J ARQ 26, 271-276 ( 1993) Suppression of Lepidopterous Pest Populations in Apple Orchards through Mating Disruption with Synthetic Sex Pheromones

ToshioOKU

Morioka Branch, Fruit Tree Research Station (Shimo-kuriyagawa, Morioka, 020-01 Japan)

Abstract Effect of mating disruption using the major component of the sex pheromone, (z)-7-eicosen-11-one, on the fruit , sasakii Matsumura, was more pronounced at lower moth densities. When supplemented with adequate insecticide sprays, the treatment caused a drastic decrease in the pest population even at extremely high levels. Release of the common pheromonal component onto leafrol­ lers of the tribe Archipini, (z)-11-tetradecenyl acetate, prevented the population recovery of the apple tortrix, Archips fuscocupreanus Walsingham, the Asiatic I eafroll er, A. braviplicanus Walsingham, and the summer fruit tortrix, Adoxophyes oranafasciata Walsingham, under conditions of reduced insecti­ cide sprays, The effect on the last species, however, decreased remarkably under outbreak conditions. Also, a significant increase of the incidence of the brown tortrix, Pandemis heparana (Schiffermuller et Denis), occurred in a few pheromone-treated fields. Mixture of the two pheromone components, (z)- 10-tetradecenyl acetate and E4, z 10-tetradecadienyl acetate, in the ratio of 10: 3 showed a significant disruptive effect on the mating of the apple leafminer, Phyllonorycter ringoniella (J)i.[atsumura).

Discipline: pest Additional key words: apple leafminer, integrated pest management, leafroller, peach fruit moth

also. Main aspects of the studies concerned are Introduction reviewed in this article, including unpublished data.

In Japan, the occurrence of pests resis­ The peach fruit moth tant to spray chemicals is a serious constraint on ap­ ple production. Moreover presently in the case of I) Control problems dessert apple the consumers prefer cleaner fruits with The peach frui t moth, Carposina sasakii Matsu­ fewer chemical residues. These conditions require mura [ = niponensis: auct.). has long been the most the development of an integrated pest management important fruit borer in the major apple-growing (1PM) system, in which the conventional sprays are, areas. The life cycle of the moth has been described at least in part, substituted by new control tech­ by Narita & Otake2>. Adult emergence of the over­ niques. Mating disruption of pests by using synthe­ wintering generation continues for more than 2 sized sex pheromones is a method of control that months, which results in the partial overlapping of could be implemented. The technique has been the two separate generations and continuous ovipo­ developed for some lepidopterous pests of apple, and sition from June to early September. Repeated has recently been used for the control of the peach sprays to control the were responsible for the fruit moth and a few apple leafrollers. Experiments development of insecticide resistance in some other are currently in progress for the apple leafminer pests, although the fruit moth itself has not become 272 JARQ 26(4) 1993 resistant 10 1hc chemicals yet•>. on fruits.

2) Synthetic pheromone 4) Control effect Among 1he pheromone compone111s of 1he peach Pheromone-trap catches revealed that 1he syn1he1ic fruit moth, 1he major one, (z)-7-eicosen-11-one, alone pheromone can be con1inuously dis1ributcd over the allrac1s male mo1hs4>. It is also effective in the mat­ field, if it is released at a rate of more lhan 300 mg ing disrup1ion against the pest, without enhancemen1 per day from 1,000 10 1,500 points per ha with some of the effect by the addilion of 1he minor element, addicion to 1he periphery of the trea1ed orchard6l. (z)-7-nonadecen- I l-one5>. The role of the minor Field 1rials of the peach fruit moth control were un­ component is still unknown. Thus, only the major dertaken along chis line. clement was employed as 'peachflure' for practical Fig. I shows some of the resul1s obtained under use . Two 1ypes of pheromone dispensers are avail­ convemional sprays in small plots of approximately able for mating disruption; a capillary tube made 0.5 ha in Fukushima Prefeccurc'>. Comparison of of polyethylene coniaining more than 35 mg of the the populacion trend be1wcen 1he treated and untreat­ syn thesized pheromone for hanging on, and a paste ed plo1s indicaced 1hat 1he macing disruption reduced containing it at 1he rate of 1.80/o for sticking on the fruit moth population by about 750/o on an aver­ branches. Unless 01herwise stated, 1he data on the age for the 3-ycar results. A similar estimate was control effect given later are based on the 1ube-1ypc provided based on questionnaires prepared for farm­ material, from which 1he pheromone can be released ers who par1icipa1ed in another trial covering an area a1 a s1eady rate for 2 months or more. of 15 ha. The pas1e-type dispenser was similarly ef­ fec1ive in the same experimenl. J) Method for field evaluation Besides, a series of tests was cominued for a period The peach fruit moth adult showed a limi1ed of 7 years in a European pear orchard of a few ha 2 5 response to optical and chemical a1tractams >. in the vicinity of Morioka i. The overall results are Catches by pheromone traps were subs1a111ially illustrated in Fig. 2. Suppression of the moth abun­ preven ted by the disruption 1rca1mem, irrespec1ive dance was not achieved by 1he 'disruption alone and of the levels of 1hc control 5>. Tethered females were wi1h I or 2 sprays at the ini tia l high population of limited significance for 1he evaluation of the dis­ levels. However, 1he same pheromone trea1ment in ruption effect, as 1heir mating ra1e was unexpected­ combina1ion wi1h 4 well-timed sprays was able 10 ly low in untreated plo1s'> and the effect could only cause a dras1ic population decrease, which was fol­ be evaluated by direct examination of larval attacks lowed thereafter by a subsequent decrease wi1h

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80\40 _. .J 40 '.\ _./ 0 O L..8~2-'8~3-.~84 '81 '83 ·g4 O '82 ·53 ·g4 '81 ·g3 '84 ·s3 ·s4 ·ss

Fig. I. Annual change in the number or larval exit holes of the peach fru it mot h on harvcsied apple fruits in treated and untreated plots with pheromone for mating disrup1ion ai Fukushima Conventional sprays were applied over the test period. In orchard 8, plots were exchanged wi1h each other in 1983. Source: Sa10 (1986)71• 273

orchards•>. Some local associations of farmers plan 500 10 reduce the frequency of sprays by the introduc­ I 300 I tion of si multaneous mating disruption for the fruit I 200 I moth and for the leafrollers (see the next section). I I I 100 I I Apple leaf-roll ers I I 50 I I I) Control problems I ~ 30 I Recemly, major apple leafrollers in Japan have I 8. 20 ._ been limited to the tribe Archipini, Tortricidae, in­ ~ \ cluding the summer fruit tortrix, Adoxophyes ora11a o" 10 \ .c \ Insecticide \ fascia /a Walsingham, the apple tortrix, Archips f11s­ ·;; \ " s 4! cocuprea1111s Walsingham, the Asiatic lcafrollcr, A. .; - No spruy breviplicanus Walsingham, and the brown tonrix, ~ 3 \ I Pa11de111is heparana (Denis et Schiffermuller). Their - I or 2 sprays i ~ 2 I seasonal occurrence has been described by Oku3>. ,:," i E --· 3 sprays i Local populations of the former two species have i developed a resistance to some spray chemicals re­ o.s --- 4 sprays cen tl y. The larvae of th e apple tortrix are active 0.3 \ around the apple blooming period when insecticide 0.2 \ sprays against them are avoided for the safety of i the pollinators. 0.1 1. 2) Synthetic pheromo11e 0 .05 LL-----'-----'------'------'------'---'-- ...L.I A multi-component pheromone material has been ·so ·s 1 ·s~ ·s3 '84 '85 ·sG ·s1 used for the control of the summer fruit tortrix in Ycor •>. In Japan, on the other hand, the single l'ig. 2. Annual change in the larval population of 1.he component, (z)-11-tetradecenyl acetate, is utilized for peach fruit moths in a European 11car orchard simultaneous mating distruption of two leafrollers, treated with pheromone for mating disruption Adoxophyes sp. and Homona mag11a11i111a Di­ in the vicinity of Morioka akonoff, in tea plantations12>. As this substance is Number of larvae is indicated in a logarith· a common component of the sex pheromones to the mic scale. The annual populaiion was csti· mated based on the total number or exit holes leafrollers of the tribe Archipini, the possibility of on rruits and of larvae left within them at applying the same control material as that used in harvest. Sec the text for the arrow. tea plantations, 'tetradecenylacetatc' , for the control 5 Source: Oku Cl al. (1989) >. of the apple leafrollers was considered. The tube­ rype dispenser which comains 80 mg of the syn the­ reduced sprays. 1n the final trial, half of the or­ sized pheromone component releases it steadily for chard was kept unsprayed. Although the frui t inju­ 2 months or more. ry sl ightly increased there (indicated by an arrow in Fig. 2), the resumption of infestation was restricted 3) Methods for field evaluation 10 some of the outermost trees. Pheromone-trap catches and mating rate of These and some other resu lts suggested 1ha1 the tethered females were of limited significance in the control effect may be more conspicuous at lower evaluation of the control efficacy for these apple leaf­ moth densi ties and cou ld be stabilized by simul­ rollers, as in the case of the peach fruit moth. As taneous treatment over a wide area, especia lly if well the apple tortrix is univoltine and lays eggs on the protected from the wind. This technique has been trunk and branches3>, reliable estimates for the dis­ used in combination with conventional sprays to um­ ruption effect can be obtained by the annual changes prove the peach fruit moth colllrol in commercial in the number of egg-masses in experimental plots. 274 JARQ 26(4) 1993

Table I. Annual change in lhc number of egg-masses of Ute apple lorlrix In treated and untreated plots with pheromone for ma Ung disrup1ion a l Morioka •l

Year of No. of trees No. of egg-masses

Molasses-trap attracted the female moths arter mat­ ing, and enabled to estimate the mating period. 7 Treated 4299/ t 2 trnps For the other polyvoltine leafrollers, egg-mass counting was very difficult, as they oviposit on 5 leaves. Evaluation of their control can solely be based on the numbers of shoots and fruits damaged.

4) Control effect In tea fields, lcafroller adults are active immedi­ ately above the crown. This open condition requires ~ Un1rea1cs per ha, for effective control. Adults of the apple '- 0 leafrollers, in contrast, become active within the tree­ _g 5 E crown, and only 1,000 to 1,500 dispensers per ha ::, afford an adequate distribution of the released phero­ z mone. Some results in the leafroller control are 3 described below based on unpublished data. At Morioka, the late-spring treatment clearly reduced the number of egg-masses laid by the apple tortrix during the current summer (Table I). Female 18 2 I 24 28 I 4 7 IO 14 17 21 2 5 28 3 l June July moth caiclles by molasses-traps in the pheromone­ Date treated plots were delayed by about one week, as compared with those in the untreated plots (Fig. 3). Fig. 3. Daily mean catches of mated female moths of the In captivity, the delay of mating for such a period apple tortrix by sticky traps baited with molasses resulted in a considerable decrease of egg deposition in lreatcd and untreated plots at Morioka Trap catches were derived from the field test, by the female moths. The control effect in the field 1990, shown in Table I ; date corresponding to could be substantiated not only by the complete 500/o moth catches is indicated by an arrow in prevention of mating but also by its delay. each column. Trials for the control of polyvoltine leafroUcrs have been carried out under different spray condi­ an appreciable increase in the incidence of the tions in several prefectures. Mating disruption summer fruit tortrix over one season, when the ini­ without or with only one effective spray prevented tial population was relatively low. Under outbreak 275

Table 2. Larval injuries of 1he summer fruil torlrix in 1rca1ed and unlrcatcd plols wilh pheromone for mali11g disruption in Akita Prefecture•>

Rate of injury (%) Lcafroller Test Plo1 Spray Shoot bl Frui1<> population No. I Treated A Conventional 29.0 15.0 High T rca1ed B Convc111io nal 31.7 15.0 High Un1rea1cd Conventional 29.7 16.5 High No. 2 T rca1ed Convcn1ional 5.9 Medium Un1rea1ed No insec1icides 5.4 Medium a) : 1,500 dispensers of 1t1be-1ypc/ha were applied 10 the 'treated' plots in lace May. Source: Takahashi (unpublished). b): On July 3, 50 shools from 6 trees/plot were examined. c): Al harvest, more 1han 600 fru i1s from 3 central trees/plo t were examined. conditions, however, the disruption treatment did not 2) Synlhetic pheromone and preliminary control enable to control the larval attacks, even when com­ tests bined with conventional sprays (Table 2). Although Two components of the apple leafminer phero­ the resistance of the local moth population to the mone, (z)-10-tctradecenyl acetate and E4, zIO· sprayed chemicals may have been responsible for this tetradecadienyl acetate, have been isolated11 >. Their failure of control, it account ed only partially for Lhe mixtu.re in a ratio between IO: 1 and 10 :3 attracted phenomenon observed and the disruption effect ap­ male adulis. Important aspects in the unpublished peared to change with the moth density. The AsiaLic results of control experiments in the field are as fol­ leafroller did not cause any problem throughout these lows. The symhetic pheromone in the mixture ratio experiments in different areas, while the incidence of LO: I showed only a limited disruptive effect on of the brown tortrix significantly increased in a few the mating. Change of the mixture ratio to 10: 3 plots along with the reduction of the number of sum­ was more effective. Studies are currently underway mer sprays. to confirm this observation. These facts suggest the presence of differences in sensitivity to Lhe disruption treatment among the spe­ Concluding remarks cies. This aspect can not be overlooked for improv­ ing local spray programs. At least, one effectnvc Mating disruption for the peach fruit moth and spray has to be maintained in the program against a few leafrollers was highly effective, especially when the brown tortrix in areas, where the species a wide area was treated and provided that the pest predominates. populations were not very high. This measure was also effective for the control of the apple leafminer. The app le leafminer Thus, the disruption technique has reached a practi­ cal phase, and its introduction into the pest control I) Comrol problems program may contribute significantly to the develop­ The apple leafminer, Phyl/011orycter ri11go11iella ment of a new 1PM system, because the technique (Matsumura), became an important pest of apple af­ is not detrimental to natural enemies of. pests in ter World War IJ 10>, presumably due to the elimina­ general. Studies on the simultaneous disruption on tion of effective parasitoids by the intensive use of mating of these major lepidopterous pests arc organic insecticides. Sekita8> studied the population promoted. However, it is generally recognized that dynamics of the pest in detail. Although the para.si­ the incidence of predominant apple pests has changed toids are recovering in some areas, they have usual­ depending on the control measures currently ly failed to afford an economic control of the adopted 10>. In fact, the reduction of sprays in the lcafminer only by themselves. disruption plots resulted in occasional attacks by such 'old' pests as caterpillars, beetles, and scale . 276 JARQ 26(4) 1993

Therefore, in the second step, the fPM system should. 16 , 63-81 (In Japanese with English summary). be centered on the development of methods that can 6) Sato, R. (1981): Application of sex pheromone for be applied to these secondary pests without apprecia­ regulating insect pests of deciduous fruit trees in Japan. /11 Proc. 1st Jpn./Canada Joint Symp. 1PM, MoriO· ble disturbance of the natural enemy complex. The· ka, 21-28. apple 1PM does not involve only the development 7) Sato, R. (1984): Control of the peach fruit moth (Car· of new control measures but entails a cominuous posi11a 11ipo11e11sis Wal singham) by communication dis· process of improvement in taking account of the rup1ion. Sltok11b111s11 Boeki, 40, 13-16 (In Japanese). 4 8) Seki1a, N. (1991): Comparative population dynamics equilibrium among fauna! components in orchards '. of two species of leaf miner Phyl/011orycter ri11go11iel· la Matsumura and prunifoliella 111ali11ella Ma· tsumura in apple orchards. Bull. Aomori Apple Exp. References Sta., 27, 1-98 [In Japanese with English summary). 9) Shirasaki , S. cl al. (1979): Field tests on attrac1ivc· I) Chamillot, P ..J. ct at. (1981): Technique de confu. ncss of 1hc synthetic sex pheromone of the peach fruit sion cont re la tordeusc de la pelu re Adoxophyes ora11a moth, Carposina 11ipo111msis Walsingham (: F. v. R. (Lep. To rtricidac) : I. Innucnce de la difru. ). Jpn. J. Appl. £111. Zoo!. , 23, 240-245 sion d'allractif sexuel sur le componcmem. Miu. Schw. (In Japanese wit h English summary), £111. Ges .• 54, 173-190. 10) Sugawara, H. & Ujiie, T. (1972) : Chronological change 2) Narita, H. & Otake, A . (1979): Peach fruit moth, in apple pest outbreaks. Nogyo oyobi Engei, 41, Carposi11<1 11ipone11sis Walsingham (Lcpidop1era: 533-537 (In Japanese). Carposinidac): bionomics and control measures. Re•. 11) Sugic, H. c1 al. (1986): Sex pheromone of the apple Pla111 Prot., 12, 40-63. leaf.miner moth, Pltyl/011orycter ri11go11iella (Ma· 3) Oku, T. (1970): Studies on life-histories of apple leaf. 1sumura) (Lcpidoptera : Tortricidae): ac1ivi1y of ge· rollers belonging 10 the tribe Archipsini (Lepidoptera: ometrical isomers of tctradeccnyl acetates. Appl. Em. Tortricidac). Rep. Hokkaido Pref Exp. Sta .• 19, 1-52 Zoo!.. 21, 578-581. ll n Japanese with English summary). 12) Tamaki, Y. cl at. (1983): Simuhancous disruption of 4) Oku, T. (1986) : Use of synthetic sex pheromone in phcromonal communication of the two Tortricid moths pest management ror fruit production in cooler areas. in the tea pla11tation. /11 IUPAC pesticide chemistry, Tohoku Nogyo Ke11ky11 , 38, 93-102 [In Japanese). human welfare and the environment. eds. Miyamoto, 5) Oku, T ., Wakou, M. & Ohira, Y. (1989): Suppression J. cl al., Pergamon Press. Oxford, New York, Toron­ of the Oriental peach moth population, Carposi11a to, Sydney, Paris, & Frankfun, 103- 108. 11ipo11e11sis Walsingham, through mating disruption with sex pheromone. 8111/. Fruit Tree Res. Sta. Ser. C, (Received for publicarion, Nov. 18, 1992)