Insects Generally Use Multicomponent Pheromones - ACS Publications

1 Insects Generally Use Multicomponent Pheromones ROBERT M. SILVERSTEIN SUNY College of Environmental Science and Forestry, Syracuse, Ν. Y. 13210

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J. CHRISTOPHER YOUNG Chemistry and Biology Research Institute, Ottawa, Ontario, Canada K1A 0C6 In 1964, Wright (1) suggested that multicomponent pheromones would be widely used because they could convey more information than a single compound; evolutionary selectivity would favor the organisms that had the better communication systems. Wright had little compunction in overriding the evidence reported prior to 1964 for single compounds in two moth species (the silkworm moth and the gypsy moth). But, in general, this proposal was ignored, and throughout the 1960s, a number of moths were reported to use single component pheromones. What happened to lead so many investigators astray? Why was the "magic bullet" concept -- one insect, one specific compound -so firmly implanted? The story goes back to the heroic achievement by Butenandt's group, reported in 1959 (2): the isolation and identification of the chemical compound that elicited the sexual excitation response from the male silkworm moth; the work was done without benefit of modern instrumentation -- not even gas chromatography. The short -range bioassay used was entirely appropriate for a unique domes ticated animal that had no field population. Unfortunately the title of the paper was "Über den Sexuallockstoff des Seidenspinners....". And the term, "Sexuallockstoff", immediately became synonymous with "sex attractant", the material responsible for the ability of female moths to attract males over spectacular distances. Subsequent investigators uncritically adopted Butenandt's bioassay and succeeded in identifying a single compound that elicited short-range excitation from each moth. In almost every case, field trials based on a single compound were disappointing. In 1971, Silverstein (3) influenced by findings of multicomponent pheromones in several beetle species and by the repeated failures of field tests based on single compounds, decided that Wright was probably right. 1Contribution No. 877 from Chemistry and Biology Research Institute. 1

Beroza; Pest Management with Insect Sex Attractants ACS Symposium Series; American Chemical Society: Washington, DC, 1976.


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A seminal paper i n the area of moth pheromones was the r e port by Klun et a l . (4) , who demonstrated that a d d i t i o n of a s m a l l amount of trans-11-1etradecen-1-ol acetate t o c i s - l l - t e t r a d e c e n - l - o l acetate was necessary to trap the redbanded l e a f r o l l e r and the European corn borer i n the f i e l d . The l a t t e r compound had been reported as the sex a t t r a c t a n t of both i n s e c t s (5.,.6) on the b a s i s of i s o l a t i o n , electroantennogram responses, and success f u l f i e l d t e s t s with the s y n t h e t i c compound. Apparently these reports were based on the f a i l u r e t o separate the isomers by g l c , and on the presence of j u s t the " r i g h t " amount of the trans compound as an impurity i n the s y n t h e t i c m a t e r i a l . In a r e i n v e s t i g a t i o n , R o e l o f s (J) showed that s e v e r a l percent of the trans isomer was indeed present i n the redbanded l e a f r o l l e r ; f u r t h e r more, dodecyl acetate, which had been found e m p i r i c a l l y t o enhance f i e l d catches, was a l s o i d e n t i f i e d . The i d e n t i f i c a t i o n by Jacobson et a l . i n 1970 (8) of 2 components of the sex pheromone of the southern armyworm, Spodoptera e r i d a n i a , seems to be the f i r s t reported example of a multicomponent pheromone i n moths. The compounds were c i s - 9 - t e t r a d e c e n l - o l acetate and c i s - 9 - t r a n s - 1 2 - t e t r a d e c a d i e n - l - o l acetate; each e l i c i t e d the short-range e x c i t a t i o n response i n the l a b o r a t o r y , but both together were necessary f o r a t t r a c t i o n i n the f i e l d . It i s i n t e r e s t i n g t o note how many moth pheromones have been d e s c r i bed as multicomponent i n the past f i v e years (Table I ) . In f a c t , a recent paper (9) by Persoons and R i t t e r i s e n t i t l e d "Binary sex pheromones i n T o r t r i c i d a e . Role of p o s i t i o n a l and geometric isomers". These authors suggest, on the b a s i s of s i x species s t u d i e d , that " i n t h i s f a m i l y of i n s e c t s , the feature of b i n a r y sex pheromones may w e l l turn out t o be a general one". They f u r t h e r suggest that " s e v e r a l e a r l i e r reports may need r e c o n s i d e r a tion". N e s b i t t e t a l . r e c e n t l y reported (10) that the sex pheromone of the red bollworm moth c o n s i s t s of f i v e components. Hendry eit a l . d e s c r i b e d (11) the oak l e a f r o l l e r pheromone as a "complex mixture of chemical s i g n a l s " . Beetle pheromones (see Table I I ) , from the beginning, p r e sented a more complex p i c t u r e . The very f i r s t report (12) d e s c r i bed the aggregating pheromone produced by the male bark b e e t l e , Ips paraconfusus, as a mixture of three terpene a l c o h o l s . None of the compounds i n d i v i d u a l l y i s e f f e c t i v e i n the f i e l d , but the ternary mixture a t t r a c t s both males and females i n the f i e l d , mimicking the e f f e c t of a b e e t l e i n f e s t e d t r e e . The aggregating pheromone of the western pine b e e t l e , Dendroctonus brevicomis, c o n s i s t s of two b i c y c l i c k e t a l s , one produced by the female and one by the male, and a terpene hydrocarbon component produced by the host tree (13-18). The aggregating pheromone of the s m a l l e r European elm bark b e e t l e , Scolytus m u l t i s t r i a t u s , c o n s i s t s of a b i c y c l i c k e t a l and an a l c o h o l produced by the female, and a t e r pene hydrocarbon component produced by the host t r e e (19).



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Multicomponent Pheromones

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I n t e r e s t i n g l y , the insect-produced components are found i n the hindguts of a l l species of Ips and Dendroctonus examined, whereas t h i s does not seem t o be the case f o r the s i n g l e species i n the genus Scolytus examined to date (19) . The male b o l l w e e v i l , Anthonomus g r a n d i s , produces a 4-component aggregating pheromone (20) c o n s i s t i n g of two terpene a l c o h o l s and two terpene a l d e hydes. Again, the pheromone components were i s o l a t e d from f e c a l pellets. In the coleopteran family Dermestidae (which i n c l u d e s many s e r i o u s pests of s t o r e d food*products), we can c i t e s e v e r a l s p e c t a c u l a r examples of multicomponent sex a t t r a c t a n t s . I t has been shown that there i s a great d e a l of cross a t t r a c t i v e n e s s among s e v e r a l species of the genus Trogoderma (21,22). The chemical b a s i s o f cross a t t r a c t i o n among four species (23) i s shown i n Table I I I . Of the s i x components shared by the four s p e c i e s , 14-methyl-8-hexadecenal i s by f a r the most potent — i . e . , e f f e c t i v e at lowest concentration. T h i s compound was com p l e t e l y missed i n previous i s o l a t i o n s t u d i e s of T\ inclusurn (24) and Τ.· g lab rum (25) , which were done on e x t r a c t s of macerated b e e t l e s . Despite t h i s cross a t t r a c t i o n , each species can r e a d i l y d i s t i n g u i s h i t s own pheromone, and i s r e p r o d u c t i v e l y i s o l a t e d by t h i s preference — and presumably by other f a c t o r s . For example, each species has a t h r e s h o l d response t o i t s own geometric isomer of 14-methyl-8-hexadecenal that i s about 1000 times more s e n s i t i v e than i t s t h r e s h o l d response t o the other isomer (26). Greenblatt eit a l . (26) c a r r i e d out a d e t a i l e d study of the mating behavior of T. g lab rum and showed how the i n d i v i d u a l components mediated the v a r i o u s phases of the t o t a l behavior. Some s p e c u l a t i o n might be i n order on the reasons f o r the f a i l u r e t o i d e n t i f y the most important pheromone component i n the e a r l i e r s t u d i e s of T. inclusurn (24) and T. glabrum (25). Two p o s s i b i l i t i e s are suggested. In these s t u d i e s , the whole i n s e c t was macerated with a solvent i n a Waring blender; i t i s p o s s i b l e that t i s s u e enzymes may have s e l e c t i v e l y destroyed one of the components. A l t e r n a t i v e l y and p o s s i b l y more c o n v i n c i n g l y , one component may be produced continuously i n very s m a l l amounts from a precursor; t h i s component might not be detected i n a d i r e c t e x t r a c t i o n of the i n s e c t , but i t would accumulate during the a e r a t i o n process. At l e a s t four other s i m i l a r examples have appeared i n the l i t e r a t u r e : Shearer and Boch (27) observed c i t r a l i n the Nassanoff gland pheromone only when a s e c r e t i o n was allowed t o stand overnight at room temperature. B i e r l et a l . (28) detected only minute amounts of the a c t i v e component (an epoxide) and much l a r g e r amounts of the apparent p r e c u r s o r (an o l e f i n ) i n the e x t r a c t of abdominal t i p s of the gypsy moth. H i l l et a l . (29) i d e n t i f i e d an aldehyde as a major pheromone component by a e r a t i o n of female orange t o r t r i x moths, but could detect only minute amounts i n the e x t r a c t of abdominal t i p s . Weatherston et^ a l . (30) could not i d e n t i f y the sex a t t r a c t a n t compound of the spruce



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budworm by e x t r a c t i o n of abdominal t i p s , but the compound d i d accumulate on the g l a s s w a l l s of the containers ; t h i s compound was a l s o an aldehyde. In the Hymenoptera, Boch et_ a l . (31) have shown t h a t the pheromone r e l e a s e d by the queen honey bee t o s t a b i l i z e swarms of workers does not c o n s i s t of (E)-9-oxodec-2-enoic a c i d alone. Methyl 4-hydroxybenzoate, i s o l a t e d from queen e x t r a c t , synergizes the swarm a t t r a c t i o n of the oxo a c i d and there are yet other a c t i v e components i n the e x t r a c t t o be i d e n t i f i e d (Young et_ a l . , unpublished). Mediterranean and Carribean f r u i t f l i e s use m u l t i component sex pheromones (32,33). There i s no need here to document f u r t h e r the prevalence of multicomponent pheromones i n the complex s o c i e t i e s of ants and bees. Several e x c e l l e n t , recent reviews are a v a i l a b l e (34-36). We now r a i s e the question: "Are there r e a l l y any s i n g l e component pheromones?" We cannot say. A number have been r e p o r t e d , and i n some cases, a conscious e f f o r t was made to search f o r other components, b u t , of course, i t i s d i f f i c u l t t o show that something may be m i s s i n g . The only s a t i s f a c t o r y c r i t e r i o n i s to show that the component e l i c i t s the same t o t a l response as does the t e s t animal at the same concentration. But how does one compare concentrations? An e x t r a c t , as mentioned above, does not n e c e s s a r i l y contain detectable amounts of a l l of the a c t i v e components. The Trogoderma s t u d i e s (24,25) showed that the compounds i d e n t i f i e d from the e x t r a c t were equivalent i n a c t i v i t y to the t o t a l e x t r a c t , but the most important component was, i n f a c t , missing from the e x t r a c t . U n t i l recent s t u d i e s based on aerat i o n , we could be s a t i s f i e d by a comparison w i t h the e x t r a c t of the whole i n s e c t or a p o r t i o n thereof. No longer! A number of r e i n v e s t i g a t i o n s based on a e r a t i o n would seem t o be i n order. But i n some cases, there remain t e c h n i c a l d i f f i c u l t i e s . For example, Sonenshine et^ a l . (37,38) reported that the sex pheromone of two species of t i c k s (we i n c l u d e t h i s non-insect) was 2,6-dichlorophenol. No other f r a c t i o n of the e x t r a c t e l i c i t e d a response. The i n v e s t i g a t o r s , conscious of the p i t f a l l , attempted a e r a t i o n of the t i c k s feeding on the body of a r a b b i t , but they were defeated by the mechanical d i f f i c u l t i e s i n v o l v e d i n a e r a t i n g thousands of t i c k s , not t o mention the overwhelming c o n c e n t r a t i o n of r a b b i t odor. One m i t i g a t i n g feature of t h i s study might be c i t e d : the complex r i t u a l of the sex response e l i c i t e d by a feeding female from a male that has been feeding on the same animal was reproduced p r e c i s e l y by very low concentrations of authentic 2,6-dichlorophenol. The a e r a t i o n technique i s i d e a l l y s u i t e d t o i n s e c t s such as adult dermestid b e e t l e s and moths, which do not feed and which go through a p e r i o d i c " c a l l i n g " performance. I t can be used on bark and ambrosia b e e t l e s , but the components of the aggregation pheromone must be i s o l a t e d from the complex mixture of host



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compounds. A good l a b o r a t o r y bioassay becomes the sine qua non, but one s t i l l runs the r i s k of d i s c r e p a n c i e s between the l a b o r a tory response and f i e l d behavior. One f e a t u r e of absorption on Porapak should be noted: I t i s not a very good absorbent f o r s m a l l p o l a r molecules, but, of course, i t i s t h i s very feature that permits passage of water. Furthermore, the aerated i n s e c t s , container and contents should be i n v e s t i g a t e d f o r the presence of a c t i v e components of low v o l a t i l i t y . We have t a l k e d about s i n g l e components without f u r t h e r d e f i n i t i o n , but an a d d i t i o n a l refinement remains. Many n a t u r a l products are c h i r a l compounds, but u n t i l r e c e n t l y the question of enantiomeric p u r i t y has been g e n e r a l l y ignored. In the f i r s t p l a c e , i t i s f r e q u e n t l y d i f f i c u l t t o i s o l a t e enough m a t e r i a l to obtain an accurate o p t i c a l r o t a t i o n . Secondly, two t a c i t assumptions prevail: c h i r a l n a t u r a l products are e i t h e r one enantiomer or the other, and i t probably makes l i t t l e d i f f e r e n c e i n the communication system. The above d i f f i c u l t y has been overcome with the advent of c h i r a l s h i f t reagents and c h i r a l d e r i v a t i z i n g agents, and o f pulsed NMR; determinations of o p t i c a l p u r i t y are f e a s i b l e i n many cases at the l e v e l of about 50 micrograms (39,40). The t a c i t assumptions have been destroyed by s e v e r a l f i n d i n g s of the presence of both enantiomers i n pheromones, and by r e p o r t s that at l e a s t s e v e r a l i n s e c t s can d i s c r i m i n a t e between enantiomers. R i l e y and S i l v e r s t e i n (41) showed that the l e a f c u t t i n g ants, At t a texana and A. cephalotes respond to a lower concentration o f the n a t u r a l l y occurring alarm pheromone, ( S ) (+)-4-methyl-3-heptanone, than of i t s enantiomer. Kafka et a l . (42) and Lensky and Blum (43) conditioned honeybees to d i s c r i m i nate between enantiomers, which, however, were not part of the n a t u r a l communication system of the t e s t i n s e c t . Mori (44,45) synthesized the enantiomers of exo-brevicomin and f r o n t a l i n , pheromone components of the western and southern pine b e e t l e s (13-18). A determination was made of the enantiomeric composit i o n of these components produced by the b o r i n g i n s e c t (40). exo-B r e v i comin i s present i n the western pine b e e t l e , and only i n the (R)-(+) form. Laboratory bioassays showed that the b e e t l e s responded more s t r o n g l y to (R)-(+) exo-b r e v i comin than to i t s enantiomer when these enantiomers were t e s t e d i n combination with myrcene (the host component) and racemic f r o n t a l i n (D. L . Wood and L. E. Browne p r i v a t e communication). The f r o n t a l i n present i n the southern pine b e e t l e i s approximately 85% ( S ) - ( - ) / 15% (R)-(+) (40). I p s d i e n o l from Ips_ paraconfusus i s 90% (+)/10% (-). C a l i f o r n i a and Idaho populations of Ips p i n i c o n t a i n the (-) enantiomer, whereas the New York p o p u l a t i o n c o n t a i n a 65% (+)/35% (-) mixture. Seudenol from the Douglas f i r b e e t l e i s a 50:50 mixture (39). 4-Methyl-3-heptanol from the elm bark b e e t l e c o n s i s t s of a s i n g l e enantiomer out of four p o s s i b l e enantiomeric



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structures (39). Thus a description of ipsenol, ipsdienol, sulcatol, transverbenol, seudenol, 4-methyl-3-heptanol, 4-methyl-3-Tieptanone, exo-b revi comin, frontalin, or multistriatin as a single compound would be valid only in a world devoid of chirality. A complete identification of a chiral pheromone should therefore include a statement of enantiomeric composition and a description of the absolute configuration of the chiral center(s). In summary, communications in the insect world are a good deal more complex than was thought by the early investigators. This statement is probably true of most natural phenomena despite the common misconception that Occam's Razor demands simplistic answers· Literature Cited (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15)

Wright, R. H., Nature (1964), 204, 121-125. Butenandt, Α., Beckman, R., Stamm, D., and Hecker, Ε., Z. Naturforsch. (1959) 14b, 283-284. Silverstein, R. Μ., in "Chemical Releasers in Insects", A. S. Tahori, Ed., pp. 69-89, Gordon and Breach, Ν. Υ., 1971. Klun, J. Α., Chapman, O. L . , Mattes, K. C., Wojtkowski, P. W., Beroza, Μ., and Sonnet, P. Ε., Science (1973) 181, 661. Roelofs, W. L. and Arn, Η., Nature (1968) 219, 513. Klun, J. Α., and Brindley, Τ. Α., J . Econ. Entomol. (1970) 63, 779-780. Roelofs, W. L . , Hill, Α., and Cardé, R., J . Chem. Ecol. (1975) 1, 83-89. Jacobson, M., Redfern, R. E . , Jones, W. Α., and Aldridge, M. H., Science (1970) 170, 542-543. Persoons, C. J . and Ritter, F. J., Z. angew. Entomol. (1975) 77, 342-346. Nesbitt, B. F., Beevor, P. S., Cole, R. Α., Lester R., and Poppi, R. G., J. Insect Physiol. (1975) 21, 1091-1096. Hendry, L. Β., Anderson, M. E . , Jugovich, J., Mumma, R. O., Robaker, D., and Kosarych, Z., Science (1975) 187, 355-356. Silverstein, R. Μ., Rodin, J. O., and Wood, D. L., Science (1966) 154, 509-510. Silverstein, R. M., Brownlee, R. G., Bellas, T. E . , Wood, D. L. and Browne, L. E . , Science (1968) 159, 889-891. Bedard, W. D., Tilden, P. E . , Wood, D. L . , Silverstein, R. Μ., Brownlee, R. G., and Rodin, J. O., Science (1969) 164, 1284-1285. Kinzer, G. W., Fentiman, A. F., Page, T. F., Foltz, R. L . , Vité, J. P., and Pitman, G. Β., Nature (1969) 221, 477-478.



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(16) Vité, J. P. and Pitman, G. B., J. Insect Physiol. (1969) 15, 1617-1622. (17) Bedard, W. D., Silverstein, R. Μ., and Wood, D. L., Science (1970) 167, 1638-1639. (18) Wood, D. L., Symposia of the Royal Entomological Society of London (1972) No. 6, 101-117. (19) Pearce, G. T., Gore, W. E . , Silverstein, R. Μ., Peacock, J. W., Cuthbert, R. Α., Lanier, G. Ν., and Simeone, J . B., J. Chem. Ecol. (1975) 1, 115-124. (20) Tumlinson, J . Η., Hardee, D. D., Gueldner, R. C., Thompson, A. C., Hedin, P. Η., and Minyard, J . P., Science (1969) 166, 1010-1012. (21) Vick, Κ. W., Burkholder, W. E . , and Gorman, J . Ε., Ann. Entomol. Soc. Am. (1970) 63, 379-381. (22) Levinson, Η. Z. and Bar Ilan, A. R., J. Insect Physiol. (1970) 16, 561-572. (23) Cross, J . H., Cassidy, R. F., Ravid, U., Silverstein, R. Μ., Greenblatt, R. E . , Burkholder, W. Ε., Levinson, Η. Z. and Levinson, A. R. Submitted for publication. (24) Rodin, J . O., Silverstein, R. Μ., Burkholder, W. E. and Gorman, J . E . , Science (1969) 165, 904-906. (25) Yarger, R. G. and Silverstein, R. M., J . Chem. Ecol. (1975) 1, 323-334. (26) Greenblatt, R. E., Burkholder, W. E . , Cross, J . Η., Byler, R. C., and Silverstein, R. M. Submitted for publication. (27) Shearer, D. A. and Boch, R., J. Insect Physiol. (1966) 12, 1513-1521. (28) Bierl, Β. Α., Beroza, Μ., Collier, C. W., Science (1970) 170, 87-89. (29) Hill, A. S. Cardé, R. T., Kido, Η., and Roelofs, W. L., J . Chem. Ecol. (1975) 1, 215-224. (30) Weatherston, J., Roelofs, W. L., Comeau, Α., and Sanders, C. J., Can. Entomol. (1971) 103, 1741-1747. (31) Boch, R., Shearer, D. Α., and Young, J . C., J . Chem. Ecol. (1975) 1, 133-148. (32) Jacobson, Μ., Ohinata, Κ., Chambers, D. L., Jones, W. Α., and Fujimoto, M. S., J . Med. Chem. (1973) 16, 248-251. (33) Nation, J . L., Environ. Entomol. (1975) 4, 27-30. (34) Blum, M. S., in "Pheromones", M. C. Birch, ed. , pp. 190199, North-Holland, London/American Elsevier, Ν. Υ., 1974. (35) Gary, Ν. E . , in "Pheromones", M. C. Birch, ed., pp. 200221, North-Holland, London/American Elsevier, Ν. Υ., 1974. (36) Blum, M. S., in "Pheromones", M. C. Birch, ed., pp. 222249, North-Holland, London/American Elsevier, Ν. Y., 1974. (37) Sonenshine, D. Ε., Silverstein, R. M., Layton, E. C., and Homsher, P. J., J . Med. Entomol. (1974) 11, 307-315. (38) Sonenshine, D. Ε., Silverstein, R. Μ., Plummer, E. L . , West, J . R., and McCullough, (Brother) T. F . , J . Chem. Ecol. (1976) in press.


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(39) Plummer, E. L., Stewart, Τ. Ε., Byrne, K. J., Gore, W. E . , Pearce, G. T., and Silverstein, R. M., J . Chem. Ecol. (1976) in press. Presented at the 168th ACS National Meeting, Atlantic City, N. J., Sept., 1974. (40) Stewart, Τ. Ε., Plummer, E. L., Pearce, G. T., McCandless, L . , and Silverstein, R. M., J . Chem. Ecol. (1976) in press. Presented at the 168th ACS National Meeting, Atlantic City, N. J., Sept. 1974. (41) Riley, R. G., Silverstein, R. Μ., and Moser, J . C., Science (1974) 183, 760-762. (42) Kafka, W. Α., Ohloff, G., Schneider, D., and Vareschi, Ε., J. Comp. Physiol. (1973) 87, 277-284. (43) Lensky, Y. and Blum, M. S., Life Sci. (1974) 14, 2045-2049. (44) Mori, Κ., Tetrahedron (1974) 30, 4223-4227. (45) Mori, Κ., Tetrahedron (1975) 31, 1381-1384.


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Table I. Lépidoptère reported having multicomponent pheromones b

a Species (Common name)

Pheromones (Ratio)

Bioassay

References

1°+ 2 (?) ~ ~

F ο

1

+ 6 (?)

F ο F ο F ο F ° F.

2

D. chrysippus Linnaeus (African monarch b u t t e r f l y ) D. gilippus berenice (Cramer) (queen b u t t e r f l y ) D. hamatus hamatus (Macl.)

3 ~ 2 ~ 2 ~ 3 ~ 3 ~ 1

+ 3 (?)

F

'

~

ARCTIIDAE Utetheisa l o t r i x (Cramer)


DAN AI DAE Amauris niavius Linnaeus —— Danaus a f f i n i s a f f i n i s Fabricius " D. a. a l b i s t r i g a

!

D. h. moderatus (Butler)

+ 4 ~ + 3 ~ + 3 ~ + 5

(?) (?) (?) (?)

Lycorea ceres ceres Cramer

4 5 6

1

~

3 Ο

1 + 3 (?) ~ 7 + 8 (?) ~ 11 d 1 + C-,OAc + Z C. 0Ac (?) ~ lo XO

D. plexippus Linnaeus (monarch b u t t e r f l y )

3

o

F ο F ° F

4 7,8

9 Ο

GELECHIIDAE Pectinophora gossypiella (Saunders) (pink bollworm moth)

10

Z^^CÔAc + z V ^ ^ O A c (1*1) 7

U

Z Z C OAc + z V ^ O A c l 6

F

2

F

x

F

x

11

(1:1) 7

9 + 10 + Z C O H

e

1 6

12,13

(?)

9 11 CÔAc + Ε C OAc + Δ CÔAc +

Diparopsis castanea Hmps. (red bollworm moth)

12

9

11

9

U

E A C O A c + Z A C O A c (?) 12

A

1:L

1 2

9

11

C 0Ac + E A C OAc + z V ^ O A c 12

12

T

±

(?:4:1) ο plus C 0Ac + Ε C 0Ac whose function 12

12

i s not clear.


14, 15

10


Table I. cont'd.

Pheromones (Ratio)

Species (C

Insects Generally Use Multicomponent Pheromones - ACS Publications

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