ABSTRACT
There are about half a million described species of insects on the Earth, and the true diversity may be many times this figure (Groombridge, 1992). Approximately 10 per cent of these can be considered agricultural, forestry or urban pests. If we assume that each insect species is susceptible to at least one pathogenic microorganism, often hostspecific, we have an insight into the potential importance of the study of these pathogens in the context of pest control and biodiversity.
