Behavioral activity of optical isomers of 5,9-dimethylheptadecane,the sex pheromone ofLeucoptera scitella L. (Lepidoptera: Lyonetidae)

Among the pure stereoisomers of 5,9-dimethylheptadecane, a previously identified sex pheromone component ofLeucoptera scitella L., only theS,S isomer yielded trap captures in the field. The addition of the other stereoisomers had no effect on cathes. The addition of low percentages of racemic 5,9-dimethylhexadecane, a previously identified minor component in the sex pheromone, did not influence trap catches or alter behavior of males approaching an attractant source in the field.     

Evidence for the controlled release of a crustacean sex pheromone

Evidence for the controlled release of a crustacean sex pheromone: mature malePortunus sanguinolentus (Herbst) did not give the characteristic display described by Ryan (1966) to water from a container with a carried or artificially restrained premolt female. However, the sex pheromone was still present in the urine of the restrained female, suggesting that she inhibits the emission of the sex pheromone by regulating her urine flow.Based on part of a dissertation presented by the author in partial fulfillment of the requirements for the doctoral degree in zoology at the University of Hawaii.     

Identification of a sex pheromone ofHeliothis subflexa (GN.) (Lepidoptera: Noctuidae) and field trapping studies using different blends of components

Eight compounds were isolated from the sex pheromone gland ofHeliothis subflexa (Gn.) and identified as hexadecanal, (Z)-9-hexadecenal, (Z)-11-hexadecenal, (Z)-7-hexadecen-1-ol acetate, (Z)-9-hexadecen-1-ol acetate, (Z)-11-hexadecen-1-ol acetate, (Z)-9-hexadecen-1-ol, and (Z)-11-hexadecen-1-ol. Although the whole blend was found to be an effective male attractant, the deletion of alcohols from the blend increased trap captures considerably. Further, although the binary mixture of (Z)-9-hexadecenal and (Z)-11-hexadecenal caught some maleH. subflexa, significant increases in captures were noted when the three acetate components were included in the blend.Mention of a commercial or proprietary product in this paper does not constitute an endorsement of that product by the USDA or the State of Florida.     

Chirality of synergistic sex pheromone components of the western hemlock looperLambdina fiscellaria lugubrosa (HULST) (Lepidoptera: Geometridae)

Bakers' yeast reduction of (2E)-3-(2-furanyl)-2-methyl-2-propenal yielded the synthetic intermediate, (2S)-3-(2-furanyl)-2-methylpropanol, of high chiral purity (>97% ee) for the synthesis of the enantiomers of 2,5-dimethylheptadecane and 7-methylheptadecane, two synergistic sex pheromone components of the western hemlock looper (WHL),Lambdina fiscellaria lugubrosa Hulst. In electrophysiological bioassays, (7S)- but not (7R)-7-methylheptadecane elicited strong antennal responses by male WHL antennae. In field trapping experiments, addition of (7S)- but not (7R)-7-methylheptadecane to (5R,11S)-5,11-dimethylheptadecane, the major sex pheromone component of WHL, increased attraction. Attraction to (5R,11S)-5,11-dimethylheptadecane in combination with (7S)-7-methyiheptadecane was further enhanced by the addition of (5S)- but not (5R)-2,5-dimethylheptadecane. Similarly, attraction to (5R,11S)-5,11-dimethylheptadecane combined with (5S)-2,5-dimethylheptadecane increased when 7S- but not (7R)-7-methylheptadecane was added as a third component. We conclude that (7S)-7-methylheptadecane and (5S)-2,5-dimethylheptadecane are the synergistic sex pheromone components of WHL. The synthetic methodology described is applicable to the synthesis of chiral methyl-branched pheromones in other orders of the Insecta, particularly Coleoptera, Diptera and Orthoptera.     

Behavioral and electrophysiological responses of the brownbanded cockroach,Supella longipalpa,to stereoisomers of its sex pheromone,supellapyrone

Females of the brownbanded cockroach, Supella longipalpa, release a sex pheromone (supellapyrone) during a calling behavior and attract males from a distance. Supellapyrone has four possible configurations resulting from two asymmetric carbons at positions 2 and 4 (i.e., 2R,4R; 2R,4S; 2S,4R; and 2S,4S), but only the RR isomer is produced by females. Using pure synthetic stereoisomers in field tests, we showed that males are attracted to RR but also to high concentrations of the isomer SR. To study the activity of the stereoisomers in more detail we developed behavioral and electroantennogram (EAG) dose–response curves for each. Behaviorally, RR was the most active isomer with just 0.3 pg delivered on a filter paper being sufficient to elicit 50% male response in the olfactometer. Males were also attracted to SR and SS in the olfactometer, but at much higher dosages (100×) than the natural compound; RS did not elicit behavioral responses at any of the doses tested. In EAG assays, the antenna of male S. longipalpa showed high and similar sensitivity to RR and SR, but a much lower (10%) sensitivity to SS and practically no response to RS. The lack of agreement between behavioral and electrophysiological data suggested either that RR and SR stimulate different antennal sensory neuron types, or that some aspect of the interaction between the pheromone and the sensillum environment or the receptor neuron itself is different. To test the first hypothesis we examined the response of the antenna before and after adaptation with each of the four stereoisomers. Positive cross-adaptation between RR and SR suggests that these two compounds stimulate the same receptor cells. Therefore, the lack of agreement between behavioral and EAG dose–response curves could be explained by isomer-specific molecular interactions between the pheromone and the receptor neuron. Although RR and SR produced the same EAG amplitude, stimulation with SR resulted in a slower recovery rate (i.e., wider peaks) than stimulation with RR. To gain further understanding of the response specificity of the antennae to the different stereoisomers we compared EAG responses (amplitude and recovery time) in response to individual stereoisomers and binary mixtures of isomers. These tests showed additive responses of the EAG amplitude to mixtures of compounds, but nonadditive responses of EAG recovery time. Therefore, peak height and width are independent parameters of the EAG, probably representing different intrasensillar events, and likely resulting in the expression of different behavioral responses.     

Female sex pheromone components ofHeliothis peltigera (Lepidoptera: Noctuidae)

Ten compounds were found in the sex pheromone glands ofHeliothis peltigera (Schiff) and identified as tetradecenal, (Z)-9-tetradecenal, (Z)-9-tetradecenol, (Z)-9-tetradecenyl acetate, hexadecanal, (Z)-7-hiexadecenal, (Z)-9-hexadecenal, (Z)-11-hexadecenal, (Z)-11-hexadecenol, and (Z)-11-hexadecenyl acetate. Behavioral tests in a wind tunnel and subsequent trapping studies conducted in the field indicated that (Z)-11-hexadecenal and (Z)-9-tetradecenal are the main pheromone components ofH. peltigera. Addition of (Z)-11-hexadecenol to the binary blend did not enhance the capture of males ofH. peltigera, but it decreased the number of males of the sympatricH. armigera. Rubber septa impregnated with a mixture of 2 mg (Z)-11-hexadecenal + 1 mg (Z)-9-tetradecenal + 0.6 mg (Z)-11-hexadecenol are recommended for monitoringH. peltigera. Contribution from the Agricultural Research Organization (ARO), No. 2454-E, 1988 series.     

Minor components in the sex pheromone of legume podborer: Maruca vitrata development of an attractive blend

The legume podborer, Maruca vitrata (syn. M. testulalis) (F.) (Lepidoptera: Pyralidae) is a pantropical pest of legume crops. Sex pheromone was collected by gland extraction or trapping of volatiles from virgin female moths originating in India, West Africa, or Taiwan. Analysis by GC-EAG and GC-MS confirmed previously published findings that (E,E)-10,12- hexadecadienal is the most abundant EAG-active component with 2–5% of (E,E)-10,12-hexadecadienol also present. At least one other EAG response was detected at retention times typical of monounsaturated hexadecenals or tetradecenyl acetates, but neither could be detected by GC-MS. Laboratory wind-tunnel bioassays and a field bioassay of blends of (E,E)-10,12-hexadecadienal with (E,E)-10,12-hexadecadienol and a range of monounsaturated hexadecenal and tetradecenyl acetate isomers indicated greatest attraction of males was to those including (E,E)-10,12-hexadecadienol and (E)-10-hexadecenal as minor components. In subsequent trapping experiments in cowpea fields in Benin, traps baited with a three-component blend of (E,E)-10,12-hexadecadienal and these two minor components in a 100:5:5 ratio caught significantly more males than traps baited with the major component alone, either two-component blend, or virgin female moths. Further blend optimization experiments did not produce a more attractive blend. No significant differences in catches were found between traps baited with polyethylene vials or rubber septa, or between lures containing 0.01 and 0.1 mg of synthetic pheromone. Significant numbers of female M. vitrata moths, up to 50% of total catches, were trapped with synthetic blends but not with virgin females. At present there is no clear explanation for this almost unprecedented finding, but the phenomenon may improve the predictive power of traps for population monitoring.     

Hydrocarbon components of the yellowheaded spruce sawfly sex pheromone

The primary sex pheromone of the yellowheaded spruce sawfly,Pikonema alaskensis (Rohwer) (Hymenoptera: Tenthredinidae), was found to include a series of straight-chain hydrocarbon dienes, all with the double bonds in the 9 and 19 positions and all with the (Z, Z) configuration. The major components, of 29, 31, 33, 35, and 37 carbon atoms, were synthesized. In the field and the greenhouse, the synthetic dienes were far above control levels in activity but, at least during the first hours of bioassay, were somewhat less active than the female-derived materials on a weight basis. In the field, a mixture of all five synthetic dienes, in the proportions found in the females, was more attractive than any single one, on a mole basis. In addition, (Z, Z)-9,19 dienes of 28, 30, 32, 34, 36, 38, and 39 carbons have been detected in females in minor amounts. The first five were bioassayed, and each was found to be similar in activity to the 35-carbon component when compared on a weight basis. The synthetic dienes, while active by themselves, were strongly synergized by two, more polar, Florisil fractions derived from females. Experimental design considerations are discussed.     

Field response of maritime pine scale,Matsucoccus feytaudi duc. (Homoptera: Margarodidae), to synthetic sex pheromone stereoisomers

The absolute configuration of the primary component of the maritime pine scale (Matsucoccus feytaudi) pheromone (i.e., (8E, 10E)-3,7,9-trimethyl-8,10-dodecadien-6-one) was determined as 3S,7R by field-trapping experiments using synthetic stereoisomers and according to previous NMR considerations. The 3R,7R isomer showed similar activity to 3S,7R, whereasM. feytaudi males responded very weakly to the two other candidates (3R,7S and 3S,7S). Further studies were conducted to optimize scale trapping for monitoring scale populations. Results of these studies showed that the trapping efficiency was related to pheromone dose, trap area, and wind speed but not to trap height.     

The attractivity of the female sex pheromone ofPeriplaneta americana and its components for conspecific males and males ofPeriplaneta australasiae in the field

The attractivity of virgin female odors of the American cockroach was examined in field experiments. Crude extracts of the female odor, the isolated sex pheromone fractions, periplanone-A and periplanone-B, and other compounds obtained during the isolation served as stimulants. An extract of male odors, obtained by identical collection methods, was used as a control. Males ofPeriplaneta americana were attracted by the crude extract and periplanone-B; males of the sympatric species,P. Australasiae, by periplanone-A. Experiments in which these components were presented subsequently and as mixtures indicate that, under certain conditions, periplanone-A may also function as an attracting substance forP. americana males and that periplanone-B and possibly some other components act as an inhibitor for males ofP. australasiae.     

Identification of the sex pheromone of the yellow scale

The sex pheromone of the yellow scale,Aonidiella citrina (Coquillett), was isolated from airborne collections and found to be (E)-3,9-dimethyl-6-isopropyl-5,8-decadien-1-yl acetate. Aonidiella citrina (Coquillett) (Homoptera: Diaspididae).This research was supported by a USDA cooperative research grant.     

3,13-Dimethylheptadecane: Major sex pheromone component of the western false hemlock looper,Nepytia freemani Munroe (Lepidoptera: Geometridae)

3,13-Dimethylheptadecane (3,13-dime-17Hy) is the major sex pheromone component of the western false hemlock looper (WFHL),Nepytia freemani Munroe. It was identified in extracts of female pheromone glands by coupled gas chromatographic-electroantennographic detection (GC-EAD) and coupled GC-mass spectroscopy (GC-MS). Traps baited with 100g of 3,13-dime-17Hy attracted large numbers of male WFHL. Of five additional candidate pheromone dimethylated hydrocarbons, only 3,13-dimethylhexadecane attracted male WFHL. However, neither 3,13-dime-16Hy nor the other four compounds enhanced attraction to 3,13-dime-17Hy when tested in binary or ternary combination at respective ratios of 10010, 1001, or 10011. Identification of the complete WFHL sex pheromone requires structural elucidation of all 12 EAD-active components in gland extracts, determination of their chirality, and field testing of antennally active isomers in appropriate combinations and ratios. Stereoisomeric 3,13-dime-17Hy as trap bait may already be used to monitor WFHL populations.     

Nantucket pine tip moth,Rhyacionia frustrana: Identification of two sex pheromone components

Two compounds identified as components of the sex pheromone system ofRhyacionia frustrana are (E)-9-dodecen-1-yl acetate (I) and (E)-9,11-dodecadien-1-yl acetate (II), which were found in female gland extracts in the ratio of 964, respectively. The identifications were based on chemical and instrumental analyses, electroantennogram studies, and field trapping tests. The optimum ratio for trapping maleR. frustrana is the range of 955 to 97.52.5 (III), when dispensed from rubber septa at a loading of ca. 1000/g/lure. In addition to these two compounds, evidence was obtained for the presence of dodecan-1-ol and (E)-9-dodecen-1-ol in female tip extracts and in female effluvium, and for dodecan-1-yl acetate in female tip extracts.Lepidoptera: Tortricidae: Olethreutinae.Supported in part by the Rockefeller Foundation and by National Science Foundation grants GB-38020 and PCM 78-13241.     

Sex pheromone components of the spring hemlock looper,Lambdina athasaria (Walker) (Lepidoptera: Geometridae)

Two methylated hydrocarbons, 7-methylheptadecane (7) and 7,11-dimethylheptadecane (7,11), are female sex pheromone components of the spring hemlock looper (SHL),Lambdina athasaria (Walker). Compounds extracted from female pheromone glands were identified by coupled gas chromatographic-electroantennographic detection (GC-EAD) and coupled GC-mass spectrometry (GC-MS) in selected ion monitoring mode. In field trapping experiments, (7) and (7,11) by themselves were behaviorally inactive, but in combination attracted numerous male moths. (5,11)-Dimethylheptadecane (5,11) was detected in female SHL pheromone gland extracts, but did not enhance attraction to the binary blend of (7) and (7,11). The sex pheromone of SHL is related to that of congeneric eastern hemlock looper (EHL),Lambdina fiscellaria fiscellaria (Guen.) [(5,11) and 2,5-dimethylheptadecane (2,5)] and western hemlock looper (WHL),L.f. lugubrosa (Hulst) [(5,11), (2,5) and (7)]. Specificity of the pheromonal blend, spatial separation of coseasonal EHL and WHL, and temporal separation of sympatric EHL and SHL contribute to reproductive isolation.Dedicated to my father, Johannes Dinter, in honor of his 73th birthday.     

Female sex pheromone of the Yunnan pine caterpillar moth Dendrolimus houi: first (E,Z)-isomers in pheromone components of Dendrolimus spp

The Yunnan pine caterpillar Dendrolimus houi Lajonquière is a serious defoliator of coniferous forests in southwestern China. Gas chromatography–electroantennography (GC–EAG) analyses of extracts of female sex pheromone glands of D. houi moths revealed the presence of three compounds eliciting antennal responses. These were identified as (5E,7Z)-5,7-dodecadien-1-ol (E5,Z7-12:OH), (5E,7Z)-5,7-dodecadien-1-yl acetate (E5,Z7-12:OAc), and (5E,7Z)-5,7-dodecadienal (E5,Z7-12:Ald) by comparison of their GC retention indices, mass spectra, and EAG activities with those of synthetic standards. Average amounts of E5,Z7-12:OH, E5,Z7-12:OAc, and E5,Z7-12:Ald per calling virgin D. houi female were 14.7 ± 12.9 ng (± SD), 5.8 ± 5.4 ng, and 0.8 ± 1.4 ng, respectively, in a ratio of 100:39.7:5.6. These three components were also collected from the headspace of calling virgin female moths by solid-phase microextraction (SPME). In addition, trace quantities of (Z)-5-dodecen-1-ol (Z5-12:OH), (5Z,7E)-5,7-dodecadien-1-ol (Z5,E7-12:OH), (5E,7E)-5,7-dodecadien-1-ol (E5,E7-12:OH), (5Z,7E)-5,7-dodecadien-1-yl acetate (Z5,E7-12:OAc), (5Z,7Z)-5,7-dodecadien-1-yl acetate (Z5,Z7-12:OAc), and (5E,7E)-5,7-dodecadien-1-yl acetate (E5,E7-12:OAc) were tentatively identified in female pheromone gland extracts by selected ion monitoring GC-MS. Field trapping experiments showed that E5,Z7-12:OH, E5,Z7-12:OAc, and E5,Z7-12:Ald were essential for attraction of male D. houi moths. Traps baited with a 20:1:1 blend (alcohol/acetate/aldehyde) loaded on gray rubber septa were as effective as traps baited with virgin female moths. The optimum ratio of acetate to aldehyde was 1:1, and this ratio was more critical than the ratio of either compound to the alcohol. This represents the first example of (E,Z)-isomers in pheromone blends of Dendrolimus species.     

Identification of sex pheromone components ofSpodoptera sunia Guenée (Lepidoptera: Noctuidae)

Moths belonging to the speciesSpodoptera sunia have been recognized as a new pest of cotton in Central America. By means of electro-physiologic investigations, solid sample injection gas chromatography, and combined gas chromatography-mass spectrometry, (Z)-9-tetradecenyl acetate, (9Z,12E)-9,12-tetradecadienyl acetate, (Z)-9-tetradecen-1-ol, and (Z)-11-hexadecenyl acetate, in a ratio of 10053120, were identified in the pheromone gland of female insects. These substances should serve as a base for the development of a pheromone-monitoring system for this lepidopteran pest.Pheromones, 60. Pheromones 59: Bestmann, HJ., Attygalle, A.B., Brosche, T., Erler, J., Platz, H., Schwarz, J., Vostrowsky, O., Wu Cai-Hong, Kaissling, K.E. and Chen Te-Ming. 1987. Z.Naturforsch. 42c:631–636.     

Female sex pheromone components of jasmine mothPalpita unionalis (Lepidoptera: Pyralidae)

(E)-11-Hexadecenal and (E)-11-hexadecen-1-yl acetate were found in abdomen tip extracts from females of the jasmine mothPalpita unionalis (Hübn). The identification was based on capillary GC analyses, mass spectrometry, and laboratory and field tests. In laboratory bioassays, both components elicited a low level of upwind flight by males. The two components when tested separately in the field were inactive, but the blend of the two components at a ratio of (3:7) was highly attractive to males. Traps baited with 1 mg of the two-component blend were competitive to traps baited with five virgin females. The addition of Z isomers components reduced male capture.     

Synthesis of the stereoisomers of the female sex pheromone of the Hessian fly,Mayetiola destructor

The female-produced sex pheromone of the Hessian fly,Mayetiola destructor (Say) (Diptera: Cecidomyiidae), has been identified as (10E)-tridecen-2-yl acetate. A flexible synthetic route was developed which allowed access to the chiral and racemic forms of the pheromone, and to the 10Z stereoisomer of the pheromone. The natural compound was determined to have the 2S configuration by hydrolysis of the acetate function, derivatization of the resulting alcohol with (2S)-2-acetoxypropionyl chloride, and capillary gas Chromatographic comparison of the derivative with the corresponding derivatives prepared from the synthetic enantiomers. Trace amounts of the 10Z isomer of the pheromone have also been detected in extracts of female Hessian fly ovipositors, along with (10E)-tridecen-2-ol and 2-tridecanyl acetate. Due to the small quantities of these compounds available from ovipositor extracts, the chirality of the trace components has not yet been determined.     

Attraction of male turnip mothsAgrotis segetum (Lepidoptera: Noctuidae) to sex pheromone components and their mixtures at 11 sites in Europe,Asia, and Africa

Selected combinations of (Z)-5-decenyl, (Z)-7-dodecenyl, and (Z)-9-tetradecenyl acetates, the pheromone components of the turnip mothAgrotis Segetum were tested for field attractancy at six, two, and three sites in Europe, Asia, and Africa, respectively. At all of the sites in Eurasia and in northern Africa the ternary mixture of the acetates captured most males, while at the sites south of the Sahara in Africa, (Z)-5-decenyl acetate alone was responsible for attraction. Differences in male attraction among the populations studied confirm the existence of significant population variation in the pheromone ofA. segetum. Interpretation of the present results together with earlier studies suggests that this variation is more or less continuous in Eurasia and north Africa, while a clearly distinct pheromone type is present in the areas south of the Sahara desert.     

Identification of female sex pheromone components of rice looper,Plusia festucae (L.), (Lepidoptera: Noctuidae)

The rice looper,Plusia festucae, is a defoliator of the rice plant. Chromatographic behavior, chemical reactions, and GC-MS analyses of the female sex pheromone revealed that the main component was (Z)-5-dodecenyl acetate (Z5–12: OAc, component I). The GC-MS analysis also indicated that the pheromone gland extract included another three monounsaturated components, (Z)-5-dodecen-l-ol (Z5–12: OH, component II), (Z)-7-tetradecenyl acetate (Z7–14: OAc, component III), and (Z)-7-tetradecen-l-ol (Z7–14: OH, component IV) in the following ratio: I:II:III:IV=100:6:15:1. In a paddy field, the mixture of synthetic I, II, and III in a ratio of 100:6:15 showed stronger attractancy than the virgin female, while the role of IV was unknown.