Study on Joint Effect of Neonicotinoid and Pyrethroid Insecticides Against Bean Aphid

In order to provide reference for development of insecticides, the joint effects of four neonicotinoid insecticides and two pyrethroid insecticides were tested against bean aphid, the four neonicotinoid insecticides were thiamethoxam, thiacloprid, nitenpyram, imidaclothiz and the two pyrethroid insecticides were lambda-cyhalothrin, bifenthrin. The bioassays were carried out by dipping method for bean aphid and the type of joint action was evaluated by equivalent linear method and the co-toxicity coefficient method. Contact activities of eight neonicotinoid insecticides against aphid from high to low were thiamethoxam, imidacloprid, thiacloprid, nitenpyram, acetamiprid, clothianidin, imidaclothiz and dinotefuran. Contact activities of four pyrethroid insecticides against aphid were lambda-cyhalothrin, deltamethrin, beta-cypermethrin and bifenthrin. The joint effects of the eighteen mixtures showed synergistic, additive or antagonistic. Two mixtures of nitenpyram + lambda-cyhalothrin(5∶1) and thiamethoxam + bifenthrin(5∶1) were recommended among the eighteen mixtures. In the research and development of insecticide mixtures, blind imitation was harmful and actual screening results were necessary. Also, the insecticides mixtures should be scientific and practical, and could play a role in resistance management and reduction use.