Recently, the Innovation Team for monitoring and control of crop viral diseasesat the Institute of Plant Protection, Chinese Academy of Agricultural Sciences (IPPCAAS), published a research paper entitled "Transfection of entomopathogenic Metarhizium species with a novel mycovirus confers hypervirulence against two lepidopteran pests" in the journal Proceedings of the National Academy of Sciences of the United States of America ( PNAS ). The authors identified a novel mycovirus that confers the hypervirulence of entomopathogenic Metarhizium species against two lepidopteran pests, the diamondback moth and fall armyworm, which has a huge potentiality to be developed into the synergist of fungal biocontrol agents.

Metarhizium anisopliae is widely used to control the pests in agricultural land and grassland. Although many mycoviruses have been isolated from the Metarhizium anisopliae , they always caused their hosts to be asymptomatic or to reduce virulence. However, it has not been found any mycovirus that can enhance the virulence of Metarhizium anisopliae so far.

In this study, wediscovered a novel mycovirus, MfPV1, in Metarhizium flavoviride isolated from small brown planthopper. Transfection of the commercial strains of M. anisopliae and M. pingshaense with MfPV1 enhanced virulence of the fungi to diamondback mothand fall armyworm, two important lepidoptera pests. MfPV1-infected fungi produce more conidia and upregulated pathogenesis-related genes that encode adhesin-like protein, hydrolyzed protein and destruxin synthetase. This is the first report of a mycovirus that can confer hypervirulence in Metarhizium species and may facilitate the development of entomopathogenic fungus with enhanced virulence as an environmentally safe alternative to chemical insecticides.

This research was funded by the National Key Research and Development Program of China (2023YFD1400300) and NationalNatural Science Foundation of China (32001873).