Miles Jesse C, Hua Jessica, Sepulveda Maria S, Krupke Christian H, Hoverman Jason T
Department of Forestry and Natural Resources, Purdue University, West Lafayette, Indiana, United States of America.
Biological Sciences Department, Binghamton University (SUNY), Binghamton, New York, United States of America.
PLoS One. 2017 Mar 23;12(3):e0174171. doi: 10.1371/journal.pone.0174171. eCollection 2017.
The widespread usage of neonicotinoid insecticides has sparked concern over their effects on non-target organisms. While research has largely focused on terrestrial systems, the low soil binding and high water solubility of neonicotinoids, paired with their extensive use on the landscape, puts aquatic environments at high risk for contamination via runoff events. We assessed the potential threat of these compounds to wetland communities using a combination of field surveys and experimental exposures including concentrations that are representative of what invertebrates experience in the field. In laboratory toxicity experiments, LC50 values ranged from 0.002 ppm to 1.2 ppm for aquatic invertebrates exposed to clothianidin. However, freshwater snails and amphibian larvae showed high tolerance to the chemical with no mortality observed at the highest dissolvable concentration of the insecticide. We also observed behavioral effects of clothianidin. Water bugs, Belostoma flumineum, displayed a dose-dependent reduction in feeding rate following exposure to clothianidin. Similarly, crayfish, Orconectes propinquus, exhibited reduced responsiveness to stimulus with increasing clothianidin concentration. Using a semi-natural mesocosm experiment, we manipulated clothianidin concentration (0.6, 5, and 352 ppb) and the presence of predatory invertebrates to explore community-level effects. We observed high invertebrate predator mortality with increases in clothianidin concentration. With increased predator mortality, prey survival increased by 50% at the highest clothianidin concentration. Thus, clothianidin contamination can result in a top-down trophic cascade in a community dominated by invertebrate predators. In our Indiana field study, we detected clothianidin (max = 176 ppb), imidacloprid (max = 141 ppb), and acetamiprid (max = 7 ppb) in soil samples. In water samples, we detected clothianidin (max = 0.67 ppb), imidacloprid (max = 0.18 ppb), and thiamethoxam (max = 2,568 ppb). Neonicotinoids were detected in >56% of soil samples and >90% of the water samples, which reflects a growing understanding that neonicotinoids are ubiquitous environmental contaminants. Collectively, our results underscore the need for additional research into the effects of neonicotinoids on aquatic communities and ecosystems.
新烟碱类杀虫剂的广泛使用引发了人们对其对非目标生物影响的担忧。虽然研究主要集中在陆地系统，但新烟碱类杀虫剂的低土壤吸附性和高水溶性，再加上它们在景观中的广泛使用，使得水生环境因径流事件而面临高污染风险。我们通过现场调查和实验暴露相结合的方式，评估了这些化合物对湿地群落的潜在威胁，实验暴露包括代表无脊椎动物在野外实际接触浓度的水平。在实验室毒性实验中，暴露于噻虫胺的水生无脊椎动物的半数致死浓度（LC50）值在0.002 ppm至1.2 ppm之间。然而，淡水蜗牛和两栖动物幼虫对该化学物质表现出高耐受性，在杀虫剂的最高可溶解浓度下未观察到死亡。我们还观察到了噻虫胺的行为效应。水蝽，即美洲巨田鳖，在暴露于噻虫胺后，摄食率呈现剂量依赖性降低。同样，小龙虾，即近似螯虾，随着噻虫胺浓度的增加，对刺激的反应性降低。通过一个半自然的中宇宙实验，我们控制了噻虫胺浓度（0.6、5和352 ppb）以及捕食性无脊椎动物的存在，以探究群落水平的影响。我们观察到随着噻虫胺浓度的增加，无脊椎动物捕食者的死亡率很高。随着捕食者死亡率的增加，在噻虫胺最高浓度下，猎物的存活率提高了50%。因此，噻虫胺污染可导致在以无脊椎动物捕食者为主导的群落中发生自上而下的营养级联效应。在我们于印第安纳州开展的实地研究中，我们在土壤样本中检测到了噻虫胺（最高值 = 176 ppb）、吡虫啉（最高值 = 141 ppb）和啶虫脒（最高值 = 7 ppb）。在水样中，我们检测到了噻虫胺（最高值 = 0.67 ppb）、吡虫啉（最高值 = 0.18 ppb）和噻虫嗪（最高值 = 2568 ppb）。在超过56%的土壤样本和超过90%的水样中检测到了新烟碱类杀虫剂，这反映出人们越来越认识到新烟碱类杀虫剂是普遍存在的环境污染物。总体而言，我们的研究结果强调了有必要对新烟碱类杀虫剂对水生群落和生态系统的影响进行更多研究。
