Depths and type of substrate influence the ability of Nasonia vitripennis Walker (Hymenoptera: Pteromalidae) to encounter host

The foraging behaviour of a parasitoid insect species includes the host’s habitat and subsequent location of the host. Habitats-substrate, substrate moisture and light levels can affect the host location made by different species of parasitoids. However, the depth at which parasitoids concentrate their search effort is an another important ecological characteristic and play an important role on the host location. Here, we have investigated the ability of a pupal parasitoid, Nasonia vitripennis Walker, to penetrate and kill fly pupae located at different depth of the substrate. Three different types of substrate were tested: loam soil, compost and vermiculite substrate. In both loam soil and compost, all of the parasitism activity was restricted to pupae placed directly on the surface. Parasitism activity in vermiculite showed that the average number of pupae parasitized was decreased with depth. These results suggest that fly pupae situated deeper in the substrate are less subjected to parasitism by N. vitripennis.