Behavioural interactions between the ant Lasius flavus (Formicidae) and the Myrmecophilous beetle Claviger testaceus (Pselaphidae). Interactions with the reproductives and the brood. Relations of the beetle with insect cadavers and congeners found inside the nest | Interactions comportementales entre la fourmi Lasius testaceus (Pselaphidae). Interactions avec les sexues et le couvain. Rapports du coleoptere avec les cadavres d'insectes et les congeneres presents dans le nid

The behaviour of Lasius flavus winged gynes in the presence of the inquiline beetle, Claviger testaceus, is similar to that of host workers in the same situation. Winged gynes react by approaching the beetle in an aggressive or a non-aggressive manner, by licking it, by regurgitating ingluvial food on it, by biting it, by flexing the gaster against it and by moving it on insect corpses. These reactions, like those of workers, are the same when in the presence of an edible insect corpse. The males react similarly, but their behavioural repertoire lacks the flexing of the gaster and transport and they bite only lightly. There are other, but less important, quantitative differences specific to each kind of imago. The ant's larvae try to eat the Claviger beetle, behaving in a similar manner as they would with edible meaty food. The Claviger beetle is thus treated by all the members of the host society as an insect corpse. Moreover, the reproductives and the workers exhibit aggressive behaviour which suggests that the beetle bears odour components alien to the society. The Claviger beetles feed from the ingluvial liquid regurgitated on their mouthparts by the workers and to a lesser extent by the winged reproductives. They also take liquid food spontaneously disgorged by overfed imagoes and steal part of the regurgitated liquid passed between the various members of the society. They also suck the contents of ant's eggs, lick larval secretions and excreta as well as the integumentary liquid produced by moulting nymphs. They are strongly attracted to insect cadavers and feed on their liquids. They even perceive the changes in the odour of dying ants and may also drink liquids soaked in the soil of the nest's fecal zones. The Claviger beetles are attracted to congeners on which they can behave as phoretics, even outside a reproductive context, and lick them. They behave also as phoretics on the ant reproductives and can lick their integument. A laboratory observation found that a female Claviger can survive being confined with a young founder queen, at least until the hatching of the first workers.