桃蚜对吡虫啉次亚致死用量反应的时间-剂量-死亡率模拟分析

Time-concentration-mortality modeling for responses of Myzus persicae to low sublethal sprays of imidacloprid.

采用电动弥雾法测定了桃蚜对吡虫啉次亚致死浓度 (0 0 1～ 1 0 μg·ml-1)为期 1周的反应 .所获数据经时间 剂量 死亡率模拟分析 ,获得了根据不同期望杀蚜水平的致死浓度和致死时间 ,且二者互为函数关系 ,即达到同一期望杀蚜水平的时间越长 ,所需药液浓度越低 ,反之亦然 .以弥雾后第 1d和第 5d为例 ,LC50 及其 95 %置信限分别为 2 8(1 8～ 4 6 )和 0 5 (0 4～ 0 6 ) μg·ml-1,LC90 分别为 7 1(3 8～ 13 0 )和1 2 (1 0～ 1 5 ) μg·ml-1,LC99分别为 11 9(6 0～ 2 3 9)和 2 0 (1 5～ 2 8) μg·ml-1.当药液浓度为 1 0、2 0和 3 0 μg·ml-1时 ,LT50 分别为 2 9、1 4和 1 0d ,LT90 分别为 5 8、3 6和 2 4d .结果表明 ,吡虫啉的田间常规使用浓度 (～ 33μg·ml-1)是按快速击倒要求确定的 ,它比 2 4h内LC99的上限还高 ;稍放宽时间要求 。

The response of the green peach aphid,Myzus persicae,to low sublethal concentrations of imidacloprid (0.01～1.0 μg·ml -1) sprayed by an electronic sprayer was assessed at the regime of 23℃ and 12∶12(L∶D) during a 7-day period.The resultant data were fitted to time-concentration-mortality model,generating estimates of lethal concentrations (LCs) and lethal times (LTs) that depended on each other at an expected efficacy level.On days 1 and 5 after spray,for instance,the LC 50 with 95% confidential limits were estimated as 2.8(1.8～4.6) and 0.5(0.4～0.6)μg·ml -1,LC 90 7.1(3.8～13.0) and 1.2(1.0～1.5),and LC 99 11.9(6.0～23.9) and 2.0(1.5～2.8),respectively.At the concentrations of 1.0,2.0 and 3.0 μg·ml -1,the LT 50 estimates were 2.9,1.4,and 1.0 days,respectively;and LT 90 5.8,3.6,and 2.4 days.The results indicate that the fast knockdown concentration of imidacloprid commonly recommended for field spray in aphid control(～33 μg·ml -1) was even higher than the upper limit of its LC 99 within 24 h.Based on the above response of M.persicae to the low sublethal concentrations sprayed,the application rate of imidacloprid for an expected efficacy level against aphids could be greatly decreased if a longer period of action time was allowed.A discussion was given on more rational application of imidacloprid in relation to relief of aphid resistance to the chemical insecticide and its potential to stimulate fertility of spider mites.