Identification of unique pheromone components for soybean looper mothPseudoplusia includens

Analysis of sex pheromone glands from individual female soybean looper moths showed that in addition to the previously identified main component (Z)-7-dodecenyl acetate, the compounds dodecyl acetate, 11-dodecenyl acetate, (Z)-7-dodecenyl propionate, and (Z)-7-dodecenyl butanoate were also produced. Two of the components, 12OAc and 11–12OAc, were not detected in a single analysis of female effluvium. Flight-tunnel tests showed that the five-component and three-component blends were equal to each other and to a female extract (> 80% source contacts) and that the mixtures were superior toZ7–12OAc alone. Field tests indicated that the five-component blend was significantly more attractive thanZ7–12OAc alone at a dosage of 1 mg, but that the blend was only slightly better at 3 mg.     

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.     

Activity of perfluorobutyl-containing components in pheromone blend of cabbage looper moth,Trichoplusia ni

Substitution of nine hydrogens by nine fluorines in the butyl terminus of (Z)-7-dodecenyl acetate, the major component of the pheromone blend of the cabbage looper,Trichoplusia ni (Lepidoptera: Noctuidae), produces a highly volatile analog that is significantly less active as a replacement for the natural pheromone component, either alone or substituted in the sixcomponent pheromone blend of this species. When 9,9,10,10,11,11,12,12, 12-nonafluoro-(Z)-7-dodecenyl acetate (nf-Z7-12: OAc) was tested in a wind tunnel as a single component or as part of the six-component blend, males exhibited preflight activation, but they did not orient in the pheromone plume and fly upwind over a five-decade range of doses at levels comparable with those of the natural component and blend. Addition of large amounts of nf-Z7-12:OAc to the optimal dose of the natural blend also did not effect flight arrestment as when increased amounts of Z7-12:OAc were added. The nonafluoro (nf) analog of (Z)-9-tetradecenyl acetate, a minor component in theT. ni blend, did not affect male behavior when substituted in the sixcomponent blend, and substitution of both nf analogs in the natural blend produced the same results as observed for blends containing nf-Z7-12:OAc. The lack of an effect with substitution of nf-Z9-14:OAc is discussed in relation to the reported redundancy in the action of minor components inT. ni.     

Sex Pheromone of Apple Blotch Leafminer, Phyllonorycter crataegella, and Its Effect on P. mespilella Pheromone Communication

(Z)-10,(Z)-12-Tetradecadienyl acetate (Z10,Z12–14:OAc) and (E)-10,(E)-12-tetradecadienyl acetate (E10,E12–14:OAc) are sex pheromone components of the apple blotch leafminer (ABLM), Phyllonorycter crataegella. Compounds extracted from female pheromone glands were identified by coupled gas chromatographic–electroantennographic detection (GC-EAD) analyses, retention index calculations of EAD-active compounds, and by comparative GC-EAD analyses of female ABLM-produced and authentic (synthetic) compounds. In field experiments in apple Malus domestica orchards in Connecticut, Z10,Z12–14:OAc alone attracted ABLM males. Addition of E10,E12–14:OAc to Z10,Z12–14:OAc at 0.1:10 or 1:10 ratios enhanced attractiveness of the lure. Geometrical isomers Z10,E12- or E10,Z12–14:OAc at equivalent ratios were behaviorally benign and slightly inhibitory, respectively. In field experiments in British Columbia, Z10,Z12–14:OAc plus E10,E12–14:OAc did not attract Phyllonorycter moths, supporting the contention that ABLM is not present in the fruit growing regions of British Columbia. Z10,Z12–14:OAc added to P. mespilella pheromone, (E)-4,(E)-10-dodecadienyl acetate, strongly inhibited response by P. mespilella males. Recognition of the ABLM pheromone blend by allopatric P. mespilella males suggests a phylogenetic relationship and previous sympatry of these two Phyllonorycter spp. If pheromonal attraction of ABLM males were reciprocally inhibited by P. mespilella pheromone, a generic Phyllonorycter pheromone blend could be tested for pheromone-based mating disruption of the apple leaf-mining Phyllonorycter guild in North America.     

Identification of sex pheromone components of redbacked cutworm,Euxoa ochrogaster,and modification of sex attractant blend for adult males

Pheromone washes from calling female moths of redbacked cutworm,Euxoa ochrogaster (Guenée), contained the following acetates that are structurally similar to those of known lepidopteran pheromones (%): decanyl (8.7), dodecanyl (8.5), (E)-5-dodecenyl (3.3), (Z)-5-dodecenyl (76.4), (Z)-7-dodecenyl (3.1), and (Z)-9-dodecenyl (trace<0.5%). This is the first time that (Z)-5-dodecenyl acetate has been identified as a pheromone component. Three types of specific receptor cells were found in the male antennae, and they responded to (Z)-5-decenyl acetate, (Z)-5- and (Z)-7-dodecenyl acetates, respectively. Strong electroantennographic detector responses were also recorded for these three acetates and for (Z)-5-undecenyl acetate. The evidence for the presence of (Z)-5-decenyl acetate in the pheromone washes was inconclusive. The presence of (Z)-7- and the absence of (Z)-8-dodecenyl acetates were confirmed by a special electroantennographic detector technique in which the detector antennae were from males of other species that were known to have strong responses to these acetates. This is a very useful technique. Field results show that low concentrations (0.1–1.3%) of (Z)-5-decenyl acetate were synergistic when tested in a previously reported blend, but 6% was inhibitory. Similarly, (Z)-7-dodecenyl acetate at 2% or less may be essential for the attraction of males, but in previous tests at 14% it also was inhibitory. Species-specific attractant blends for redbacked cutworm males are described.Lepidoptera: Noctuidae     

Characterization of Pheromone Blend for Grapevine Moth, Lobesia botrana by Using Flight Track Recording

The behavioral responses of Lobesia botrana males to calling females, pheromone gland extracts, and synthetic sex pheromones were recorded in a wind tunnel. Gland extracts and synthetic pheromones were released from a pheromone evaporator. The numbers of males reaching the source and their flight tracks in response to calling females and pheromone gland extracts were compared to those of synthetic blends. Upwind flights to natural sex pheromone were straighter and faster than to a three-component blend of (E)-7,(Z)-9-dodecadienyl acetate (E7,Z9–12:Ac), (E)-7,(Z)-9-dodecadien-1-ol (E7,Z9–12:OH), and (Z)-9-docecenyl acetate (Z9–12:Ac) (100:20:5). The optimum ratio of E7,Z9–12:OH and Z9–12:Ac to E7,Z9–12:Ac was found to be 5% and 1%, respectively. An additional seven compounds identified in the sex pheromone gland were investigated for their biological activity. Two unsaturated acetates, i.e., (E)-9-dodecenyl acetate (E9–12:Ac) and 11-dodecenyl acetate (11–12:Ac), increased the number of males reaching the source as well as straightness, linear velocity, and decreased the track angle of upwind flight. Optimum response was obtained by releasing 10 pg/min E7,Z9–12:Ac in a mixture with 0.5 pg/min E7,Z9–12:OH, 0.1 pg/min Z9–12:Ac, 0.1 pg/min E9– 12:Ac and 1 pg/min 11-12–Ac. The saturated acetates previously identified in the female glands were biologically inactive.     

Identification of Sex Pheromone of Adzuki Bean Borer,Ostrinia scapulalis

By means of gas chromatography with electroantennographic detection (GC-EAD), gas chromatography–mass spectrometry (GC-MS), and a series of bioassays, (Z)-11-tetradecenyl acetate (Z11–14:OAc) and (E)-11-tetradecenyl acetate (E11–14:OAc) at a ratio of 100:3 were identified as the female sex pheromone of the adzuki bean borer,Ostrinia scapulalis. The average amounts ofZ11–14: OAc andE11–14:OAc in a single sex pheromone gland were 6.6 ± 2.4 ng and 0.2 ± 0.1 ng, respectively. In a wind-tunnel bioassay, the binary blend ofZ11- andE11–14:OAc elicited almost the same male behavioral responses as did virgin females and sex pheromone gland extract. In field trapping experiments, rubber septa impregnated with the binary blend (50 g/septum) attracted more males than virgin females. The sex pheromone ofO. scapulalis thus turned out to be similar to that of theZ-type European corn borer,O. nubilalis, in both components and their ratio.     

Subtleties in Perception and Discrimination by Cabbage Looper Moths, Trichoplusia ni, of the two 14-carbon Acetate Sex Pheromone Components

Three compounds that are emitted by virgin female cabbage looper moths, Trichoplusia ni, (Z)-7-dodecenyl acetate (Z7–12:Ac), (Z)-7-tetradecenyl acetate (Z7–14:Ac), and (Z)-9-tetradecenyl acetate (Z9–14:Ac), are detected by antennal olfactory receptor neurons specialized to detect sex pheromone components. The principal evidence signifying that either or both of Z7–14:Ac and Z9–14:Ac have an effect on male behavior comes from an observed reduction in the numbers of males trapped by Z7–12:Ac paired with a six-component mixture. The evidence conforms to a hypothesis that either or both of these compounds are the basis for discrimination between the two mixtures. However, scant evidence for this hypothesis was obtained in paired-source laboratory wind-tunnel assays, even at airborne concentrations of Z7–14:Ac and Z9–14:Ac that ranged up to 1000× that emitted by a female. Furthermore, there was little evidence from single-source laboratory or field trap assays confirming that Z7–14:Ac and Z9–14:Ac at or above natural stimulus strengths modify the moth's perception of Z7–12:Ac. The data suggest that discrimination of small mixture differences may not be resolvable within the confines of a wind tunnel.     

Individual variation in the pheromone of the turnip moth,Agrotis segetum

Female turnip moths (Agrotis segetum) from a laboratory culture inbred for more than 30 generations, and the offspring (first and third generation) from field-collected insects were analyzed individually for acetates and alcohols in the pheromone gland. Quantitative analysis of individual components was performed at the subnanogram level by gas chromatographymass spectrometry (selected ion monitoring). The titer of the pheromone, i.e., the sum of the homologous acetates (Z)-5-decenyl acetate, (Z)-7-dodecenyl acetate, and (Z)-9-tetradecenyl acetate was 2.0 ± 0.3 ng in the laboratory culture and 3.2 ± 0.6 ng in the wild strain. There was no correlation between pheromone titer and female weight. The relative proportion of the pheromone components varied substantially between individuals, but there was no statistically significant difference between the two populations. The percentages of the respective compounds (¯X ± coefficient of variation) were 14.8 ± 127% for Z5-10:OAc, 55.6 ± 32% for Z7-12:OAc, and 29.6 ± 59% forZ9-14:OAc. The pheromone composition varied more in the wild strain than in the laboratory culture. The significance of the pheromone variation to the attraction of males was tested in a field experiment. The ratio of males trapped by the most attractive blend versus the least attractive one was 2.2.Schiff., Lepidoptera: Noctuidae.This study was made within the Swedish project Odour Signals for Control of Pest Insects.     

Specificity of male response to multicomponent pheromones in noctuid mothsTrichoplusia ni andPseudoplusia includens

The response of male cabbage looper (CL) and soybean iooper (SBL) moths was observed in the flight tunnel and measured in field tests to the six-component CL pheromone, the five-component SBL pheromone, and toZ7–12: OAc, the major component common to each pheromone. In both the flight tunnel and the field, male CL exhibited significantly greater levels of response to their six-component blend than toZ7–12: OAc alone. A low level of cross-attraction of male CL to the SBL pheromone was observed in both the flight tunnel and the field, but it was quantitatively and qualitatively similar to their response toZ7–12: OAc alone. Thus the minor components of the SBL blend did not appear to disrupt the flight behavior of male CL. With respect to SBL, in the flight tunnel males also exhibited a greater level of response to the five-component blend compared toZ7–12: OAc, but in the field their response was not significantly different to either treatment. There was also a low level of cross-attraction of male SBL to the CL blend, but this appeared to involve a significant arrestment effect on the upwind flight of males, as well as a difference in male sensitivity to the blend of components compared withZ7–12: OAc alone. The observed arrestment effect may have been due to male perception of one or more minor components of the CL pheromone. The results show that the multicomponent pheromones of these species function effectively as specific mating signals and that discrimination of odor quality by male moths can occur as the result of minor components affecting male sensitivity or their upwind flight response to the pheromone.     

Synergism of an insect sex pheromone specialist neuron: Implications for component identification and receptor interactions

Extracellular recordings show that the response to the sex pheromone component, (Z)-7-dodecenyl acetate (Z7–12:Ac) by the HS(a) antennal olfactory specialist neuron of the cabbage looper,Trichoplusia ni (Hübner), is synergized by two synthetic sex pheromone analogs and two components of the female sex pheromone. Complementary behavioral measures of upwind flight and copulatory responses to mixtures ofZ7–12:Ac with the analogs and sex pheromone components in a wind tunnel produced behavioral evidence consistent with the neuron's electrophysiological responses. The phenomenon of receptor neuron synergism impacts several areas and provides a note of caution for common practices of identifying secondary sex pheromone components only from field traps and/or wind tunnel tests.     

Sex pheromone components of the turnip moth,Agrotis segetum

Analysis of female abdominal tips ofAgrotis segetum by means of GC-MS showed the presence of 13 aliphatic acetates and alcohols. (Z)-7-Dodecenyl acetate was found to be the main component in the extracts at amounts of about 1 ng/female. (Z)-9-Tetradecenyl acetate and (Z)-7-dodecenol were present to the extent of 49 and 19%, respectively, of the main component. Minor components could be identified as decyl acetate, (Z)-5-decenyl acetate, dodecyl acetate, (Z)-9-dodecenyl acetate, tetradecyl acetate, a tetradecenyl acetate, hexadecyl acetate, a hexadecenyl acetate, (Z)-5-decenol, and (Z)-9-tetradecenol. The presence and biological activity of decyl acetate, (Z)-5-decenyl acetate, and (Z)-7-dodecenyl acetate in the extracts could be detected by GC-EAD. Tested by EAG (Z)-5-decenyl acetate evoked the highest response among pheromone candidates, followed by (E)-5-decenyl acetate and (Z)-7-dodecenyl acetate. Single-cell recordings from 100 male antennal sensilla trichodea revealed receptorcells highly sensitive to (Z)-5-decenyl, (Z)-7-dodecenyl, (Z)-8-dodecenyl, and (Z)-9-tetradecenyl acetate as well as (Z)-5-decenol. The (Z)-5-decenyl, (Z)-7-dodecenyl, and (Z)-9-tetradecenyl acetate receptors were activated significantly also by female extracts. When tested in a tube olfactometer, a blend of decyl, (Z)-5-decenyl, (Z)-7-dodecenyl, and (Z)-9-tetradecenyl acetate evoked the same male response as did female glands.Tested in the field, this blend was more attractive than virgin females. Other authors previously reported many of the compounds identified in the present study. However, both quantitative and qualitative discrepancies exist among the various investigations, possibly due to the existence of geographical races.Schiff., Lepidoptera: Noctuidae.This study was made within the Swedish project Odour Signals for Control of Pest Insects.     

Chemical and Behavioral Evidence for a Third Pheromone Component in a North American Population of the Black Cutworm Moth, Agrotis ipsilon

The sex pheromone of Agrotis ipsilon had been previously identified as a blend of (Z)-7-dodecenyl acetate (Z7–12:Ac) and (Z)-9-tetradecenyl acetate (Z9–14:Ac). A synthetic blend of Z7–12:Ac and Z9–14:Ac (30 g:10 g) is effective in attracting males in the field. In several countries, addition of (Z)-11-hexadecenyl acetate (Z11–16:Ac) to the previously identified blend increases male captures, but this had not been demonstrated in North America. We found Z11–16:Ac, in addition to Z7–12:Ac and Z9–14:Ac, from pheromone gland extracts of females from North America. The mean ratio of Z7–12:Ac, Z9–14:Ac, and Z11–16:Ac produced by individual females was 70.5:14.2:15.3, respectively. In Kentucky, addition of Z11–16:Ac (60 g) to a two-component blend of Z7–12:Ac and Z9–14:Ac significantly increased the trap capture rate in the field. Traps baited with this three-component blend were 3.3 times (1995) and 4.6 times (1996) more effective in capturing male A. ipsilon than the two-component blend. This improved effectiveness resulted in detection of A. ipsilon in 60% more of the sampling periods in the two years. In the wind tunnel, males flew upwind and contacted a rubber septum loaded with a three-component blend including Z11–16:Ac significantly more frequently than they did to any two-component blend. These results demonstrate that Z11–16:Ac is a pheromone component in this North American population of A. ipsilon.     

Comparison of electroantennograms from female and male cabbage looper moths (Trichoplusia ni) of different ages and for various pheromone concentrations

The electroantennogram (EAG) responses of both male and femaleTrichoplusia ni to two components of the female-released sex pheromone were determined over a range of concentrations of chemical and age of insect. The EAG was at a peak at a dose of 100 g for both dodecyl acetate and (Z)-7-dodecenyl acetate (Z7–12OAc) for both sexes. The EAG responses varied with age of the insect. Responsiveness to both components was at a maximum at three days postemergence for males followed by a fairly rapid senescence, and for females it peaked at three days followed by a rapid senescence forZ7–12OAc but not for dodcecyl acetate.     

Female Sex Pheromone Polymorphism in Adzuki Bean Borer, Ostrinia scapulalis, Is Similar to That in European Corn Borer, O. nubilalis

Individual analysis of the female sex pheromone of the adzuki bean borer, Ostrinia scapulalis, has shown that the sex pheromone of this species comprised (E)-11-tetradecenyl acetate (E11–14:OAc) and (Z)-11-tetradecenyl acetate (Z11–14:OAc) at variable blend ratios. The pheromone blend could be tentatively categorized into three types with respect to the proportion of E11–14:OAc: E type (94–100%, median 99.2%), Z type (0–16%, median 3.0%), and intermediate type (I type, 48–85%, median 63.7%). In addition to the identity of components, the blend ratios in the three types were similar to those of the E strain, Z strain, and hybrid of the European corn borer, O. nubilalis, respectively. This finding suggests that two closely related but morphologically distinct species, O. scapulalis and O. nubilalis, share almost the same sex pheromone communication systems. The significance of this similarity in the two sibling species is discussed.     

Sex pheromone of tomato fruit borer, Neoleucinodes elegantalis

Five candidate pheromone components were identified by analyzing pheromone gland extracts by gas chromatography (GC), coupled GC-electroantennographic detection (EAD), and coupled GC-mass spectrometry (MS): (E)-11-hexadecenol(E11–16 : OH), (Z)-11-hexadecenol (Z11–16 : OH),(E)-11-hexadecenal, (E)-11-hexadecenyl acetate, and (Z)-3,(Z)-6,(Z)-9-tricosatriene (Z3,Z6,Z9–23 : Hy). In electroantennogram (EAG) recordings, synthetic E11–16 : OH elicited stronger antennal responses at low doses than other candidate pheromone components. Field tests demonstrated that synthetic E11–16 : OH as a trap bait was effective in attracting males, whereas addition of Z11–16 : OH inhibited the males' response. Z3,Z6,Z9–23 : Hy strongly enhanced attractiveness of E11–16 : OH, but was not attractive by itself. A pheromone blend with synergistic behavioral activity of an alcohol (E11–16 : OH) and hydrocarbon (Z3,Z6,Z9–23 : Hy) component is most unusual in the Lepidoptera. The synthetic two-component pheromone is approximately 60 times more attractive than the female-produced blend and might facilitate the control of this pest.     

Pheromone-mediated responses of male cabbage looper moths,Trichoplusia ni,following various exposures to sex pheromone or (Z)-7-dodecenol

Prolonged preexposure (three days) of maleTrichoplusia ni to its six-component sex pheromone blend or its major pheromone component, (Z)-7-dodecenyl acetate, reduced subsequent upwind flight responses to a pheromone source. Preexposure to (Z)-7-dodecenol increased upwind flight responses to a pheromone source combined with (Z)-7-dodecenol. The impact of long-term preexposures was moderate when compared to the more immediate effects of background noise. When (Z)-7-dodecenyl acetate was presented as background noise, all maleT. ni failed to respond to a plume of the full pheromone blend. However, most moths succeeded in locking on to the pheromone plume and contacting the pheromone source in the presence of the five minor pheromone components as background noise. When (Z)-7-dodecenol was released as background noise the response rate to a pheromone source containing (Z)-7-dodecenol was increased dramatically. This indicates that males became adapted to (Z)-7-dodecenol while responding to the pheromone source. The results of this study indicate that both long-term preexposure treatments and immediate exposure to background noise can limit the ability of maleT. ni to respond to sex pheromone sources.     

Individual variation in sex pheromone of smaller tea tortrix moth,Adoxophyes sp. (Lepidoptera: Tortricidae)

Female smaller tea tortrix mothsAdoxophyes sp. (Lepidoptera: Tortricidae), which initiated calling at 1, 2, or 3 days old, respectively, were analyzed individually for (Z)-11-tetradecenyl acetate (Z11-14:OAc) and (Z)-9-tetradecenyl acetate (Z9–14: OAc) in the pheromone gland via GLC. Among different age groups, broad and similar distributions were found for pheromone quantity (¯X=58.6±52.9 ng/female; range 1.3–219.8 ng/female). The ratio of the two pheromone components averaged 6535 but ranged from 8416 to 4060. The significance of the pheromone blend variation to the attraction of males was tested in a field experiment. The ratio of males trapped by the most attractive blend versus the least attractive one was 2.2.     

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.     

Role of sex pheromone components in behavioral reproductive isolation betweenAutographa gamma (L.) and eitherTrichoplusia ni (Hübner) ORChrysodeixis chalcites (Esp.) (Lepidoptera: Noctuidae: Plusiinae)

The composition of theAutographa gamma sex pheromone was reexamined and only (Z)-7-dodecenyl acetate and (Z)-7-dodecenol were identified by capillary GC, GC-MS, and dimethyl disulfide derivatization and subsequent GC-MS analysis. The fatty acid content of the pheromone glands was also studied, and a series of saturated and unsaturated acids was identified. However, most of the related pheromonal compounds were not detected. The male response to the pheromone components was studied in a flight tunnel and compared with the response to calling females. The best synthetic baits evoked a response similar to that observed to the virgin females, but males spent significantly more time at calling females than at the synthetic baits. The preferred synthetic baits consisted of (Z)-7-dodecenyl acetate alone or of a blend with 5% (Z)-7-dodecenol. Increasing the relative amount of the alcohol caused a gradual reduction in male response, particularly in the last steps of the courtship sequence. The addition of the minor sex pheromone components of the sympatric Plusiinae species,Trichoplusia ni andChrysodeixis chalcites, to theA. gamma pheromone was also investigated in the flight tunnel. Some of these components exhibited a significantly antagonistic effect on theA. gamma male courtship behavior. The most potent antagonists were (Z)-5-dodecenyl acetate and (Z)-9-tetradecenyl acetate. The response ofA. gamma andT. ni males to conspecific and heterospecific females was also compared in the flight tunnel. WhereasA. gamma males were attracted only to their conspecific females, a small percentage ofT. ni males were also attracted toA. gamma females and 11% performed the whole courtship sequence.Contribution from the Agricultural Research Organization (ARO), No. 3459-E, 1992 series.