Jianxiong Li

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.

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.

5,11-Dimethylheptadecane and 2,5-Dimethyl-heptadecane: Sex pheromone components of the geometrid moth, Lambdina fiscellaria fiscellaiia

5,11-Dimethylheptadecane and 2,5-dimethylheptadecane, two previously unknown lepidopteran sex pheromone components, comprise the sex pheromone of the eastern hemlock looper, Lambdina fiscellaria fiseellaria (Guen.) (Lepidoptera: Geometridae). The eastern hemlock looper is found in Canada from Newfoundland to Saskatchewan and from the Lake States to the eastern seaboard of the United States [1]. It is the most important insect pest in Newfoundland, causing an estimated 20 million m 3 of mortality in balsam fir, Abies balsamia (L.) Mill., since 1900. Monitoring with pheromone-baited traps would greatly enhance forecasting of looper outbreaks. We report the identification, synthesis, and field testing of the sex pheromone of the eastern hemlock looper. Experimental insects were laboratoryreared or field-collected near St. Johns, Newfoundland. Sexed pupae and moths were kept at 20°C, 70% r.h. and a photoperiod of 16:8 (L:D). Pheromone glands of calling females were excised and extracted in hexane for 2 min. Gas chromatographic analyses on two glass capillary columns (DB-210, DB1) utilizing both flame ionization (FID) and electroantenno-

Sex pheromone of the western hemlock looper,Lambdina fiscellaria lugubrosa (Hulst) (Lepidoptera: Geometridae)

The sex pheromone of the western hemlock looper (WHL),Lambdina fiscellaria lugubrosa (Hulst), comprises three methylated hydrocarbons: 5,11-dimethylheptadecane (5,11), 2,5-dimethylheptadecane (2,5), and 7-methylheptadecane (7). Compounds extracted from female pheromone glands were identified by coupled gas chromatographic-electroantennographic (GC-EAD) analysis and coupled GC-mass spectroscopy in selected ion monitoring mode. In trapping experiments, (5,11) alone attracted male moths, but addition of either (7) or (2,5) significantly enhanced attraction. (5,11) combined with both (7) and (2,5) was significantly most attractive. (5,11) and (2,5) are also sex pheromone components of the eastern hemlock looper (EHL),Lambdina fiscellaria fiscellaria (Guen.). Although (7) is produced by the EHL, it is a pheromone component only in the WHL. It constitutes the first behaviorally active monomethyl-branched hydrocarbon to be found in a geometrid and is a novel lepidopteran sex pheromone component. The different 2- versus 3-component sex pheromone supports taxonomic division of EHL and WHL.

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

Abstract3,13-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 100μg 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 100∶10, 100∶1, or 100∶1∶1. 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.

Chiral esters: Sex pheromone of the bagworm,Oiketicus kirbyi (Lepidoptera: Psychidae)

Gas chromatographic-electroantennographic detection (GC-EAD) analyses of pheromone extract of female bagworms,Oiketicus kirbyi (Guilding), revealed five EAD-active compounds. Retention index calculations, GC-mass spectrometry in both full-scan and selected-ion monitoring modes and GC-EAD analyses of authentic standards identified the compounds as 1-methylbutyl octanoate (MBO), 1-methylbutyl nonanoate (MBN), 1-methylbutyl decanoate (MBD), 1-methylpentyl decanoate (MPD), and 1-methylbutyl dodecanoate (MBDD). Of these five chiral esters, MBD was most abundant in extracts and elicited the strongest antennal response. In field experiments in Costa Rica, (R)-MBD attractedO. kirbyi males, whereas (S)-MBD in combination with (R)-MBD inhibited response.R but notS enantiomers of MBO, MBN, and MBDD strongly synergized attraction to (R)-MBD. (S)-MBO and (S)-MBDD were inactive, whereas (S)-MBN was inhibitory. (R)-, (S)- and racemic MPD were inactive. Blends of (R)-MBD in ternary combination with either (R)-MBO and (R)-MBN or (R)-MBN and (R)-MBDD were as attractive as the five-ester blend. Five- and four-ester blends were equally attractive, suggesting redundancy of pheromone components for attraction of males. The multiple sex pheromone component blend of chiral esters inO. kirbyi may have evolved to maintain species-specific communication in bagworm communities of tropical Americas.

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

Abstract(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.

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

Abstract(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.