Abstract: The beetle (Basilepta melanopus) is one of the most serious leaf-feeding insects in tea garden, which seriously affects both tea yield and quality. In recent years, the beetle often caused serious damage in some tea gardens, especially organic tea gardens. How to effectively control this pest has become a serious problem. In order to screen high virulence strains of Beauveria bassiana to B. melanopus, 9 strains of B. bassiana isolated from the coleoptera pests in tea gardens were selected as candidates. In the preliminary screening, the biological characteristics of these 9 strains, including colony morphology, growth rate, sporulation, spore germination rate, thermotolerance and UV radiation resistance were detected. According to the above biological characteristics, three strains Bb338, Bb346 and Bb2-1 were selected for further bioassay against the adult of B. melanopus. Bioassay results showed that the strain Bb2-1 was the most virulent strain to the adults of B. melanopus, which had the highest corrected mortality rates of 100%, highest cadaver rates of 86.11% and shortest LT₅₀ of 3.32 d at a concentration of 1.0×10⁷ conidia per milliliter. The strain Bb2-1 has the best biological characteristics and the highest virulent against the adults of B. melanopus, which would play a very important role in biocontrol of B. melanopus.

Key words: Basilepta melanopus, Beauveria bassiana, biological characteristics, virulence, strain screening