松毛虫赤眼蜂对三种农田常用杀虫剂的敏感性

为明确常用杀虫剂对松毛虫赤眼蜂Trichogramma dendrolimi的安全性,室内评估了高效氯氰菊酯、阿维菌素和氯虫苯甲酰胺3种药剂对其成蜂的急性毒力以及田间推荐使用剂量对赤眼蜂各发育阶段的间接影响,并模拟自然情况,测定了不同残留期的3种药剂对赤眼蜂存活和寄生能力的影响.结果表明:以LC₅₀进行评估,对松毛虫赤眼蜂毒力最高的为阿维菌素,其次是高效氯氰菊酯,氯虫苯甲酰胺毒力最小;在田间推荐使用剂量下,阿维菌素、高效氯氰菊酯和氯虫苯甲酰胺的安全系数分别为0.017、0.066和69.175;在推荐使用剂量下,氯虫苯甲酰胺处理含有不同发育阶段赤眼蜂的米蛾Corcyra cephalonica卵后,平均羽化率最高为90.43%,其次是高效氯氰菊酯为56.46%,阿维菌素仅为9.84%;接触0~7 d残留期阿维菌素的玉米叶片24 h,松毛虫赤眼蜂全部死亡,无米蛾卵被寄生,但接触3~7 d残留期氯虫苯甲酰胺的玉米叶片,赤眼蜂的死亡率和寄生米蛾卵数量与清水对照无明显差异.表明在实施释放赤眼蜂的害虫综合治理方案中,应尽量避免使用阿维菌素,而氯虫苯甲酰胺对赤眼蜂风险性极低,具有很好的相容性,可以推广使用.

Susceptibility of the egg parasitoid Trichogramma dendrolimi (Hymenoptera: Trichogrammatidae) to three kinds of insecticides commonly used in fields

Trichogramma dendrolimi is one of the most important egg parasitoids used for mass production and biological control of insect pests in China. In order to evaluate the safety of commonly used insecticides to the parasitoid, the acute toxicity of beta-cypermethrin, abamectin and chlorantraniliprole to the adults was determined, and their influences on different developmental stages of T.dendrolimi in the host eggs of the rice moth Corcyra cephalonica at field-recommended concentrations were evaluated in the laboratory. Meanwhile, the effects of different residual periods of the three insecticides on their survival rate and parasitism were determined when host plant and host eggs were offered simultaneously. Among the tested insecticides, the wasps showed the highest susceptibility to abamectin, followed by beta-cypermethrin, and chlorantraniliprole exhibited the least toxicity. Under the recommended concentrations for abamectin, beta-cypermethrin and chlorantraniliprole, the safety coefficient to T.dendrolimi were 0.017, 0.066 and 69.175, respectively; the average emergence rates of T.dendrolimi were 90.43%, 56.46% and 9.84%, respectively, when different developmental stages in host eggs were treated with them. All introduced wasps died, and no host eggs were parasitized when T.dendrolimi females were exposed to the corn leaves with abamectin with a residual period of 0-7 d for 24 h. However, the mortality and number of host eggs parasitized were similar between the T.dendrolimi exposed to the corn leaves with chlorantraniliprole with a residual period of 3-7 d and the control. These results indicate that the abamectin should be avoided in the IPM programs with mass release of T.dendrolimi, while the chlorantraniliprole is recommended to be used together with the mass release of T.dendrolimi in IPM programs.