Abstract: This study aims to reduce the use of chemical pesticides through establishing green control technologies for aphids. With Aphis craccivora as the target insect, the insecticidal activities of the combination of three botanical pesticides and three chemical pesticides were tested by insect-soaking method and leaf-dipping method. The optimal ratios with synergistic effects were screened out and further evaluated in field trials. The results showed that the six tested pesticides including 0.3% matrine AS all showed good toxic activities against A. craccivora. Four groups of synergistic combinations were screened out by mixing the pesticides at certain ratios of the lethal medium concentration of each, which were matrine and flonicamid mixed at 7:3, matrine and imidacloprid mixed at 6:4, matrine and acetamiprid mixed at 7:3, and toosendanin and acetamiprid mixed at 5:5. The co-toxicity coefficients (CTC) of the four combinations were 124.72, 139.84, 135.82, and 123.61, respectively. Under the optimal ratios, the control efficiency of 0.3% matrine AS (835 g/hm²) mixed with 22% sulfoxaflor SC (1.5 g/hm²), 0.3% matrine AS (590 g/hm²) mixed with 70% imidacloprid WG (10 g/hm²) and 0.3% toosendanin SL (500 g/hm²) mixed with 20% acetamiprid SP (3.6 g/hm²) against A. citricola was 87.10%, 87.07% and 88.10%, respectively, at 7 days post-treatment. Compared with the recommended doses, the doses of chemical pesticides in the combination were decreased by 98.75%, 73.33% and 97.00%, respectively, and those of the botanical pesticides were decreased by 74.95%, 82.30% and 85.00%, respectively. In conclusion, the combination of chemical and botanical pesticides has shown effective control of aphids and significantly reduced the amount of chemical pesticides used, providing important technical support for green management of aphids and potential for further extension and application.

Key words: botanical pesticides, chemical pesticides, decrement and synergism, Aphis citricola, green prevention and control