Comparative chronic toxicity of imidacloprid, clothianidin, and thiamethoxam to Chironomus dilutus and estimation of toxic equivalency factors
Comparative chronic toxicity of imidacloprid, clothianidin, and thiamethoxam to Chironomus dilutus and estimation of toxic equivalency factors
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DOI：
10.1002/etc.3536
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发表时间：
2017-02-01
影响因子：
4.1
通讯作者：
Liber, Karsten
中科院分区：
文献类型：
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作者：
Cavallaro, Michael C.;Morrissey, Christy A.;Liber, Karsten
非靶标水生昆虫在发育的早期阶段易受慢性类烟碱杀虫剂暴露的影响，这些化学品来自反复的径流事件和长期的持久性。关于类烟碱对水生无脊椎动物的慢性毒性的研究仅限于少数物种，并且在不同的实验室条件下进行，这通常妨碍了对不同化合物的相对毒性进行直接比较。本研究采用稀释摇蚊进行全生命周期毒性试验，比较了3种常用的烟碱类杀虫剂：吡虫啉、噻虫胺和噻虫嗪的毒性。试验条件遵循静态更新暴露方案，其中在第14天和第40天评估致死和亚致死终点。减少出现成功，提前出现的时间，和男性偏见的性别比例是敏感的反应，低水平的类烟碱暴露。吡虫啉、噻虫胺和噻虫嗪的14d半致死浓度分别为1.52g/L、2.41g/L和23.60g/L。吡虫啉、噻虫胺和噻虫嗪的40d中效浓度（羽化）分别为0.39g/L、0.28g/L和4.13g/L。通过在20%、50%和90%致死和效应浓度下计算的等效性的3点响应平均值，估计相对于吡虫啉的毒性等效性。相对于吡虫啉（毒性当量因子[TEF]= 1.0），噻虫胺和噻虫嗪的慢性（致死）14-d TEF分别为1.05和0.14，慢性（羽化抑制）40-d TEF分别为1.62和0.11。这些人群相关终点和TEF表明，吡虫啉和噻虫胺对C.稀释，而噻虫嗪诱导类似的效果，只有在浓度高一个数量级。然而，作者警告说，在田间条件下，噻虫嗪很容易降解为噻虫胺，从而可能增加毒性。环境毒理化学2017; 36：372 - 382。(c)2016年SETAC
Nontarget aquatic insects are susceptible to chronic neonicotinoid insecticide exposure during the early stages of development from repeated runoff events and prolonged persistence of these chemicals. Investigations on the chronic toxicity of neonicotinoids to aquatic invertebrates have been limited to a few species and under different laboratory conditions that often preclude direct comparisons of the relative toxicity of different compounds. In the present study, full life-cycle toxicity tests using Chironomus dilutus were performed to compare the toxicity of 3 commonly used neonicotinoids: imidacloprid, clothianidin, and thiamethoxam. Test conditions followed a static-renewal exposure protocol in which lethal and sublethal endpoints were assessed on days 14 and 40. Reduced emergence success, advanced emergence timing, and male-biased sex ratios were sensitive responses to low-level neonicotinoid exposure. The 14-d median lethal concentrations for imidacloprid, clothianidin, and thiamethoxam were 1.52g/L, 2.41g/L, and 23.60g/L, respectively. The 40-d median effect concentrations (emergence) for imidacloprid, clothianidin, and thiamethoxam were 0.39g/L, 0.28g/L, and 4.13g/L, respectively. Toxic equivalence relative to imidacloprid was estimated through a 3-point response average of equivalencies calculated at 20%, 50%, and 90% lethal and effect concentrations. Relative to imidacloprid (toxic equivalency factor [TEF]=1.0), chronic (lethality) 14-d TEFs for clothianidin and thiamethoxam were 1.05 and 0.14, respectively, and chronic (emergence inhibition) 40-d TEFs were 1.62 and 0.11, respectively. These population-relevant endpoints and TEFs suggest that imidacloprid and clothianidin exert comparable chronic toxicity to C. dilutus, whereas thiamethoxam induced comparable effects only at concentrations an order of magnitude higher. However, the authors caution that under field conditions, thiamethoxam readily degrades to clothianidin, thereby likely enhancing toxicity. Environ Toxicol Chem 2017;36:372-382. (c) 2016 SETAC