| Novel mixture of pesticides may result in synergistic effects and reduce the pest drug resistance. Therefore, research and development of pesticide mixture formula is of importance for slowing down the process of pest drug resistance, protecting the environment, and prolonging the useful life of pesticides.Bemisia tabaci belongs to Homoptera Aphidoidea. As it invaded in the middle and later 1990 s, this pest has caused severe financial loss in many areas and become a major agricultural pest. Furthermore, long time application of a single pesticide in an increasing quantity led to a rapid development of the pest drug resistant. Therefore, seeking a mixture formula is one of the urgent research directions to control Bemisia tabaci.This experiment used acetamiprid and matrine as pesticides to evaluate the interaction strength of synergic combination on the basis of co-toxicity coefficient and to carry out field efficacy trials with the best ratio selected. Finally, the better combination of pesticides was determined by comparing the control efficiency with Duncan’s new multiple range method. The results can be used to direct the practical pest control in the field. Conclusions are as follows:(1) The median lethal concentration(LC50) was 34.50 mg/L of acetamiprid and 15.62 mg/L of matrine, respectively. Both pesticides showed strong lethal effects on Bemisia tabaci.(2) Using Interactive mensuration to determine the lethal effects of various mixture of acetamiprid and matrine, I found the best ratio of combination was 40:60(mass ratio: 13.24:9.37). Its fatality rate reached 68.7%, and the co-toxicity factor was 37.4, showing significant synergistic effects.(3) Mixture of acetamiprid and matrine showed better performance in Bemisia tabaci control. Its fast-acting property to pest contro reached 87% for three crops tested and its effectiveness reached 82%. Using 25% buprofezin WP also resulted in better control efficiency. Thus, it is recommended to manage Bemisia tabaci in Yan’an district. |
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