Effects of Mixture of Common Pesticides with Beauveria bassiana Against Spodoptera exigua

Six kinds of insecticides and three kinds of fungicides at conventional field use concentrations were measured to determine the effects on mycelial growth of B.bassiana.In terms of the result,four kinds of insecticides with more compatiblity were picked out,that is Jiaweiyan,Chujin,Tieshazhang and Kangfu.Then,the four insecticides at 1/5 and 1/10 conventional field use concentrations were mixed with the suspension of B.bassiana at concentration of 1×107 spores/mL respectively to study the effects of the mixture aginst Spodoptera exigua.As a consequence,the mixture containing insecticides at low concentration were less effective than that at high concentration.Two days after treatment,the controlling effects of the mixture containing Jiaweiyan and Chujin increased to 53%-70%.Ten days after treatment,the controlling effects were up to over 92%,and the controlling effects of the two kinds of mixture containing Jiaweiyan both increased to 97.7%.In the mixture,the pesticide was the key factor of high controlling effects,while B.bassiana was critical to persistent controlling effects.Therefore,the mixture involved B.bassiana and Jiaweiyan or Chujin at low concentration should be electded in order to get high and persistent controlling effects.