Life History and Chemical Ecology of Xenos peckii (Strepsitera, Xenidae)

I investigated life history traits and pheromonal communication of Xenos peckii, a parasitoid of the paper wasp Polistes fuscatus. To emerge, males cut the puparium with their mandibles, and then push aside the pupal cap with their head. The endoparasitic females engage in active calling (pheromone release) behaviour assuming a particular body posture. Seasonal and diel emergence periods of males coincide with seasonal and diel calling periods of females. Mate-seeking males land on the anterior portion of the host wasp’s abdomen, and then step backward until their mesothoracic legs contact the female’s cephalothorax, upon which the male initiates copulation. Analyzing pheromone gland extracts by gas chromatographic-electroantennographic detection revealed a candidate pheromone component (CPC) that consistently elicited responses from male antennae. CPC was identified as (7E,11E)-3,5,9,11-tetramethyltridecadienal based on mass and NMR spectra, and the synthesis of an authentic standard. In field experiments, traps baited with synthetic CPC captured X. peckii males.