The Influence Of Different Pesticides On Cotton Aphids And Natural Enemies In Xingjiang

In this study,using combinative methods of laboratory toxicity and field pesticide efficacy tests,aphid control efficacy of traditional pesticide imidacloprid and new pesticide sulfoxaflor were assessed,meanwhile,the effect of different pesticides on the population dynamic of predatory enemy ladybeetle(Hippodamia variegate),the rate of predators to aphids,mummy density and parasitism rate in Xinjiang cotton were systematically evaluated.In addition,this paper also addressed field trials on the newly developed insecticides on the market in recent years 17% flupyradifurone SL,24% spirotetramat SC and their combination on the control of cotton aphid and the influence on H.variegate in cotton fields.The main results are as follows:1: The recommended dosage of 70% imidacloprid WG was 2 g/mu～3 g/mu,5 days after field application,the corrected control effect of high concentration of 32 g/mu(0.8 g/L)on cotton aphids was only 59.8%,The 16 g/mu,8 g/mu and 4 g/mu treatments were all below 50%;10 days after field application,the control effects of 4 treatments were all below 45%.2: 70% imidacloprid WG had a greater impact on the population density of mummy aphids,5 days after field application,the decrease rate of 32 g/mu treatments was 32.1%;10 days after application,The decrease rates of 4 treatments were ranged from 34% to 44%.3: The higher the concentration of 70% imidacloprid WG,the more toxic to H.variegate,After 24 h and 48 h of laboratory toxicity test,the corrected mortality rate of 0.8 g/Lwere 43.3% and 80.0%.5 days after field application,the population density of H.variegate at concentration of 32 g/mu and 16 g/mu decreased by 22.2% and 20.9%,respectively;10 days after application,both were above 26%.4: 22% sulfoxaflor SC had a better control effect on Xinjiang cotton aphids.After 24 h of laboratory toxicity,the corrected mortality rate of the highest concentration of 0.375 g/L treatment was 100%.5 days after field application,the corrected control effects of 15 ml/mu(0.375 g/L)treatment was 90.12%;10ml/mu(0.250 g/L)treatment was 87.7%.5: Compared with 70% imidacloprid WG,22% sulfoxaflor SC were safe to parasitic natural enemies,5 days after field application,the parasitism rates of 15 ml/mu and 10 ml/mu treatment plots were 11.7%and 9.7%,respectively,which were significantly higher than the 70% imidacloprid WG with 8 g/mu and the water treatments.6: Compared with 70% imidacloprid WG,22% sulfoxaflor SC were safe to predatory natural enemies,After 24 h and 48 h of laboratory toxicity test,the corrected mortality rate of the concentration of 0.375 g/L and 0.250 g/L treatments were less than 10%,which were significantly lower than 70% imidacloprid WG0.2 g/L(24 h: 25.6%;48 h: 46.7%).5 days after field application,the rate of predators to aphids of sulfoxaflor treatment was significantly higher than that of the control treatment(70% imidacloprid WG 8g/mu).7: 17% flupyradifurone SL with 30 ml/mu,40 ml/mu,24% spirotetramat SC with 30 ml/mu individually application were not high effective for aphids in cotton seedling stage,but their mixed treatment(17% flurpyrone SL with 30 ml /mu+24% spirotetramat SC with 30 ml/mu)had a better control and long lasting effect on aphids in cotton seedling stage and summer.10 days after application,the control effect of aphids in cotton seedling stage was above 80%,3 days after the treatment,the control effect of aphids in summer was 78.9%,which had no significant effect on H.variegate and higher safety.