Mycoviruses in Entomopathogenic Fungi

Mycoviruses are widely distributed among different groups of filamentous fungi. An awareness of infections caused by mycoviruses was highlighted in the 1980s and 1990s, when the impact of these agents on phenotypes of agriculturally and medically important fungi was reported. However, for entomopathogenic fungi, mycovirus research has only expanded significantly in the last 15 years. Due to the agricultural importance of these fungi, reflected in their use at the forefront of biological control strategies, recent studies have extensively described novel viruses and their effects on their hosts in terms of altered morphological, phenotypical, and ecological characteristics. To summarise the historical progress of mycovirology and recent discoveries, here we describe the state of the art in the study of mycoviruses associated with entomopathogenic fungi. We have limited the review to the occurrence of mycoviruses in fungi of the genera Beauveria, Cordyceps, Entomophthora, Metarhizium, and Trichoderma and have compiled an inventory of the viruses reported to infect these entomopathogenic genera, as well as a comprehensive review of the biological effects described with respect to infection by mycoviruses in fungi that are relevant to the biological control of insects. Finally, we have outlined possible research scenarios in the light of recent discoveries in the field of mycovirology, such as the use of mycoviruses as virulence modulating factors: the main character sought in biological pest control.