Optimization of a Pheromone Lure for Spodoptera frugiperda (Smith) in Central America

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1 J. Brz. Chem. Soc., Vol. 11, No. 6, , Printed in Brzil c 2000 Soc. Brs. Químic $ Article Optimiztion of Pheromone Lure for Spodopter frugiperd (Smith) in Centrl Americ Romno Andrde, Crlos Rodriguez nd Alln C. Oehlschlger * ChemTic Interncionl, S. A., Apdo , Sn Jose, Cost Ric DelMonte Fresh Produce, Pvs, Cost Ric A cptur em mss d Spodopter frugiperd (Smith) n Améric Centrl requer um trtivo ltmente eficiente e com consistênci n tx de cptur. Atrtivos empregdos pr S. frugiperd provenientes d Améric do Norte e Inglterr presentrm txs de cptur irregulres qundo plicdos no cmpo. A reinvestigção de qutro cettos (Z9-14Ac, Z11-16Ac, Z7-12Ac e Z9-12Ac) pr S. frugiperd encontrd n Cost Ric revelou que Z7-12Ac e Z9-12Ac, qundo empregdos de mneir isold, se mostrrm ltmente trentes. Cominção inári de Z7-12Ac e Z9-14Ac umentou considervelmente o poder de trção sendo, no mínimo, dez vezes mis trentes à S. frugiperd d Cost Ric que os trtivos provenietes d Améric do Norte e Inglterr. A dição de Z11-16Ac à cominções ináris de Z9-14Ac e Z7-12Ac, cusou um pequeno umento ns txs de cptur. Qundo concentrção de Z7-12Ac é umentd pr 5% em trtivos contendo Z9-14Ac, Z11-16Ac e Z7-12Ac s txs de cptur diminuem significtivmente. O trtivo otimizdo contém Z7-12Ac que é um composto não descrito nteriormente pr S. frugiperd d região crienh. Mss trpping of Spodopter frugiperd (Smith) in Centrl Americ required high performnce lure with consistent cpture rtes. S. frugiperd lures from North Americ nd Englnd gve errtic cpture rtes under field conditions. A reinvestigtion of four cette ttrctnts (Z9-14Ac, Z11-16Ac, Z7-12Ac nd Z9-12Ac) for S. frugiperd present in Cost Ric reveled tht Z7-12Ac nd Z9-12Ac were highly ttrctive to S. frugiperd when presented lone. Binry comintion of Z7-12Ac with Z9-14Ac significntly incresed ttrction nd ws t lest 10 times more ttrctive to S. frugiperd in Cost Ric thn North Americn or English lures. Addition of Z11-16Ac to inry comintions of Z9-14Ac nd Z7-12Ac mrginlly incresed cpture rtes. If the concentrtion of Z7-12Ac is incresed to 5% in lures contining Z9-14Ac, Z11-16Ac nd Z7-12Ac cpture rtes significntly decrese. The optimized lure contins Z7-12Ac tht is component not previously reported in S. frugiperd from the Crien region. Keywords: Spodopter frugiperd, pheromone lend, trpping Introduction Spodopter frugiperd is mjor pest of mny crops in the Americs 1. Mngement is most often y ppliction of chemicl insecticides or iologicls such s Bcillus thuringiensis. The femle-produced sex pheromone of S. frugiperd is often used to monitor popultions to time insecticide ppliction 2,3. Additionl pheromone-sed mngement strtegies include disruption of mting nd mss trpping 4,5. The explosive popultion growth of S. frugiperd nd S. suni during the two month crop cycle of wtermelon nd cntloupes mke these importnt pests of these crops in Cost Ric 6. The high tempertures nd windy conditions in the region in which melons re grown mke use of mting disruption techniques for mngement of Spodopter species especilly chllenging. Success of mss trpping of Lepidopter hs een chieved only under low popultion conditions 4,5. Melon pest mngers in Cost Ric egn mss trpping S. suni nd S. frugiperd in 1992 s mens to mintin initil low popultions nd reduce expensive pplictions of Bcillus thuringiensis. Since 1992 mss trpping (4-5 trps per hectre) hs een prcticed in > hectres of melons to help mnge popultions of oth Spodopter species. This technique hs routinely lowered y 30-70% the numer of Bcillus thuringiensis pplictions required to mintin lrvl dmge t economiclly cceptle levels *. While pheromone lures for S. suni consistently gve high * e-mil: info@mil.pheroshop.com * C. Rodriguez, unpulished results.

2 610 Andrde et l. J. Brz. Chem. Soc. performnce under field conditions 6 lures for S. frugiperd gve errtic field results. This study ws prompted y the inility of S. frugiperd lures from North Americn nd Europen sources to ttrct significnt numers of S. frugiperd to universl moth trps used in opertionl mss trpping progrms. Filure of pheromone lures constructed to ttrct S. frugiperd in North Americ to ttrct this species in Cost Ric might e understood in terms of popultion isoltion. The high migrtory ility of S. frugiperd in North Americ would e expected to mintin homogeneous popultions within North Americ 7. A study of popultion fluctution of S. frugiperd from the French Guyn to Cnd suggested migrtion from the Crien region to North Americ ws not significnt 8. The pheromone glnd of North Americn S. frugiperd is reported to contin Z9-14Ac : Z9-14Al : Z11-16Ac : Z7-12Ac : Z11-16Al : Z11-12Ac : 12Ac : Z9-12Ac in rtio of 63 : 13 : 9 : 4 : 3 : 2 : Trce : Trce 9. The effluvium consisted of Z9-14Ac : Z11-16Ac : Z7-12Ac : Z11-12Ac : 12Ac in the rtio of 90 : 3 : 3 : 2 : 2 9. Femle pheromone glnd extrcts of S. frugiperd from Gudloupe re reported to contin Z9-14Ac : Z11-16Ac : Z9-12Ac in rtio of 7 : 1 : 2 (cited s personl communiction from C. Descoins) 10. Field trpping results in North Americ demonstrted tht lures contining Z9-14Ac or Z9-12Ac lone were ttrctive 11. Addition of Z,E,9,12-14Ac nd Z7-12Ac or E9-12Ac to Z9-12Ac decresed cpture rtes 11,12 while ddition of 2% Z11-16Ac or Z9-14Ac to Z9-12Ac did not lter cpture rtes 10. Superior ttrction ws reported to lures contining Z9-14Ac nd Z7-12Ac in rtio of 99.4 : 0.6 nd to the five cettes in the effluvium of S. frugiperd from North Americ t their nturl rtios 9. Given errtic cpture rtes of lures constructed to cpture S. frugiperd in North Americ nd our requirement for consistently high cpture rtes we investigted the composition of existing temporte zone lures nd reexmined ttrction of S. frugiperd in Cost Ric to lends of Z9-14Ac, Z11-16Ac, Z7-12Ac nd Z9-12Ac which re the four cettes most commonly ssocited with ttrction from previous studies. Experimentl Chemicls: Pheromone components were used s purchsed from Bedoukin Reserch, 21 Finnce Drive, Dnury Conn., USA. Extrction of commercil lures: Commercil lures for S. frugiperd (2 from ech source, Trece, Inc., USA nd Agrisense, Englnd) were seprtely extrcted y plcing ech lure in glss vil with 2 ml of nlyticl grde hexne for 48 hrs. After this time known mount of tetrdecne internl stndrd ws dded nd n liquot removed y syringe for gc nlysis. Identities of eluting components were confirmed y co-elution with known stndrds. Anlyticl Procedures: Purity of pheromone components nd nlysis of commercil lures ws conducted y gs chromtogrphy nd gs chromtogrphy/mss spectrometry. In the cse of purchsed pheromone components nlyses reveled ech component ws > 95% pure. In the cse of Z9-12Ac we confirmed tht E9-12Ac which is n inhiitor ws present in less thn 1%. GC nlysis were conducted on HP 5890 gs chromtogrph using 30 meter DB-5 fused silic column 0.25 mm ID (0.25 mm film thickness) with FID detection. GC/MS nlysis ws conducted on HP 5973 mss detector coupled to HP6890 gs chromtogrph using the sme column. Lures: Commercil lures from North Americ nd Englnd were sept nd cpsules respectively nd contined ~1.6 mg pheromone lend. Lures produced in Cost Ric consisted of memrne relese devices contining 1-2% solutions of test pheromones in proprietry crrier. Lures produced in Cost Ric contined 2 mg of pheromone lend. Field Experiments: Trps used were green Universl Moth Trps mnufctured in Cost Ric nd contining wter or DDVP s the killing gent. Trps were plced on iron rs just ove the cnopy in cntloupe or rice plnttions in Guncste or the Centrl Pcific Cost of Cost Ric. Trps were t lest 20 meters prt nd 20 meters from ny order. Complete rndomized lock design ws used for ll experiments. Sttistics: Cptures were nlyzed for norml distriution nd where necessry trnsformed s indicted to chieve homogeniety. ANOVA (fully fctoril routine) ws conducted using Systt with susequent nlysis of mens y Bonferonni t-test comprison. Within the sme experiment mens followed y different letter re significntly different y Bonferonni t-test, P > Results nd Discussion Bsed on reported trpping studies it ws expected tht commercil lures for S. frugiperd from North Americ nd Englnd would contin Z9-14Ac nd Z7-12Ac or ll five cettes found in the effluvium found from S. frugiperd in North Americ 9. Anlysis of S. frugiperd lures from North Americn nd English sources yielded Z9-14Ac nd Z11-16Ac in rtios vrying from 80 : 20 to 85 : 15. This result ws surprising since ddition of Z11-16Ac nd Z9-14Ac

3 Vol. 11 No. 6, 2000 Optimiztion of Pheromone Lure for Spodopter frugiperd (Smith) 611 did not increse ttrction to Z9-12Ac 10. The oservtion of Z9-14Ac, Z11-16Ac nd Z9-12Ac in S. frugiperd from Gudeloupe (cited s personl communiction from C. Descoins) 10 suggested n exmintion of the ntennlly ctive components (GC/EAD) in the pheromone glnd of S. frugiperd from Cost Ric could e eneficil. This nlysis reveled Z9-14Ac, Z11-16Ac nd Z7-12Ac s the mjor ntennlly ctive pheromone glnd extrct components (R. Gries, unpulished). The ove suggested tht we should concentrte on Z9-14Ac, Z11-16Ac, Z7-12Ac nd Z9-12Ac in the development of lure for S. frugiperd in our region. A test of ttrction y these cettes presented singly reveled tht only Z7-12Ac nd Z9-12Ac significntly ttrcted S. frugiperd mles. In North Americ S. frugiperd exhiit significnt ttrction to Z9-14Ac nd Z9-12Ac when these cettes re presented singly 11. Z9-14Ac Z11-16Ac Z9-12Ac Z7-12Ac S. frugiperd (SEM) / Trp Figure 1: Test of Z9-14Ac, Z11-16Ac, Z7-12Ac nd Z9-12Ac s single component ttrctnts for S. frugiperd. Test conducted Ferury 12-26, 1998 in Cost Ric. Insects were counted nd removed from trps every 3 dys. ANOVA (n = 10) gve df = 3,24; F = 13.07; p < In test of inry comintions of the four cettes under study ttrction of S. frugiperd to Z7-12Ac ws incresed when it ws comined with Z9-14Ac ut not with Z11-16Ac or Z9-12Ac (Figure 2). The only inry comintion of cettes exhiiting significnt ttrction in this experiment contined oth Z9-14Ac nd Z7-12Ac. The rtios Z11-16Ac to Z7-12Ac nd Z9-14Ac to Z7-12Ac used in this experiment were chosen to reflect the rtio of Z11-16Ac nd Z9-12Ac to Z9-14Ac in the glnd extrct of S. frugiperd from Gudloupe nd the most ttrctive rtio of Z9-14Ac (only common component to oth these lends) to Z7-12Ac used in lures exmined y Tumlinson 9. Compositions of other inry lends re sed on the reported compositions of glnd extrcts of S. frugiperd from Gudeloupe nd the most ttrctive lends s determined y field trils for S. frugiperd in North Americ 9. Since North Americn nd English lures for S. frugiperd were inry mixtures of cettes we compred these lures with lures contining the est inry lend from Figure 2 nd lend contining Z9-14Ac nd Z11-16Ac tht more nerly mimicked the reported rtio of these components in femle pheromone glnd extrcts of S. frugiperd in North Americ thn did the commercil lures (Figure 3). This test reveled tht the inry lend of Z9-14Ac nd Z7-12Ac (99.6 : 0.4) cptured ~10 X more mle S. frugiperd thn other inry comintions tested. To determine if dditionl components would increse ttrction to the most ttrctive lend from previous experiments (Z9-14Ac : Z7-12Ac, 99.6 : 0.4) this lend ws tested ginst lends prepred y dding either Z11-16Ac or Z9-12Ac lone or in comintion to this lend Z9-14Ac (0) : Z11-16Ac (96.2) : Z7-12Ac (3.8) : Z9-12Ac (0) Z9-14Ac (0) : Z11-16Ac (33.3) : Z7-12Ac (0) : Z9-12Ac (66.7) Z9-14Ac (0) : Z11-16Ac (0) : Z7-12Ac (2.1) : Z9-12Ac (97.9) Z9-14Ac (0) : Z11-16Ac (0) : Z7-12Ac (0) : Z9-12Ac (100) Z9-14Ac (77.8) : Z11-16Ac (0) : Z7-12Ac (0) : Z9-12Ac (22.2) Z9-14Ac (87.50) : Z11-16Ac (12.5) : Z7-12Ac (0) : Z9-12Ac (0) Z9-14Ac (99.4) : Z11-16Ac (0) : Z7-12Ac (0.6) : Z9-12Ac (0) S. frugiperd (+SEM) / Trp Figure 2: Test of inry comintions of Z9-14Ac, Z11-16Ac, Z7-12Ac nd Z9-12Ac vs Z7-12Ac s ttrctnts for S. frugiperd. Test conducted Jnury 3-22, 1999 in Cost Ric. Insects were counted nd removed from trps every week. ANOVA (n = 10) gve df = 6,62; F = 6.82; p < 0.05.

4 612 Andrde et l. J. Brz. Chem. Soc. Z9-14Ac (97.5): Z11-16Ac (2.5) : Z7-12Ac (0) : Z9-12Ac (0) Z9-14Ac (80) : Z11-16Ac (20) : Z7-12Ac (0) : Z9-12Ac (0) Engl Z9-14Ac (85) : Z11-16Ac (15) : Z7-12Ac (0) : Z9-12Ac (0) N A Z9-14Ac (99.6) : Z11-16Ac (0) : Z7-12Ac (0.4) : Z9-12Ac (0) S. frugiperd (+SEM) / Trp Figure 3: Comprison of North Americn, English nd Cost Ricn formultions for S. frugiperd. Test conducted Septemer 22-30, 1997 in Cost Ric. Insects counted nd removed every 3-4 dys. ANOVA (n = 10) gve df = 3,36; F = 9.9; p < Z9-14Ac (70) : Z11-16Ac (10) : Z7-12Ac (0) : Z9-12Ac (20) Z9-14Ac (77.4) : Z11-16Ac (0) : Z7-12Ac (0.47) : Z9-12Ac (22.1) Z9-14Ac (69.7) : Z11-16Ac (9.96) : Z7-12Ac (0.42) : Z9-12Ac (19.9) Z9-14Ac (99.4) : Z11-16Ac (0) : Z7-12Ac (0.6) : Z9-12Ac (0) Z9-14Ac (87) : Z11-16Ac (12.5) : Z7-12Ac (0.5) : Z9-12Ac (0) S. frugiperd (+SEM) / Trp Figure 4: Test of ternry nd quternry lends of Z9-14Ac, Z11-16Ac, Z7-12Ac nd Z9-12Ac s ttrctnts for S. frugiperd. Tests conducted Octoer 6-30, 1997 in Cost Ric. Five replictes t one loction, ten replictes t second loction nd 10 replictes t third loction. Insects counted nd removed every 3-4 dys. ANOVA gve no loction effects so loctions were comined. ANOVA on comined dt gve on log(x+0.5) trnsformed dt, F = 79.96, df = 4, 120, p < Mens presented un-trnsformed. Z9-14Ac (85) : Z11-16Ac (10.0) : Z7-12Ac (5.0) : Z9-12Ac (0) Z9-14Ac (85.5) : Z11-16Ac (12.5) : Z7-12Ac (2.0) : Z9-12Ac (0) Z9-14Ac (87) : Z11-16Ac (12.5) : Z7-12Ac (0.5) : Z9-12Ac (0) S. frugiperd (+SEM) / Trp Figure 5: Test of ternry mixtures of Z9-14Ac, Z11-16Ac, Z7-12Ac nd Z9-12Ac s ttrctnts for S. frugiperd in which proportion of Z7-12Ac is incresed. Test conducted Mrch 27 to April 13, 1999 in Cost Ric. Insects were counted nd removed from trps every week. ANOVA (n = 10) gve df = 2,27; F = 25.24; p < 0.05 (Figure 4). In this experiment the mounts of Z11-16Ac or Z9-12Ac dded to the lend of Z9-14Ac nd Z7-12Ac were chosen to reflect either the composition of glnd extrcts of S. frugiperd from Gudeloupe or ttrctive lends for S. frugiperd in North Americ. An dditionl tretment in Figure 4 ws used to exmine the possiility of replcement of Z7-12Ac y Z11-16Ac nd Z9-12Ac. This ltertion completely destroyed the ctivity of the lend. Addition of Z11-16Ac or Z9-12Ac to the previously ttrctive lend of Z9-14Ac nd Z7-12Ac did not significntly increse ttrction. However, it ws noted tht in the three trils undertken in this experiment tht numericlly higher cptures were consistently otined to lends of Z9-14Ac, Z11-16Ac nd Z7-12Ac thn to the inry lend of Z9-14Ac nd Z7-12Ac. Since our gol ws development of mss trpping lure we dopted the numericlly superior lure from Figure 4 for n dditionl optimiztion.

5 Vol. 11 No. 6, 2000 Optimiztion of Pheromone Lure for Spodopter frugiperd (Smith) 613 Since Z7-12Ac ws n essentil nd minor component of the numericlly superior lure in Figure 4 we conducted n experiment to determine the sensitivity of S. frugiperd to the mount Z7-12Ac present in the ternry lend of Z9-14Ac, Z11-16Ac nd Z7-12Ac (Figure 5). Incresing the concentrtion of Z7-12Ac from 0.5% to 2% in the ternry lend did not significntly lter ttrction wheres incresing the concentrtion of Z7-12Ac to 5% significntly decresed ttrction. The composition of the lure emerging from this study is similr one of the optiml lures deduced for S. frugiperd in North Americ tht contins Z9-14Ac nd Z7-12Ac (99.4 : 0.6). 9 Our optimized lure is significntly different in composition thn the commercil lures ville from North Americ nd Englnd tht contin Z9-14Ac nd Z11-16Ac (~8 : 2). Current commercil lures produced nd used in Cost Ric utilize the most ttrctive ternry lends of Z9-14Ac, Z11-16Ac nd Z7-12Ac shown in Figure 5. These lures re lso significntly ttrctive to S. frugiperd in Brzil (E. Vilel, Unpulished). It is noteworthy tht Z- 12Ac is n essentil component of the optimized lend ut ws not detected in S. frugiperd from Gudeloupe (cited s personl communiction from C. Descoins) 10. Acknowledgements We wish to thnk the technicl stff t DelMonte Fresh Produce of Cost Ric for excellent field ssistnce. References 1. Sprks, A. Fl. Entomol. 1979, 62, Lopez, J. D. Jr.; Shver, T. N.; Goodenough, J. L. J. Chem. Ecol. 1990, 16, Weer, D. C.; Ferro, D. N. J. Econ. Entomol. 1991, 84, Huer, R. T.; Moore, L.; Hoffmnn, M. P. J. Econ. Entomol. 1979, 72, Willson, H. R.; Trmmel, K. J. Econ. Entomol. 1980, 73, Dunkellum, E., C.; Rodriguez, C.; Oehlschlger, A. C.; Vrgs, M. Mnejo Integrdo de Plgs, Cost Ric, 1995, 37, Pir, S. D.; Rulston, J. R.; Westrook, J. K.; Wolf, W. W.; Adms, S. D. Fl. Entomol. 1989, 74, Mitchell, E. R.; McNeil, J. N.; Westrook, J. K.; Silvin, J. F.; Llnne-Cssou, B., Chlfnt, R. B.; Pir, S. D.; Wddill, V. H.; Sotomyor-Rios, A.; Proshold, F. I. J. Entomol. Sci.; 1991, 26, Tumlinson, J. H.; Mitchell, E. R.; Tel, P. E.; Heth. R. R.; Mengelkoch, L. J. J. Chem. Ecol., 1986, 12, Mitchell, E. R.; Sugie, H.; Tumlinson, J. H. J. Environ. Sci. Helth 1983, A18, Mitchell, E. R.; Doolittle, R. E. J. Econ. Entomol. 1976, 69, Mitchell, E. R.; Copelnd, W. W.; Sprks, A. N.; Sekul, A. A. Environ. Entomol. 1974, 3, 778. Received: July 24, 2000