The Entomopathogen Paecilomyces fumosoroseus Among the many fungal insect pathogens encountered in nature, the genera Beauveria and Metarhizium are probably the most widely known by entomologists. A common attribute of these fungi is the lack of sexual forms, thereby the name Fungi Imperfecti. The infection cycle of entomopathogenic fungi, including enzyme production on the cuticle, remains one of the most fascinating areas of research involving these organisms.
Fungal penetration can also occur through the spiracles, the mouth, and anal opening.
Development occurs in the hemolymph with mycelia eventually exiting from the insect, and producing conidia. Insect mortality due to fungal infection has been ascribed to the destruction of insect tissues, the release of toxins, and nutritional deficiencies. Some members in the genus, such as P. lilacinus, are active against plant parasitic nematodes. One major impediment towards the widespread use of PFR is the lack of a commercial formulation in the USA, although one is being marketed in Europe under the trade name PreFeRal. A commercially-viable formulation should have low production costs in order to compete advantageously with conventional insecticides.