螺虫乙酯对丽蚜小蜂寄生能力的亚致死效应

Sublethal effect of spirotetramat on parasitic ability of Encarsia formosa Gahan

为了明确螺虫乙酯大量使用后残留剂量对丽蚜小蜂寄生能力的亚致死效应,本研究在测定螺虫乙酯对丽蚜小蜂室内毒力的基础上,研究了不同浓度螺虫乙酯对丽蚜小蜂寄生功能反应的影响。结果表明LC_(10)、LC_(30)和LC_(50)的螺虫乙酯均可降低丽蚜小蜂对烟粉虱若虫的瞬时攻击率。经LC_(50)的螺虫乙酯处理后的丽蚜小蜂对烟粉虱若虫的处理时间延长,达0.13 d,寄生上限降低,寄生效能被抑制。经LC_(10)的螺虫乙酯处理后的丽蚜小蜂对烟粉虱若虫的处理时间缩短,仅0.04 d,寄生上限提高,寄生效能被促进,但其平均寿命仅13.07 d;当烟粉虱若虫密度较高时,LC_(10)的螺虫乙酯处理后的丽蚜小蜂对烟粉虱若虫的搜寻效应提高。LC_(50)的螺虫乙酯可抑制丽蚜小蜂的寄生能力,而LC_(10)的螺虫乙酯可刺激丽蚜小蜂,提升寄生效能,但缩短了成虫寿命。田间使用螺虫乙酯防治烟粉虱时,应注意其残留量对丽蚜小蜂寄生能力的亚致死效应。

In order to determine the effect of lethal concentration of spirotetramat on the parasitic ability of Encarsia formosa Gahan,we investigate the functional responses of E.formosa on Bemisia tabaci Gennadius under lethal concentration of spirotetramat based on determining the laboratory toxicity of spirotetramat on E.formosa.The results showed that instantaneous attack rates of E.formosa on B.tabaci under lethal concentration spirotetramat at LC_(10),LC_(30) and LC_(50) were reduced.The treatment time of E.formosa on B.tabaci was extended and reached to 0.13 d after exposure to spirotetramat at LC_(50),while its maximum parasitized hosts was reduced and its parasitic efficiency was inhibited.The treatment time of E.formosa on B.tabaci was shortened,only 0.04 d,and the average life of E.formosa was shortened,only 13.07 d after exposure to spirotetramat at LC_(10),while its maximum parasitized hosts was increased and its parasitic efficiency was promoted.Meanwhile,the searching efficiency of E.formosa on B.tabaci was promoted when the host density was high.These findings demonstrated that spirotetramat inhibited parasitic ability of E.formosa upon exposure to its LC_(50) concentration,and induced hormesis in E.formosa upon exposure to its LC_(10) concentration and accelerated its parasitic ability,but the average life was shortened.We should pay attention to sublethal effect of spirotetramat on parasitic ability of E.formosa when it was used for B.tabaci control in field.