Cd2+和Pb2+对花翅摇蚊(Chironomus kiiensis)幼虫生长发育的影响及富集效应

河流、湖泊等水生环境中普遍存在的重金属污染破坏水生生态系统并间接威胁人类健康。为探究重金属胁迫下水生昆虫花翅摇蚊（Chironomus kiiensis）生态毒理，测定了重金属Cd²⁺和Pb²⁺胁迫对花翅摇蚊化蛹率和羽化率的影响，检测了摇蚊的口器致畸与富集效应。研究结果表明，Cd²⁺和Pb²⁺影响摇蚊幼虫化蛹和羽化过程，单一重金属离子处理14 d Pb²⁺处理组的化蛹率和羽化率分别为22.22%和8.89%，低于Cd²⁺的化蛹率（25.56%）和羽化率（11.11%），表现出更强的抑制效应。混合离子1：2和2：1配比处理组化蛹率和羽化率均为11.11%和4.44%，显著低于单一重金属离子胁迫下的化蛹率和羽化率。单一重金属离子及混合离子处理均能导致花翅摇蚊幼虫口器致畸，表现为上颚前齿断裂，中齿和基齿磨损、缺失，下唇板齿部不规则，下唇板边缘齿与中央齿磨损、断裂、增生、缺失。不同重金属离子处理下幼虫口器致畸率不同，并与暴露时间呈正相关，其中1：2配比处理14 d致畸率达到40.61%。重金属离子在摇蚊幼虫体内产生生物富集效应，单一重金属离子处理下的Pb²⁺富集含量7 d至14 d由11.46 mg/kg上升至31.32 mg/kg，不同配比混合离子处理下Pb²⁺富集含量均呈增加趋势，其中1：2配比处理组由15.48 mg/kg上升至42.50 mg/kg，而Cd²⁺在单一重金属与1：1混合离子处理组7 d至14 d的富集含量无显著性变化，2：1配比处理组由14.20 mg/kg下降至9.52 mg/kg，1：2配比由5.85 mg/kg上升至20.99 mg/kg。这些研究结果表明Cd²⁺和Pb²⁺胁迫影响花翅摇蚊幼虫生长发育且口器出现畸型，与重金属在幼虫体内的富集密切相关，为研究重金属对水生生态系统多重效应提供了理论依据。

Effects of Cd2+ and Pb2+ on growth and development of Chironomus kiiensis larvae and its enrichment effects

Heavy metal pollution was observed in rivers, lakes, and other aquatic environments that damaged the aquatic ecosystem and indirectly threatened human health. To explore the ecotoxicology of heavy metal on aquatic insect Chironomus kiiensis, the pupation rate, emergence rate, teratogenic of the mouthparts and enrichment effects of C. kiiensis were measured under Cd²⁺ and Pb²⁺ stresses. The results showed that both Cd²⁺ and Pb²⁺ affected pupation and emergence of C. kiiensis larvae. The pupation rate and emergence rate of the C. kiiensis larvae treated by Pb²⁺ were 22.22% and 8.89%, which was lower than that of larvae treated by Cd²⁺ with 25.56% and 11.11% for 14 d stress, respectively, showing a higher inhibitory effect. The pupation rate and emergence rate of C. kiiensis larvae treated by 1:2 and 2:1 of Cd²⁺ and Pb²⁺ were all 11.11% and 4.44%, respectively, which was significantly lower than those of single heavy metal stress. The treatments of single and mixed heavy metals could lead to teratogenicity of mouthparts in C. kiiensis larvae, manifesting as the apical teeth of mandible fracture, middle teeth, basal teeth wear and loss, mentum irregular, marginal teeth and central teeth of the mentum wear, fracture, hyperplasia, and loss. The mouthpart teratogenicity rates of C. kiiensis larvae varied with the treatment of different heavy metal ions and showed a positive correlation with the exposure time. Among different treatments, the teratogenic rate of C. kiiensis larvae treated by 1:2 of Cd²⁺ and Pb²⁺ reached 40.61%. Moreover, heavy metal ions produced bioaccumulation effects in C. kiiensis larvae. Exposed for 7 d to 14 d, the concentration of Pb²⁺ in C. kiiensis larvae increased from 11.46 mg/kg to 31.32 mg/kg. The Pb²⁺ concentration in C. kiiensis larvae treated by the different mixed ions showed an increasing trend, and the Pb²⁺ concentration in C. kiiensis larvae treated by 1:2 mixed ion treatment ranged from 15.48 mg/kg to 42.50 mg/kg. However, the concentration of Cd²⁺ in C. kiiensis larvae treated by the single heavy metal and 1:1 mixed ion treatment from 7 d to 14 d had no significant difference. The Cd²⁺ concentration in C. kiiensis larvae treated by 2:1 mixed ion treatment group decreased from 14.20 mg/kg to 9.52 mg/kg, whereas that in 1:2 mixed ion treatment group increased from 5.85 mg/kg to 20.99 mg/kg. The results indicated that Cd²⁺ and Pb²⁺ could inhibit the growth and development and produce mouthpart teratogenicity of C. kiiensis larvae, which was closely related to the accumulation of heavy metals in C. kiiensis larvae. These results provided a theoretical basis for the multiple effects of heavy metals on the aquatic ecosystem.