吡虫啉对稻虱缨小蜂的致死和亚致死效应研究

设定2种吡虫啉浓度(有效浓度分别为37.5、15.0 g·hm~(-2)),探讨其对褐飞虱的卵寄生蜂稻虱缨小蜂的毒性.剂的对照死亡率为(1.67±1.67)%].携带稻虱缨小蜂幼体的稻苗经高浓度吡虫啉处理后,稻虱缨小蜂的羽化率为(83.53±1.81)%,显著地低于未经药剂处理的对照(92.09±0.75)%.吡虫啉对稻虱缨小蜂的致死中浓度(LC_(50))为790.89 μg·kg~(-1).稻虱缨小蜂接触250、500μg·kg~(-1) 2种亚致死浓度吡虫啉后,分别有40%和65%残存个体未能对褐飞虱为害稻株挥发物作出反应;而作出反应的个体亦不能区分虫害稻株与健康稻株的气味.然而,接触2种亚致死浓度吡虫啉后,存活的稻虱缨小蜂对褐飞虱利它素的行为反应及对褐飞虱卵的寄生率无明显改变.

Lethal and sublethal effects of imidacloprid on Anagrus nilaparvatae(Hymenoptera: Mymanidae), an egg parasitoid of the rice planthopper,Nilaparvata lugens (Homoptera: Delphacidae)

Lethal toxicity of two concentrations of imidacloprid (37. 5, 15.0 g · hm~(-2)) against Anagrus nilaparvatae, an egg parasitoid of the rice planthopper, Nilaparvata lugens were assessed in this study. Mortalities of adult wasp expo-sure to high concentration of imidacloprid reached 100% at 1.5 h exposure-period, and mortalities of adult wasp exposure to low concentration of imidacloprid reached 100% at 2.0 h exposure-period. They were both significantly higher than that of the control (1.67±1.67)% mortality]. The emergence rate of A. nilaparvatae in rice plants treated with high concen-tration of imidacloprid was (83.53±1.81)%, which was significantly lower than that of the control (92.09±0.75)%]. Imid-acloprid was toxic to adult parasitoid with a LC_(50) value of 790.89μg·kg~(-1). Then, two sublethal concentrations (250, 500 μg·kg~(-1)) were selected to evaluate the sublethal effect of imidacloprid on A. nilaparvatae. After exposure to two sublethal concentrations of imidacloprid, 40% or 65 % survived individuals had no response to volatiles from rice plants infested by N. lugens. The survived individuals who had response can not distinguish volatiles from N. lugens damaged plants or healthy plants. However, compared to the untreated control, the surviving A. nilaparvatae treated with imidacloprid had same response to kairomone of N. lugens and exhibited same parasitizing capacity.