Olfactometer responses of a wild strain of the parasitic wasp Venturia canescens (Hymenoptera, Ichneumonidae) obtained from its natural host Cadra figulilella (Lepidoptera, Pyralidae) to odours from three stored food products infested with pyralid pests

Abstract

The host-finding ability of a field strain of the parasitoid Venturia canescens (Hymenoptera, Ichneumonidae) collected from dried cherries infested with the raisin moth (Cadra figulilella) was investigated in the presence of cues from larvae of three pyralid moth species, Ephestia kuehniella, Plodia interpunctella and C. figulilella, and also the hexane extract of infested host-food products, using a Y-tube olfactometer. Venturia canescens strongly preferred the larval-infested substrate or the kairomonal extract obtained from the same material over filtered air or uninfested substrate, demonstrating that the parasitoid was also attracted to the allelochemicals regardless of host species. The parasitoid had a preference for the product infested with the larvae of the species on which it had been reared (C. figulilella). This finding suggests that the emission of volatiles from the infested products in response to the feeding activity of the host larvae played an important role in the attraction of the parasitoid. The host-finding strategy of female parasitoids varied with the presence of different host species. This behaviour is important for both the mass rearing of V. canescens and for evaluating this species for the biological control of pyralid moth pests.