Isolation, identification, and behavioral response of methyl 6-methylsalicylate, a female-specific sex pheromone component of the parasitoid wasp Spalangia endius (Hymenoptera: Pteromalidae)

Although mate attraction is known to involve pheromones for many insects, the chemical identity of those pheromones is frequently unknown. Males of the wasp Spalangia endius (Hymenoptera: Pteromalidae), a parasitoid of house flies, arrested to female extracts, whereas females did not arrest to male extracts. Males fanned and mounted female heads, thoraces and abdomens equally even without the female having had a chance to groom and spread any pheromone. Using GC/ MS, two female-specific compounds were found. One was methyl 6-methylsalicylate, a compound reported only for some ants and a few other insect taxa, but never Pteromalidae. Males, including just male antennae, responded to methyl 6-methylsalicylate, as shown by male arrestment, fanning and by GC/EAD. Males also occasionally fanned to related isomers, but males arrested more strongly to methyl 6-methylsalicylate than to related isomers. The chemical structure of the other female compound is still unknown, but male antennae responded to it.