环境激素氯氰菊酯对萼花臂尾轮虫繁殖的影响

Effects of the Environmental Hormone Cypermethrin on the Reproduction of Brachionus calyciflorus

以2 d种群增长率为指标研究了环境抗雄激素氯氰菊酯对萼花臂尾轮虫的急性毒性;以3 d种群动态参数(种群增长率、混交率、混交雌体受精率和携卵雌体/非携卵雌体)、7 d休眠卵产量和休眠卵孵化率为指标研究了低剂量氯氰菊酯(0.001～0.316 mg.L-1)对萼花臂尾轮虫繁殖的影响;以2 d种群参数分析了在氯氰菊酯中形成休眠卵孵化后的生长性能;以3 d种群参数为指标分析了母体暴露氯氰菊酯,对其后代繁殖的影响.结果表明氯氰菊酯浓度对数与种群增长率呈直线负相关.氯氰菊酯半数效应浓度(EC50)、最低可观察效应浓度(LOEC)和无可观察效应浓度(NOEC)分别为14.22、10和3.16mg.L-1;0.0316 mg.L-1氯氰菊酯组7 d休眠卵产量较对照组下降了41.23%,休眠卵孵化率亦较对照组显著下降;氯氰菊酯试验组中形成的休眠卵孵化后的种群增长率和混交率显著下降;萼花臂尾轮虫母体暴露0.316 mg.L-1氯氰菊酯其后代种群增长率比对照下降了15.96%.试验表明,萼花臂尾轮虫2 d种群增长率对氯氰菊酯较不敏感;低剂量氯氰菊酯可降低休眠卵产量、休眠卵孵化率及孵化后种群增长率,从而减少萼花臂尾轮虫后代早期对种群增长的贡献.

The toxic effects of the antiandrogen cypermethrin on B.calyciflorus were investigated using the 2 d population growth rate（r） of B.calyciflorus.The effects of low-dose of cypermethrin（0.001-0.316 mg·L^-1） on the 3 d population parameters,the 7 d resting egg production and the hatching rate of resting eggs of B.calyciflorus were also studied.The 2 d population parameters of B.calyciflorus were used to estimate the growth ability of larvae hatched from the resting eggs formed in cypermethrin.The 3 d population parameters were used to estimate the effect on the the reproduction of the offspring of B.calyciflorus,whose parent generation was pre-exposed in cypermethrin.The results indicated that the logarithmic concentration of cypermethrin had a linear negative correlation with the population growth rate.The half maximal effective concentration（EC50）,the lowest observed effect concentration（LOEC） and no-observed effect concentration（NOEC） of cypermethrin were 14.22 mg·L^-1,10 mg·L^-1 and 3.16 mg·L^-1,respectively.The resting egg production was decreased by 41.23% at 0.031 6 mg·L^-1 cypermethrin.The hatching rate of resting eggs was significantly decreased when formed in 0.031 6 mg·L^-1 cypermethrin.The population growth rate and mictic rate were significantly decreased for the individuals hatched from the resting eggs formed in cypermethrin.The 3 d population growth rate was significantly decreased by 15.96% compared to the control when their parent generation was pre-exposed in 0.316 mg·L^-1 cypermethrin.The results showed that the 2 d population growth rate of B.calyciflorus was less sensitive to cypermethrin.Low doses of cypermethrin reduced the resting egg production,the hatching rate of resting eggs and the population growth of hatched resting eggs,which would thus decrease the contribution of the offspring to the population growth.