螺虫乙酯对桃蚜的毒力及持效期

目的]明确新型内吸型杀虫剂螺虫乙酯对桃蚜(Myzus persicae)的毒力及持效期.方法]利用3种生物测定方法开展螺虫乙酯对桃蚜的室内生物测定,用定量数据概率和时间剂量死亡率模型分析螺虫乙酯对桃蚜的毒力,并利用微虫笼法对螺虫乙酯的持效期进行研究.结果]玻璃板法、微虫笼法和圆片法的测定结果存在差异,微虫笼法进行生物测定时植物叶片的保持时间较长,测定结果更加可靠.3种生物测定方法测得的桃蚜若蚜死亡率随着时间的延长呈上升趋势,到120 h达稳定.利用定量数据概率的方法分析表明,玻璃板法、微虫笼法和圆片法测定的螺虫乙酯对桃蚜若蚜的LC50分别为0.0886、0.1258和0.8459 mg·kg-1,利用时间剂量死亡率模型分析表明,在1.5625 mg·kg-1下的LT50分别为2.5、2.9和3.5d,LT50随着药剂浓度的增大而递减.螺虫乙酯具有较长的持效期,防治效果在施药7d后开始下降,死亡率由100％降低至20％以下.结论]本研究提出的用微虫笼进行螺虫乙酯生物测定的方法,可为长持效期药剂的生物测定提供参考；目前田间桃蚜种群对螺虫乙酯仍处于非常敏感的状态.

Toxicity and Persistence of the Insecticide Spirotetramat on the Peach Aphid (Myzus persicae)

【Objective】The objective of this study is to evaluate the toxicity and persistence of the spirotetramat, a new two-way systemic insecticide, to the peach aphid (Myzus persicae).【Method】Three bioassay methods were tested in the laboratory. The toxicity was analyzed using probit analysis and time-dose-mortality. Additionally, the persistence of this pesticide was studied using clip-cage method.【Result】The bioassay results differed among the three bioassay methods, i.e. clip-cage, triplex-glass and round-leaf methods. The clip-cage method kept the leaf the longest time and generated more reliable result. The mortality of the aphid nymph increased with the increasing of detecting time, reached the highest value at 120 h after spray. The probit analysis showed that the LC50 of triplex-glass, clip-cage and round-leaf method was 0.0886, 0.1258 and 0.8459 mg•kg-1, respectively. The time-dose-mortality analysis showed that, at 1.5625 mg•kg-1, LT50 of triplex-glass, clip-cage and round-leaf method was 2.5, 2.9 and 3.5 d, respectively. The LT50 decreased with the increasing of the concentration of the spirotetramat. The spirtetramat had a long time of persistence. The mortality of the aphid nymph decreased from 100% to less than 20% after spray for seven days.【Conclusion】The study suggests that the clip-cage for the bioassay of the spirotetramat will contribute to the bioassay method of those pesticides with long time of persistence. The peach aphids collected from the field of Beijing area of China are sensitive to the spirotetramat.