Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2010
Publication Date: 9/5/2010
Citation: Nichols, W.J., Cosse, A.A., Bartelt, R.A., King, B.H. 2010. Methyl 6-methylsalicylate: A female-produced pheromone component of the parasitoid wasp Spalangia endius (Hymenoptera: Pteromalidae). Journal of Chemical Ecology. 36(10):1140-1147. Interpretive Summary: Spalangia endius is a widely distributed, 2-3 mm long parasitoid wasp. Its natural hosts are the pupal state of various flies (Diptera, for example, the pupae of the house fly, which can be found in manure and rotting organic matter. This natural enemy of flies might be used in environmental friendly biological fly control programs. However to implement such programs, one needs to know as much as possible about the life cycle of the parasitoid. This research investigated the mating behavior of male and female wasps; and the results demonstrated that female wasp emit two compounds that are sensed by the males. One compound was chemically identified and synthesized, and this compound caused the male to stay in place (arrestment) and display its courtship behavior. The identity of the second compound is still under investigation.
Technical Abstract: Sex pheromone-related behavior and chemistry were studied in the wasp Spalangia endius Walker (Hymenoptera: Pteromalidae), a pupal parasitoid of house flies Musca domestica L. (Diptera: Muscidae). Males responded behaviorally to female extracts by arrestment, whereas females did not arrest to male extracts. In a comparison of male and female extracts by GC/MS, two female-specific compounds were found. One was identified as methyl 6-methylsalicylate (gas chromatographic retention time and mass spectrum versus an authentic standard), but the chemical structure of the second compound is still unknown. Male antennae were sensitive to both compounds in electrophysiological tests (GC/EAD). Males responded behaviorally to methyl 6-methylsalicylate by arrestment, but they did not arrest to the second compound. The methyl 6-methylsalicylate has been previously reported from some ant and beetle species, but never from Pteromalidae. The analytical data and the male behavioral results are consistent with the idea that methyl 6-methylsalicylate functions as a female-emitted pheromone component at short range, but the exact role of both compounds in intersexual interactions in S. endius remains to be determined.