Habitat Considerations for Parasitic Wasps (Hymenoptera)

Parasitic wasps operate at a high trophic level and, because of their biology, tend to be highly specialised, sometimes having very narrow host ranges with at least local monophagy a frequent outcome. These features, in addition to our poor state of autecological knowledge, render them particularly vulnerable in conservation terms and suggest that their habitat needs should be analysed differently from those of most other insects. The basic life history of parasitic wasps and some of the ways in which they interact with host populations and in communities are outlined. Then, against a background of very limited autecological data, and therefore somewhat speculatively, habitat parameters that seem likely to be of importance to parasitoids are discussed, largely by reference to the host relations and ecology of ichneumonoid parasitoids of Lepidoptera in N. W. Europe. Some considerations of environmental change are included.