Toxic Effects of Indoxacarb Enantiomers on the Embryonic Development and Induction of Apoptosis in Zebrafish Larvae (Danio rerio)

Indoxacarb is a highly potent insecticide widely used to control Lepidoptera insects in vegetable, tea, cotton, and rice fields. It can run off into aquatic environments. It is consisted of two enantiomers. Environmental risks and aquatic toxicity of indoxacarb enantiomers have not been fully investigated. In this study, zebrafish (Danio rerio) embryos were exposed to varying concentrations of (2)-R-indoxacarb and (1)-S-indoxacarb until 96-h post-fertilization (hpf) to assess the embryonic toxicity. (2)-R-indoxacarb was 1.3-fold more toxic than (1)-S-isomer to zebrafish embryos at 96 hpf. (2)-R-indoxacarb exhibited reduction in body length and pericardial edema compared with (1)-S-indoxacarb. (2)-R-indoxacarb decreased the hatching rate sixfold greater than (1)-S-indoxacarb. The rate of pericardial edema induced by (2)-R-indoxacarb was 2.5 times greater than that by (1)-S-indoxacarb. The heart rate of the larvae exposed to (2)-R-indoxacarb was 30% lower than that to (1)-S-indoxacarb. In addition, exposure to the chiral isomers resulted in significant increases in apoptosis; interestingly (2)-R-indoxacarb induced apoptosis in the heart area, whereas (1)-S-indoxacarb induced apoptosis in the head area. (C) 2015 Wiley Periodicals, Inc.