Meeting Abstract

68.5  Monday, Jan. 6 09:00  Why is the antlion trap a trap? Comparing the locomotion of ants on two media with different slope and roughness HUMEAU, A.*; CASAS, J.; Institut de Recherche sur la Biologie de l’Insecte, Université de Tours, CNRS, France; Institut de Recherche sur la Biologie de l’Insecte, Université de Tours, CNRS, France ant.humeau@wanadoo.fr

Some predatory antlion larvae (Neuroptera: Myrmeleontidae) build an unstable conical trap in sand and wait at the bottom for arthropods to fall down. This trap can efficiently retain prey but the causes are poorly understood. The trap, compared to the simplest surface, suggests that three factors make the locomotion of prey harder; the type, the slope and the roughness of the medium. The aim of this study was to distinguish their relative impacts on the locomotion of prey. Because ants are the main prey of antlion larvae, the locomotion of the ant Aphaenogaster subterranea walking on a combination of the three factors was described. We compared a granular and a solid medium, respectively a Fontainebleau sand and a glass. We also compared a flat surface and a slope of around 37 °. Finally, the smoothness of glass was compared with the roughness of sand. Locomotion was characterized by global trajectory parameters, like the sinuosity and the velocity, as well as by gait parameters like the duty factor and the stride length.