Comparison of pathogenicities of Beauveria bassiana and Metarhizium anisopliae to chestnut pests

Beauveria bassiana strain HF338 had the highest pathogenicity among 77 isolates to larvae of the chestnut weevil, Curculio sikkimensis (Heller) (Coleoptera: Curculionidae). Its pathogenicity at 25°C was similar to that of Metarhizium anisopliae strain HF293. Its pathogenicity at 15°C remained high, whereas that of M. anisopliae HF293 was greatly reduced. Its pathogenicity to chestnut weevil adults and nut fruit moth, Cydia kurokoi (Amsel) (Lepidoptera: Tortricidae), was also higher than those of M. anisopliae HF293. In field tests, the survival rate of chestnut weevil larvae decreased to 2.9% when B. bassiana HF338 was applied at 1×1011 conidia/pot. The high pathogenicity of B. bassiana HF338 makes the strain a potential microbial agent for the control of chestnut pests.