3种生物源杀虫剂对杜仲梦尼夜蛾的毒力及防效

针对专性为害杜仲的食叶害虫杜仲梦尼夜蛾(Orthosia songi Chen et Zhang)幼虫进行室内毒力测定,比较了3种生物源杀虫剂对其3龄和5龄幼虫的杀虫活性,并进行了林间药效测定和防治示范试验。结果显示:甲氨基阿维菌素苯甲酸盐(甲维盐)对3龄和5龄幼虫的LC50值分别为0.152 5和0.204 7μg/L,苦参碱的LC50值分别为65.306 0和124.735 8μg/L,印楝素的LC50值分别为165.871 7和257.749 0μg/L。林间药效测定结果显示5.7%甲维盐微乳剂300万倍液防治效果最好,7d后校正死亡率达91.34%。防治示范试验表明,5.7%甲维盐微乳剂75 000倍液防治效果达95.69%,显著高于0.3%苦参碱水剂750倍液的防治效果(80.28%),且药剂成本7.5元/hm2,仅为后者的1.9%。

Toxicity and field efficacy of three biopesticides to Orthosia songi

To understand the current status of insecticide resistance in diamondback moth (DBM), Plutella xylostella (L.) and the control efficacy of some common insecticides to DBM in Tonghai County, Yunnan Province, the indoor leaf-dipping bioassay and field trial were conducted, respectively. The results showed that the susceptibility of the Tonghai DBM to diafenthiuron and Bt were the highest, and exhibited sensitive levels. The resistance level was low to indoxacarb. The resistance ratios to chlorfenapyr and spinosad were 24.28 and 31.68 fold, respectively, which showed a middle resistance level. As to chlorantraniliprole, the resistance ratio was 44.62 fold with a high resistance level. The susceptibility to abamectin was the lowest and the resistance ratio was high to 829.90-fold. There was some correlation between the resistance ratio and the field control efficacy. The control efficacy of chlorantraniliprole and abamectin to the DBM was below 50% seven days after treatment. Indoxacarb, spinosad and diafenthiuron provided good control efficacy to the DBM, which can be selected for the DBM control in Tonghai with rational rotation and alternative using strategy.