Neonicotinoids influence on trophic relations and ecosystem functioning in freshwater ecosystems (NITRO)

生物多样性的下降可能导致重要的生态系统功能的丧失，如树叶的分解。毒物在多大程度上影响淡水生态系统中的多样性和生态系统功能之间的关系在很大程度上是未知的。新烟碱类代表了植物中吸收的一组相对较新的内吸性杀虫剂。植物材料可能进入溪流，并可能对食虫昆虫的分解产生不利影响。在这个项目中，我们将阐明类烟碱对资源多样性和叶分解之间的关系的影响，以及调查在一个三营养系统中的累积效应和效应传播。在该项目的第一部分，将在有天然溪流的微型生态系统中研究重复接触类烟碱杀虫剂吡虫啉对六种食虫动物的潜在累积亚致死效应。随后，将仔细检查两个种属的毒理学，以收集对生理过程的机械理解。在第二部分中，将调查来自凋落叶和资源多样性的吡虫啉对叶片分解率的影响。这项实验将在三个原始河流站点的野外围栏中进行。在该项目的最后一部分，我们将研究来自落叶的类尼古丁是否会对食物链产生影响。这将在实地和实验室实验中进行研究，捕食者将捕食摄入受污染树叶的食草动物。此外，采集物种将被喂以食虫动物在被吡虫啉污染的叶子上进食时分泌的细颗粒有机物。总的来说，这个研究项目将大大增加系统性杀虫剂对食虫动物种群的影响，营养关系和资源多样性与生态系统功能之间的关系的机械理解。

The decline of biodiversity may result in losses of crucial ecosystem functions such as leaf breakdown. To which extent toxicants influence the relationship between diversity and ecosystem functioning in freshwater ecosystems is largely unknown. Neonicotinoids represent a relatively new group of systemic insecticides that are taken up in plants. Plant material may enter streams and may adversely affect the breakdown by insect detritivores. In this project we will elucidate the effects of neonicotinoids on the relationship between resource diversity and leaf breakdown as well as investigate cumulative effects and effect propagation in a tri-trophic system. In the first part of the project, the potential cumulative sublethal effects of repeated exposures to the neonicotinoid insecticide imidacloprid on six detritivores will be studied in microcosms with natural stream water. Subsequently, the toxicodynamics will be scrutinised for two species to gather a mechanistic understanding of physiological processes. In the second part the effects of imidacloprid originating from leaf litter and resource diversity on the leaf breakdown rate will be investigated. This experiment will be conducted in field enclosures in three pristine stream sites. In the last part of the project, we will investigate whether neonicotinoids originating from leaf litter can have effects in the food chain. This will be examined in field and laboratory experiments where predators will prey on detritivores that ingested contaminated leaves. In addition, collector species will be fed with fine particulate organic matter excreted by detritivores feeding on imidacloprid-contaminated leaves. Overall this research project will add considerably to the mechanistic understanding of the effects of systemic insecticides on detritivore populations, trophic relations and the relationship between resource diversity and an ecosystem function.