Dispersal of the parasitoid Habrobracon hebetor in storage warehouses

Abstract

Habrobracon hebetor is an ectoparasitoid that attacks the last-instar larvae of moth pests, such as Ephestia kuehniella, an important pest of grain and flour in storage facilities and in bakeries. To improve the efficacy of commercial releases of this parasitoid in store houses it is important to know how good its dispersal in real conditions of premises is. In this study, we evaluated the capacity of mated H. hebetor females to locate host larvae when released in two warehouses during the spring and summer seasons. Individual E. kuehniella larvae were placed at two distances from the release point, and the number of attacked larvae was assessed two weeks later. The results indicate that many parasitoids were able to reach larvae placed at a distance of 5 m and 20 m from the release point. We also observed that the proportion of attacked larvae increased with the density of released parasitoids. We conclude that the parasitoid could be released every 40 m to ensure good distribution in a warehouse.