Budischak Sarah A, Belden Lisa K, Hopkins William A
Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, 100 Cheatham Hall, Blacksburg, VA 24061-0321, USA.
Arch Environ Contam Toxicol. 2009 Jan;56(1):123-8. doi: 10.1007/s00244-008-9167-9. Epub 2008 Apr 10.
Amphibian populations around the world are facing threats that include disease and pollution. Although the effect of environmental contaminants on susceptibility to infection has been demonstrated for several amphibian species, to our knowledge, the opposite interaction, infection status affecting contaminant susceptibility, has not been studied. We conducted standard 48-h toxicity tests to compare susceptibility to malathion, a widely used organophosphate insecticide, of uninfected pickerel frog (Rana palustris) tadpoles and tadpoles infected with two levels (10 or 30 cercariae) of the trematode Echinostoma trivolvis. Trematode encystment rates were high (>90%) in both trematode treatment groups. LC(50) values ranged from 16.5 to 17.4 mg/L, within the range reported for other amphibian species. However, we found no differences in susceptibility to malathion among parasite treatments. Although we detected no effect of parasites on pesticide susceptibility in this system, it is important to investigate this question using other pesticides, parasites, and amphibian hosts before dismissing this potentially threatening interaction.
全球两栖动物种群正面临包括疾病和污染在内的威胁。虽然环境污染物对几种两栖动物物种感染易感性的影响已得到证实，但据我们所知，相反的相互作用，即感染状况影响污染物易感性，尚未得到研究。我们进行了标准的48小时毒性试验，以比较未感染的北美豹蛙（Rana palustris）蝌蚪以及感染了两个水平（10或30个尾蚴）的棘口吸虫（Echinostoma trivolvis）的蝌蚪对马拉硫磷（一种广泛使用的有机磷杀虫剂）的易感性。在两个吸虫处理组中，吸虫包囊化率都很高（>90%）。半数致死浓度（LC(50)）值在16.5至17.4毫克/升之间，处于其他两栖动物物种报告的范围内。然而，我们发现寄生虫处理组之间对马拉硫磷的易感性没有差异。虽然我们在这个系统中未检测到寄生虫对农药易感性的影响，但在排除这种潜在威胁的相互作用之前，使用其他农药、寄生虫和两栖动物宿主来研究这个问题很重要。
