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.     

Chirality of 5,11-dimethylheptadecane,the major sex pheromone component of the hemlock looper,Lambdina fiscellaria (Lepidoptera: Geometridae)

Of the four possible stereoisomers of 5,11-dimethylheptadecane, the major sex pheromone component of the eastern hemlock looper (EHL),Lambdina fiscellaria fiscellaria Guen., and the western hemlock looper (WHL),Lambdina fiscellaria lugubrosa Hulst, (5R,11S)-5,11-dimethylheptadecane was the only stereoisomer eliciting electrophysiological responses by male EHL and WHL antennae. In field bioassays with EHL and WHL populations, traps baited with (5R,11S)-5, 11-dimethylheptadecane caught as many males as did traps baited with all four stereoisomers combined or a synthetic mixture of 5,11-dimethylheptadecanes. Catches in traps baited with the other three stereoisomers did not significantly differ from those in the unbaited control traps. We conclude that male antennae lack chemoreceptors for the other three stereoisomers of 5,11-dimethylheptadecane and hypothesize that only (5R,115)-5,11-dimethylheptadecane is produced by female EHLs and WHLs.     

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.     

Sex Pheromone Components of Pitch Pine Looper, Lambdina pellucidaria

Two methylated hydrocarbons, 7-methylheptadecane (7) and 7,11-dimethylheptadecane (7,11), are sex pheromone components of female pitch pine looper (PPL), Lambdina pellucidaria. Compounds extracted from the pheromone glands of female moths 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 in combination, but not singly, attracted numerous male moths. 5,11-Dimethylheptadecane (5,11) was detected by GC-EAD in female PPL pheromone gland extract, but did not significantly increase attraction of PPL males to 7 plus 7,11. Although 7 was > 10 times more abundant than 7,11 in pheromone gland extracts, traps baited with synthetic 7 plus 7,11 at a blend ratio of 1:1, rather than 1:0.1 or 1:0.01, captured the most PPL males. The chemical communication of PPL and spring hemlock looper (SHL), Lambdina athasaria, is strikingly similar. Both species employ 7 plus 7,11 as sex pheromone. Restriction of SHL to forests with eastern hemlock or balsam fir and PPL to forests with pitch or other hard pines contributes to their reproductive isolation. PPL and SHL may also use different optical isomers of enantiomeric 7 and stereoisomeric 7,11 to maintain specificity of their chemical communication.     

Does Pheromone Biology of Lambdina athasaria and L. pellucidaria Contribute to Their Reproductive Isolation?

Recently, 7-methylheptadecane and 7,11-dimethylheptadecane have been reported as sex pheromone components of both spring hemlock looper (SHL), Lambdina athasaria, and pitch pine looper (PPL), Lambdina pellucidaria. Our objective was to test the hypothesis that SHL and PPL are reproductively isolated, in part, through species specificity in: (1) absolute configuration of pheromone components, (2) diel periodicity of pheromonal communication, and/or (3) seasonal flight period. In coupled gas chromatographic-electroantennographic detection (GC-EAD) analyses of stereoselectively synthesized (7S)- and (7R)-7-methylheptadecane [7S; 7R] as well as (7S,11S)-, (7R,11R)-, and (meso-7,11)-7,11-dimethylheptadecane [7S,11S; 7R,11R; meso-7,11], only 7S and meso-7,11 elicited responses by male SHL and PPL antennae. In field experiments, male SHL and PPL were attracted only to lures containing 7S plus meso-7,11. In hourly recordings of trap-captured males, SHL and PPL in their respective habitats were trapped between 24:00 and 03:00 hr. Capture of both SHL and PPL in pheromone-baited traps throughout June indicated overlapping seasonal flight periods. These findings of identical absolute configuration of pheromoal components, diel periodicity of pheromonal communication, and overlap of seasonal flight periods support synonymy of SHL and PPL. Finite taxonomic classification of PPL and SHL must await careful assessment of further criteria, such as morphometrics, molecular comparisons and ecological analyses.     

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.     

Optical isomers of 3,13-dimethylheptadecane: Sex pheromone components of the western false hemlock looper,Nepytia freemani (Lepidoptera: Geometridae)

(3S, 13R)-3, 13-Dimethylheptadecane [(3S, 13R)-3, 13-dime-17Hy] is the major pheromone component of the western false hemlock looper (WFHL),Nepytia freemani. In comparative gas chromotographic-electroantennographic detection (GC-EAD) analyses of stereoselectively synthesized isomers, 1 pg of (3S, 13R)-dime-17Hy elicited significantly stronger electrophysiological responses by male WFHL antennae than did 1 pg of separately injected (3R, 13R)-, (3R, 13S)- or (3S, 13S)-3, 13-dime-17Hy. In field experiments with individually tested stereoisomers. (3S, 13R)-3, 13-dime-17Hy was the only stereoisomer to attract males, but the four-stereoisomer blend was 3.6 times more attractive. Quaternary and all binary combinations of (3S, 13R)-3, 13-dime-17Hy with the other stereoisomers were equally attractive, suggesting that synergisytic behavioral activity in WFHL resided with either one of (3R, 13R)-, (3R, 13S)-, or (3S, 13S)-3, 13-dime-17Hy. Because optical isomers of (di)methylhydrocarbons do not separate on currently available columns, it remains unknown whether female WFHL also produce a four-stereoisomer pheromone blend. Substitutionality of pheromone stereoisomers without loss of behavioural activity has not previously been reported, but favorably compares with the concept of pheromone redundancy that was first suggested for the multiple pheromone component blend of the cabbage looper moth,Trichoplusia ni.     

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.     

Role of female-produced sex pheromone in behavioral reproductive isolation betweenTrichoplusia ni (Hübner) andPseudoplusia includens (Walker) (Lepidoptera: Noctuidae,plusiinae)

In laboratory flight tunnel bioassays, response rates of male cabbage looper,Trichoplusia ni (Hübner), to female soybean looper,Pseudoplusia includens (Walker), were similar to response rates of maleT. ni to conspecific females for plume tracking and source contact. Male soybean loopers, however, exhibited a greatly reduced response to female cabbage loopers compared to conspecific females. Similar differences were observed in male responses to extracts of female abdominal tips. Studies of flight tunnel responses of male soybean loopers to the different chemicals known to be components of the female cabbage looper sex pheromone indicated that the reduction in response was due to inhibitory effects of (Z)-5-dodecen-1-ol acetate and (Z)-9-tetradecen-1-ol acetate, when added singly to (Z)-7-dodecen-1-ol acetate (major component of both species) at release rates and at ratios close to those observed in female cabbage loopers.     

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.     

Sex pheromone of oriental beetle,Exomala orientalis: Identification and field evaluation

A gas chromatograph coupled with a behavioral bioassay was used to identify two sex pheromone components, 7-(Z)- and 7-(E)-tetradecen-2-one of the Oriental beetle (OB),Exomala orientalis. Field experiments showed that the blend of the two isomers (Z:E, 7:1) was not significantly more attractive than theZ component alone. The best performance of traps baited with the synthetic sex pheromone was achieved when they were set with the pheromone device at 30 cm above the ground. Catches in traps baited with 1 and 10 mg were not significantly different, but they were higher (2.9-fold) than captures in traps loaded with 0.1 mg of the pheromone. Further investigations by GC-EAD revealed the presence of a possible minor component, but the small amount of material prevented its identification. 2-(E)-Nonenol, with the same retention time as the natural product, did not affect the attractancy of the synthetic sex pheromone. GC-EAD screening of previously identified sex pheromones of scarab beetles showed that male antennae of the Oriental beetle responded to japonilure, but it showed neither synergism nor inhibition to the OB sex pheromone.     

Effects of host plant,Gossypium hirsutum L., on sexual attraction of cabbage looper moths,Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae)

Unmated female or male cabbage looper moths,Trichoplusia ni (Hübner), were attracted more often in a flight tunnel to a cage with moths of the opposite sex and a bouquet of cotton foliage. Increased sexual attractiveness of females with plants may be a result of stimulation of pheromone release in response to plant odor, since more males were attracted when odor of cotton foliage was passed over females than when odor of females was passed over cotton foliage before venting into the flight tunnel. Increased sexual attractiveness of males with plants is due in part to host odor enhancement of female attraction to male pheromone, since more females were attracted to synthetic male pheromone (a blend of enantiomers of linalool and isomers of cresol) and a cotton leaf extract than were attracted to male pheromone alone. A short synthesis procedure was developed for (S)-(+)-linalool, the major component of the male sex pheromone, isolated from hair pencils, used in these tests.     

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.     

(E)-11,13-tetradecadienal: Major sex pheromone component of the eastern blackheaded budworm,Acleris variana (Fern.) (Lepidoptera: Tortricidae)

(E)-11,13-Tetradecadienal (E11,13–14:Ald) is the major sex pheromone component of the eastern blackheaded budworm (EBB),Acleris variana (Fern.). The compound was identified in female pheromone gland extracts by coupled gas chromatographic-electroantennographic detection (GC-EAD), coupled GC-mass spectrometry in selected ion monitoring mode, and retention index calculations of candidate pheromone components.E11,13–14:Ald alone as trap bait was very attractive to male EBB. Addition of the corresponding diene alcohol or acetate or both did not enhance attraction. (Z)-11,13-Tetradecadienal in binary combination with (E)-11,13–14:Ald neither enhanced nor reduced trap catches. Increasing the amounts of pheromone from 0.01 to 10 µg increased trap catches, but increase of pheromone quantity above 100 µg proportionately reduced attraction. Stabilization of slowly polymerizingE11,13–14:Ald and development of a sustained, adequate release rate is required for pheromone-based monitoring of EBB populations.     

Identification of male cabbage looper sex pheromone attractive to females

A multicomponent pheromone produced by male cabbage looper moths that is attractive to female moths in a flight tunnel bioassay was isolated and identified. Based on analyses of hairpencil extracts of male cabbage loopers and volatiles emitted by males, the pheromone has been identified as a blend consisting of (S)-(+)-linalool,p-cresol, andm-cresol. The chirality of the major component, (S)-(+)-linalool, is important for behavioral response of females. These pheromonal compounds were also identified as volatiles released by males when males were exposed to the principal pheromone component of female cabbage loopers, (Z)-7-dodecen-1-ol acetate. The amount of male pheromone released was increased significantly when males were exposed to a combination of (Z)-7-dodecen-1-ol acetate and the odor from cabbage. Neither linalool nor the cresols were detected in volatiles from cabbage or from males exposed to cabbage odor.     

Sex phermone components of mulberry looper,Hemerophila atrilineata butler (lepidoptera: Geometridae)

(6Z-9S, 10R)-Epoxy-octadecene (SR-1) and (3Z, 6Z-9S, 10R)-epoxy-octadecadiene (SR-2) are sex pheromone components of the mulberry looper (MBL),Hemerophila atrilineata Butler. Compounds extracted from female MBL pheromone glands were identified by coupled gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometry. In field experiments in China,SR-2,RS-2, or both combined were hardly attractive, butSR-2 in combination withSR-1 attracted significant numbers of MBL males. Synergistic behavioral activity ofSR-1 plusSR-2, but not of corresponding antipode mixtures, indicates enantiospecificity of MBL pheromone communication. Because blends of racemic and enantiospecific (SR)1 plus2 were similarly attractive, racemic1 plus2 may have potential for mass trapping or confusion of MBL males in commercial mulberry plantations.     

(2S,12Z)-2-Acetoxy-12-heptadecene: Major Sex Pheromone Component of Pistachio Twig Borer, Kermania pistaciella

The sex pheromone of the pistachio twig borer, Kermania pistaciella (Lepidoptera: Oinophilidae), one of the most important insect pests of pistachio, Pistacia vera, in Turkey and Iran, was identified. In gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometric analyses of pheromone gland extracts of female K. pistaciella from Turkey, (2S,12Z)-2-acetoxy-12-heptadecene was identified as the major candidate pheromone component. In field experiments in Turkey, lures containing synthetic (2S,12Z)-2-acetoxy-12-heptadecene attracted large numbers of male moths. Its attractiveness was significantly reduced by the presence of the R-enantiomer or of either enantiomer of the corresponding alcohol. (2S,12Z)-2-Acetoxy-12-heptadecene is the first pheromone component identified in the Oinophilidae and the first secondary acetate pheromone component identified in the Lepidoptera. An erratum to this article can be found at     

Right stereoisomers for sex pheromone components of the apple leafminer,Lyonetia prunifoliella,in Korea

The sex pheromone of the American population of Lyonetia prunifoliella (Lepidoptera: Lyonetiidae) was reported to be composed of three components, 10,14-dimethyloctadec-1-ene (10me14me-1-ene-18Hy), 5,9-dimethyloctadecane (5me9me-18Hy), and 5,9-dimethylheptadecane (5me9me-17Hy). Studies with a Korean population showed that the 10S,14S isomer of the major compound was the major electrophysiologically by active stereoisomer. The 5S,9S isomers of the minar constituents also elicited electrophysiological responses. In field trappings, among the three components, the racemic mixture of 10me14me-1-ene-18Hy attracted L. prunifoliella males strongly, and the binary or tertiary combinations with racemic mixtures of the other two components did not increase trap catches. Among the four stereoisomers of 10me14me-1-ene-18Hy, only the 10S,14S isomer attracted L. prunifoliella males, as suggested by the EAG test, and attraction to the other three isomers was not observed. All stereoisomers of each minor component, as well as their racemic components, did not seem to have any additional effect on male attraction in Korea.     

Sex attractant of the alfalfa looperAutographa californica and the celery looperAnagrapha falcifera (Lepidoptera: Noctuidae)

In field tests, traps baited with a combination of (Z)-7-dodecen-1-ol acetate (previously proposed to be the sex pheromone ofA. californica) and (Z)-7-dodecen-1-ol formate caught about 100 times as many males as (Z)-7-dodecen-1-ol acetate did alone. Highest catches of males were obtained with traps baited with 0.5 mg of (Z)-7-dodecen-1-ol acetate and 0.1 mg of (Z)-7-dodecen-1-ol formate impregnated on red rubber sleeve stoppers. The celery looper,Anagrapha falcifera, was also caught in traps baited with a combination of these two chemicals.     

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.