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

生物多样性的下降可能导致关键的生态系统功能的丧失，如树叶的破裂。毒物在多大程度上影响淡水生态系统中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。新烟碱类化合物代表了一类相对较新的系统性杀虫剂，它们在植物中被吸收。植物材料可能进入溪流，并可能对害虫的分解产生不利影响。在这个项目中，我们将阐明新烟碱类化合物对资源多样性和叶片破裂之间的关系的影响，并调查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，将在具有天然溪水的微型宇宙中研究反复暴露于新烟碱类杀虫剂吡虫啉对六种有害动物的潜在累积亚致死效应。随后，将仔细研究两个物种的毒理动力学，以收集对生理过程的机械理解。在第二部分中，将研究来自落叶的吡虫啉和资源多样性对叶片破碎率的影响。这项实验将在三个原始溪流地点的野外围栏中进行。在项目的最后部分，我们将调查来自落叶的新烟碱类化合物是否会在食物链中产生影响。这将在野外和实验室实验中得到检验，在这些实验中，捕食者将捕食摄入受污染树叶的有害食肉动物。此外，收集器物种将获得由以吡虫啉污染的树叶为食的有害动物排泄的细颗粒有机物。总体而言，这一研究项目将大大增加对系统性杀虫剂对更多种群的有害影响、营养关系以及资源多样性和生态系统功能之间关系的机械理解。

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.