The freshwater snail Physa fontinalis was used as a bioindicator to study the effects of the herbicide Paraquat (PQ) in laboratory assays. The test solutions used, 0.125, 0.25, and 0.5 mg/l PQ, were in the range of the concentrations recommended for aquatic weed control. The study was carried out in two stages to determine the influence of PQ on the ovipository activity of Physa fontinalis, and the histological effects on these snails. Specimens exposed to PQ continued to be reproductively active, but the number of egg masses and eggs laid decreased significantly. Mortality was almost the same in all the experimental lots, but was significantly related to the production of egg masses only in the controls. The histological analysis showed a clear trend among PQ concentrations and degenerating oocytes, but no visible effects on the male sex-line were observed. By interfering with fertility, PQ has an action that may go well beyond its lethal effect on individuals, suggesting that this herbicide should be strictly regulated in weed control programmes. Moreover, since PQ was observed to interfere with the reproductive process, its endocrine disrupting action must not be excluded.

中文翻译：

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百草枯在淡水蜗牛 PHYSA Fontinalis（腹足纲：PULMONATA）中引起的卵细胞退化和卵子活性改变

淡水蜗牛 Physa fontinalis 被用作生物指示剂，以研究除草剂百草枯 (PQ) 在实验室检测中的作用。所用的测试溶液 0.125、0.25 和 0.5 mg/l PQ 处于推荐用于水草控制的浓度范围内。该研究分两个阶段进行，以确定 PQ 对 Physa fontinalis 排卵活动的影响，以及对这些蜗牛的组织学影响。暴露于 PQ 的样本继续繁殖活跃，但产卵量和产卵数量显着减少。所有实验批次的死亡率几乎相同，但仅在对照组中与产蛋量显着相关。组织学分析显示 PQ 浓度和退化卵母细胞之间的明显趋势，但没有观察到对男性性系的明显影响。通过干扰生育力，百草枯的作用可能远远超出其对个体的致死作用，这表明这种除草剂应在杂草控制计划中受到严格监管。此外，由于观察到 PQ 会干扰生殖过程，因此不能排除其内分泌干扰作用。