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.