Neonicotinoids in nature: The effects on aquatic invertebrates and their role in ecosystems

This thesis describes the role of pollution, specifically neonicotinoid insecticides, as an actor of the ongoing biodiversity decline. Using a new research facility, the Living Lab, the effects of field relevant concentrations of neonicotinoids and fertilizers to aquatic invertebrates was assessed in 36 experimental ditches. This showed that neonicotinoids had profound impacts on both single species as well as macroinvertebrate biodiversity and had severe consequences for the ecosystem processes the invertebrates fulfilled. Many of the results found in this thesis have not been discovered before because of the simplicity of standardized ecotoxicological testing, which not fully incorporates the myriad of ecological factors governing toxicity. It was found that the addition of fertilizers directly stimulated primary production which in turn reduced toxic effects indirectly. In addition, the neonicotinoid thiacloprid induced indirect effects on aquatic biodiversity which persisted much longer than the presence of this insecticide in the ditch ecosystem. The results in this thesis therefore show how the inclusion of environmentally realistic testing is essential to predict the actual risks of agrochemicals in the actual environment.