S -Dinotefuran Exhibits Higher Toxicity in an Earthworm–Soil System via Enantioselective Persistence, Bioaccumulation, and Metabolic Stress

Dinotefuran, a widely used chiral neonicotinoid, persists in soil and may threaten non-target soil fauna. However, its enantioselective behavior and ecological effects in the earthworm–soil system remain unclear. Herein, we comprehensively investigated the degradation, bioaccumulation, toxicity, and underlying mechanisms of chiral dinotefuran at an environmentally relevant concentration (0.5 mg/kg) in Eisenia fetida . Compared with R -dinotefuran, S -dinotefuran persisted 1.5-fold longer in soil and accumulated up to 6.0-fold more in earthworms. It also exhibited markedly higher toxicity, increasing lethality by 9.9-fold in 48 h filter paper assays and 13.3-fold in 14 day soil exposure tests, coupled with 18.0-fold higher avoidance behavior. Additionally, sub-chronic 28 day exposure caused significant weight loss, reduced survival, and pronounced disturbances in CYP450, GST, and CarE activities. Transcriptomic profiling showed that S -dinotefuran induced stronger metabolic stress by activating cytochrome P450-mediated and glutathione pathways while suppressing cellular homeostasis and immune defense pathways, with qRT-PCR confirming upregulation of CYP3A4, CYP2, and GPx . Notably, earthworm activity reshaped soil microbial communities and partially buffered chiral dinotefuran-induced disturbances at the community level. These findings support enantiomer-specific regulation and suggest that chirally resolved formulations may help safeguard soil ecosystem function.