Pheromone Components of the Wheat Stem

Volatiles collections and cuticular extracts of the wheat stem sawfly, Cephus cinclus Norton (Hymenoptera; Cephidae), were analyzed by coupled gas chromatographic-electroantennographic detection (GC-EAD) in order to detect possible pheromone components ofthis species. Volatiles collections from male and female sawflies contained the same 13 GC-EAD-active compounds that stimulated both male and female antennae. GC-EAD-active compounds were identified by mass spectrometry, and the identities were verified by acquiring or synthesizing authentic standards with identical GC retention times and mass spectra. 9-Acetyloxynonanal gave the strongest EAD response, Additional GCEAD-active compounds included 13-acetyloxytridecanal, aldehydes with 9-16 carbon chain lengths, acids with 8-10 carbon chain lengths, and phenylacetic acid. The last was instantly detectable by human nose when several males were allowed to interact. but not from isolated insects. On a per-insect basis, grouped males overall released higher amounts of the GC-EAD-active compounds than grouped females. Notable quantitative differences between the sexes were relatively higher amounts of 9-acetyloxynonanal, phenylacetic acid, and tetradecanal from males and hexadecanal from females. In the absence of an absolute. qualitative difference between sexes, these relative differences might be im*To whom correspondence should be addressed. E-mail; [email protected] I Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture.