Comparative morphology of V an der V echt's organ in P olistes social parasites: host ecology and adaptation of the parasite

Camouflage strategies are common in insect social parasites. Being accepted into an alien colony as a dominant nestmate favours behavioural and morphological adaptations to mimic a specific odour. In P olistes social parasites, abdominal tegumental glands are involved in this camouflage strategy. These glands secreting cuticular hydrocarbons are connected with a modified cuticular area of the last gastral sternite of female wasps, named V an der V echt's organ, whose secretion is involved in rank and dominance recognition. The size of this exocrine area has been demonstrated to be under selective pressure in P olistes , as a response to an efficient dominance recognition. Because chemical and behavioural integration differs between parasitic species, we carried out a comparison of V an der V echt's organ size between the three P olistes social parasites and their respective hosts. The parasites P olistes sulcifer and P olistes semenowi , capable of a rapid chemical mimicry and specialized to exploit a lowland host, also show an enlarged V an der V echt's organ. Conversely, the parasite P olistes atrimandibularis , specialized on a mountain species and showing a slow chemical integration, has a smaller organ. The time available for the parasite to tune up its chemical mimicry, before the emergence of workers to be accepted as a dominant nestmate, appears to be the most important selective pressure acting on the size of this abdominal organ. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society , 2013 , 109 , 313 – 319 .