title: Does the stereochemistry of methylated cuticular hydrocarbons contribute to mate recognition in the egg parasitoid wasp Ooencyrtus kuvanae?
abstract: Close-range sexual communication of the egg parasitoid wasp Ooencyrtus kuvanae (Hymenoptera: Encyrtidae) takes place on host gypsy moth, Lymantria dispar (Lepidoptera: Lymantriidae), egg masses. We tested the hypothesis that mate recognition in O. kuvanae is mediated, in part, by low-volatility cuticular hydrocarbon (CHC) pheromone components. Gas chromatographic and GC-mass spectrometric analyses of body surface extracts of male and female wasps revealed no sex-specific components, but 5-methylheptacosane (5-me-27Hy) and 5,17-dimethylheptacosane (5,17-dime-27Hy) were consistently more abundant in extracts of males. The ratio of 5-me-27Hy and 5,17-dime-27Hy was similar in extracts of males and females, and quantitative differences alone seemed insufficient to impart sex-specific CHC profiles. Therefore, we further hypothesized that the absolute configuration of 5-me-27Hy and 5,17-dime-27Hy contributes to mate recognition or attraction. As the stereoisomers of 5-me-27Hy and 5,17-dime-27Hy cannot currently be separated chromatographically, we could not determine the stereochemistry of the insect-produced components. Instead, we synthesized all stereoisomers and bioassayed synthetic blends in laboratory experiments. Of eight 2-component blends, each blend containing one of the two enantiomers of 5-me-27Hy and one of the four stereoisomers of 5,17-dime-27Hy, the blend of (5S)-methylheptacosane and (5R,17S)-dimethylheptacosane attracted males, whereas the blend of (5R)-methylheptacosane and (5R,17R)-dimethylheptacosane repelled males. Apparent recognition of both pheromone components and pheromone antagonists by males supports the hypothesis that the stereochemistry of 5-me-27Hy and 5,17-dime-27Hy, and possibly other methylated CHCs, may differ between male and female O. kuvanae, and that these differences may serve in mate attraction and recognition.
authors.affiliation: Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby BC V5A 1S6, Canada.
authors.forename: Kelly
authors.initials: K
authors.lastname: Ablard
authors.forename: Regine
authors.initials: R
authors.lastname: Gries
authors.forename: Grigori
authors.initials: G
authors.lastname: Khaskin
authors.forename: Paul W
authors.initials: PW
authors.lastname: Schaefer
authors.forename: Gerhard
authors.initials: G
authors.lastname: Gries
mesh_terms: D000818:Animals; D057506:Arthropod Antennae / Q000187:drug effects; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006838:Hydrocarbons / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D008297:Male; D010414:Pennsylvania; D012724:Sex Attractants / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D013237:Stereoisomerism; D014863:Wasps / Q000737:chemistry / Q000187:drug effects / Q000502:physiology*
chemical_list: D006838:Hydrocarbons; D012724:Sex Attractants