ealate si svita l forunderstandin g theepidemic .D othe yemigrat e ord othe ysta yi nth efiel dan dreproduce ?Fiel dobservation sindicat etha tmos to fthe m emigratebu tsom ema yreproduce .N ocorrelatio nwa sfoun dbetwee nth enumbe ro falate s swarmingabov eth efiel dafte rth emiddl eo fJun ean dth enumbe ri nth efiel do nth eplants . Noincreas ei nth enumbe ro fL iwa sfoun di ntha tperiod .Moreove rth enumbe ro faptera e decreasedi ncontradictio nt oa nimportan trol eo falate sremainin gi nth efiel dan drepro ­ ducing,a sthes ealate sshoul dhav emainl yapterou soffspring . Inth emodel ,w eassume dtha ti nthi sphas en oimmigratio noccurre dan dtha talate swer e lostfro mth esystem .A sth ecurve so fsimulatio nan dfiel dobservation sreasonabl ycoincide , thissupport sou rhypothesi so nalat ebehaviour .

Prédation

Withemigratio nalone ,th epopulatio ncollaps ewa sno tcompletel ypredicted .Th ecalcu ­ lationsshowe dth enecessit yo fa nimportan tmortalit y factor.Beside s Entomophthora spp., predatorslik eSyrphid swer eimportant .I nth efina lphas eo fth eepidemic ,suc hfactor s thateliminat eapterou sadult sar evita lt oth ecollapse .Prédatio no nlarva ei sles sim ­ portantthen ,a smos to fthes edevelo pint oemigratin galates .Th erol eo fparasite sto o hast ob econsidere dwit hthi saspec ti nmind .Whe nthe yprefe rt oattac konl yyounge rsta ­ ges,the yar eunlikel yt ocontribut emuc ht opopulatio ncollapse . Theim.'de lcalculation sreveale dtha tth eplac eo fth ebreakin gpoin ti nth efunctiona l responsecurv efo rpredator' sprédatio nrat eo npre ydensit ywa sessentia li ndescribin g itseffect .

ABIOTICFACTOR S

Inth esimulatio nmodel ,a decreas eo ftemperatur edelaye dpopulatio ngrowt hbu tth e populationfinall yreache da highe rlevel ,perhap sbecaus eo fdifference si nrespons et o temperatureo fgrowt hrate so fplan ta naphid . Notincorporate d inth emode lwer eth eparasite san ddiseases .Th eaphidii dparasite s Aphidius uzbékistanieus resembling A. ervi, A. piaipes and Praon voluore werefoun dreg ­ ularly. Eachyear ,anothe rspecie spredominated .Onl yi n1977 ,a clea reffec to fparasite swa s foundwhe nthe ywer eprobabl yresponsibl efo ra 60%decreas ei nth enumbe ro faptera edur ­ ingth egrowt hphas eo fth eepidemic .I nth efina lphas emos taphidiid sar eattacke db y hyperparasites.I n1977 ,a ver yhig hpercentag eo faphid swa sattacke db y Entomophthora spp.I twa sno tincorporate d inth emode la slittl ewa sknow no fth ebiology .

294 POPULATIONCOUNT S

Infiel dwork ,al llarva lstages ,apterae ,alates ,mummifie daphids ,predator san daphid s attackedb y Entomophthora spp.wer ecounted .W etrie dt oobtai na naccurac y levelo f S (x)/x <0. 1 forth etota lnumbe ro flivin gaphids .S osampl esiz ewa sconstantl ychanging . Asa rule ,th enumbe ro fsample sdecrease swhe nth enumbe ro faphid sincreases .Wit ha doub ­ lingtim eo fabou tthre edays ,th epopulatio ngrow sb ysom e 25%pe rday .S oi norde rt o keepth evarianc e low,al lcount shav et ob ecomplete dwithi na day . Weatherstrongl yaffect svariance .Whe nth eweathe ri sbad ,aphid sbecom emor eevenl y distributedove rth eplants .I ti sye tunclea rho wthi sfacto rwil laffec tth efutur egrowt h rateo fth epopulation .I nth enotabl yba dsumme ro f1978 ,thi smor eeve ndistributio nwa s clearlyobserved .

PROSPECTS

Knowledgeabou tth eprocesse si nth esyste mi slacking .A smor eexperimenta ldat abecom e availablefo rus ei nth emodel ,ou rconfidenc eca nincrease .O fmuc himportanc ei sth ehel p ofth emode li nintegratio no ffragmentar yknowledg ean dguidanc ei nexperiments . Thedevelopmen to fa forecastin gmode lform sjus ton epar to fth ewarnin gsystem .Mor e knowledge isneede do fth eeffec to fth eaphid so nthei rhos tplan tan do fhos to naphi d toreac ha reliabl emanagemen tsystem .Th eresult so fa combine dpopulatio nmode lan d plantmode lar eencouragin g (Rabbinge& Vereijken ,1979 )bu tstil lmuc hmor eresearc hi s neededt omak ethes emodel sapplicabl ei npractice .

REFERENCES

Rabbinge,R .& P.H .Vereijken , 1979.Th eeffec to fdisease so rpest supo nth ehost .Proc . 3rdInt .Congress .PI .Path .Munic h1978 . Rabbinge,R. ,G.W .Ankersmi t &G.A .Pak , 1979.Epidemiolog y and simulationo fpopulatio n developmento fSitobio navena ei nwinte rwheat .Neth .J .PI .Path .8 5 :197-220 . Vereijken,P.H. , 1979.Physiologica lan decologica laspect so fth ecerea laphid-whea trela ­ tionship.Versl .landbouwk .Onderz .888 ,Pudoc ,Wageningen .5 8p .Als odoctora lthesis .

29S Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 10.3 Meteorology and integrated pest control

W.N.Lablan s

RoyalNetherland sMeteorologica l Institute,D eBilt ,th eNetherlands .

INTRODUCTION

Populationso fplant san danimal smee twit hth einfluence so fthei rbiotic ,chemica l andphysica lenvironment .Th equantitativ eassessmen to fthes einfluence so nth edevelop ­ mento fpopulation so fa plan to ra ninsec ti sa tas kfo rbiologists .Assistanc e fromothe r disciplines,however ,ca nb ehelpful .S oi twa sdecided ,whe nth eexperimenta lorchar do f theWorkin gPart yo nIntegrate dContro lo fPest swa sse tu pa tLienden ,t oprovid esupportin g meteorologicalobservations .

METEOROLOGICALOBSERVATION SI NTH EEXPERIMENTAI ,ORCHAR D

Since1969 ,temperature ,humidity ,win dan dradiatio nhav ebee nrecorde di nth eorchar d withclassica lmeteorologica l instrumentssuc ha sthermometers ,thermographs ,hygrographs , aMoll-Gorczynsk imete rfo rdiffus eradiatio nan da Lambrech tcu panemomete rfo rwin dspee d anddirection .Th edat ahav ebee nuse di nbiologica linvestigations .Notabl ei sth einves ­ tigationo fRabbing e (1976;Sectio n10.1 )o nth efeasibilit yo fbiologoca lcontro lo fth e fruit-treere dspide rmit e (Panonyahus ulnri). Fortha tproject ,th emeteorologica lmeasure ­ mentsa tLiende nwer eintensifie di nselecte dsituation sdurin gth eyear s 1973-1975.Espe ­ ciallyattentio nwa spai dt oth etemperatur eregim ei nth eorchard .

METEOROLOGICALASPECT SO FRESEARC HO NTH EBIOLOGICA LCONTRO LO FTH EFRUIT-TRE ERE DSPIDE R MITE

Fromlaborator yresearch ,Rabbing e (1976)foun dtha tth einfluenc eo ftemperatur eo n developmentan dfluctuation so fa populatio no f Panonyahus ulmi iso fsuc hsignificanc e thati na mathematica lmodel ,whic hsimulate sdevelopmen to fa populatio no fth emite ,th e temperatureshoul db eintroduce da sa drivin gvariable . Foroutdoo rresearc han dth eapplicatio no fth emode li npractice ,i twa srecognize d thatth eindividua lmite swil lb esubjec tt oth etemperatur eo fth etre eleaves ,whic hma y bedifferen t fromth eai rtemperatur ea smeasure di na standar dmeteorologica lcabinet . Thesedifference soriginat ebecaus eth etemperatur eo fth elea fi sno tonl ydetermine db y thetemperatur eo fsurroundin gai rbu tals ob yprocesse s likeradiatio nan devaporation .

297 Agoo dstartin gpoin tfo rth eassessmen to fth ecircumstance sunde rwhic han dt owha t extentth etemperatur eo fa lea fca ndeviat efro mth etemperatur eo fth eai ri sth enotio n thatth estorag ecapacit y forenerg yo fa lea fi snegligible .S oth etota linciden tenerg y fluxesequal ,th eenerg yrat eo floss .No wenerg y isgaine db yth elea fi nvariou sforms : ashea twhe nth elea fi scolde rtha nth esurroundin gair ,a sradiatio nfro msu nan dsk y anda sradiatio nemitte do rreflecte dfro mth egroun dan dfro mobject si nth eenvironment . Energyi slos tb yth elea fi nth efor mo fhea twhe nth elea fi swarme rtha nth eair ,a s thermalradiatio nemitte db yth elea fan da slaten thea tdu et oevaporatio no fwater . Sowhe nther ei sconsiderabl einciden tradiation ,th eleaf' stemperatur erise ssuffi ­ cientlytha tth ehea tflu xan dth eflu xo fwate rvapou rt oth eenvironmen tkee pth eenerg y fluxesbalanced . Inbrigh tsunshine ,suc hdeviation so fth elea ftemperatur efro mth eai rtemperatur e mayamoun tt oove r 10 C,a si sdemonstrate di nFigur e 1wher eobservation sar erecorde d ofa typica lsumme rda yi nth eorchar da tLienden . Leaftemperature sca nnowaday sb eeasil ymeasure dwit hradiatio nthermometers ,bu tca n alsob ecalculate dfro mth emathematica lexpressio no fth eenerg ybalanc edescribe dabove . Adrawbac kbot hfo rmeasurement san dfo rcalculation si sth evariabilit yo flea ftempera ­ tures.Firstl yther ei sth evariabilit yi ntime ,correspondin g tovariation si nth eenerg y fluxes.Bu ta ta certai nmoment ,th etemperatur eo fa nindividua l leafo fa tre edepend s stronglyo nth eexposur eo ftha tlea ft osunshin eo rshadow . Thedetai li nwhic hmeteorologica lquantities ,suc ha slea ftemperatures ,hav et ob e

Temperature(°C ) 35-

25

15-

1 10.00 12.00 14.00 16.00 Hours(M.E.T. ) Fig. 1.Temperature s of leaves and air in the experimental orchard on a bright summer day (28Augus t 1973). • Temperature of leaves exposed to bright sunshine, Temperature of the air at 1.50 m (thermograph).

298 Height(m ) 4

4 5 Distancebetwee ntree s(r Fig.2 .Temperatur eprofil ei nth eorchar do n2 0Jun e 1974a t00:3 5h an d thegeometr yo f theorchard .

knowndepend so nth enatur eo fth ebiologica lproble munde rstudy .Rabbing etherefor etest ­ edth esensitivit yo fhi smode lcalculation swit hpopulation so f Panonychus ulmi tovari ­ ationsi nth edetai lo fth emeteorologica lsub-model .H efoun dtha tcalculation swit hspe ­ cifiedlea ftemperature san dcalculation swher eaverag eai rtemperature swer euse dgav e onlysligh tdifference si nth eresult so fth esimulatio no fth epopulatio no f P.ulmi, so fortha tpurpose ,th eai rtemperature smeasure di na cabine ta theigh t1.50 mcoul db e usedt orepresen tth etemperatur eo fth epopulatio ni nth esimulatio nmodel . Besidesth edifferenc ebetwee nai ran dlea ftemperature ,variation so ftemperatur ewit h heighti nth eorchar dcoul dals ob eneglected ,sinc evertica ltemperatur egradient s inor ­ chardsar esmal l (Landsberge tal .1973) .Th edevelopmen to fstee ptemperatur egradient s sucha soccu rove rope nterrai ndurin gcal mclea rnight si sstrongl yimpede di norchard s byth evegetation .Th ecoolin go fbranche san dleave sdu et othei renerg ylos sa sinfrare d radiationcause sa coolin gthroughou tth edept ho fth eorchar dan dth ecoolin go fth egroun d ishampere db yth einfrare dradiatio nfro mth evegetation .A typica lexampl eo fth enoctur ­ nalcoolin gi na clea rnight ,a sobserve di nth eorchar da tLiende ni sshow ni nFigur e2 .

CONCLUDINGREMAR K

Therequirement s formeteorologica lsuppor tt obiologica lo ragricultura lresearc hrang e fromth esupplyin go fmeteorologica ldat atha tca neasil yb egathere dt oth estud yo fmicro - meteorologicalproblem stha tg obeyon dexistin gknowledg eo ravailabl eresearc hcapacity . Iti stherefor eadvisabl etha ti nth eplannin gstag eo fbiologica lresearc hi tb erecognize d whetherth ephysica lenvironmen twil lpla ya nimportan trol ean dtha tth efeasibilit yb e investigatedo fadequat esuppor tfro mmeteorologica lo rphysica ldisciplines .

299 REFERENCES

Rabbinge, R., 1976.Biologica l control of fruit-tree red spider mite. Simulation Monographs, Pudoc,Wageningen , 234 p. Landsberg, J.J., Powel, D.B.B. &D.R . Butler, 1973.Microclimat e in an apple orchard. J. appl. Ecol. 10 :881-896 .

300 Integrated control of insect pests in the Netherlands. Pudoc, Wageningen, 1980. 10.4 Radionuclides and ionizing radiation in research on integrated control

J.Ph .W .Noordin k

ResearchInstitut efo rPlan tProtectio n (IPO),Wageningen ,th eNetherlands .

Duringth epas ttwent yyear sradionuclide shav ebee nuse dextensivel y inentomologica l research.Som easpect sar edescribe dt ogiv ea nimpressio no fth erol eisotope splaye di n researcho nintegrate dcontrol .

DISPERSAL

Oneda ystarve dpredator ymites , Amblyseius potentillae, werelabelle dwit h 32P. mixedwit hhone yan drelease di na nappl etree .Afte r2 week si twa spossibl et ofin dsom e ofthe mwit ha smal lportabl eGeige rcounter .Thei rdispersa lwa sfoun dt ob eabou t2 m , butmos to fth erelease dspecimen swer estil la tth epoin to frelease . Inintegrate dcontrol ,predator ywasp s like Trichogramm spp.an d Colpoclypeus spp.ca n playa majo rrole .T ostud ydispersa lo fthes einsects ,isotope swer eused .Fo r Trichogvamma. eggso f Sitotroga cerealella weresprinkle dove rstick ypiece so fcardboar ddistribute di n anorchard . Trichogramm labelledwit h 32Pwer erelease dan dafte ra wee kth epiece so f cardboardwer ecollected .Whe nautoradiographed ,th eblackenin go fth efil move rsom e Sitotroga eggsprove dparasitizatio nb yth eradioactiv ewasps ,thu sestablishin gthei rdis ­ persal. Colpoclypeus florus waslabelle dwit hvariou sisotope ssuc ha s x"*C ,32 P and65 Zni nstu ­ dieso ndispersa lan deffectiveness .I twa sfoun dtha t 1'*C-leucinewa sa satisfactor ylabe l thatwa stransferre d fromth elabelle dparen tt oit sprogen ywher ei tcoul db edetecte db y autoradiography. Sometrial swer edon ewit h 32P-labelled Adoxophyes orana tostud yit sfligh trang ei n thefiel dan dth eeffec to fit spheromone .Tagge dmal especimen swer erelease di na norchard . Speciallydesigne dse xtrap swer edistribute d inth eorchar dan dth einsect scaugh twer e assayedfo rradioactivity .Minimu mnigh ttemperature sbelo w 12 Clowere dth efligh tactiv ­ ityan dals oth ese xtra pcatches .Dat acollecte db yusin ga releas ecentr eshowe dtha t thewin di sa determinin gfacto rfo rth eupwin dorientatio no fth emal emoth st oth eattrac ­ tivefemale s (Minks& Noordink ,1971) . Inpreliminar ytrial swit hth estrawberr yblosso mweevil , Anthonornus mibi, severaliso ­ topeswer euse dt olabe lth eadult s( 22Na,32 P, 60Coan d 65Zn). Thefirs tresult sindicate d that 32Pwa sa nexcellen ttrace rfo rdispersa lstudie swit hth eoverwintere dgeneration . Evenafte r2 months ,th einitia lmar kcoul db edetecte dautoradiographically ,no tonl yi n

301 theparen tgeneratio nbu tals oi nit sprogeny .Th eothe risotope swil lb euse dt olabe l theoverwinterin ggeneratio nbecaus elonge rhal flive san dmor epenetrativ eradiatio nar e needed.

PREY-PREDATORRELATIONSHI P

Intrial so nth eprey-predato rrelationshi pbetwee nth epredator ymit e Amblyseius po- tentillae andit spre y Tetranychus uvticae, thepre ywa s labelledwit h 32P andoffere dt o thepredato rfo ra measure dtime .The nth eradioactivit yi npredato ran dpre ywa sdetermine d separately ina scintillatio ncounte rb yth eCerenko vtechnique .Fro mth erati oo fth eradio ­ activitybetwee npredato ran dprey ,th erelevan tdat acoul db ecalculated . Thelabelle d Colpoolypeus florus wasuse dt ostud yth eeffectivenes so flaboratory-rear ­ edspecimen so nth eparasitizatio no flea froller si nth efield .Als oth erati ocoul db e estimatedbetwee nnumbe ro finsect srelease di nth eorchar dan dimmigratin ginsects .

DIETARYPREFERENC E

Theinfluenc eo fsom echemica lconstituent so fa syntheti cdie to ndie tuptak ean deg g 32 productiono fyoun g Tetranychus urtiaae femaleswa sinvestigate dwit hNa 2H POi,.Th ehighes t dietaryuptak ean deg gproductio noccurre da tp H 10wit hth estandar ddiet .Additio no f adenosinetriphosphat eincrease dth erat eo fingestion . Inanothe rtrial ,th eturn-ove ro fphosphoru swa sdetermine db yputtin gspecimen so f thetwo-spotte dspide rmit eo nplant smad eradioactiv ewit h 32P.Ever y 2h ,th eegg sproduc ­ eddurin gtha ttim ewer ecollecte dan dmounte do ndiscarde dX-ra y film.Afte r2 4h ,th e assembledegg swer eautoradiographe dan dexpose dfo r2 weeks .B y5 h afte rthei rtransfe r toth eradioactiv eplant ,th emite sproduce dradioactiv eeggs ,s otha tturn-ove ro fphospho ­ ruswa srapid .Whe nth emite stha tha dproduce dth elabelle degg swer epu to nnorma lplants , ittoo kthe m5 day st odeposi tnormal ,no tradioactiv eeggs .Th efemale sthemselves ,how ­ ever,wer estil lver yradioactive .Thi simplie stha tth emite sus eonl yrecentl yacquire d phosphorusfo reg gproduction . Radiophosphoruswa suse dt ostud yth etast eperceptio no f Myzus persioae. Withparafil m sachetsaphid swer eoffere da choic ebetwee ndifferen tsolution sand ,b ymakin gon eo fthe m radioactiveth eaphid sprove deasil yan dquickl yt odistinguis hbetwee na basi cdie tan da sugarsolution .Autoradiograph swer emad eo faphid swhic hha da nhour' schoic ebetwee ntw o solutionso fdifferen tnutritiv evalue ,on eo fwhic hwa sradioactiv e (Harrewijn& Noordink , 1971).

MOVEMENTO FAPHI DSALIV AI NSEEDLING S

Translocationo faphi dsaliv ai na nappl eseedlin gwa sprove db ycontainin g 32P-labelled Dysaphis deveata immediatelybelo wth ecotyledons .Non-radioactiv eaphid swer eplace da t theape xo fth eseedlin gwher ethe yfe dfo ra week .Th eleaves ,roots ,cotyledon san dth e aphidstha tha dfe da tth eshoo tti pwer eautoradiographe d for3 weeks .Th eblackenin go f theplan tpart san dth erecepto raphid sshowe dtha tth eradioactiv esaliv ao fth einitiall y

302 labelledaphid swa s transportedthroughou tth eplan tan dwa ssubsequentl y takenu pb yth e aphidsfeedin ga tth eplan tape x (Forrest& Noordink ,1971) .

STERILEMAL ETECHNIQU E

Inth emid-sixties ,i tbecam eclea rtha tth eonio nfly , Delia antiqua, haddevelope d resistancet oa numbe ro forganochlorin e insecticides.T oensur eth efutur econtro lo fth e fly,i twa sdecide dt ostud yth efeasibilit yo fth esteril emal etechnique .Apar t fromscien ­ tifican dtechnica laspect ssuc ha sdispersal ,an drearing ,th eappropriat eradiatio ndos e hadt ob eestablished .Afte ra numbe ro ftrial si twa sdecide dt ous e3 0G y (3krad )o f hardgamm arays ,emitte db y 60Co,t osterilis eth eflie sa spupae .Receivin gtha tdos eth e maleswer esteril efo rmor etha n98° &wherea sth efemale swer einfecun dafte ra dos eo f2 0 Gy (2krad) .Wit hsevera lisotopes ,th epolygam yo fth efemales ,th edispersa lo firradiate d flies,th eoverwinterin gmortalit yan dth elengt ho fspermatogenesi swer eestablished .Now , about 15year slater ,ther ei sevidenc etha tthi stechniqu ei ssuitabl efo rimplementatio n incommercia lonio ngrowin g (Ticheler& Noordink , 1968).

NEMATODES

With ^C-labelledoxamyl ,a nematicide/insecticide ,severa ltrial swer edon et oestablis h itssystemi cbehaviour .Leave so f Vicia faba plantswer etreate dwit ha solutio no fconcen ­ tration4 g/ 1an dafte ra certai ntim edried ,mounte do nfilte rpape ran dautoradiographed . Allplan tpart sbecam eradioactiv e inbot hth esymplasti can dapoplasti cdirectio nfro m thepoin to ftreatment .Extremel ylarg eplant swhos emiddl e leafwa streate dals oshowe d agenera ldistributio no fradioactivit y inothe rleave san di nth eroots .B ythin-laye r chromatographyan dsubsequen tautoradiography ,roo texudate swer eexamined .Beside ssom e breakdownproducts ,a smal lamoun to f'"'C-oxamy lapplie dt oth eleave swa spresen ti nth e rootexudate s (Bunt& Noordink , 1977).

MISCELLANEOUS

Biogenicamine slabelle dwit h lhC wereinjecte di nver ysmal lamount sint o Myzus persiaae. Mienth enex tgeneratio nwer et ob eapterous ,certai ncell so fth eprotocerebru man do fth e abdominalganglio nan dth ebrai no fth eunbor nembry obecam elabelle dwithi n 15mi no fth e injection.N osuc hreactio ntoo kplac ewhe nth eembry owoul dproduc ea nalate .I napterou s larvae,th eserotonergi c activity inth ewin gbud swa sno tenhanced .S osubstance saffectin g thisproces shav ea direc timpac to nth ebrai nan dca ninfluenc ewin gdimorphis mver y quickly. Theefficienc yt odetec tradioactivit yo fX-ra y filmswa scompare dwit htha to fa thin - -windowGeige rcounter .Unte rth ecircumstance so fou rtrial ,th efil mwa sabou tsevent y timesa ssensitiv et o 32Pradiatio na sth eelectroni ccounte r (Noordink& Minks ,1970) .

303 REFERENCES

Bunt, A.J. &J.Ph.W . Noordink, 1977.Autoradiographi c studies with 'V-oxamyl inVici a faba infested with Pratylenchus penetrans.Meded . Fac. Landbouwwet. Rijksuniv. Gent 42(2) : 1549-1558. Forrest, J.M.S. &J.Ph.W . Noordink, 1971.Translocatio n and subsequent uptake by aphids of 3 P introduced into plants by radioactive aphids. Entomologia exp. appl. 14 :133-134 . Harrewijn, P. &J.Ph.W .Noordink , 1971.Tast e perception of Myzus persicae in relation to food uptake and developmental processes. Entomologia exp. appl. 14 :413-419 . Minks, A.K. &J.Ph.W . Noordink, 1971. Sex attraction of the summerfruit tortrix moth,Ado - xophyes orana: an evaluation in the field. Entomologia exp. appl. 14 :57-72 . Noordink, J.Ph.W. &A.K . Minks, 1970.Autoradiography : a sensitive method in dispersal stu­ dies with Adoxophyes orana. Entomologia exp. appl. 13 :448-454 . Ticheler, J. &J.Ph.W .Noordink , 1968.Applicatio n of the sterile male technique on the onion fly, Hylemya antiqua (Meig.), in the Netherlands. Progress report. In:LAEA : Radia­ tion, radioisotopes and rearing methods in the control of insect pests. International Atomic Energy Agency, Vienna p. 111-115.

Instituut voor onderzo ;k van bestrijdingsmiddelen Marijkeweg 22 6709 PG Wageningen Tel. 08370 -11821/11752

304