Inhibitory Effects of Insecticides on Entomogenous Fungi Metarhizium Anisopliae and Beauveria Bassiana

The effect on spores of Metarhizium anisopliae and Beauveria bassiana of insecticides recommended for the control of the brown planthopper [Nilaparvata lugens] and of insecticides that cause resurgences of this pest on rice was studied in the Philippines. The insecticides were mixed into the culture medium before planting or were surface-applied to hardened media. All insecticides significantly reduced spore germination of both fungi, M. anisopliae being the more sensitive. The recommended insecticides (monocrotophos, BPMC [fenobucarb], carbosulfan, and a mixture containing azinphos-ethyl and fenobucarb) reduced germination more than did the resurgence-causing insecticides (azinphos-ethyl, deltamethrin, parathion-methyl and MIPC [isoprocarb]), probably because a higher dose of the recommended insecticide was applied.