Ecotoxicological assessment of dinotefuran on plankton communities in a freshwater microcosm system

Despite being detected globally in surface waters, the ecological impacts of the third-generation neonicotinoid dinotefuran (DIN) on aquatic communities remain poorly understood. The toxic effects and ecological risks of DIN on freshwater planktonic communities were systematically evaluated using a multi-trophic indoor microcosm system (plankton-submerged macrophytes-zebrafish) based on sediment from wild freshwater ponds near a rice field in Danzhou city, Hainan province, China. Results indicated that ambient concentrations of DIN significantly altered planktonic community structure and functional attributes, suggesting impaired primary productivity and disrupted trophic transfer within the aquatic food web, as validated by both microscopic examination and environmental DNA metabarcoding. Its metabolites were detected in both sediment and zebrafish visceral organs. The community-level response threshold was below the lowest nominal test concentration (0.4 μg/L), and measured concentrations in this exposure group fell below the analytical quantification limit (0.229 μg/L) during part of the experiment. This threshold was substantially lower than the field-detected levels in Hainan Island. These findings challenge the current perception of DIN as a relatively low-risk neonicotinoid, demonstrating its potential to compromise aquatic ecosystem stability at ambient concentrations.