Chlorpyrifos, an organophosphate (OP) insecticide, is prevalent in aquatic systems globally and is often implicated in aquatic toxicity during storm events. Chlorpyrifos induces toxicity by inhibition of acetylcholinesterase (AChE) activity, which has been related to alterations to fish swimming performance. Resistance to organophosphate insecticides, including chlorpyrifos, is prevalent in populations of the epibenthic amphipod Hyalella azteca in areas with known OP exposure. Previous studies have demonstrated an elevated bioaccumulation potential of insecticide-resistant prey items, however the potential for trophic transfer of chlorpyrifos from OP-resistant prey items and associated neurotoxic effects in fish predators has not been studied. Consequently, the present study aimed to determine the potential for trophic transfer of chlorpyrifos from OP-resistant H. azteca to a known predator, the inland silverside, Menidia beryllina at two temperatures (18 and 23 °C) to simulate temperature changes associated with global climate change (GCC). Fish were fed either ¹⁴C-chlorpyrifos-dosed H. azteca or control animals for 7 d, after which total bioaccumulation, percent parent chlorpyrifos, brain AChE activity and swimming performance (ramp-U_crit) were determined. Fish fed chlorpyrifos-dosed H. azteca bioaccumulated chlorpyrifos ranging from 29.9 to 1250 ng/g lipid, demonstrating the potential for trophic transfer. Lower bioaccumulation and greater biotransformation were observed in M. beryllina at 23 °C as compared to 18 °C, though this was not statistically significant. A significant 36.5% reduction in brain AChE activity was observed in fish fed chlorpyrifos-dosed H. azteca at 23 °C only, which may be attributed to increased biotransformation of parent chlorpyrifos to more potent AChE-inhibiting metabolites. Dietary chlorpyrifos exposure had no significant effect on swimming performance in M. beryllina, though ramp-U_crit was significantly increased by 25% at 23 as compared to 18 °C. These findings confirm the potential for trophic transfer of chlorpyrifos from OP-resistant prey to fish predators and the potential for elevated temperatures to exacerbate the neurotoxic effects of chlorpyrifos.

毒死蜱是一种有机磷 (OP) 杀虫剂，在全球水生系统中普遍存在，并且经常与风暴事件期间的水生毒性有关。毒死蜱通过抑制乙酰胆碱酯酶 (AChE) 活性诱导毒性，这与鱼类游泳性能的改变有关。对包括毒死蜱在内的有机磷杀虫剂的抗药性在底栖片脚类Hyalella azteca种群中很普遍在已知 OP 暴露的区域。先前的研究表明，抗杀虫剂的猎物具有较高的生物蓄积潜力，但是尚未研究毒死蜱从抗 OP 的猎物中营养转移的潜力以及对鱼类捕食者的相关神经毒性作用。因此，本研究旨在确定毒死蜱在两个温度（18 和 23 °C）下从抗 OP 的阿兹台克人向已知捕食者内陆银边白蚁的营养转移的可能性，以模拟与全球相关的温度变化。气候变化 (GCC)。给鱼喂食¹⁴ C-毒死蜱剂量的H. azteca或对照动物 7 天，之后测定总生物积累、母体毒死蜱百分比、脑 AChE 活性和游泳性能（ramp-U _crit）。鱼饲喂毒死蜱给药H. Azteca的生物积累毒死蜱范围从29.9至1250纳克/克脂肪，证实为营养转移的潜力。与 18 °C 相比，在 23 °C下在M. beryllina中观察到较低的生物积累和较大的生物转化，尽管这没有统计学意义。在鱼供给毒死蜱给药未观察到脑乙酰胆碱酯酶活性的显著减少36.5％H.阿兹特克仅在 23 °C 时，这可能是由于母体毒死蜱向更有效的 AChE 抑制代谢物的生物转化增加。膳食毒死蜱暴露对M. beryllina 的游泳表现没有显着影响，尽管与 18 °C 相比，ramp-U_暴击在 23 时显着增加了 25%。这些发现证实了毒死蜱从 OP 抗性猎物向鱼类捕食者的营养转移的潜力，以及温度升高可能加剧毒死蜱的神经毒性作用。