不同温湿度对草地螟白僵菌的致病力影响

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

测试了不同温、湿度下白僵菌(Beauveria bassiana)对草地螟(Loxostege sticticalis)幼虫的致病力。实验设置了17、20、23、26、29℃5个温度水平,相对湿度(95±5)%、(85±5)%、(75±5)%、(65±5)%和(55±5)%5个梯度,用浓度为1×109孢子/mL的白僵菌孢子液感染2龄的草地螟幼虫。结果表明:在温度为26℃时的致死中时(LT50)最短,死亡速度最快,死亡率最高;高于或低于此温度时,草地螟幼虫的LT50延长,死亡速度减慢。相对湿度发生变化时,草地螟幼虫死亡速度和死亡率不同。相对湿度为95%时,棉铃虫死亡速度最快,死亡率最高;相对湿度低于55%时,棉铃虫死亡率显著降低。相对湿度越高,草地螟幼虫死亡速度越快。

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.