Department of Forest and Conservation Sciences, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada; Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria (CIPAV), Carrera 25 No. 6-62, Cali, Colombia.
Centro de Investigación Esquel de Montaña y Estepa Patagónica (CONICET-UNPSJB), Roca 780, Esquel, Chubut, Argentina.
Sci Total Environ. 2019 Nov 20;692:1291-1303. doi: 10.1016/j.scitotenv.2019.06.301. Epub 2019 Jul 11.
Pesticides are important contributors to the global freshwater biodiversity crisis. Among pesticides, neonicotinoids are the best-selling class of agricultural insecticides and are suspected to represent significant risks to freshwater and terrestrial ecosystems worldwide. Despite growing recognition that neonicotinoid impacts may be modified by the presence of additional stressors, there is limited information about their interactions with other agricultural stressors in freshwater ecosystems. We conducted an outdoor pond-mesocosm experiment to investigate the individual and interactive effects of nutrients, fine sediment, and imidacloprid (a neonicotinoid insecticide) inputs on freshwater community structure (density, diversity, and composition of zooplankton and benthic invertebrates) and ecosystem functioning (ecosystem metabolism, primary production, and organic matter decomposition). We hypothesized antagonistic nutrient-imidacloprid, and synergistic sediment-imidacloprid interactions, affecting aquatic invertebrate communities. The three stressors had significant individual and interactive effects on pond ecosystems. The insecticide neutralized the positive effects of nutrient additions on benthic invertebrate richness and mitigated the negative effects of sediment on zooplankton communities (antagonistic interactions). Moreover, we observed compensatory responses of tolerant benthic invertebrates, which resulted in reversal interactions between sediment and imidacloprid. Furthermore, our observations suggest that imidacloprid has the potential to increase net ecosystem production at environmentally relevant concentrations. Our findings support the hypothesis that the impacts of imidacloprid may be modified by other agricultural stressors. This has important implications on a global scale, given the widespread use of these pesticides in intensive agricultural landscapes and the growing body of literature suggesting that traditional pesticide assessment frameworks, based on laboratory toxicity tests alone, may be insufficient to adequately predict effects to complex freshwater ecosystems.
杀虫剂是全球淡水生物多样性危机的重要贡献者。在杀虫剂中，新烟碱类杀虫剂是最畅销的一类农用杀虫剂，被怀疑对全球淡水和陆地生态系统构成重大风险。尽管越来越多的人认识到，新烟碱类杀虫剂的影响可能会因其他压力因素的存在而发生变化，但关于它们在淡水生态系统中与其他农业压力因素相互作用的信息有限。我们进行了一项户外池塘中观实验，以研究营养物质、细沉积物和吡虫啉（一种新烟碱类杀虫剂）单独和相互输入对淡水群落结构（浮游动物和底栖无脊椎动物的密度、多样性和组成）和生态系统功能（生态系统代谢、初级生产和有机物质分解）的影响。我们假设营养-吡虫啉拮抗作用和沉积物-吡虫啉协同作用，会影响水生无脊椎动物群落。这三个压力源对池塘生态系统具有显著的单独和相互作用。杀虫剂中和了营养物质添加对底栖无脊椎动物丰富度的正面影响，并减轻了沉积物对浮游动物群落的负面影响（拮抗作用）。此外，我们观察到耐受底栖无脊椎动物的补偿反应，这导致了沉积物和吡虫啉之间的相互作用逆转。此外，我们的观察结果表明，在环境相关浓度下，吡虫啉有可能增加净生态系统生产力。我们的研究结果支持这样一种假设，即其他农业压力因素可能会改变吡虫啉的影响。鉴于这些杀虫剂在集约化农业景观中的广泛使用，以及越来越多的文献表明，仅基于实验室毒性测试的传统杀虫剂评估框架可能不足以充分预测对复杂淡水生态系统的影响，这在全球范围内具有重要意义。
