Abstract：
Ivermectin (IVM) is a broad-spectrum veterinary antiparasitic used worldwide in cattle breeding. The aim of this study was to evaluate the lethal effects of the active ingredient and a commercial formulation of IVM (1 % active ingredient) in the embryonic stage (S. 4-6) and larval stage (S. 25) of the South American amphibian Rhinella arenarum through chronic standardized bioassays. Also, behavior analysis and oxidative stress and cholinergic effects biomarkers were analyzed at 1, 10 and 100 μg IVM/L concentrations. For the embryonic stage, the active ingredient (96 h- LC50: 15900 μg/L) was more toxic than the commercial formulation (96 h-LC50: 51230 μg/L) during the acute period, while at chronic exposure the commercial formulation was more toxic (504 h-LC50: 10.25 μg/L), compared to the active ingredient (504 h-LC50: 312.80 μg/L). For the larval stage, in acute exposure, the active ingredient (96 h-LC50: 800 μg/L) was more toxic than the commercial formulation (96 h-LC50: 1550 μg/L). In the chronic exposure, the commercial formulation (504 h-LC50: 77.33 μg/L) was more toxic than the active ingredient (504 h-LC50: 195.25 μg/L). Overall, larvae exhibited greater sensitivity to both the active ingredient and the commercial formulation. However, during chronic exposure, embryos were more sensitive to the commercial formulation than larvae. The commercial formulation primarily induced oxidative stress, and both forms of the compound affected behavior and cholinergic effect biomarkers, even at low environmentally relevant concentrations (1 μg/L). These results highlight the potential impact of IVM on aquatic ecosystems.
摘要：
伊维菌素（IVM）是一种广谱的兽用抗寄生虫药，在世界范围内用于牛的育种。这项研究的目的是评估活性成分和IVM（1％活性成分）的商业制剂在胚胎阶段的致死作用（S.4-6）和幼虫期（S.25）通过慢性标准化生物测定的南美两栖动物Rhinellaarenarum。此外，行为分析以及氧化应激和胆碱能效应生物标志物在1,10和100μgIVM/L浓度下进行分析。对于胚胎阶段，在急性期，活性成分（96h-LC50：15900μg/L）比商业制剂（96h-LC50：51230μg/L）毒性更大，而在长期接触时，商业制剂毒性更大(504h-LC50:10.25μg/L)，与活性成分（504h-LC50：312.80μg/L）相比。对于幼虫阶段，在急性暴露中，活性成分(96h-LC50:800μg/L)比商业制剂(96h-LC50:1550μg/L)毒性更大。在慢性暴露中，商业制剂(504h-LC50:77.33μg/L)比活性成分(504h-LC50:195.25μg/L)毒性更大。总的来说,幼虫对活性成分和商业制剂都表现出更高的敏感性。然而,在慢性暴露期间，胚胎对商业配方比幼虫更敏感。商业配方主要诱导氧化应激，和两种形式的化合物影响行为和胆碱能效应生物标志物，即使在低环境相关浓度（1μg/L）。这些结果突出了IVM对水生生态系统的潜在影响。
