Effect of Wind Speed on the Pheromone-Mediated Behavior of Sexual Morphs of the Potato Aphid, Macrosiphum euphorbiae (Thomas) Under Laboratory and Field Conditions

The effect of wind on the potato aphid, Macrosiphum euphorbiae, male responsiveness to the sex pheromone, and on the calling behavior of virgin oviparae, was studied under constant wind speeds in the laboratory and in the field. A significant proportion of females called at wind speeds up to 4 m/sec, whereas male flight behavior in clean air was inhibited at velocities > 2 m/sec. However, males continued to walk over the range of wind speeds at which females called. Under constant wind velocities in a wind tunnel, males downwind of calling females oriented on the upwind edge of the release stand, and fewer individuals took flight at low constant wind speeds than in a clean air plume. In all cases, whether calling females were present or not, the males that took flight moved downwind. However, when a bridge was available, a significant proportion of males walked upwind to the pheromone source. The same orientation and walking behaviors were observed when males were placed downwind of calling females under variable wind conditions in the field. However, contrary to the laboratory results, 30% of the males tested flew upwind and landed on the source. A more detailed examination found that males orienting toward a source would walk if wind speeds were high but initiated flight in an “upwind” direction if there was a lull in wind velocity. These findings suggest that for the potato aphid, and probably for many other insect species with weak flight capacity, walking behavior is a significant component of pheromone-mediated mate location. This would permit males to continue foraging for calling females in the vicinity when wind velocities inhibit flight.     

Comparative Responses of Parasitoids to Synthetic and Plant-Extracted Nepetalactone Component of Aphid Sex Pheromones

The responses of aphid parasitoids to completely synthetic and plant-extracted nepetalactone, a component of aphid sex pheromones, were investigated. In wind tunnel tests, Praon volucre and Aphidius ervi responded equally strongly to both plant-extracted and 99% pure synthetic (4aS,7S,7aR)-nepetalactone. In the field, aphid-infested cereal trap plants were used to test the attractiveness of plant-extracted and synthetic (4aS,7S,7aR)-nepetalactone, as well as the synthetic enantiomer (4aR,7R,7aS)-nepetalactone. There was no significant difference in parasitisation levels by Praon spp. between plants baited with the synthetic or with the plant-extracted 7S isomers. However, the 7R isomer was unattractive alone and rendered the synthetic 7S isomer unattractive when combined to form a 50% blend of the two. It is concluded that the response of aphid parasitoids to nepetalactone is influenced more by enantiomeric purity rather than the possible presence of plant-related contaminants associated with plant extraction. The results are compared with data on male aphid responses to the compounds, which indicate that plant-derived contaminants can reduce attractancy, and the implications for the manipulation of parasitoids in the field are discussed.     

Effect of Solanum Glycoalkaloids on Potato Aphid, Macrosiphum euphorbiae: Part II

We report the deterrent, toxic, and antireproductive effect of several Solanum glycoalkaloids on the potato aphid, Macrosiphum euphorbiae, and discuss the structure–activity relationship of the tested compounds. The results indicate a structure-dependent biological effect of the glycoalkaloids, suggesting that, while the structure of the aglycone defines a basal biological effect, the carbohydrate moiety is crucial for the overall biological effect.     

(2R,7S)-Diacetoxytridecane: Sex Pheromone of the Aphidophagous Gall Midge, Aphidoletes aphidimyza

In a recent study, evidence was presented that females of the aphidophagous midge Aphidoletes aphidimyza (Rondi) (Diptera: Cecidomyiidae) release a sex pheromone to attract mates. Our objectives were to identify and bioassay the pheromone. Coupled gas chromatographic-electroantennographic detection(GC-EAD) analyses of untreated and hydrogenated pheromone extract on three fused-silica columns (DB-5, DB-23, DB-210) revealed a single compound that elicited responses from male antennae. Retention index calculations of this candidate pheromone (CP) suggested that it was a di-acetate. Considering that most of the presently identified cecidomyiid pheromones consist of a 13-carbon chain with (at least) one acetate group in C2, we synthesized 2,6-, 2,7-, 2,8-, 2,9-, 2,10-, 2,11-, and 2,12-diacetoxytridecane. In GC analyses of these compounds, only 2,7-diacetoxytridecane cochomatographed with CP on all columns. In laboratory two-choice experiments with stereospecifically synthesized stereoisomers, only (2R,7S)-diacetoxytridecane elicited significant anemotatic responses by male A. aphidimyza. In trapping experiments in greenhouse compartments, only traps baited with (2R,7S)-diacetoxytridecane captured significant numbers of male A. aphidimyza, clearly revealing the absolute configuration of the pheromone. Failure of the stereoisomeric mixture (containing all four stereoisomers including the pheromone) to attract males is due to inhibitory characteristics of the (2R,7R)- and (2S,7R)-stereoisomers. The pheromone of zoophagous A. aphidimyza resembles those from phytophagous cecidomyiid midges, suggesting a common, diet-independent pathway for pheromone biosyntheses.     

Sex Pheromone Components of Casuarina Moth, Lymantria xylina

cis-7,8-Epoxy-2-methyleicosane is a sex pheromone component of the Casuarina moth, Lymantria xylina Swinhoe. The compound was extracted from pheromone glands of female moths and was identified by coupled gas chromatographic–electroantennographic detection (GC-EAD) and GC–mass spectrometry. In field experiments in Taiwan, traps baited with either or both of (7R,8S)-cis-7,8-epoxy-2-methyleicosane (>99% ee) [termed here (+)-xylinalure] and (7S,8R)-cis-7,8-epoxy-2-methyleicosane (>99% ee) [termed here (–)-xylinalure] captured male L. xylina. Addition of further candidate pheromone components to xylinalure did not enhance its attractiveness. Demonstration of whether or not female L. xylina produce both optical isomers of xylinalure, and determination of the ratio, will require pheromone extract analyses on a chiral, enantiomer-separating column (as yet unavailable) or derivatization of epoxides in accumulated gland extracts. Attraction of male L. xylina to either enantiomer of xylinalure contrasts with enantiospecific production of, and/or response to, epoxy pheromones in congeners. With no other nocturnal lymantriid moth known in Taiwan to utilize xylinalure for pheromonal communication, enantiospecific fine tuning of xylinalure, or evolution of a more complex pheromone blend, may not have been necessary for L. xylina to maintain specificity of sexual communication. Racemic xylinalure will be appropriate for pheromone-based detection surveys of L. xylina in North America.     

Identification and Field Evaluation of Components of Female Sex Pheromone of Millet Stem Borer, Coniesta ignefusalis

Five active compounds were detected during analyses of ovipositor washings and effluvia from virgin female Coniesta ignefusalis moths by gas chromatography (GC) linked to electroantennographic (EAG) recording from a male moth. These were identified as (Z)-7-dodecen-1-ol (Z7–12:OH), (Z)-5-decen-1-ol (Z5–10:OH), (Z)-7-dodecenal (Z7–12:Ald), (Z)-7-dodecenyl acetate (Z7–12:Ac), and (Z)-9-tetradecen-1-ol (Z9–14:OH) by comparison of their GC retention times, mass spectra, and EAG activities with those of synthetic standards. Laboratory tests of dispensers for these compounds showed that release rates from polyethylene vials increased to relatively uniform values after three to four days, but release from septa was very rapid and nonuniform and decreased to low levels after two to three days. Trapping tests in Niger showed that the major component, Z7–12:OH, and two of the minor components, Z5–10:OH and Z7–12:Ald, were essential for attraction of male C. ignefusalis moths. The most attractive blend contained these three components in a 100:5:3.3 ratio in a polyethylene vial, which emitted the components in similar proportions to those produced by the female C. ignefusalis moth. Water traps baited with this blend containing 1 mg of Z7–12:OH caught more male C. ignefusalis moths than traps baited with newly emerged female moths. Addition of up to 10% of the corresponding E isomers of the pheromone components had no effect on catches, but addition of the other two minor components detected, Z7–12:Ac and/or Z9–14:OH, to the attractive blend at naturally occurring levels caused significant reductions in trap catch.     

Laboratory and Field Study of the Attraction of Male Pea Midges, Contarinia pisi, to Synthetic Sex Pheromone Components

Behavioral activity of the recently identified sex pheromone components of the pea midge, Contarinia pisi, (2S,11S)-diacetoxytridecane, (2S,12S)-diacetoxytridecane, and 2-acetoxytridecane, was tested in wind tunnel and field-trapping experiments. In the wind tunnel, the attractancy of the three-component blend in a 7 : 10 : 0.1 ratio (following the above order, mimicking the ratios found in gland extract) did not differ significantly from female gland extract, whereas a mixture of the two major components (7 : 10) only attracted 2% of the males to the source. In the field, traps baited with the three-component blend caught by far the largest number of males. Traps baited with the two major components only caught slightly more than the blank traps, and catches in traps baited with 2-acetoxytridecane alone did not differ from catches in the blank traps. Traps baited with the racemate of all three components did not catch more than the blank traps, indicating that some of the enantiomers are inhibitory.     

Identification of Epoxyhenicosadiene and Novel Diepoxy Derivatives as Sex Pheromone Components of the Clear-Winged Tussock Moth Perina nuda

Four EAG-active components (A–D) were found in the solvent extract of virgin females of the clear-winged tussock moth, Perina nuda. The most abundant component (B, ca. 250 ng/female) was identified as (3Z,6S,7R,9Z)-6,7-epoxyhenicosa-3,9-diene by GC-MS analyses of the extract, chemical derivatization, and comparative chiral HPLC. Minor components also elucidated were (3Z,9Z)-cis-6,7-epoxyicosa-3,9-diene, (A); (3R,4S,6S,7R,9Z)-3,4-6,7-diepoxyhenicos-9-ene, (C); and its 3S,4R,6S,7R isomer, (D); with amounts of 0.4, 5, and 8 ngt/female, respectively. Component B showed weak attractiveness to male moths in the field. The attractiveness was significantly enhanced by addition of component(s) C and/or D. No males were captured with either the antipode of component B or its mixtures with the minor components. In this field test, noctuid Hypocala rostrata males were also attracted with the synthetic P. nuda pheromone.     

Identification of a Sex Pheromone Component of Pseudococcus cryptus

A sex pheromone component of Pseudococcus cryptus has been isolated and identified. The crude pheromone extract obtained by airborne collection was fractionated by liquid chromatography (LC) on Florisil, and further purified by high performance liquid chromatography and preparative Gas Chromatography (GC). The pheromone component was shown to be an ester, the alcohol part of which was identical to the known alcohol moiety of the pheromone of Planococcus citri. The chemical structure was determined to be 3-isopropenyl-2,2-dimethylcyclobutylmethyl 3-methyl-3-butenoate by MS and ¹H NMR analyses. The absolute configuration of the pheromone was assigned as (1R,3R) by comparison of the retention time of the alcohol derived from the P. cryptus pheromone with those of the alcohol derived from P. citri pheromone, and a synthetic sample of alcohol enriched in the (1R,3R)-enantiomer, using a chiral GC stationary phase. The structure of the pheromone was confirmed by synthesis, and by bioassays in a glasshouse.     

Identification of the Sex Pheromone of the Swede Midge, <Emphasis Type="Italic">Contarinia nasturtii</Emphasis>

Coupled gas chromatographic–electroantennographic detection analyses of ovipositor extracts of calling Contarinia nasturtii females revealed two compounds that elicited responses from antennae of male midges. Using synthetic reference samples, these components were identified by gas chromatography–mass spectrometry and enantioselective GC as (2S,9S)-diacetoxyundecane and (2S,10S)-diacetoxyundecane. In addition, trace amounts of 2-acetoxyundecane were found in ovipositor extracts, and the (S)-enantiomer was synthesized. When tested in the wind tunnel, a blend of 5ng (2S,9S)-diacetoxyundecane and 10 ng (2S,10S)-diacetoxyundecane (mimicking the ratio found in the extracts) did not attract any of the males tested, but when 0.1 ng (S)-2-acetoxyundecane was added to the blend, 86.8% of the males were attracted to the bait. Three-component blends with lower or higher relative concentrations than 1% of (S)-2-acetoxyundecane [relative to (2S,10S)-diacetoxyundecane] were less attractive. In a field trapping experiment with released laboratory-reared C. nasturtii adults, traps baited with 500:1000:10 ng of (2S,9S)-diacetoxyundecane/(2S,10S)-diacetoxyundecane/(S)-2-acetoxyundecane applied to rubber septa or dental cotton rolls were tested. Traps without dispensers were used as controls. All three treatments were tested at 20 and 50 cm above ground. The estimated recapture rate was 30–50%, and 81.9% of the recaptured males were caught in traps positioned at 20 cm above ground, and 88.4% in traps with dental cotton rolls as dispensers.     

Sex Pheromone of Female Vine Bud Moth, Theresimima ampellophaga Comprises (2S)-Butyl (7Z)-Tetradecenoate

The sex pheromone of the vine bud moth, Theresimima ampellophaga, released at the 3rd–5th abdominal tergites, was identified by coupled GC-EAG, GC-MS, and synthesis as (2S)-butyl (7Z)-tetradecenoate. For the first time, full stereochemistry is unambiguously defined for the sex pheromone of a member of the Zygaenidae. The synthetic compound caught significant numbers of males in field-trapping experiments.     

Sex Pheromone Components of Nettle Caterpillar, Setora nitens

Gas chromatographic–electroantennographic detection (GC-EAD) analyses of pheromone gland extracts of female nettle caterpillars, Setora nitens, revealed four compounds that consistently elicited responses from male moth antennae. Retention indices on three fused silia columns (DB-5, DB-23, and DB-210) of two EAD-active compounds were almost identical to those of (E)-9-dodecenal (E9–12 : Ald) and (E)-9,11-dodecadienal (E9,11–12 : Ald), two pheromone components previously identified in congeneric Setothosea asigna. However, comparative GC, GC-EAD, and GC-mass spectrometry of extracted S. nitens compounds and authentic standards revealed that the candidate pheromone components were (Z)-9-dodecenal (Z9–12 : Ald) and (Z)-9,11-dodecadienal (Z9,11–12 : Ald). The two other EAD-active compounds in pheromone gland extracts proved to be the corresponding alcohols to these aldehydes. In field-trapping experiments in Tawau, Malaysia, synthetic Z9–12 : Ald and Z9,11–12 : Ald at a 1 : 1 ratio, but not singly, attracted male S. nitens. Attractiveness of these two aldehydes could not be enhanced through the addition of their corresponding alcohols. Whether these differences in pheromone biology and chemistry between S. nitens and S. asigna are sufficient to prevent cross-attraction of heterospecific males or whether nonpheromonal mechanisms are required to maintain reproductive isolation is currently being studied.     

Pheromone chirality of african palm weevil,Rhynchophorus phoenicis (F.) and palmetto weevil,Rhynchophorus cruentatus (F.) (Coleoptera: Curculionidae)

There are four stereoisomers of both 3-methyl-octan-4-ol, the aggregation pheromone of the African palm weevil,Rhynchophorus phoenicis (F.) and 5-methyl-octan-4-ol, the aggregation pheromone of the palmetto weevil,Rhynchophorus cruentatus (F.). Synthetic stereoisomers of 3-methyl-octan-4-ol and 5-methyl-octan-4-ol were baseline-separated on a Cyclodex-B fused silica column. Use of this column in gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometric (GC-MS) analyses revealed that only one stereoisomer, (3S,4S)-3-methyl-octan-4-ol and (4S,5S)-5-methyl-octan-4-ol, is produced by maleR. phoenicis and maleR. cruentatus, respectively, and elicits good antennal responses by conspecific male and female weevils. In field trapping experiments, withR. phoenicis in Côte d'Ivoire andR. cruentatus in Florida, (3S,4S)-3-methyl-octan-4-ol and (4S,5S)-5-methyl-octan-4-ol strongly enhanced attraction of fresh palm tissue, whereas other stereoisomers were behaviorally benign. Stereoisomeric 3-methyl-octan-4-ol and 5-methyl-octan-4-ol may be utilized to monitor and/or manage populations of these two palm weevils.     

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.     

Identification of Components of Male-Produced Pheromone of Coffee White Stemborer, Xylotrechus quadripes

The coffee white stem borer, Xylotrechus quadripes Chevrolat (Coleoptera: Cerambycidae), is the foremost pest of arabica coffee in India, Sri Lanka, China, Vietnam, and Thailand. Previous work showed that female beetles were attracted to traps baited with male beetles. Analyses of volatiles from male X. quadripes of Indian origin by gas chromatography (GC) linked to electroantennographic (EAG) recording from a female beetle antenna showed three male-specific components comprising more than 90% of the volatiles, two of which elicited EAG responses. The major EAG-active component was produced at up to 2 μg hr⁻¹ insect⁻¹ and was identified as (S)-2-hydroxy-3-decanone (I) by comparison of GC data, and mass (MS), infrared, and nuclear magnetic resonance (NMR) spectra with those of synthetic standards. The second component was identified as 3-hydroxy-2-decanone (II) produced in part by isomerization of I under the conditions of the GC analysis, although the NMR spectrum suggested it is naturally produced at up to 7% of I. The minor component that elicited an EAG response, present at 7% of the amount of I, was identified as (S,S)-2,3-dihydroxyoctane (III) from GC and MS data. 2-Hydroxy-3-octanone (0.2–0.5% of I), 2,3-decanedione (2% of I), 2-phenylethanol (3% of I), and octanoic acid (4% of I) were also identified in volatiles from male beetles. A general, stereospecific synthetic route to the enantiomers of 2-hydroxy-3-alkanones from the enantiomers of ethyl lactate was developed. The enantiomers of III were synthesized from (E)-2-octene by Sharpless asymmetric dihydroxylation. (S)-(I) was attractive to male X. quadripes in laboratory bioassays, but addition of (S,RS)-(III) at 10% of I reduced attractiveness. In field trials carried out in India with sticky, cross-vane traps, (S)- and (RS)-(I) attracted male X. quadripes and addition of (S,S)-(III) at 10% of I reduced attractiveness. Significant numbers of female Demonax balyi Pascoe (Coleoptera: Cerambycidae) were sometimes caught in traps baited with (S)-(I) alone.     

Queen Sex Pheromone of the Slave-making Ant, Polyergus breviceps

Workers of the slave-making ant, Polyergus breviceps, raid nests of Formica ants and return with Formica pupae that mature into worker ants in the slave-makers’ colony. These Formica workers then tend the Polyergus brood, workers, and reproductives. During raids in the mating season, winged virgin Polyergus queens accompany the workers in the raiding columns. During the raid, the virgin queens release a pheromone that attracts males that quickly mate with the queens. We report the identification, synthesis, and bioassay of the sex attractant pheromone of the queens as an approximately 1:6 ratio of (R)-3-ethyl-4-methylpentan-1-ol and methyl 6-methylsalicylate. The ants produce exclusively the (R)-enantiomer of the alcohol, and the (S)-enantiomer has no biological activity, neither inhibiting nor increasing attraction to blends of methyl 6-methylsalicylate with the (R)-enantiomer.     

(Z)-7-Tricosene and Monounsaturated Ketones as Sex Pheromone Components of the Australian Guava Moth Coscinoptycha improbana: Identification, Field Trapping, and Phenology

Pheromone gland extracts of the Australian guava moth Coscinoptycha improbana (Lepidoptera: Carposinidae), contained four compounds that elicited responses from male moth antennae in gas chromatography-electroantennogram detection (GC-EAD) analyses. These were identified by GC-mass spectrometry as (Z)-7-tricosene (Z7-23Hy), (Z)-7-octadecen-11-one (Z7-11-one-18Hy), (Z)-7-nonadecen-11-one (Z7-11-one-19Hy), and (Z)-7-tricosen-11-one (Z7-11-one-23Hy) at a ratio of 65:23.5:1.5:10, respectively. Z7-23Hy, Z7-11-one-18Hy, and Z7-11-one-23Hy have not previously been reported as lepidopteran sex pheromone components. Z7-11-one-18Hy was active as a single component, and was synergized by Z7-11-one-23Hy but not Z7-11-one-19Hy, although the latter compound was weakly attractive as a single component. Addition of Z7-23Hy further increased attraction. The amount of the major pheromone component, Z7-11-one-18Hy in female pheromone gland extracts was estimated to be 16.4 ng/female (N = 8). Phenological data gathered over a 12-mo period in 2002 and 2003 using the binary blend indicated that moths are active throughout the year. The pheromone has already been employed to monitor the spread of C. improbana in New Zealand and detect its presence in Queensland, Australia.     

Sex Pheromone Components of Indian Gypsy Moth, <Emphasis Type="Italic">Lymantria obfuscata</Emphasis>

The Indian gypsy moth, Lymantria obfuscata (Lepidoptera: Lymantriidae), has been recognized as a distinct species since 1865 but closely resembles a diminutive form of gypsy moth, Lymantria dispar. We tested the hypothesis that the sex pheromones of L. obfuscata and L. dispar are similar. In laboratory mate acceptance studies, very few male L. dispar made copulatory attempts when paired with female L. obfuscata, suggesting that female L. obfuscata emit one or more pheromone components antagonistic to male L. dispar. In coupled gas chromatographic–electroantennographic detection (GC–EAD) analyses of pheromone gland extract of female L. obfuscata, (Z)-2-methyloctadec-7-ene (2Me-7Z-18Hy) and (7R,8S)-cis-7,8-epoxy-2-methyloctadecane [(+)-disparlure] were most abundant and elicited the strongest responses from male L. obfuscata antennae. In field experiments near Solan (Himachal Pradesh, India), 2Me-7Z-18Hy and (+)-disparlure in combination attracted more male L. obfuscata than did either component alone. This two-component sex pheromone contrasts with the single-component sex pheromone [(+)-disparlure] of L. dispar. The contrasting composition of the lymantriid communities inhabited by L. obfuscata and L. dispar may explain why 2Me-7Z-18Hy is a pheromone component in L. obfuscata and a pheromone antagonist in L. dispar and why (−)-disparlure reduces pheromonal attraction of male L. dispar but not male L. obfuscata.     

Identification of Sex Pheromone Components of the Box Tree Pyralid,Glyphodes perspectalis

Analysis of ovipositor extracts of the box tree pyralid, Glyphodes perspectalis (Lepidoptera: Crambidae), by coupled gas chromatography-electroantennogram detection and gas chromatography yielded three candidate pheromone compounds. Gas chromatography-mass spectrometry, and reaction with dimethyl disulfide (DMDS), identified these compounds as (Z)-11-hexadecenal (Z11-16:Ald), (E)-11-hexadecenal (E11-16:Ald), and (Z)-11-hexadecenol (Z11-16:OH). The ratio of these three compounds in crude extract was 5:1.25:1, and the total amount was approximately 100 ng/female. In laboratory bioassays, Z11-16:Ald alone was attractive to males. In field bioassays, however, Z11-16:Ald alone was not attractive to males, but a mixture of Z11-16:Ald and E11-16:Ald was. The addition of Z11-16:OH to the two aldehydes, significantly reduced attractiveness to male moths in a field trial. From these results, we conclude that the aldehyde compounds comprise the sex pheromone components of G. perspectalis. A rubber septum containing 0.6 mg of the two aldehydes at the natural ratio was an effective lure for monitoring this pest.     

Identification Of Sex Pheromone Components Of The Painted Apple Moth: A Tussock Moth With A Thermally Labile Pheromone Component

The sex pheromone of the painted apple moth, Teia anartoides (Lymantriidae) was investigated using GC-EAD and GC-MS analysis, derivatization, TLC analysis, and field cage and field trapping bioassays. The major sex pheromone components were identified as (6Z,9Z)-henicosa-6,9-dien-11-one and (6Z,9Z)-henicosa-6,9-diene. Other minor components of pheromone gland extracts included (6Z)-9R,10S-epoxyeicos-6-ene, (6Z)-9R,10S-epoxyhenicos-6-ene, (6Z,9Z)-henicosa-6,9-dien-11-ol, (6Z)-henicos-6-en-11-one, and (6Z, 8E)-henicosa-6,8-dien-11-one, but the roles of these minor components remain equivocal. In field cage and field experiments, a blend of all seven identified components [(6Z,9Z)-henicosa-6,9-dien-11-one (relative amount 100), (6Z,9Z)-henicosa-6,9-diene (100), (6Z)-9R,10S-epoxyeicos-6-ene (5), (6Z)-9R,10S-epoxyhenicos-6-ene (10), (6Z,9Z)-henicosa-6,9-dien-11-ol (5), (6Z)-henicos-6-en-11-one (1), and (6Z,8E)-henicosa-6,8-dien-11-one (25)] was as attractive to males as calling females, but tests with blends of the major component(s) with subsets of the minor components did not produce consistent results that unequivocally showed the various minor components to be critical components of the active blend. (6Z,9Z)-henicosa-6,9-dien-11-one is thermally labile and rearranges to (6Z,8E)-henicosa-6,8-dien-11-one and other products at ambient temperature, rendering the synthetic pheromone lure inactive after two days of field exposure.