Biological observations on pachyteles larvae (coleoptera carabidae paussinae)

Abstract

Larvae of Paussinae are poorly known. They are characterised by a hyperprognathous head, a U-shaped body and the end of the abdomen (and the urogomphi) transformed into a 6-lobed terminal disk. Most of them are myrmecophilous and live in ant nests; others, such as those of the genus Pachyteles Perty 1830, are non-parasitic and live in burrows in sandy banks or rotten wood. On the basis of field and laboratory observations, we describe defensive and predatory behaviours of larvae of two species of Pachyteles, which use their terminal disk as both a phragmotic and trapping organ. These larvae attract small invertebrates by secreting certain substances and catch their prey by an ambush strategy. This is interpreted as a primitive predation strategy in larvae of Paussinae. In the laboratory, we observed that ants and termites are strongly attracted by substances covering the terminal disk. This behaviour could have played an important role in the origin of symphily, also suggesting the possibility of a multiple, independent evolution of myrmecophily in pre-adapted Paussine tribes like Ozaenini, Protopaussini and Paussini.