Toxicity and Field Control Efficacy of Six Pesticides to the Bean Aphid Aphis craccivora Koch(Hemiptera:Aphididae)

Taking Aphis craccivora Koch as tested pest,the toxicity and field control efficacy of six insecticides to bean aphid Aphis craccivora Koch(Hemiptera:Aphididae)were studied.The toxicity test results showed that the bean aphid developed high resistance to 74.6% Emamectin benzoate with a mortality of 30.36% after 24hours under the concentration of 1 000mg/L.This aphid showed the highest sensitivity to 95% Beta-cypermethrin with a LC50 of 8.1609mg/L.The order of the toxicity of the six tested pesticides to the bean aphid from high to low was 95% Beta-cypermethrin,95% Chlorpyrifos,98% Acetamiprid,94% Abamectin,96% Imidacloprid and 74.6% Emamectin benzoate.The field experiments showed that the tested pesticides all had good control efficacy to the bean aphid with at least 99%control efficacy in 3and 7days except for Emamectin benzoate.Most of the presently used pesticides had high control efficacy to the bean aphid except for the 74.6% Emamectin benzoate.