The indoor toxicity test results showed that:the mixture of Ethofenprox and Pymetrozine (1∶2, mass ratio) had LC50 value 2.89 mg/L to the third instar nymphs of brown planthopper (Nilaparvata lugens), and their co-toxicity coefficient was 146. 84, with obvious synergism .Field test results showed that applying 21%Ethofenprox · Pymetrozine SC 375, 525 mL/hm2 had the control effects of 84.19%and 90.37%respectively against the nymphs of brown planthopper on the 3rd day after spraying , which were better than that of Ethofenprox and Pymetrozine; applying 21% Ethofenprox · Pymetrozine SC 375 ~525 mL/hm2 had the control effect of over 87.00%against brown planthopper from the 7th to 14th day after spraying, it was very significantly better than that of Ethofenprox and Pymetrozine , and this mixture had no adverse effects on rice growth .Therefore, the recommended dosage of 21%Ethofenprox · Pymetrozine SC should be 375 mL/hm2 , but it could be increased to 525 mL/hm2 in outbreak year .%室内毒力测定结果表明，以醚菊酯与吡蚜酮质量比为1∶2对褐飞虱3龄若虫生物活性LC50值为2．89 mg/L，共毒系数为146．84，具有明显的增效作用。田间试验结果表明，21％醚菊·吡蚜酮SC 375、525 mL/hm2在药后3 d对褐飞虱若虫的防治效果分别为84．19％、90．37％，速效性好，好于吡蚜酮、醚菊酯药剂；其在药后7～14 d对褐飞虱的防治效果均在87％以上，极显著优于对照药剂吡蚜酮、醚菊酯处理，且对水稻生长无不良影响。由此可知，21％醚菊·吡蚜酮SC 推荐用量为375 mL/hm2，大发生年份用量可以增加到525 mL/hm2，对水50 kg均匀喷雾。
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