Pathogenicity of Metarhizium anisopliae to the chestnut weevil larvae under laboratory and field conditions

抄録

We used a baiting method to isolate 65 entomopathogenic fungi with pathogenicity to the chestnut weevil larva from soil samples. Metarhizium anisopliae strain HF293 showed the highest pathogenicity. Under laboratory conditions, the LD₅₀ value of strain HF293 on the 10th day after treatment of newly emerged larvae was 9.9×10³ conidia/larva, and the mortality rate of larvae reached 56% at five weeks after treatment with a conidial dose of 2.0×10²/larva. Susceptibility of the larvae that had been stored at 6°C to strain HF293 gradually decreased over the first three months of storage but stabilized by the fourth month. The results of a field study of larvae in flowerpots indicated that the survival rate of larvae decreased with increasing doses of conidia of M. anisopliae strain HF293.