藻类对大型溞抵抗农药的毒理学影响及其机制

为探究藻类对大型溞农药抗性的影响及其机制,分别将5种淡水广布的甲藻、硅藻、绿藻、隐藻、蓝藻等量培育大型溞后,再将大型溞分别暴露于2种杀虫剂吡虫啉(水溶性)和氰戊菊酯(脂溶性)中,测定大型溞的半数致死剂量、化学计量比(P/C,N/C)和脂肪酸含量.研究表明:与生源性化学元素氮磷相比,N3不饱和脂肪酸能更好揭示大型溞对藻类的捕食关系;藻类的N3不饱和脂肪酸含量是影响大型溞对水溶性农药抗性的关键因子;大型溞对脂溶性农药的抗性差异比暴露在水溶性农药中更明显.因此,藻类的N3不饱和脂肪酸是预测大型溞对水溶性农药抗性强度的最佳因子,其有助于更准确地预测以不同藻类为食的大型溞食物链对自然环境中污染物的抗性和风险.

Ecotoxicological effects and mechanism of algae on Daphnia Magna's resistance to pesticides

To explore the effects and mechanisms of algae on Daphnia magna's resistance to pesticides, five algal species (Pyrrophyta, Bacillariophyta, Chlorophyta, Cryptophyta and Cyanophyta) were fed in equal amount to zooplankton Daphnia magna, which was then exposed to two insecticides: imidacloprid (water-soluble) and esfenvalerate (fat-soluble). The median lethal concentration (LC₅₀), stoichiometric ratio (P:C, N:C) and fatty acid content of Daphnia magna were determined. The results show that, compared with biogenic chemical elements such as nitrogen and phosphorus, N3 unsaturated fatty acids can better reveal the predation of Daphnia magna on planktonic algae. The content of N3 unsaturated fatty acids in algae was a key factor affecting the resistance of Daphnia magna to water-soluble pesticides. The difference in Daphnia magna resistance was more obvious to fat-soluble pesticides than to water-soluble pesticides. Therefore, the N3 unsaturated fatty acids is the best predictor of the resistance of Daphnia magna to water-soluble pesticides, and can be used to monitor the resistance and risk of Daphnia magna food chain to pesticides in a natural environment.