Community responses of aquatic insects in paddy mesocosms to repeated exposures of the neonicotinoids imidacloprid and dinotefuran.

Pesticides are one of major threats to wetland environments and their communities, and thus the information about ecological impact assessment of agro-chemicals on ecosystems is essential for future effective pesticides management. Here, effects of the yearly application of two neonicotinoids, imidacloprid and dinotefuran on aquatic insect communities of experimental rice fields were assessed during two years of monitoring. Both neonicotinoid-treated fields and controls were monitored biweekly throughout the 5-month experimental period until harvest (late October) in each year.

Comparative ecotoxicity of imidacloprid and dinotefuran to aquatic insects in rice mesocosms.

There are growing concerns about the impacts of neonicotinoid insecticides on ecosystems worldwide, and yet ecotoxicity of many of these chemicals at community or ecosystem levels have not been evaluated under realistic conditions. In this study, effects of two neonicotinoid insecticides, imidacloprid and dinotefuran, on aquatic insect assemblages were evaluated in experimental rice mesocosms. During the 5-month period of the rice-growing season, residual concentrations of imidacloprid were 5-10 times higher than those of dinotefuran in both soil and water.