School of Environmental Sciences, University of Guelph, 50 Stone Rd. E., Guelph, Ontario N1G 2W1, Canada,.
Laboratory Services Branch, Ontario Ministry of the Environment and Climate Change, 125 Resources Rd., Toronto M9P 3V6, Ontario, Canada.
Sci Total Environ. 2018 Oct 15;639:1543-1552. doi: 10.1016/j.scitotenv.2018.05.259. Epub 2018 May 29.
Neonicotinoid insecticides used in agriculture can enter freshwater environments in pulses; that is, a short-term period of a higher concentration, followed by a period of a comparatively lower concentration. Non-target aquatic arthropods are exposed to these fluctuating concentrations of neonicotinoids. The present study investigated the potential latent effects of a single environmentally-relevant 24-h pulse of imidacloprid and thiamethoxam, in separate experiments, on the early life-stages of four aquatic arthropods (Hyalella azteca, Chironomus dilutus, Hexagenia spp., and Neocloeon triangulifer). At least three nominal pulse concentrations were tested for each neonicotinoid-species combination: 2.5, 5, and 10 μg L, which were based on environmental monitoring in Ontario, Canada. After exposure to the pulse, organisms were assessed for survival and immobilization. Surviving organisms were then moved into clean water for a chronic post-treatment period, where endpoints including survival, growth, reproduction or emergence, depending on the species, were evaluated. Immediately after the 24-h pulse, immobilization was seen in C. dilutus and N. triangulifer in the highest imidacloprid concentrations tested (8.8 and 8.9 μg L, respectively). After transfer to clean water, immobilized organisms recovered, and no latent toxicity was seen for any of the evaluated endpoints. H. azteca and Hexagenia spp. showed no effects immediately after the imidacloprid pulse, or after the chronic post-treatment period. No effects were seen in any species after the thiamethoxam pulse, or the post-treatment period. The present study shows that toxic effects due to short-term pulse exposures of ~9 μg L imidacloprid can occur in sensitive insect species. However, organisms can recover when the stressor ceases, with no long-term effects on test organisms.
农业中使用的新烟碱类杀虫剂会以脉冲的形式进入淡水环境；也就是说，在一个短期的较高浓度之后，会有一个相对较低浓度的时期。非靶标水生节肢动物会暴露于这些波动浓度的新烟碱类杀虫剂中。本研究分别在两个实验中，调查了单一环境相关的 24 小时吡虫啉和噻虫嗪脉冲对四种水生节肢动物（霍氏溪蟹、摇蚊幼虫、六足蚬和三爪金龙）早期生命阶段的潜在潜在影响。对于每种新烟碱类-物种组合，至少测试了三个名义脉冲浓度：2.5、5 和 10 μg/L，这是基于加拿大安大略省的环境监测结果。在暴露于脉冲后，评估了生物体的存活率和固定率。幸存的生物体然后被转移到干净的水中进行慢性治疗后阶段，根据物种的不同，评估包括存活率、生长、繁殖或出现的终点。在 24 小时脉冲后，最高浓度的吡虫啉测试中，摇蚊幼虫和三爪金龙立即出现固定（分别为 8.8 和 8.9 μg/L）。转移到干净的水后，固定的生物体恢复了，在任何评估的终点都没有发现潜在的毒性。在吡虫啉脉冲后，霍氏溪蟹和六足蚬立即或慢性治疗后阶段均未出现任何影响。噻虫嗪脉冲或治疗后阶段，在任何物种中均未观察到任何影响。本研究表明，在敏感昆虫物种中，短期脉冲暴露约 9μg/L 吡虫啉会导致毒性效应。然而，当应激源停止时，生物体可以恢复，对试验生物没有长期影响。
