Lack of scientific evidence and precautionary principle in massive release of rodenticides threatens biodiversity: old lessons need new reflections

Abstract

SUMMARYPesticides are widely used throughout the world to control agricultural pests. Owing to their well identified side-effects on wildlife, the release of high quantities of pesticides to the environment should always require responsible use of both science-based information and the precautionary principle, however decision making in wildlife management and conservation is not systematically supported by scientific evidence. This is particularly worrying when decision making involves release of toxic substances to the environment, as often occurs in rodent plague control. Poorly-informed management decisions to control a rodent plague can adversely affect wildlife, especially when chemical-based treatments are generically designed and applied on a broad scale, with high economic cost. Evidence-based and environmentally sustainable management should be used to control rodent plagues in Spain.

Is insecticide spraying a viable and cost-efficient management practice to control pine processionary moth in Mediterranean woodlands?

“…Such decline occurs not only because trees react to strong defoliation by producing inadequate food for the next generation of insects , but also because there is an increase in insect parasitoid and predatory bird populations (Berryman, 2002;Barbaro and Battisti, 2011), all of which causes a collapse of the PPM population density. Similar results have been found for pheromone traps that aim to control bark beetle (Ips typographus L.) outbreaks in Poland (Grodzki et al, 2006), and massive releases of rodenticides that were used to control outbreaks of common voles Microtus arvalis between 2006 and 2007 in areas of north-western Spain (Olea et al, 2009). These authors attributed lack of difference between treated and untreated samples to natural declines of the pest populations due to exhaustion of resources and an increase of natural enemies (predators, parasitoids, etc.).…”

Factors influencing diet variation in a generalist predator across its range distribution

“…More precisely, for lagomorphs and small mammals we used published data on the distribution of the main Montagu's harrier mammal prey species in order to determine their presence/absence in each study site included in the analysis (Mitchell-Jones et al 1999). If a species was present in a study area, we assessed whether its abundance warranted a classification of three (particularly abundant) by referring to other literature sources, such as maps of small rodent outbreaks (Spitz 1977;Myllymäki 1977;Delattre et al 1992;Olea et al 2009) and maps of lagomorph abundance (Villafuerte et al 1998;Rogers et al 1994). In the case of birds, we used the European atlas of breeding birds (Hagemeijer and Blair 1997) to assess how many of the species known as regular prey of the Montagu's harrier (larks, pipits, wagtails, wader and galliform chicks) were present at each study site, and created an index of abundance by adding the number of bird species present at each site.…”

Conservation conflicts involving mammals in Europe

“…In some European countries, for example, anticoagulant rodenticides (i. e. bromadiolone) are sometimes applied intensively to control rodents that cause crop damage, such as common voles (Microtus arvalis) and water voles (Arvicola terrestris) in Spain and France, respectively (Olea et al 2009;Coeurdassier et al 2014). Anticoagulant rodenticides invariably cause secondary poisoning of non-target species, and bromadiolone particularly is known to affect predators and scavengers (Berny 2007).…”

“…In France, for example, some raptors of conservation concern like red kites (Milvus milvus) and common buzzards (Buteo buteo) were poisoned by bromadiolone after a recent vole control campaign (Coeurdassier et al 2014). Similarly, in Spain other protected bird species like the great bustard (Otis tarda) were affected by rodenticide treatments (Olea et al 2009). The high level of poisoning of wildlife that follows such treatments over large areas is something that concerns conservationists and leads to frequent tensions between these and farmers (Ferreira and Delibes-Mateos 2012).…”