阿维菌素与多杀霉素混配对小菜蛾的增效作用及田间防效

摘要

The indoor leaf-dipping bioassay and field plot tests were conducted respectively to research the synergism and field control effects of mixtures of avermectin and spinosad against diamondback moth ( DBM) , Plutella xylostella.The best syner-gistic effect was discovered in the mass ratio of 3.0∶2.0 ( avermectin∶spinosad) , and the co-toxicity coefficient of this mixture a-gainst DBM was 161.9.On the 10th day after spraying 18.75 g/hm2 or 22.50 g/hm2 5%avermectin・ spinosad (3.0∶2.0) EW in field, its control effect against DBM populations in 3 different districts was 86.66%~93.64%, and that against 2 avermectin-highly-resistant DBM populations with the resistant ratio of 158.88 or 95.03 was over 83.21%.It was suggested that 5%avermec-tin・ spinosad EW should be sprayed at the dosage of 18.75~22.50 g/hm2 at the low-instar larva peak stage of DBM in vegetable production.%采用浸叶法和田间小区试验分别测定了阿维菌素与多杀霉素的混配剂对小菜蛾的增效作用和田间防治效果。试验结果显示：阿维菌素与多杀霉素混配对小菜蛾具有最大增效作用的质量比为3．0∶2．0，其共毒系数为161．9；在药后10 d，按上述比例配制成的5％阿维菌素・多杀霉素水乳剂18．75 g／hm2和22．50 g／hm2处理对3个不同地区小菜蛾种群的防治效果达86．66％～93．64％，对2个阿维菌素高抗小菜蛾种群（抗性倍数分别为158．88和95．03）的防效在83．21％以上。建议5％阿维菌素・多杀霉素水乳剂的施用量为18．75～22．50 g／hm2，在小菜蛾低龄幼虫高峰期施用。