Biology and control of the groundnut leafminer, Aproaerema modicella (Deventer) (Lepidoptera: Gelechiidae)
T. G. Shanower*, J. A. Wlghtman and A. P. Gutlerrez' Legumes Entomology, ICRISAT, Patancheru PO, Andhra Pradesh 502 324, Indla and '~lvlslonof B~olog~calControl, University of California. Berkeley. 1050 San Pablo Avenue, Albany. CA 94706, USA
Abstract The gr~)~~ndr~c~tI~,:~tniincr. ,.?~~rocrtr-c~rt~ri rtroclrii'l!i.r (Ilcvcntcr) (I.cpidoptera: (iclcchlldac). I\ ;In 1ri1lxnta111pC\1 of \cvcr;ll lcyl~rnccrop\ in South anil So~~th-I:a\tA\ia. For grountlnut. \iclll loh\c\ of --.511",, h;~\cIhcxcn rclx>rtc(l 11. ;~dd~t~on(1) grouriclnut and \o\hci111 (the main crops att;~ckcd).I2 ;iltcrr~;~t~\clio\~ plants h;~vct~,clr :i~por-tctl ,I, r~rr~ilrccllo IS prc\cnt thro~tgh~~~ttlic rcgioli. ;iIthough it ha\ licc~i\~LI~IL~ rr~o\t iri~cnsivrl~ in 11id1;1:11icI '~II;III~III~I I
Keywords Groundnut Atachrs Aproa~remarnod~celia qroundnut leafmtner natural enemles biology host plants
Taxonomy and distribution Victn;~ni. ('hin:~. the Philippines. Indonesia anrl ,M;iIi~ysi;l(hlohamm;~d. 10Sl: ('amphell. 1083: Islam r7/ The groundnu1 Izafm~ncr ((;LI\I), ,.lprotrc,r.c~rr~(~ ill.. 1083; ('SONC.1985). In India, u here GI M has hccn tnotiicc~llu(L)c\'cnter) (I cpicloptcr;~:Ciclcchiid;~c), i\ a sludicd mo\t cstcnsively. il ii found in 'I'ornil Nadu, scrious pc\t ot gr'ouridnut ;rntl \oybe;~nin So~crh:tnd Aridhra 13ratle.;h, K;~rnatak;r. Mah:~r;~hhtra.Madhy;~ South-Ea\t Asi;~(W~ghtnian (,/ (11.. IOVO). Arnln ( IOSi) F'r;ldc.hh. Ciujxrat. Punj;lb. Ilclhi. Raj;lsthan. Orissa has callcd it thC most impc~rtarit grounclnut pc.;t in and \%'cst Rcng;rl {klloliamrnad, 1081) India. Originally clcscril>ed ;i.; ilrtrrcc~rrlpsi,~ric~r/c,r.in With the esccption ,IS Rorc'ria hi.~pidti(Kuhiaccr~e). Meyr. Iron1 specimens collcctcd in India (Mcyrick. (i1.M tcc>ds onl! on leguminous host pl;lnts (7hhlc 1). 1006). five othcr binomial\ have rclcrr-cd to the silrnc pcst: Hilohri .~~rh.rc~r~i~~clltr~Zcllcr. .S/orr~optcr,~.r rtc,rtclrlci Mcyr.. S/otnol,/r.ry.\ trr,r/nrin Mqr.. S/orriop/rrv.\ Table 1. Host plants of Aproaerema modrcella .s~cOst~c~ii~c~llnZellcr. and AprcjclrrcJr7llr tir7rtcria Meyr. 'The ~~nccrtaintaxonomy was due to the euistcncc of Sc~critltli.11;lnic K~lcrcncc Iwo, nun-congcricric leaf-miners: onc from South .\tu( /ir\ /iipo,qi~~,uI bl;~xw~~ll-lct~o! ;~tl~i IiouI~Yt, IYOV Africa is now c;~llcd,S/ornol~/rry.r .snl~.rc~c~i~~c~lla (%cller) : (;I\ c itti, rti~it (I. ) bfcrr R,itn,~hr~\hn.lAy\.:ir luJ0 rhc second is the Indian-Indonesian groundnut Ic;if- 1'1gri(r~III!I(I~II (I ) Wil/i.~,k miner, Aproctercrli~u rliiodic.e~llii (Dcventcr) [J. I). ( = I'IIuY~~~111i.\(III~CII.! IJr&,id PI id/ , IV7 I ( III I , 1 hll B,~inhr~dgc-FIc~cIit~~.102(1 Drndley, British Muscum (N;ltural Ilistory) personal I.li~lill~ll,ql,\oil1 ,I I.. S,iii~lli~~,1'177 comniunic;~tior~in Mohamrnad. lOXI] Ilcvcnter (1904. /'\,>I~I/~YI ( O~\,/I~O/III L. Mi~sucll-1ctrc~! and Howlcll. 1')011 /rz~,pifi,rir/II~SIIIII I .. J,II Rao and '1't11r111ii;1I;tcli;ir.1477 in Moh;~nirn;~d.1981 ) origin;rlly described A. rrrodic~cllu I 'IXII~III~I~~I~II~I~I (Thunb.) from ;I moth collected in Java. Incloncsia. Ohui and Oli;~\hi The geographical range of A. rnoilic~lluis rcstrictcd (=Mrnrr.olir.rr~irlur.ur<~/tc\ .lai Hao :ind 'I'h~rum;il;ich;ir.1077 (;lvi~r~r.\r,/ii Sich. 't 7.iic.c L'anl~;~ll.ti)?? (in Mohanimad. IVRI) to South and South-East Asia, from Pakistan to China j111rt11111tlri11r1 I Ttion~ad,~r,;~.Jill KCio iind Kumar. and as far south as the Philippines arid Sri Lanka. It has 11)70 been rcported from Pakistan, India. Sri I.ankir. /~~rllt~11111.\i~llllfllf,\ (I . ) Sprcng 1):ih and MI~~:I,ION4 13angladesh, Myanmar, I'hailnnd. I.aos, Kampuchea, I uhl~lhj)~irlwro~(.\ l [)a\ and M~\ra.1984 KIIYIIC/r,~.sru trto~rniu I )c SII~IV;I\;I~and S~vn K;Io. lYh4 liort2r~uIIIS[IIL/~ K Sch Srin~v:~\anand Slv:~K;I 0261-21 94/93/01 /000348 @ 1993 Butterworth-Heinemann Ltd CROP PROTECTION Vol. 12 Februav 1993 4 B~ologyand control of Aproaerema mod~cella:T G. Shanower etal. Several are crop plants, the most important being ments indicate that, in peninsular India, GI.M larvac groundnut (Arachis hypoguea L.), soybean [Glyc-inr pass through five instars (Shanower. 1989). mux (L.) Merr.], pigeonpea [('ajanu.~ c,ujan (L.) Pupation occurs within the webbed leaflet\ and Millsp.] and alfalfa (Medicago sutiva L.). Phisitkul requires 72 degree-days above a threshold of 14.7"C (1985) tried unsuccessfully to rear GLM on a variety of (Shanower, 1989) and can be completed in .%I0 days at other plants, sunhcmp (('rotuluriu juncou I>.), winged ambient temperatures (Chcrian and Hasheer, 1942; bean [/?sophocurpus tctrugono1ob1c.s (L..) I) .C.], yard Sandhu, 1978). 'l'he egg-to-adult lifc cycle is completed long bean [Vignu sincn,si.s (L.) Saviex tlask subsp. in roughly 450 degree-days (Shanower, 1989) or 15-28 .se.squi~~edafi.sFruwirthj, siratro (Macropfilium atro- days in southern lndia (Chcrian and Basheer, 1942). In purpurcum I,.), hamata (Stylosunth~s harnutu 1,. ), northcm India. when mean temperatures rangc cowpea [Vignu sinensis (L.) Saviex Hask]. showy between 14 and 22°C'. the lifc cyclc may require 2735 crotolaria (('rotuluriu pallida Ait.), and sword bean days (Sandhu, 1978). (C'unuvulia gladiula 1) .C.). Females oviposited on these plants at a much lower rate than on groundnut and soybean, and larvae did not survivc beyond the first instar. Seasonal population dynamics A. modic,~lluhas been an important pest of groundnut Life-cycle and population dynamics in India for >?O !car5 (Amin and Mohanimad, 1980). ('ontinuous cultivation of groundnut using irrigation. Maxwcll-1,efroy and Howlett (1909) and D'tinbrtdgc- or a groundnutlsoybca~irotation. allow CiLM popula- Fletcher (1920) were among the first to dcscribc ;nd tions to build up (Wightman and Amin. 1088). Even in document the life cyclc of GLM. C'herian and Riishccr thc abscncc of groundnut or soyhcan. GLM popula- (1942), Kapadia, Bharodia and Vera (1Y83) arid tion> can persist on one 01 several wild host\ (Tuhli, I). Phisitkul (1985) also givc detailed accounts of CiLM Morc than 3000 GLM larvae havc hcen found on a biology. Small (320 very active. Males and females can be distinguished in larvae per plant. Extremely high densities (>50 larvae the larval stage by the distinctive pink gonads of the per plant) were recorded in two rainy seasons (1984 and male which are visible through the cuticle. Larval 1987) and two postrainy seasons (1981 and 1982). In the development requires approx~mately325 degree-days other seasons, densities ranged between 10 and ?(I above a threshold temperature ot 11.3"C (Shanower. larvae per plant. 1989). Under ficld cond~tionsat amb~enttemperature. Two GLM generations per crop are typical in larval development lasts between nine and 28 days Thailand (Campbell. 1983), whereas in China seven (Chcrian and Basheer, 1942; Sandhu, 1978; Kapadia et generations havc been reported on a single soybean al., 1982). crop (Yang and Liu. 1966). Three to four generations Different numbers of instars have been reported in per season are common on groundnut in India, although the literature. Kapadia et al. (1982) reported three, five generations havc been reported during the rainy Gujrati cJt 01. (1973) four, Amin (1987) five, and Islam season in south lndia (Logiswaran and Mohana- et (11. (1983) six larval instars. Head capsule measure- sundaram. 1986). Climatic factors and artificially infested groundnut plants with different levels of Ci1.M. A regression of yield loss versus Abiotic factors, principally rainfall, humidity arid infestation rcvcalcd that each 1'%# inlcstation ot G1.M temperature, arc frequently suggested as causes of resulted in 1.2'%,yield loss. Data from screen cages can populatiori fluctuations. Khan and Raodeo (1087) bc misleading because the cages reduce sunlight, thus obscrvcd GLM populations over two years in 'I'amil possibly confounding the results. Nadu. High populations were recorded from August The irnpact of (i1,M on groundnut growth and yieltl through February, but in March dcclincd to a low level. is in part dctcrmincd by the time of infestation, An 'I'hc authors claimed that high rainfall was the key infestation of five larvac pcr plant 10 days aftcr factor regulating G1.M populations, although their data emergence has u much greater impact than 30 larvac do not support this conclusion. The high populations per plant at 75 days aftcr emergence. (ihule ~t a/. obscrvcd in August- September occurred during a high (IO87b) fotlnd that groundnuts need protection from rainfall period; populations dcclincd in March whcn no CiLM bctwccn 45 and 75 days after emergence; rain was rccordcd (Khan and Kaodco, 1987). howevcr, this is truc only if G1.M populations arc lob. Amin (1987) has suggcsterl that heavy rainhll early in the ae;ison. A recornmended action threshold reduces lcafminer populations, although Wheatley et in India is 61 70 I;irvae pcr 100 leaflets ((;liew;~ndc. (11. (1089) found that water from an ovcrhcad irrigation Nandagopal and Kcddy. 1987). systcm did not lower (i1.M density. Lewin et ul. (1070) found a sign~ficantnegative correlation bctwccn GLM incidence and rainfall: highcr CLM incidcncc was Cultural control and host-plant resistance correlated with lower rainfall. Tcrnperi~turc.within the rangc experienced in the trial, was also posit~vcly Scvcral cultural mcthods havc hccn rccommenilcd for correlated with CiLM incidence and accounrcd for control of C;I,M. although only intcrcropping and morc of thc variation than rainfall (Lewin (,/ cil.. 1070). manipulation of planting cliitc have been tc5tcd. Another study at the some location rcvcalcd a signific- Logiswaran and Mohanasundarani (1985) founci lower ant negative correlation hctwcen infestation and G1.M larval densities whcn groundnut was intcr- tcrnperaturc (Logiswaran 1'1 a/., 1087). Lxpcrimcrits cropped with sorghum, millet or cowpca. than in using a rain sim~~latorindici~tcd that the physical irnpact rnonoculturc groundnut at -30 X 10 cm spacing. Ilow- of rainf;rll on GLM eggs and larvac docs not signific- cvcr, the lowest (i1.M larval dcnsitit.5 in thih trir~luerc aritly increase mortality (Shanower. IYXY). Howcvcr. rccordcd in monoculture groundnut at close spacing rainfall niay havc a more suhtlc influcncc (c.g. iri- (15 X I0 cm). Mulching with rice straw hrid no effect on creasing huniiclity and favouring furigal pilthogcn5) on (i1.M lcvcls but ditl have a pos~tivccttcct on parasitism (iLM populr~tiondynamics. Icvcls: monocropped groundnut at 30 X 10 crn spacing had the lowest level of parr~sitisrn whereas a similrrr rrionocrop at 15 X I0 cm \p;~cirigh;~d the highat; inter- Damage and yield loss crop trt,;~trnt.ritsrill h;~dintcrmccliatc Ic\el\ of para\it- 17;ltion (Logiswaran and Motiaria\und:lra~ii, 1085). 'l'tit. 'The groundnut leafminer reduce\ groundnut and soy- i~uthorsdill not J~.;cuss thc ditfcrc~iccsbetuccn treat- bean yields by tccding on leaves, thereby reducing the rncntv.- nor clirl tlic!, \uggcct the rnccti;~riisminvol\cd. photosynthetically activc Ical arc;]. Islam rt (11. (1983) I tic effect of sowing date on (ilLIL? infestations has rcportcd that the feeding act~vityof a single larva will hccn the focus ot two studics: the first study (I-ewin ct destroy 34.8 cm' of lci~fti~suc. 'l'his is cquivalcnt to ul., 1079) showed that e;~rlysowing Icd to highcr consuming &I0 groundnut leaflets, depending on thc infestations ol (iLM, uhcrerls the second study genotypc, and seerns excessive tor such a small (L,ogiswarrui ct 141.. 1982) concluded that later plantings caterpillar. Sh;~nowcr(1980) mcasurcd the consump- werc more heavily attackcci. tion of individual larvae rind calculated that on average J'rogrcss has been m;rde in dcvcloping GLM-resistant 170.3 mrn2 of leal arca was catcn. or -tolerant cultivars. GLM resistance has hccn Jagtap, Ghulc and Deokal- (1984) tound that insect demonstrated in a wide rangc of genotypes. including pests, principr~lly CiLM ant1 Aphis cruc~c,ir~oruKoch. spreading. Spanish hunch. and Valencia growth habits accounted for a 16'b reduction in pod dry weight in (IC'RISA'I', 1086). Onc varicty. ICGV 8003l. has varicty JL 14 over a 3-year period (cquivalent to 303 kg shown good toler;incc to G1.M as well as to other ha I). 1,ogiswaran and Mohanasundaram (1985) defoliators (ICRISAI'. 1001). ICGV 86031 is an reportcd pod yield losscs of >50%, in 'I'aniil Nadu. improved genotype that may he grown in GL.M- Yield increases of up to 65% have been obtained in endemic areas and may he uscd as a suitable parent for sprayed plots comp;ired with unspraycd (check) plots germplasm enhanccmcnt by national agriculrtlral (Sivasubramanian and Palaniswamy, 1983; Rajput, research centres (ICRISAT. 10')l). Dalaya and Awate, 1985). Fiowevcr, using this tech- Bunch varieties arc generally considcrcd to hc less nique it is difficult to separate the losses attributable to susccptihlc to GLM, although Motka, Rhalan~and GLM from those caused hy other insects. Bharodia (1485) havc shown enhanccd growth and 'Tej Kumar and Devaraj Urs (1983) used scrccn cages development of GLM on thcse types. (irowth rate. CROP PROTECTION Vol. 12 February 1993 6 Biology and control of Aproaerema mod~cella:T. G. Shanower et a1 body weight arid percentage survival of larvae and Stage pupae, and weight and longevity ot' adults were Family Parasitold Host plant attacked compared in 10 varieties: Irrrval, pup;tl and utlult Rracori~d;~c weights were significantly higher un the bunch varicty Al,unti,h~rp. Ciro~~t~driucand JL 24 than on other varieties. L,arval survival ratc was si~vhcan alqo higher and aclults lived 5ignificantly longer when A, joi I,II\I.\ Rcrhwer (i~out~dr~ul I.arva /I \Lll~"~"""ll\i.\ SKI' (;riiund~i~~t Larva reared on this variety (Motka 1.1 (I/., lO8.5). A lrtuf Mxc~ri Soy1)c;ln I .arvu (;I,M-resistant soybcirn varieties have not, as yet, .4rSpotlrou\/~r\ N~xon iiri)u~idnut I.arv;~ Ixen Sound. Mundlic (1480) comp:rrcd 20 varieties and A IIILIJIII Suhh;~Ra~r & Sh,~rrna (iroundnut I.;I~\LI /j1141 Oli \p (rrr~u~idriut l-ar~;~ Sound no diffcrcnces in G1.M populations until 75 days llri,t if (J~III,\Wr\r~i (;ri,untlnut larva after sowing. In another trial 18 varieties wcrc compared I3 p~,lci,lirtrcA\hm Clroundnut and I .;irv:i (Slictgar and Fl'hc~ml>rc.IOX4j. hut again no dit'fercrices \oyl,can Iiroundnut in leafmincr populations were obser\ed. More recently, (irol~ndnut:~nd 30 soyhean varieties were cv:iluatccl during two r:~tny \ovhc;~ri seasons and a11 wcrc attacked by Ci1.M. although thrcc (;roundnut (ililur~dnut varieties hail significantly lower larv;\I populattonx (iroundtllir (Shrivastava. Sricast;~va;rrid Dcolc. 1088). Natural control ('tii~l~~d~d:~c, /I1 ill 11 rn71,riiI \p I-;I~\';I:i!i(I tiatural control, by disease\. prcd;ltor\ and p:1rasitoid5. pupa is irnportanl in suppressing (i1.M pcipul;rtton gt-owth. Lar\ :i :111tl At least tlirec disease agent\ (ncmatci~lcs.viruse\ and pupa I :Is\ :I fungi) infect (i1.h.l larvac In India. Ilni~lcntil'icd L.arv;~ rtlcrniithid nenlatodcs have heen found infcctlng I;rrvac I itl.\il (Kotti:li. 1Y73 in Mohamrnad. 1981: S~.intv;~sinand Siv:~ R;lo. 1080). a\ N;IS a new nuclear po1I1cclroi ~irui, (Ciodsc ;rnd Patil. I'X3l ). 'l'hc lungus ,~~.v/~c~r~illri.\f/u~.~(.\ hits also hccn reco\crcd from C;I>M larkac (Oblizanii. Kanl;~riioorthi and f Table 2. Parasitoids reared from Aproaerema mod~cella" L3cthvlictac Gor~iozushp. (;roundnut ;ttid lurva coybc;in (; .~ii~~~~op/rr.vc.isRam Kc Suhba Crr(1u11dnut I .arva Rail I'c~r~,sierolusp. Groundnut I .nrva 6 B~ologyand control of Aproaerema mod~cella:T. G. Shanower eta1 body weight and percentage survival of larvae and Srage pupae, and weight and longevity of adults wcrc Family Parautoid Host plant attacked compared in 10 varieties: I~irval, pupal and adult Dr;tcl~nltl,~c wcights wcrc significantly higher on the hunch variety A/I~III/~'/~,\\I>. r11ticIr1~11n larva S1. 74 than on other varieties. L,arvul survival rate was ~oyhcan also higher and adults lived zignific;lntly longer when A. /UI rn\r\ Rc,hv.er (i~oundnut Larva A \tf1Ropnr(.f1.\1\SIC[). (iroun(lnu1 I.srva reared on this variety (Motka rt (11.. 1085). A Iir1o2 N~xon S(1yt1can I iirvii GLM-resihtanl soybean iarietics have not, as yct, .4 ~y(ithouspct Nlxon (rroundnur I.ar\a heen found. M~~ntlhc(1080) compared 20 varieties and 11 ftrroni Suhh;~Kecr & Sh;~rm;~ (;roundnut I iirvi~ Ilra~ot~\p. (;riiurtdrtut I .:~rv;~ found no diffcrcnccr; in GLM populations until 75 days I$ I~rr,~,i(orf~r\W'C~III Ciri~undiiul I .~irva atter sowing. In another triirl 18 varieties wcrc compared Ij Natural control N;rturul control, t)y eliscase\, predator\ arlcl para\itoids. is importarit in \upprcssing (i1.M population growth. At least thrcc d~seawagent\ (ncm:~tcidc\.ciruse\ and fungi) infect (;LM larvae in India. llni(lentificd mcrnlilhici ncrniitotlca hakc 1,ccn found ir~lcctinglarbac (Kcitli~~i.1973 in Motii~nimacl.1081 : Srin~v:is;rrland Slva Itao, 1980)3 a\ W:I~ ;I new titiclc:tr pol~hcci~-o\i\\irus (Godsc ~undr'atil. IONI). I'hc lungu\ As/~u,~illrrsfltr1,~c.c h:~\;~lso hccn rccovcrcd lrorn GLM I;lr\;ie (Ohl~\;~mi. Ramamoorttii and l<;irig:rswami. IOhO). Iri \omc gcner;rtions LI~to 30':;1 01 the larvae are killed by v~ritl :rrirl fungal p:ithogc.n\ (Slii~riowcr(,t (11.. 1003). Several prcdatorj have hecri itlcntificd that :~tt;~ch GLM lurv;re llut their i~iipucthas not hccn iluantificd. M;~xwc.ll-l,cfro and I lo\+lctt ( 1000) reported that Od~trt~ru.\prrt~ciutr~ F;lhr. (1 1yrncnoptc1-a: F.:.unicnid;rc) woulcl attack (i1.M larv:~e rid carry them awa!. 'l'hc 1i1rv;icol' a carahid (C'l~l~rorilrc\I>.) ti;^\'^ Ixui obscrve~l ;ittacking (i1.M larvac In the f~cld (Shanower ancl Karigi~Rao. 1000). I'rcdation hy spiders ancl rohher flies (Iliptera: Asilidac) Iiirs also hecn rcportcd (Srinivasan and Siva Rao. IO8h). 1 ~~pclri~i~l~~c 'l'hc most important and ubund:lnt GLM natural t,i~l~~~l~rrri\ (irii~inil~~~~r I ;tr\a ;~nd cnernics ;~rcp;~rasitic !lymcnopler:~ ('/i~hl(~2). pI'hr pup:1 parasiloid community associated with (i1.M is largr and I. \I> 11' ~iflpu~g~u\r\ (i~i~u~lclrii~l L.nr\;t and pullla complex. involving at lei~sttwo trophic Icvcls. TuOlc -7 irlcludcs hoth PI-iniary and secondary pirrasitoids re:~~.ctl from GLM. Sh;lnowcr cr (11. (1093) found nine primary Table 2. Parasitoids reared from Aproaerema modicella* Sr;igc Fittiitly P;~r;~\ir~itd HOSI plan! attuckcd Hcthylidac C;IIIIIOZ~~.\sp. tirc~undnuti~nd L.ar\'a wyhcal~ (; storno1'tt~ryc.i.sRam & Suhh (iroundn~~t 1.>tr\ii Kilo P~~rrsicmla51). Cirountlnut I ,iirvii Government Consultahon of Strlga Control Maroua Cameroon (Rome RAMAIAH. K V 1985 Hand-pulling of Stnga henonth~caon pear(-mtllet FAO), pp 51-53 Troprcal Pest Management 31, 326327 OBILANA A T and RAMAIAH K V 1992 Strfga (wttchweeds) in sorghum RAMAIAH. K V , 1991 Breed~ngfor Str~garesistance In sorghum and millet and knowledge and luture research needs In W A J M~lllano R A In S K Klm (ed) Combabng Strlga rn Afnca (Ibadan N~ger~aIITA). Fredericksen and G D Bengston (eds) Sorghum M~lletand Dfseases a Pp 75-80 Second World Rewew (Patancheru lnd~alntematlonal Crops Research SANOGO, D , DEBRAH. S K and ADESINA A A 1992 Crop productlon In lnslltute for the Semt-Ar~dTroplcs) pp 187-201 sorghum.based cropping systems A diagnostic study of four villages In the OGBORN J 1984 Research priontles in agronomy In E S Ayensu H OHV and CMDT zones of Mali ICRISATIWASIP Economics sub-pro- Doggetl R D Keynes J Marton-Lefevre L J Musselman C Parkerand gramme Progress Report No 1 Bamako Mall 72 pp A Pickerlng (eds) Str~ga Bfology and Control (Pans ICSU Press) SAUERBORN J 1991 The economlc importance of the phytoparasttes pp 195212 Orobancheand Str~gaIn J K Ransom L J Musselman A D Worsham PARKINSON V 1985 Strfga serious threat to malze productlon In Africa and and C Parker (eds) Proceedfngs of the 5th International Symposrum of research bang conducted at IlTA In Proceedfngsof OAU/FAO Workshop Parasitfc Weeds Na~rob~Kenya pp 137-143 on Str~gaYaounde Cameroon (Rome FAOJ pp 47-57 SAUERBORN J MUSSA. H and LlNKE K H 1991 Phys~calcontrol of PIETERSE A H 1985 Control of Strfgaat the level of the small scale farmer Strfga In S K Kim (ed) Combat~ngStr~gamAfnca(lbadan Nfgeria IITA) In Proceed~ngsof OAU/FAO Workshop on Striga Yaounde Cameroon PP 55-60 (Rome FAO) pp 23-27 SMITH J 1992 Soc~o-economiccharactertzat~on of environments and RAMAIAH K V 1984 Patterns of Strrga resistance In sorghum and m~lletswith technologies In humid and sub humtd regions of West and Central Afnca speclal emphasls on Africa In E S Ayensu H Doggett R D Keynes J Resource and Crop Management Research Monograph No 10 (lbadan Marton Letevre L J Musselman C Parker and A Plckertng (eds) Stnga N~ger~aInternattonal lnstltute of Troplcal Agr~culture) 85 pp Brology and Control (Pans ICSU Press) pp 71-92