Evitement des individus conspécifiques lors de la recherche de patchs d'hôtes chez Venturia canescens (Hymenoptera: Ichneumonidae): Effets de la présence d’hôtes et de la densité de conspécifiques.

DESOUHANT, E.; CASTELO, M.K.; CORLEY, J.C.; BERNSTEIN, C.

Bordeaux, Francia

Congreso; XXXIème Journée des Entomophagistes; 2003

ASAB

We explored the effects of the presence of conspecifics on host patch choice decisions made by the parasitoid Venturia canescens. Different odour sources were located in plastic boxes at the end of each arm of a glass Y-tube olfactometer. In a set of experiments, odour sources were either (a) host patches with or without conspecifics (5 or 20) or (b) two odour sources located in successive boxes (host patch and patch with 20 conspecifics in one arm versus a host patch and empty patch in the other). Our results indicate that V. canescens avoids competition only at high conspecific densities. Avoidance occurs when foraging wasps smell the combined odours from hosts and conspecific females. Separating the host patch from conspecific parasitoids does not perturb avoidance behaviour. Consequences on dispersal and on the dynamics of host-parasitoid systems of conspecific avoidance are discussed.