关键词: 稻飞虱杀虫剂, 稻螟赤眼蜂, 螟黄赤眼蜂, 毒性, 亚致死影响

Abstract: The toxicity of four insecticides targeting rice planthoppers, which included imidacloprid, thiamethoxam, buprofezin, and nitenpyram, to the adult and pupae of Trichogramma japonicum and T. chilonis were detected. The sublethal dose effects of the insecticides on T. japonicum and T. chilonis were also evaluated over several generations under laboratory. The results showed that the four insecticides targeting rice planthoppers all had moderate toxicity to T. japonicum adults, while to T. chilonis adults, only thiamethoxam was moderate toxic but the other insecticides were safe. The four insecticides had low toxicity to the pupae of the two Trichogramma. Treatments with sublethal doses of thiamethoxam and nitenpyram stimulated the parasitic ability of the two Trichogramma, and the stimulating effect did not decrease with the increase of treatment over generations. However, imidacloprid and buprofezin significantly reduced the parasitic ability of T. chilonis. With the increase of imidacloprid treatment, the parasitic ability of T. chilonis decreased gradually. The four insecticides had no significant effect on the emergence rate of the two Trichogramma offspring or on the female ratio of T. japonicum offspring. Except for imidacloprid, the ratios of females in the offspring of T. chiloni were all slightly decreased when the wasps were treated with thiamethoxam, buprofezin and nitenpyram for multiple generations. In summary, if insecticides must be applied for controlling rice planthoppers during the periods of releasing Trichogramma, buprofezin or nitenpyram would be a good choice and should be applied 4-6 days after the release of Trichogramma.

Key words: rice planthoppers-target insecticides, Trichogramma japonicum, Trichogramma chilonis, toxicity, sublethal impact