Can we use entomopathogenic fungi as endophytes for dual biological control of insect pests and plant pathogens?

An increasing number of recent studies demonstrate that entomopathogenic fungi, often solely considered as insect pathogens, play additional roles in nature, including endophytism, plant disease antagonism, plant growth promotion, and rhizosphere colonization. These newly emerging, but not yet fully understood, ecological roles hint at the possibility that we have been overlooking important attributes in our quest to develop fungal entomopathogens exclusively as inundative biopesticides against insect and other arthropod pests. Such additional roles recently-discovered to be played by entomopathogenic fungi provide opportunities for the multiple use of these fungi in integrated pest management (IPM) strategies. Of particular interest is the ability displayed by various genera of entomopathogenic fungi to colonize a wide variety of plant species in different families, both naturally and artificially following inoculation, and confer protection against not only insect pests but also plant pathogens. This article reviews the literature currently available on the endophytic colonization of different host plants by fungal entomopathogens, and summarizes the negative effects of such colonization on insect pests and plant pathogens that have been reported to date. It also addresses the possible mechanisms of protection conferred by endophytic fungal entomopathogens and explores the potential use of these fungi as dual microbial control agents against both insect and pathogen pests. Moreover, interactions amongst endophytic fungal entomopathogens and other endophytes are discussed. Finally, current limitations and future research directions for the innovative use of endophytic fungal entomopathogens as dual microbial control agents are summarized.