Enantiomer-Specific Study of Fenpropathrin in Soil-Earthworm Microcosms: Enantioselective Bioactivity, Bioaccumulation, and Toxicity

Abstract

In this study, the enantiomer-specific bioactivity, bioaccumulation, and toxicity of fenpropathrin (FEN) enantiomers were investigated in soil-earthworm microcosms. The bioactivity order was S-FEN > rac-FEN > R-FEN for Spodoptera litura and Conogethes punctiferalis. Moreover, S-FEN was 12.0 and 32.2 times more toxic than rac-FEN and R-FEN to earthworms, respectively. S-FEN degraded faster than R-FEN with the enrichment of R-FEN in the soil environment. Furthermore, the peak-shaped accumulation curves for FEN enantiomers were observed, and R-FEN was preferentially bioaccumulated by earthworms. As compared to R-FEN, S-FEN induced greater changes in the activities of detoxification enzymes, antioxidant enzymes, and malondialdehyde content, which suggested that earthworms exhibited enantioselective defense responses to S-FEN and R-FEN. Integrated biomarker response results indicated that S-FEN exhibited higher toxic effects on earthworms than R-FEN. Finally, molecular simulation revealed that the greater interaction forces between S-FEN and sodium channel protein could be the primary reason for the enantioselective bioactivity and toxicity of FEN enantiomers. This study comprehensively highlights the enantiomer-specific bioactivity, bioaccumulation, toxicity, and mechanism of FEN in soil-earthworm microcosms at the enantiomer level. Our findings will contribute to a better risk assessment of FEN in the soil ecosystem.

Enantioselective metabolism of fenpropathrin enantiomers by carboxyl/choline esterase 6 in Tetranychus cinnabarinus

“…9 As for FEN, a previous study has revealed that the bioactivity of S-FEN is 7.9 and 18.3 times higher than that of R-FEN against Spodoptera litura and Conogethes punctiferalis, respectively. 10 However, few studies have yet been conducted to investigate the different bioactivity of FEN enantiomers against T. cinnabarinus as well as the mechanism underlying enantiomer-specific toxicity in T. cinnabarinus at the enantiomer metabolism level, therefore studying the bioactivity and metabolic differences of FEN enantiomers in T. cinnabarinus will help us understand the enantiomer-specific toxicity mechanism of chiral acaricides in leaf mites.…”