不同杀虫剂对烟粉虱两种优势寄生蜂的毒性及风险评估

采用指形管药膜法分别测定了5种田间常用于防治烟粉虱的杀虫剂对烟粉虱两种优势寄生蜂—丽蚜小蜂和浅黄恩蚜小蜂的毒性，明确不同杀虫剂对丽蚜小蜂和浅黄恩蚜小蜂的安全性，为烟粉虱的综合防治和农药的合理施用提供科学依据。结果显示，22.4%螺虫乙酯对丽蚜小蜂和浅黄恩蚜小蜂的LC₅₀最高，分别为136.465和119.408 mg/L；20%呋虫胺对丽蚜小蜂和浅黄恩蚜小蜂的LC₅₀最低，分别为14.496和9.259 mg/L；相较于浅黄恩蚜小蜂，不同杀虫剂对丽蚜小蜂的LC₅₀相对较高。供试杀虫剂中，22.4%螺虫乙酯和50%氟啶虫胺腈对两种优势寄生蜂的安全系数较高，均为中等风险；10%烯啶虫胺、10%溴氰虫酰胺和20%呋虫胺对两种优势寄生蜂的安全系数较低，均为高风险。22.4%螺虫乙酯、50%氟啶虫胺腈对丽蚜小蜂和浅黄恩蚜小蜂的毒性中等，田间用于防治烟粉虱时，应在保证防治效果的前提下适当降低杀虫剂浓度，减少施药次数，避开在寄生蜂成虫羽化高峰期施药；10%烯啶虫胺、10%溴氰虫酰胺和20%呋虫胺对丽蚜小蜂和浅黄恩蚜小蜂的毒性较高，不应在丽蚜小蜂和浅黄恩蚜小蜂发生期施药。

Toxicity and Risk Evaluation of Different Insecticides on Two Dominant Parasitoids of Bemisia tabaci

To evaluate the safety of different insecticides to two parasitoids Encarsia formosa and Encarsia sophia of Bemisia tabaci, and to provide scientific basis for integrated pest management and rational application of insecticides in B. tabaci control, laboratory toxicity of different insecticides on E. formosa and E. sophia was determined by residual film in glass tube method. Meanwhile, the risk of E. formosa and E. sophia was evaluated in laboratory conditions. The results showed that 22.4% spirotetramat showed the lowest laboratory toxicities on E. formosa and E. sophia during in all of the tested insecticides, with the LC₅₀ being 136.465 mg/L and 119.408 mg/L, respectively. The highest laboratory toxicities to both of this two parasitoids were from 20% dinotefuran among in all of the tested insecticides, with the LC₅₀ being 14.496 mg/L against E. formosa and 9.259 mg/L against E. sophia, respectively. The LC₅₀ of different kinds of tested insecticides against E. formosa were higher than that against E. sophia. Among which, 22.4% spirotetramat and 50% sulfoxaflor showed medium risk against both E. formosa and E. sophia, 10% nitenpyram, 10% cyantraniliprole and 20% dinotefuran showed high risk to the two parasitoids. 22.4% spirotetramat and 50% sulfoxaflor showed medium risk on E. formosa and E. sophia. The concentration of insecticides and the times of application should be properly reduced on the premise of ensuring the control effect when it was used to control B. tabaci in the field. Meanwhile, the application of these insecticides should be avoided to use during the peak period of adult parasitoid emergence. 10% nitenpyram, 10% cyantraniliprole and 20% dinotefuran had higher risk than the other two insecticides on E. formosa and E. sophia, which should be avoided to use during the active period of E. formosa and E. sophia in B. tabaci control.