Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, SE-750 07, Uppsala, Sweden.
Ecotoxicology. 2010 Oct;19(7):1201-8. doi: 10.1007/s10646-010-0505-0. Epub 2010 Jun 5.
We quantified sublethal and sex-specific cypermethrin effects in experiments (29 days) with the midge Chironomus riparius at different levels of sediment organic matter content (0, 5, and 20%). We found highly significant effects of cypermethrin concentrations and sediment type on emergence, mean development rate, and adult size. For example, emergence/survival rates were 70-100% below 0.8 μg/l and unaffected by organic matter content. At 3.2 μg/l, however, no larvae survived in sediment without organic matter, but survival successively increased to 26 ± 11% in sediment with 20% organic matter. Mean development rates were always higher for males than for females, and significant differences between sexes occurred consistently in controls and in treatments with our lowest concentration of 0.05 μg/l. Sex-specific differences in mean development rate decreased across the cypermethrin gradient, suggesting that male development was affected more than that of females at similar concentrations. We also found an increase in adult size across the concentration gradient in sediments lacking organic matter and suggest an increased feeding activity due to sublethal toxic stress as a probable causal mechanism. We speculate that the observed sex-specific effects on development rates and adult size can have strong repercussions on emergence timing and fecundity, respectively.
我们在不同水平的底泥有机质含量（0、5 和 20%）下，用摇蚊（Chironomus riparius）进行了为期 29 天的实验，量化了亚致死和性别特异性的氯菊酯效应。我们发现氯菊酯浓度和底泥类型对羽化、平均发育率和成虫大小有非常显著的影响。例如，在 0.8μg/l 以下，羽化/存活率低于 70-100%，不受有机质含量的影响。然而，在 3.2μg/l 时，无有机质的底泥中没有幼虫存活，但在含有 20%有机质的底泥中，存活率逐渐增加到 26±11%。平均发育率男性总是高于女性，在对照组和我们最低浓度 0.05μg/l 的处理组中，性别间始终存在显著差异。随着氯菊酯浓度的增加，平均发育率的性别特异性差异减小，表明在相似浓度下，雄性的发育比雌性更易受影响。我们还发现，在缺乏有机质的底泥中，成虫大小随浓度梯度增加，这表明由于亚致死的毒性胁迫，摄食活动增加，这可能是一种潜在的因果机制。我们推测，观察到的发育率和成虫大小的性别特异性效应分别会对羽化时间和繁殖力产生强烈影响。
