Beketov Mikhail A, Liess Matthias
Western Siberian Center for Environmental Monitoring, P.O. Box 156, 630048 Novosibirsk, Russia.
Environ Toxicol Chem. 2005 May;24(5):1281-6. doi: 10.1897/04-256r1.1.
Results of environmental risk assessments based merely on toxic effects of contaminants at the individual level, without consideration of population-level effects, may be questionable. The aim of the present study was to investigate how limited food resources, resulting in intraspecific competition, could interact with the chronic effect of short-term contamination with the insecticide esfenvalerate. Larvae of the mayfly, Cloeon dipterum, were exposed to esfenvalerate (0.001-100 microg/L) for 1 h and then transferred to indoor microcosms containing insecticide-free water, where they were maintained at various food levels until emergence. The results showed that short-term exposure to 10 or 100 microg/L resulted in acute mortality. Chronic effects on survival occurred at concentrations up to three orders of magnitude lower than that causing the acute effect (0.01 microg/L). Food limitation increased effects on organisms during medium-term observation (8-15 d), but assessment of long-term survival rates suggested that the chronic effects of low insecticide concentrations could be compensated for, at least regarding some endpoints. The authors assume that in limited-food conditions, lethal and sublethal effects reduced competition between individuals, resulting in significantly increased final survival.
仅基于污染物在个体水平上的毒性效应而不考虑种群水平效应进行的环境风险评估结果可能存在问题。本研究的目的是调查有限的食物资源（导致种内竞争）如何与杀虫剂乙氰菊酯短期污染的慢性效应相互作用。蜉蝣Cloeon dipterum的幼虫暴露于乙氰菊酯（0.001 - 100微克/升）1小时，然后转移到含有不含杀虫剂的水的室内微观世界中，在那里它们被维持在不同的食物水平直至羽化。结果表明，短期暴露于10或100微克/升会导致急性死亡。对生存的慢性影响发生在浓度比导致急性效应的浓度低三个数量级（0.01微克/升）的情况下。食物限制在中期观察（8 - 15天）期间增加了对生物的影响，但长期存活率评估表明，至少在某些终点方面，低浓度杀虫剂的慢性影响可以得到补偿。作者认为，在食物有限的条件下，致死和亚致死效应减少了个体之间的竞争，从而导致最终存活率显著提高。
