SPECIES-SPECIFIC VOLATILE SUBSTANCES IN THE VENOM SAC OF HOVER WASPS

Analyses of the volatile compounds in the venom sacs of seven species of stenogastrine wasps, belonging to three different genera, have reve aled a mixture of linear alkanes and alkenes, with a chain length rang ing from C(11 )to C-17 in all the species. Among conspecifics, the com position of the mixture was consistent, while clear differences have b een found between different species. Venom glands of some species also contained oxygenated compounds and, in one species, some pyrazines. M ost of these compounds were found to be species-specific but were not always found in every individual of a species. In the genus Parischnog aster, P jacobsoni and P. mellyi showed the presence of some spiroacet als that were not found in P. alternata and P. striatula. The possible functions of the venom sac volatiles in the biology of the Stenogastr inae are discussed.