Prey handling and feeding habits of the snail predator Licinus depressus (Coleoptera, Carabidae)

Abstract

Carabid beetles of the tribe Licinini use their asymmetric mandibles to open the shells of land snails. Prey handling of large snails has been described in a few Licinini species. We observed for the first time how a male of Licinus depressus (Paykull, 1790) opens the shells of small prey snails (Chondrina arcadica (Reinhardt, 1881)) and eats their soft bodies. The beetle holds the conical snail shell with its forelegs and breaks the wall of the right-hand coiled shell. In doing so, the beetle rotates the shell counter-clockwise opening it stepwise along the dorsal part of the whorls towards the apex. After some bites, the beetle interrupts the opening process and begins to feed on the snail’s soft tissue. Then the beetle continues to break up the shell, shortly after which there is another feeding phase. The alternating sequence of shell breaking and feeding ends after 2 to 2.5 whorls when the beetle can no longer hold the prey’s remaining intact shell. We compare this previously unknown way of prey handling with the reported predatory behaviour in large snails by other Licinini species. Our observations confirm the high plasticity of predatory behaviour in Licinini beetles.