MUTANTS OF ENTOMOPATHOGENIC FUNGI THAT GERMINATE AND GROW AT REDUCED WATER ACTIVITIES AND REDUCED RELATIVE HUMIDITIES ARE MORE VIRULENT TO NEPHOTETTIX VIRESCENS (GREEN LEAFHOPPER) THAN THE PARENTAL STRAINS

A method was developed to isolate mutants of Metorhizium anisopliae an d Paecilomyces farinosus able to germinate and grow at lower water act ivities (a(W)) and relative humidities than the parental strains. Prod ucing blastospores of these mutants in cultures grown on low water act ivity medium (a(W) = 0.969) further increased their ability to germina te at low a(W). At a relative humidity of 96-98%, some of the mutants were more virulent against green leafhopper than the parental strains, i.e. they had reduced LT(50) values.