Singular use of activity assays or staining dyes to assess pathogen agrochemical tolerance can underestimate tolerance if pesticides cause sublethal effects. We exposed Schistosoma mansoni cercariae, the aquatic life stage of this trematode that infects humans, to 4 insecticides at 5 concentrations using a 24‐h time‐to‐death assay. We used Trypan blue dye, which stains dead tissue, and activity assays simultaneously to discriminate dead from live but paralyzed individuals. Whereas cypermethrin, deltamethrin, and dimethoate exposure did not affect cercariae at any ecologically relevant concentrations, methamidophos exposure increased survival of cercariae compared with those in the controls. This was because methamidophos‐induced paralysis reduced cercarial activity and thus energy expenditures, extending the lifespan of this short‐lived parasite that causes human schistosomiasis. These findings highlight that sublethal effects should be considered when pesticide effects on disease are under investigation. Environ Toxicol Chem 2020;39:1421–1428. © 2020 SETAC

中文翻译：

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农药暴露对曼氏血吸虫尾蚴存活和活动的影响。

如果农药引起亚致死效应，单独使用活性测定或染色染料来评估病原体农用化学品耐受性可能会低估耐受性。我们暴露了曼氏血吸虫尾蚴是这种感染人类的​​吸虫的水生生物阶段，使用 24 小时至死亡时间测定将其添加到 5 种浓度的 4 种杀虫剂中。我们使用台盼蓝染料染色死组织，同时使用活性测定来区分死者和活的但瘫痪的个体。尽管氯氰菊酯、溴氰菊酯和乐果暴露在任何生态相关浓度下都不会影响尾蚴，但与对照组相比，甲胺磷暴露增加了尾蚴的存活率。这是因为甲胺磷引起的麻痹减少了尾蚴活动，从而减少了能量消耗，延长了这种导致人类血吸虫病的短命寄生虫的寿命。这些发现强调，在调查农药对疾病的影响时，应考虑亚致死效应。环境毒理学化学2020；39：1421-1428。© 2020 SETAC