Transfection of entomopathogenic Metarhizium species with a novel mycovirus confers hypervirulence against two lepidopteran pests

Although most known mycoviruses are asymptomatic or reduce the virulence of their host fungi, those that confer hypervirulence to entomopathogenic fungus still need to be explored. Here, we discovered and studied a novel mycovirus in Metarhizium flavoviride, isolated from Laodelphax striatellus. Based on molecular analysis, we tentatively designated the mycovirus as Metarhizium flavoviride partitivirus 1 (MfPV1), a novel species in genus Gammapartitivirus, family Partitiviridae. MfPV1 has two double-stranded (ds) RNAs as its genome, 1,775 and 1,575 bp in size respectively, encapsidated in isometric particles. When we transfected commercial strains of M. anisopliae and M. pingshaense with MfPV1, conidiation was significantly enhanced (t-test; P-value?