几种农药对美国白蛾幼虫活性比较及生物学效应

The Lethality and Effect to Growth of Some Pestcides a gainst Hyphantria cunea

[目的]筛选出对美国白蛾高效低毒药剂,明确其致死、亚致死效应;延缓害虫抗性进程。[方法]室内采用饲毒法进行生物测定,统计农药的致死和亚致死效应。[结果]25%吡虫啉粉剂和4.5%高效氯氰菊酯乳油对美国白蛾2龄幼虫48 h LC50值分别为10.93、6.02 mg/L;当20%灭幼脲III乳油、1.8%阿维菌素乳油、3%高渗苯氧威乳油有效含量分别为400、3.6、4 mg/L时,96 h对3龄美国白蛾校正死亡率分别达到20.0%、30.0%和10.0%;化蛹率分别降低43.0%、57.0%、50.5%;幼虫期较对照分别延长4、5、4 d。[结论]美国白蛾密度高时,可以采用高效氯氰菊酯乳油和吡虫啉交替用药,密度低时,建议用另外3种药剂。

[Aims] The fall webworm, Hyphantria cunea Drury （Lepidoptera： Arctiidae） is a pest case rampantly damage in forestry in recent years. To determine the lethal and sub-lethal effect of pesticides and to delay the process of resistance to webworm, the research was conducted in the lab. [Methods] The lethality of five kinds of pesticides, which are used to prevent the larvae ofH. cunea in practice, was tested and compared respectively by Feeding method in this experiment. And the lethal and sub-lethal effect of the pesticides to the growth was analyzed by reared in the lab. [Results] The results showed that the LCs0 of imidacloprid 25% DP and/3-cypermethrin 4.5% EC to the 2nd instar larvae of web worm was 10.93 and 6.02 mg/L respectively. While the corrected mortality to the 3rd instar larvae of fall webworm＇s achieved to 20, 30 and 10% treated by diflubenzuron III 20% EC, abamectin 1.8%and high penetrable fenoxycarb 3% EC at the effective concentration 400, 4, 3.6 mg/L in the field, respectively. Moreover, the pupation rate decreased by 43.0, 57.0 and 50.5%, respectively, and 4, 5, 4 d of the larvae stage longer than CK group. [Conclusions] The fl-cypermethrin 4.5% EC and imidacloprid 25% DP was chosen when the pests population is large enough, while the others were recommended to prevent the pests when they are in small quantities. The alternate of pesticides maybe slow down the resistance speed of the web worms in the practice.