Are there any risks in using entomopathogenic fungi for pest control, with particular reference to the bioactive metabolites of Metarhizium, Tolypocladium and Beauveria species?

Entomopathogenic fungi are promising alternatives to chemical insecticides. However, a major hurdle concerning the registration of these fungi as plant protection agents is the possible toxicity of secreted metabolites, especially secondary metabolites. This review summarizes data on specific secondary metabolites (destruxins, efrapeptins, oosporein, beauvericin and beauveriolides) produced by the important genera Beauveria, Metarhizium and Tolypocladium. The quantities of secondary metabolites produced by these fungi in vivo are usually much less than those secreted in nutrient rich liquid media. Methods and strategies are suggested which could standardize the risk assessment of fungal biological control agents.