Relation between Intensity of Biocide Practice and Residues of Anticoagulant Rodenticides in Red Foxes (Vulpes vulpes)

Abstract

Anticoagulant rodenticides (ARs) are commonly used to control rodent infestations for biocidal and plant protection purposes. This can lead to AR exposure of non-target small mammals and their predators, which is known from several regions of the world. However, drivers of exposure variation are usually not known. To identify environmental drivers of AR exposure in non-targets we analyzed 331 liver samples of red foxes (Vulpes vulpes) for residues of eight ARs and used local parameters (percentage of urban area and livestock density) to test for associations to residue occurrence. 59.8% of samples collected across Germany contained at least one rodenticide, in 20.2% of cases at levels at which biological effects are suspected. Second generation anticoagulants (mainly brodifacoum and bromadiolone) occurred more often than first generation anticoagulants. Local livestock density and the percentage of urban area were good indicators for AR residue occurrence. There was a positive association between pooled ARs and brodifacoum occurrence with livestock density as well as of pooled ARs, brodifacoum and difenacoum occurrence with the percentage of urban area on administrative district level. Pig holding drove associations of livestock density to AR residue occurrence in foxes. Therefore, risk mitigation strategies should focus on areas of high pig density and on highly urbanized areas to minimize non-target risk.

Poisoning by Anticoagulant Rodenticides in Humans and Animals: Causes and Consequences

“…Wildlife expositions or intoxications to ARs have been reported around the world for many mammals such as minks [70], bobcats [71], stoats and weasels [72], foxes [73,74] and boars [67] and as well for many birds [75][76][77]. Exposition of ish was reported near an island where an eradication of rodent with brodifacoum was performed and the risk for human through the consumption appeared very low [78].…”

Development of an Ecofriendly Anticoagulant Rodenticide Based on the Stereochemistry of Difenacoum

“…Because of this increased persistence in animal tissues, especially in liver (Langford et al, 2013), the use of SGARs is associated with an increased risk of secondary poisoning for predators and scavengers feeding on contaminated rodents. Evidence of secondary poisoning was confirmed in predatory bird species such as barn owl (Tyto alba), buzzard (B. buteo), kestrel (Falco tinnunculus), Red kyte (Milvus milvus), and tawny owl (Strix aluco) (Christensen et al, 2012 ;Hughes et al, 2013 ;Geduhn et al, 2015), in predatory mammals such as red foxes (Vulpes vulpes) (Sage et al, 2010), European mink (Mustela lutreola) (Fournier-Chambrillon et al, 2004), weasels (Mustela nivalis) (Elmeros et al, 2011). Therefore, ARs were identified by the European Union as candidates for future comparative risk assessment and substitution in view of their unacceptable risk of secondary poisoning for wildlife.…”

A negative association between bromadiolone exposure and nestling body condition in common kestrels: management implications for vole outbreaks

“…Regardless of its use, our results confirm that bromadiolone concentration is detectable in the blood of non‐target species during their development, and that this might reduce their body condition. Further research is required about how and to what extent the concentration levels we describe in this study can be accumulated in the liver of individuals, what might increase the persistence of bromadiolone in non‐target species and the conservation implications beyond the time of use of SGARs …”

“…These undesired effects have led to management strategies for controlling the spatiotemporal use of these rodenticides by farmers to reduce their environmental impacts . SGARs are widely used both as biocides in more urbanised areas and as pesticides in croplands, increasing the exposure to bromadiolone for non‐target species . The European Union (EU) has recently implemented a new legal framework for their use in open land, so baits must be buried or disposed of within rodents' burrows, in an attempt to reduce exposure to other taxa .…”