title: Elucidating Structure-Bioactivity Relationships of Methyl-Branched Alkanes in the Contact Sex Pheromone of the Parasitic Wasp Lariophagus distinguendus.
abstract: The exoskeletons of insects are covered by complex mixtures of cuticular hydrocarbons (CHCs) which are involved in social and sexual communication. However, little is known about the relationship between the structures of CHCs and their behavioral activity. The key component of the contact sex pheromone of the parasitoid Lariophagus distinguendus is 3-methylheptacosane (3-MeC27), which is present in CHC profiles of both females and newly emerged males. The CHCs of females and young males elicit wing-fanning behavior in older males. However, as young males age, 3-MeC27 disappears from their CHC profiles and they no longer elicit wing-fanning responses from other males. We applied enantiopure 3-MeC27 and structurally related CHCs (with respect to chain length or methyl-branch position) to the cuticle of aged male dummies and recorded the wing-fanning behavior of responding males. Only the two enantiomers of 3-MeC27 restored the dummies' attractiveness. The addition of structurally related CHCs or various n-alkanes to bioactive dummies of young males and females significantly decreased wing-fanning by test males. Hence, L. distinguendus males respond specifically but not enantioselectively to 3-MeC27, and perceive the CHC profiles as a whole. Both removal (as is the case with 3-MeC27 in aging males) and addition of individual compounds may disrupt the behavioral response.
authors.affiliation: Institute of Zoology, University of Regensburg, Universitätsstraße 31, Regensburg D-93053, Germany. marsupials@web.de.
authors.forename: Stephan
authors.initials: S
authors.lastname: Kühbandner
authors.affiliation: Department of Chemistry, University of California, Riverside, CA 92521, USA. jbell011@ucr.edu.
authors.forename: Jan E
authors.initials: JE
authors.lastname: Bello
authors.affiliation: Photosensitive Materials Research Center, Toyo Gosei Co., Ltd., 4-2-1 Wakahagi, Inzai-shi, Chiba 270-1609, Japan. kjk-mori@arion.ocn.ne.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Mori
authors.affiliation: Department of Chemistry, University of California, Riverside, CA 92521, USA. jocelyn.millar@ucr.edu.|Department of Entomology, University of California, Riverside, CA 92521, USA. jocelyn.millar@ucr.edu.
authors.forename: Jocelyn G
authors.initials: JG
authors.lastname: Millar
authors.affiliation: Institute of Zoology, University of Regensburg, Universitätsstraße 31, Regensburg D-93053, Germany. joachim.ruther@ur.de.
authors.forename: Joachim
authors.initials: J
authors.lastname: Ruther
keywords: 3-methylheptacosane; Lariophagus distinguendus; Pteromalidae; chemoreception; contact sex pheromone; cuticular hydrocarbons; parasitic wasp