Screening for Highly Virulent Entomopathogenic Fungi Against Lasioderma serricorne (Fabricius) Larvae

In order to screen for entomopathogenic fungi with better control effect on the second instar larvae of Lasioderma serricorne, in this experiment, 5 strains of Verticillium lecanii and 5 strains of Beauveria bassiana were determined by the impregnation method. Two Beauveria bassiana strains Bb05 and Bbr81 with high virulence to the second instar larvae of Lasioderma serricorne were obtained, and the two strains were prepared into different concentrations of spore suspension, and their virulence was determined. The infection process of the Bb05 strain was observed. The results showed that, at the concentration of 1.0×10⁸ mL^-1, Bb05 had the highest cumulative death rate to L. serricorne (77.78%) and LT₅₀ (8.18 d). The cumulative mortality of strain Bbr81 and LT₅₀ was 74.44% and 7.60 d respectively. After treating the Lasioderma serricorne with different concentrations of spore suspensions, the cumulative mortality increased with the increase of spore concentration and inoculation time. The LC₅₀ of strain BB05 was 8.3×10⁷ spores mL^-1, and that of strain Bbr81 was 1.2×10⁷sporesmL^-1. The two strains were highly virulent to the 2nd instar larvae of tobacco beetle, and have a certain potential for development and application.