Impacts of different temperatures and humidity on pathogenicity of Beauveria bassiana to Loxostege sticticalis

The pathogenicity of Beauveria bassiana to Loxostege sticticalis under different temperatures and humidity was studied in laboratory.The 2th-instar larvae of the L.sticticalis were infected with 1×109 sporus/ml concentrations of B.bassiana under 17,20,23,26 and 29 ℃.The results showed that under 26 ℃,the LT50 of larvae treated with 1×109 sporus/ml concentrations of B.bassiana were the shortest,the larvae died quickly and the mortalities were the highest.The LT50 were prolonged as the ambient temperature turned higher or lower than 26 ℃,and the larvae died slowly under these temperatures.There were significant differences among the mortalities of L.sticticalis under different humidity.The larvae died quickly and the mortality was the highest under 95% relative humidity,while the mortality decreased greatly under 55% relative humidity,the larvae died more quickly along with the increasing of relative humidity.