Abstract:  In order to screen entomopathogenic fungi strains with high virulence against the new pest Basilepta melanopus on Camellia oleifera, the growth rate and sporulation of different Beauveria bassiana and Metarhizium anisopliae strains were investigated, and bioassay evaluation of B. bassiana and M. anisopliae against B. melanopus adults was carried out through dipping in spore suspension. The results showed that the growth rate and sporulation of different fungi strains were significantly different. The four strains, i.e., MaYTTR-04, BbFZ-17, MaZPTR-01 and BbTK-01, had higher growth rate and sporulation than other strains. The cumulative mortality of B. melanopus adults was gradually increased with time after inoculation with B. bassiana and M. anisopliae. The cumulative mortality of B. melanopus adults reached 100% at 7 d after inoculation with B. bassiana, while the mortality of adults at 14 d after inoculation with MaZPTR-01 and MaYTTR-04 were 80.3% and 78.8%, respectively. The cadaver rate of adults inoculated with B. bassiana was significantly higher than that inoculated with M. anisopliae. The cadaver rates of BbTK-01 and BbFZ-17 were highest, being 85.7% and 75.8%, respectively. The median lethal time (LT₅₀) values of B. bassiana strains BbXJ-01, BbFZ-17 and BbTK-01 were shortest, being 3.0, 3.3 and 3.4 d, respectively. However, the LT₅₀ values of the two M. anisopliae strains, MaZPTR-01 and MaYTTR-04, were 6.0 d and 6.2 d, respectively. The results of bioassay showed that B. bassiana strains had higher virulence to B. melanopus adults than M. anisopliae, especially the two strains, BbTK-01 and BbFZ-17, had higher lethality and infection rate than other strains, and at the same time, they had the characteristics of rapid growth and high sporulation, suggesting that the two strains have great potential in biocontrol of B. melanopus adults.

Key words: Beauveria bassiana; Metarhizium anisopliae, biological characteristics; Basilepta melanopus, median lethal time (LT₅₀), cadaver rate