Sophisticated acoustical mimicry between a myrmecophilous carabid beetle (Paussini, Paussus favieri) and its host ant (Myrmicinae, Pheidole pallidula)

Animals use a variety of sounds for communicating. Acoustic communication is well known among vertebrates, whereas it seems restricted to few invertebrate groups that use acoustic signals mainly as a species-specific recognition system to assist mating. However, it has been recently discovered that caterpillars of a butterfly (Maculinea) that lives in ant nests are able to mimic the acoustic signals of their queen host ants. Maculinea caterpillars are not an isolated case. We found an even more surprising case of acoustic mimicry in insects. Here we show the ability of an ant nest beetle, Paussus favieri (Coleoptera, Carabidae, Paussini), in mimicking host ant, Pheidole pallidula, stridulations. The presence of stridulatory organs in Paussini has long been known, but the significance of their stridulation has remained a matter of speculation. The sound analyses revealed that Paussus has a repertory of three melodies, in contrast with the monotonic stridulation pattern of Maculinea. Paussus melodies correspond to sounds produced by different ant castes (queen, workers and soldiers). This ant parasite uses a single, anatomically simple structure to “speak” different “languages” by modulating the emissions of three types of pulses. In particular, by mimicking the queen’s stridulations the beetle can elevate its social status to solicit more effective cares, and to acquire free access to the nest. Paussus is the only known case of an invertebrate with a complex repertoire of acoustic signals among which it can choose according to its needs