| Cotton spider mite is commonly known as starscream and dragon. It belongs to the Arachnida, Acarina, Tetranychidae. During the whole growth period of cotton, it can be harmful, mainly through sucking juice of cotton leaf. Cotton spider mite is recorded as one of the major insect pests of cotton in China. In this paper, a kit for rapid detection of acaricide sensitivity in contton spide mite was designed. Acaricide mixtures with synergistic effect on cotton spider mite were screened and processed into EC formulations, and field control efficacies were assessed. These studies will provide theoretical basis for rapid dectection of acricide resistance and efficient control of cotton spider mite. The main results are as follows:Through the comprehensive evalutaions on the ease of operation, accuracy of the results and structure advantages of flat-membrane method and ampere bottle-membrane method, it could be found that the ampere bottle-membrane method is the best method for the kit of rapid dectection of acaricides sensitivity, the LC99 value for the diagnosis dose of this acricide is 0.2 mL, and the measuring time is 4h. The diagnosis doses for abamectin, propargite, azocyclotin and pyridaben are 14 mg/L, 1667 mg/L,233 mg/Land 4447 mg/L, respectively. The best way to store abamectin kit is in the dark under the condition of low temperature (5℃), and the longest shelf life is up to 90d. The best preservation conditions for propargite kit is at room temperature or low temperature (5℃) and avoid light, and the longest shelf life is up to 60d. The best preservation conditions for azocyclotin kit is in the dark and at low temperature (5℃), and the longest shelf life is up to 90d. The best preservation conditions for pyridaben kit is in the dark and at low temperature (5℃), and the longest shelf life is up to 45 d. For testing acricide sensitivity in the cotton spider mite in jingzhou area with abamectin, propargite, azocyclotin and pyridaben kits, the 4h correction mortality rates were 98.75%,92.00%,95.14% and 98.75%, respectively. For testing the cotton spider mite in Anhui province with abamectin and propargite kits, the 4h correction mortality rates were 90.67% and 95.00%, respectively.The toxicities of commonly used acaricides to cotton spide mite were bioassayed by agar leaf dipping method. The LC50 values for abamectin, diafenthiuron, pyridaben and propargite were 0.0350,10.79,414.45 and 44.11 mg/L, respectively. Using Co-toxicity factor to screen the optimum mixture proportion for synergism. The co-toxicity factors for mixture of abamectin and diafenthiuron at the ratio of 1:1 and 1:49 were 89.9,107.0. respectively. The co-toxicity factors for mixture of abamectin and pyridaben at the ratio of 1:19 and 1:29 were 80.0 and 88.0, respectively. The co-toxicity factors for mixture of abamectin and propargite at the ratio of 1:1,1:3,1:3, 1:4,1:9,1:19 and 1:39 were 86.0,104.2,32.0,100.0,26.0,88.0 and 83.7, respectively. The co-toxicity coefficient (CTC) values for abamectin and diafenthiuron at the ratio of 1:1 and 1:49 were 465.9 and 582.5, respectively. The CTC values for abamectin and pyridaben at the ratio of 1:19 and 1:29 were 350.9 and 488.4, respectively. The CTC values for abamectin and propargite at the ratio of 1:1,1:2,1:4 and 1:39 were 349.7, 350.5,436.1 and 452.5, respectively.According to GB1603-79 (88), the following formulated acricide mixtures were processed:1.2% abamectin (0.6%)-diafenthiuron (0.6%) EC,30% abamectin (0.6%)-diafenthiuron (29.4%) EC,4% abamectin (0.2%)-pyridaben (3.8%) EC,6% abamectin (0.2%)-pyridaben (5.8%) EC,0.6% abamectin (0.3%)-propargite (0.3%) EC, 0.9% abamectin (0.3%)-propargite (0.6%) EC,1.5% abamectin (0.3%)-propargite (1.2%) EC, and 12% abamectin (0.3%)-propargite (11.7%) EC. The emulsifiers for 1.2% abamectin-diafenthiuron EC and 30% abamectin-diafenthiuron EC all were 50# 2.2%+601# 2.8%+602# 1.0%. The emulsifiers for 4% abamectin-pyridaben EC and 6% abamectin-pyridaben EC were 500# 2.9%+1601$ 1.4%+1606# 1.35%. The emulsifiers for 0.6% abamectin-propargite EC,0.9% abamectin-propargite EC,1.5% abamectin-propargite EC and 12% abamectin-propargite EC were 500$ 2.0%+601$ 2.8%+602# 1.2%. Studies on the quality of the processed EC indicated they all reached the national standard for the EC formulation.Field efficacies were assayed for the screened and processed acricide mixtures with synergism. Plot area is 20 m2, with four replicates and the experiments were random block arranged. Conrol efficacy was meaused 1 d,3 d,7 d and 14 d after acricide appliations. The results showed that the most effetive was for 12% abamectin propargite EC, with the control efficacies of 96.86%,99.01% and 99.58% for 1 d,3 d,7 d and 14 d after acricide appliations, respectively. The recommended application rate was 120-180 g/hm2. Other mixtures also had control efficacy of more than 95%. |
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