关键词: 玉米螟赤眼蜂, 杀菌剂, 杀虫剂, 死亡率, 寄生能力, 羽化率

Abstract: 【Aim】 This study aims to evaluate the safety of fungicides and insecticides commonly used in corn fields to Trichogramma ostriniae. 【Methods】 Corn leaves were applied with four fungicides (thiophanate-methyl, tebuconazole, bismerthiazol, and pyraclostrobin) and four insecticides (avermectins, chlorantraniliprole, beta-cypermethrin, and imidacloprid) at the field recommended dosages in the laboratory. At 1, 3, 5 and 7 d after pesticide application, the mortality rates, parasitic abilities (numbers of Sitotroga cerealella eggs parasitized) and offspring emergence rates of T. ostriniae adults exposed to corn leaves containing pesticide residues for 24 h were investigated. 【Results】 Different fungicides and insecticides at different time after application had significant effects on the mortality rate, parasitic ability and emergence rate of T. ostrinia adults. Among the four fungicides, the effects of bismerthiazol and pyraclostrobin on the parasitic ability of T. ostrinia lasted for a long time. After 7 d of application, the number of S. cerealella eggs parasitized by T. ostrinia adults exposed to corn leaves containing bismerthiazol and pyraclostrobin residues for 24 h were 20.25 and 20.80, respectively. Tebuconazole had the greatest effect on T. ostrinia. After T. ostrinia adults were exposed to corn leaves containing tebuconazole residue for 24 h, their emergence rate was 18.48% at 7 d after pesticide application and their mortality was 37.03% at 3 d after pesticide application. Among the four insecticides, avermectins and imidacloprid had a more long-lasting effect on the parasitic ability of T. ostrinia and showed greater toxicity. After T. ostrinia adults were exposed to corn leaves containing avermectins and imidacloprid residues for 24 h, the numbers of S. cerealella eggs parasitized were 3.43 and 9.19, respectively, at 7 d after pesticide application, and their mortality rates were 96.21% and 74.00%, respectively, at 1-3 d after pesticide application. The emergence of T. ostrinia offspring was damaged for a longer time after application of beta-cypermethrin, and the offspring emergence rate was 27.92% at 7 d after application. In general, the four insecticides had a greater impact on T. ostriniae than the four fungicides. 【Conclusion】 It is not recommended to use the three fungicides, tebuconazole, bismerthiazol and pyraclostrobin, and the two insecticides, avermectins and imidacloprid, in the field in 7 d before T. ostriniae are released to control Ostrinia nubilalis, and to use thiophanate-methyl and beta-cypermethrin in 5 d before T. ostriniae release. Chlorantraniliprole should be reasonably used depending on the recommended field dosages.

Key words: Trichogramma ostriniae, fungicides, insecticides, mortality rate, parasitic ability, emergence rate