Concealing identity and mimicking hosts: a dual chemical strategy for a single social parasite? (Polistes atrimandibularis, Hymenoptera: Vespidae).

Polistes atrimandibularis is a species of obligate social wasp parasite, which introduces into nests of the host species P. biglumis, where it rears its own brood relying on the workers of the host species. Wasps of the host species discriminate between nestmates and non-nestmates by means of their epicuticular hydrocarbons. To overcome the host recognition systems, parasites have to modify their epicuticular recognition cues. Compared to individuals of the host species, parasites have 3-4 times less epicuticular hydrocarbons, although they share with their hosts the habitat and even the nests. We hypothesize that a dilution of the recognition cues in social parasites could have a facilitating role in entering host nests, in integrating within their host colony and in sneaking into secondary colonies to steal larvae and pupae.