Parasite-host relationship: a lesson from a professional killer

This paper outlines some of the main features of parasites immunoevasion/depression strategies. Insects humoral and cellular responses are briefly discussed and correlated to the active and passive strategies of insects parasites, with particular emphasis on nematocomplexes used as biological insecticides. We have reviewed data on the interaction, at immunological level, of the parasite Steinernema feltiae (Rhabditidae) with the host model Galleria mellonella (Lepidoptera, Pyralidae); the putative role of the parasite body-surface in active and passive evasion mechanisms has been evaluated and discussed.