Activity of the entomopathogenic fungus Beauveria bassiana (Deuteromycota : Hyphomycetes) against three Coleopteran pests of stored grain

A Beauveria bassiana isolate from the rice water weevil, Lissorhoptrus oryz ophilus Kuschel (Coleoptera: Curculionidae),was evaluated as a conidial pow der against 3 coleopteran pests of stored grain: the rice weevil, Sitophilu s oryzae (L.) (Coleoptera: Curculionidae); the lesser grain borer, Rhyzoper tha dominica (F.) (Coleoptera: Bostrichidae); and the red flour beetle, Tri bolium castaneum (Herbst) (Coleoptera: Tenebrionidae). Bioactivity of B. ba ssiana isolate 22292A was assessed on 3 types of food substrates (red flour beetle media. medium grain brown rice, and long grain rough rice) at 27 de grees C and 60% RH. Adult mortality was 80-100% at the higher dosage levels for all insects tested on all media types at 21 d after treatment. Emergen ce of adult progeny on brown and rough rice was reduced by 83-99% at the 2 highest dosage level. The abrasive nature of rice hulls on the rough rice m ay contribute to the accelerated mortality seen on this medium.