Environmental Sciences Graduate Program, Oregon State University, Corvallis, Oregon, USA.
Environ Toxicol Chem. 2013 Dec;32(12):2855-60. doi: 10.1002/etc.2379. Epub 2013 Oct 21.
Despite the use of model species to predict the effects of chemicals in the environment, unpredicted variation in levels of risk to organisms from xenobiotics can be observed. Physiological and morphological differences between species and life stages may lead to differences in sensitivity, while seasonal and spatial variation in pesticide concentrations may affect the level of risk faced by organisms in the environment. Because anurans breed in aquatic habitats subject to contamination by runoff and spraying, they are particularly vulnerable to pesticides. In the present study, embryos, newly hatched larvae, and larvae with limb buds of 3 anuran amphibian species--Pseudacris regilla, Rana cascadae, and Rana aurora--were exposed for 48 h to either 0.5 µg/L or 5.0 µg/L cypermethrin under laboratory conditions. The authors monitored hatching success, larval survival, and measured growth. Additionally, they assayed avoidance behavior 2 wk after exposure or 2 wk after hatching for individuals exposed as embryos. Hatching and survival were not affected in animals of any species exposed as embryos. After exposure as embryos and as newly hatched larvae, however, P. regilla displayed behavioral abnormalities in response to prodding. Cypermethrin increased mortality in P. regilla exposed in both larval stages. Cypermethrin also increased mortality in larval R. cascadae when exposed at the early stage. These results indicate variation in sensitivity to environmentally relevant concentrations of cypermethrin among anuran species and life stages.
尽管使用模式物种来预测环境中化学物质的影响，但仍可能观察到外来生物对生物体风险水平的不可预测的变化。物种和生命阶段之间的生理和形态差异可能导致敏感性的差异，而农药浓度的季节性和空间变化可能会影响环境中生物体面临的风险水平。由于两栖动物在水生栖息地繁殖，容易受到径流和喷洒的污染，因此它们特别容易受到农药的影响。在本研究中，将 3 种蛙类两栖动物的胚胎、刚孵化的幼虫和带有肢芽的幼虫——红耳滑蟾（Pseudacris regilla）、瀑布蟾蜍（Rana cascadae）和极光蟾（Rana aurora）——暴露在实验室条件下 48 小时，浓度分别为 0.5 µg/L 或 5.0 µg/L 的氯菊酯中。作者监测了孵化成功率、幼虫存活率，并测量了生长情况。此外，他们还在暴露后 2 周或孵化后 2 周评估了暴露于胚胎的个体的回避行为。暴露于胚胎的任何物种的动物的孵化和生存均未受到影响。然而，在暴露于胚胎和刚孵化的幼虫后，红耳滑蟾在受到刺激时表现出行为异常。氯菊酯增加了暴露于两个幼虫阶段的红耳滑蟾的死亡率。氯菊酯也增加了早期暴露的幼体瀑布蟾蜍的死亡率。这些结果表明，在蛙类物种和生命阶段中，对环境相关浓度的氯菊酯的敏感性存在差异。
