The acute toxicity, mechanism, bioconcentration and elimination of fluxametamide on zebrafish (Danio rerio)

Fluxametamide is a completely novel and the first isoxazoline insecticide used to control agricultural pests and has high insecticidal properties. To expand its usage in the paddy field, its potential toxicological effects on fish are necessary to make clear. In this study, the acute toxicity, bioconcentration and elimination of fluxametamide to zebrafish Danio rerio, and the action mode of it on the heteromeric Dra1 ss 2S.2 and Dra1 ss 2S GABA receptor was respectively determined by HPLC and two-electrode voltage clamp technique. Fluxametamide exhibited high toxicity to D. rerio, whereas slightly inhibited the GABA-stimulated current of Dra1 ss 2S.2 or Dra1 ss 2S. It showed high bioconcentration level in D. rerio at 0.0314 mg L 1 and 0.157 mg L 1, with bioconcentration factors at steady state of 1491.55 and 2875.28, respectively. The concentration of fluxametamide in D. rerio rapidly decreased from 47.84 +/- 0.12 to 9.77 +/- 1.13 mg kg 1 in 0.0314 mg L 1 or from 393.19 +/- 0.46 to 46.93 +/- 2.88 mg kg 1 in 0.157 mg L 1 within 10 days, and steadily kept at a low level after 18 days. In conclusion, fluxametamide has highly acute toxicity to D. rerio, and might induce high bioconcentration in a short time. As we know, this is the first report to provide a theoretical basis for evaluating the potential risk of fluxametamide on fish, and guidance for the application of fluxametamide.