Page - 78 - in Biodiversity and Health in the Face of Climate Change

78 On 17 May 2018, the European Commission banned the neonicotinoids imidaclo- prid, clothianidin and thiamethoxam for field applications in EU member states. With climatic changes, the efficiency of chemical insecticides can change (thermal- dependent toxicity of specific chemicals; Kreß et  al. 2014) and the distri- bution of chemical insecticides in the environment will alter (Op de Beeck et  al. 2017). Probably enhanced by a warmer climate, insecticide resistance of arthropod vectors to chemical insecticides will evolve further (Maino et  al. 2018). In contrast, non-target organisms in aquatic environments are threatened by manifold stressors, while the combined effects of pesticides and warming may accelerate the ongoing biodiversity loss (Liess et  al. 2016). Thus, even if the use of chemical insecticides currently appears to be an easy-to-use tool, in the long term, we need new, eco- friendly and sustainable vector control tools. 4.4.2 Biological Insecticides There is a consensus between researchers, that biodiversity is a valuable resource for discovering novel insecticides (Silva-Filha 2017; Huang et  al. 2017). The ongo- ing dramatic loss of biodiversity under climate and other global changes may empty this treasure chest faster than new biological insecticides can be discovered. For a few decades, control measures have made use of natural insect toxins from Bacillus israelensis thuringiensis (B.t.i.) and the bacterial endoparasite Wolbachia spp. (mostly W. pipientis) (Baldacchino et  al. 2015). The application of B.t.i. in wetlands against floodwater mosquitoes, which are primarily annoying insects but are also known as vectors for Usutu and West Nile viruses, is assumed to be envi- ronmentally safe, although discussions on this topic are highly controversially dis- cussed (Niemi et  al. 2015; Jakob and Poulin 2016). Unfortunately, first resistance against B.t.i. has been observed, for instance in the dengue vector Aedes aegypti, and is expected to be supported by a warming climate (Paris et  al. 2011). A great success story is the contamination of Aedes mosquitoes with natural Wolbachia bacteria (Iturbe-Ormaetxe et  al. 2011). The presence of the bacteria inhibits the dengue and West Nile virus replication and hence reduces the pathogen load of mosquitoes (Ant et  al. 2018). This biological technique can also be used to suppress mosquito populations since wild females become sterilised when mating with a Wolbachia-contaminated male mosquito. The World Mosquito Program developed a Wolbachia method that enables the transmission of Wolbachia to off- spring and spreads through the whole population (http://www.eliminatedengue. com/our-research/wolbachia). This theoretically self-sustaining Wolbachia method is now in the large-scale trial phase (reviewed in Mishra et  al. 2018). Many other biological approaches have been discussed (Huang et  al. 2017). As one example, copepods have been used for a long time to control Aedes species (e.g. Vu et  al. 1998) and are now also proposed as biological agents against Culex mos- quitoes. Copepods feed on mosquito larvae (and other prey) and hence suppress populations. Since the growth rates of both prey and predator strongly depend on R. Müller et al.