Chemical Integration of myrmecophilous guests in Aphaenogaster ant nests

International audienceSocial insect nests provide a safe and favourable shelter to many guests and parasites. In Aphaenogaster senilis nests many guests are tolerated. Among them we studied the chemical integration of two myrmecophile beetles, Sternocoelis hispanus (Coleoptera: Histeridae) and Chitosa nigrita (Coleoptera: Staphylinidae), and a silverfish. Silverfishes bear low quantities of the host hydrocarbons (chemical insignificance), acquired probably passively, and they do not match the colony odour. Both beetle species use chemical mimicry to be accepted; they have the same specific cuticular hydrocarbon profile as their host. They also match the ant colony odour, but they keep some specificity and can be recognised by the ants as a different element. Sternocoelis are always adopted in other conspecific colonies of A. senilis with different delays. They are adopted in the twin species A. iberica but never in A. simonellii or A. subterranea. They are readopted easily into their mother colony after an isolation of different durations until one month. After isolation they keep their hydrocarbons quantity, showing that they are able to synthesize them. Nevertheless, their profile diverges from the host colony, indicating that they adjust it in contact with the hosts. This had never been demonstrated before in myrmecophile beetles. We suggest that the chemical mimicry of Sternocoelis is the result of a coevolution with A. senilis with a possible cleaning symbiosis