Genetics and Infection Biology of the Entomopathogenic Fungi

Insects and fungi, both megadiverse groups of organisms, have a long history of associations with each other. Among the fungi, Hypocreales (Ascomycota) and Entomophthoromycotina (Zoopagomycota), contain the most common pathogens of insects. Ascomycete entomopathogenic fungi (EPF) are mostly well-studied and have been found to be either heterothallically or homothallically sexual with a divergent number of genes at the mating-type loci of different species. So far more than 100 strains of >60 EPF species have been genome sequenced which demonstrated substantial variations in genome size and gene content among each other. However, convergent evolution of fungal entomopathogenicity has been coined, especially in terms of the similar expansion of protease and chitinase gene families in EPF for targeting the protein- and chitin-rich insect cuticles. Functional genetic studies have unveiled an array of EPF genes involved in mediating host recognition and interactions with insect hosts, especially mechanisms of invading or evading host immunity to facilitate fungal colonization of insect body cavities. The discovery of small molecules and their essential roles in mediating EPF associations with insect hosts also have been advanced. In addition to advancing the mechanisms of fungus–insect interactions, these works highly benefit the development of cost-effective mycoinsecticides and the protection of ecologically and economically important beneficial insects.