Abamectin at environmentally relevant concentrations impairs bone development in zebrafish larvae

Abamectin (ABM) is a widely used pesticide in agriculture and veterinary medicine, which primarily acts by disrupting the neurological physiology of pests, leading to their paralysis and death. Its extensive application has resulted in contamination of many natural water bodies. While the adverse effects of ABM on the growth and development of non-target organisms are well documented, its impact on bone development remains inadequately studied. The present study aimed to investigate the effects of environmentally relevant concentrations of ABM (1, 5, 25 μg/L) on early bone development in zebrafish. Our results indicated that ABM significantly affected both cartilage and bone development of zebrafish larvae, accompanied by dose-dependent increase in deformity and mortality rates, as well as exacerbated apoptosis. ABM exposure led to deformities in the ceratobranchial (cb) and hyosymplectic (hs), accompanied by significant increases in the length of the palatoquadrate (pq). Furthermore, significant decreases in the CH-CH angle, Meckel's-Meckel's angle, and Meckel's-PQ angle were noted. Even at the safe concentration of 5 μg/L (1/10 of the 96 h LC