Chiral pesticides enantiomers usually interact with biological systems selectively and may result in enantioselective toxicity, environmental fate, and different effects on nontarget organisms. However, these properties are usually ignored when evaluation the environmental risk and public health. Indoxacarb, which belongs to the oxadiazine compounds, is a chiral insecticide with activities against a wide range of pests in crops. However, the enantioselective toxicity and bioaccumulation of indoxacarb is almost unknown. In this study, the enantioselective bioaccumulation of indoxacarb enantiomers in adult zebrafish and its enantiomer-specific toxicity to embryos-larvae of zebrafish were investigated. The results demonstrated a clear enantioselectivity of indoxacarb in bioaccumulation. The concentrations of (-)-R-indoxacarb were both approximately 13-fold more than that of (+)-S-indoxacarb in adult zebrafish after exposure to 0.025 and 0.1 mg/L indoxacarb, respectively, suggesting zebrafish enantioselectively uptake the (-)-R-enantiomer of indoxacarb. During the elimination experiment, the degradation of the two enantiomers in zebrafish followed first-order kinetics after the exposure medium was replaced by a non-contaminated water, and the average half-lives of (-)-R-indoxacarb and (+)-S-indoxacarb were 4.2 and 2.4 d, respectively. Significant difference in toxicity to embryos and larvae of zebrafish between the two enantiomers was observed. The (-)-R-indoxacarb showed significantly higher toxicity to embryo-larval zebrafish than (+)-S-indoxacarb in the mortality, inhibition of hatching, and heart beats, as well as causing yolk sac edema and pericardial edema. The rac-indoxacarb had the lowest toxicity to zebrafish as compared to its two enantiomers.Acknowledgments:  This study was financially supported by National Twelfth Five-Year Plan for Science & Technology (2011BAE06B09)of China.

Enantioselectivity bioaccumulation and toxic effects of indoxacarb in zebrafish (<i>Danio rerio</i>)

248th National Meeting (2014)

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Enantioselectivity bioaccumulation and toxic effects of indoxacarb in zebrafish (Danio rerio)