Contact toxicity and efficacy of pyrethroid insecticides to rice pests

The results were as follows: the LD_(50) of deltamethrin to Chilo suppressalis and C.medinalis were 0.0089 and 0.0579 μg per pest,but the LD_(50) of fenvalerate to these two kinds of pests were 0.0766 and 0.1688 μg per pest, respectively,it was lower than that of deltamethrin;the efficacies of 25 g·L~(-1)deltamethrin EC at the dose of 0.375 and 0.450 L·hm~(-2) were 74.88% and(81.18%),respecctively.It suggested that deltamethrin could control C.suppressalis more effectively than fenvalerate,and there was no significant difference of control efficacy to C.medinalis between deltamethrin and fenvalerate,they could control C.medinalis effectively.