Effects of fenpropathrin on adult zebrafish reproduction and offspring development

Fenpropathrin (FEN), a widely used insecticide, is frequently detected in aquatic environments, raising significant concerns about its ecological risks. In this study, a subacute exposure experiment was conducted on adult zebrafish exposed to FEN for 28 d to evaluate reproductive toxicity and developmental effects on the F1 and F2 generations, as well as underlying mechanisms. FEN exposure significantly increased the proportion of immature oocytes in females and decreased the percentages of spermatids and spermatozoa in males. These gonadal alterations were accompanied by dysregulation of gametogenesis-related genes, elevated gonadal apoptosis, and sex-dependent disruptions in hypothalamic-pituitary-gonadal (HPG) axis gene expression and hormonal imbalances, collectively indicating that FEN poses a potential threat to gonadal development and reproductive health in zebrafish. Molecular docking analysis predicts FEN exerts its biological effects through complex mechanisms involving hormone receptor-dependent pathways. Further studies revealed that paternal and maternal exposure to FEN impairs growth, development, and behavior in F1 larvae and induces widespread transcriptomic alterations. In contrast, the F2 generation showed no statistically significant differences in morphology, physiology, or behavior compared with unexposed controls. These findings indicate that, under the tested subacute exposure conditions and at the experimental concentration, FEN induced intergenerational effects in the F1 offspring but no transgenerational effects in the F2 generation. Nevertheless, these findings provide robust evidence that FEN exerts direct reproductive toxicity and adversely affects the F1 generation, thereby enhancing our understanding of its non-target reproductive toxicity and clarifying its potential ecological risks.