低剂量新烟碱类杀虫剂长期暴露土壤的毒性效应及其机理研究

The potential toxicity of neonicotinoid insecticides to non-target organisms has attracted widespread attention, but little has been done regarding the toxicity and its mechanism of the insecticides to soil organisms following long-term and low-dose exposure. In this study, six neonicotinoid insecticides (imidacloprid, acetamiprid, clothianidin, nitenpyram, thiacloprid and dinotefuran) were investigated for their acute and subacute toxicity to the soil invertebrate earthworm based on body weight, reproduction and avoidance behavior. Using single cell gel electrophoresis, liquid chromatography, Western blot analysis and reverse transcription PCR technology, we studied and analyzed the impact of the insecticides on the morphology, body weight, enzyme activity, DNA damage and gene expression in earthworm offsprings. The changes between the parental and offspring earthworms were compared to draw the dynamic curve of change in order to elucidate the potential toxicity risks of neonicotinoid insecticides on earthworm and its toxicity mechanism. These data were used to screen sensitive biomarkers for early diagnosis of low-dose pesticide pollution of soil. The results of this work can provide diagnostic methods for pesticide soil pollution following long-term and low-dose exposure, and scientific basis of rational pesticide use and protection of ecological environment.

新烟碱类杀虫剂对非靶标生物的潜在毒性影响已经引起了国内外的普遍关注，但是有关该类杀虫剂在低剂量长周期暴露下对土壤生物的毒性效应及其机理的研究十分薄弱。本项目拟选择六种新烟碱类杀虫剂（吡虫啉、啶虫脒、噻虫胺、烯啶虫胺、噻虫啉和呋虫胺等）为对象，以土壤无脊椎动物蚯蚓为受试生物。根据其对蚯蚓急性和亚急性毒性指标（体重、繁殖及回避行为等）影响的毒性信息，采用单细胞凝胶电泳、液相色谱、蛋白质印迹分析和逆转录PCR等技术，探究对子代蚯蚓形态、体重及生化酶活性、DNA损伤、基因差异表达等的影响，明确其变化规律，并与亲代蚯蚓进行比较，绘制出变化的动态曲线，以期阐明新烟碱类杀虫剂对蚯蚓的潜在毒性风险及其致毒机理，并筛选出用于早期诊断土壤低剂量农药污染的敏感生物标志物。本项目研究结果可为低剂量农药长期暴露污染土壤生态毒理诊断提供方法论，同时亦为农药合理使用和生态环境保护提供基础科学依据。

新烟碱类杀虫剂是目前世界上发展最快的一类杀虫剂，然而随着该类药剂的大量广泛使用，其对生态环境的不利影响逐渐表现出现。蚯蚓是土壤中普遍存在的无脊椎动物，其被多个国际组织列为土壤污染的指示生物。本研究开展了部分典型新烟碱类杀虫剂（吡虫啉、啶虫脒、噻虫胺、烯啶虫胺、噻虫啉和呋虫胺）对蚯蚓的急性毒性、回避行为、繁殖毒性、酶活性和基因差异表达的影响等。研究结果表明测试的新烟碱类杀虫剂对蚯蚓表现出了极高的毒性效应，但不同的杀虫剂的毒性效应存在差异。总体来看，吡虫啉。烯啶虫胺和啶虫脒对蚯蚓产生了极强的毒性效应。羧酸酯酶和谷胱甘肽转移酶都参与了蚯蚓对新烟碱类杀虫剂的解毒，但仍然存在其他的解毒机制。蚯蚓体内3个基因tctp、hsp70和gst可作为低剂量新烟碱类杀虫剂污染土壤的早期诊断灵敏指标。本项目研究结果不仅可为新烟碱类杀虫剂的合理使用奠定基础，同时也为低浓度新烟碱类杀虫剂进入土壤早期预警和修复治理提供技术支撑，这对于保护生态环境和人类健康都具有重要的理论和现实意义。