What is the problem/issue being addressed? Vole populations can attain extremely high densities during their multiannual population cycles (Krebs 2013). As a result, they produce damages in agriculture lands and are controlled with anticoagulant rodenticides by some farmers (Sage et al. 2008, Delattre and Giraudoux 2009). That poses a human-wildlife conflict because vole control reduces the amount of key food sources for predators but also increases the risks of secondary poisoning to predators that eat intoxicated voles (Delibes-Mateos et al. 2011, Coeurdassier et al. 2014). If predator populations are eliminated there may be higher chances of recurrent vole outbreaks and thus long-lasting need of controlling the vole population by rodenticides.
Why is it important for society? Vole damages may inflict economic losses up to of 10000 € for each worker unit in farms during an entire cycle (Schouwey et al. 2014). Using rodenticides can impose higher costs for production and thus reduce the profits of farmers (Stenseth et al. 2003). In addition, society is increasingly concerned about the origin of products, the way they are produced and the potential side effects of the use of pesticides given their negative effects on biodiversity and public health (Jacquot et al. 2013, Mitchell et al. 2017).
What are the overall objectives? To study the role of rodenticides as super-predator that eliminates both voles and predator populations, through the transfer of this pesticide within the trophic chain. Moreover, to understand the demographic impacts that rodenticides may have on the long term. In addition, to explore protocols of rodenticide application beneficial for both agriculture and conservation.
Conclusions: Anticoagulant rodenticides may produce population declines in voles and their predators like small mustelids (weasels and stoats). The findings obtained here from model show the super-predator role of anticoagulant rodenticides, affecting the population dynamics of predators and voles. For treatments carried out homogeneously over large areas, this happens especially with rodenticide application at very low vole densities, which produce the deepest declines in small mustelid populations and favors further treatments to buffer the vole population growth. To reach consensus between farm production and conservation purposes, the best way to apply rodenticides would include treatment during the increase phase of vole population cycles, with low quantity of bromadiolone and time breaks of treatment stop, in which vole and predator populations are maintained. Anyway, the results of the modeling part are non-spatial and should be further validated. This is because, in real conditions, treatment is not conducted in all agricultural parcels and there are refuges, for instance, woodlands. Therefore, next steps should take into account this spatial heterogeneity.
