Abstract
Anticoagulant rodenticides (ARs) are widely used pesticides to control rodent populations. Bromadiolone, a second generation anticoagulant rodenticide (SGARs), is authorized in France to control the population of water voles (Arvicola scherman). The persistence of SGARs in rodents is responsible for secondary exposure or poisoning of predators and scavengers, and is of ecological concern for the conservation of endangered species. Commercial formulations are a mixture of two diastereoisomers of bromadiolone: 70–90% is trans-bromadiolone and 10–30% is cis-bromadiolone. Both diastereoisomers have been shown to inhibit coagulation function with the same potency. On the other hand, cis-bromadiolone has been shown to be less tissue-persistent than trans-bromadiolone in rats. This difference led to residue levels in rats with substantially weakened proportion in cis-bromadiolone compared to the composition of baits.In this study, a multi-residue LC-MS/MS method for the quantification of the diastereoisomers of SGARs was used to investigate their proportions in field samples of predators. In 2011, 28 red kites (Milvus milvus) were found dead within a few months of bromadiolone application in grassland to control water vole outbreaks. In this study, we report the concentrations of the two diastereoisomers of bromadiolone measured in the livers of thirteen red kites. Exposure to bromadiolone was apparent in all the kites with hepatic concentrations of trans-bromadiolone ranging from 390 to 870ng/g (89 to 99% of summed SGARs). However, cis-bromadiolone was not detected in 5 of 13 red kites and was present at very low concentrations (below 2.2ng/g) in 8 of 13 kites, demonstrating that cis-bromadiolone is not involved in this red kite poisoning event. The results suggest that a change of the proportions of bromadiolone diastereoisomers in baits could reduce the risk of secondary poisoning of predators, but retain primary toxicity for control rodent outbreaks.
Highlights
Anticoagulant Rodenticides (ARs) are used worldwide to control or eradicate rodent populations
“The presence of large quantities of trans-bromadiolone in liver (390-871ng/g), and macroscopic haemorrhages in 77% of the birds provides strong evidence that bromadiolone was involved in the death of the red kites.”
Bromadiolone, a second generation anticoagulant rodenticide (SGARs), is 29 authorized in France to control the population of water voles (Arvicola scherman)
Summary
Anticoagulant Rodenticides (ARs) are used worldwide to control or eradicate rodent populations. These pesticides have often been associated with non-target secondary poisonings of predatory and scavenging birds (Sanchez-Barbudo et al, 2012; Hughes et al, 2013; Ruiz-Suarez et al, 2014; Langford et al, 2013; Jaffe et al, 2016; Christenssen et al, 2012; Hughes et al, 2013 ; Coeurdassier et al, 2014a) and carnivorous mammals (Geduhn et al, 2016; Sage et al, 2010; López-Perea et al, 2015; Ruiz-Suarez et al, 2016; Jacquot et al., 2014) through the ingestion of contaminated rodents. Secondary exposure has not completely disappeared and new additional approaches are required to reduce adverse effects of ARs on predators and scavengers (Rattner et al, 2014; Coeurdassier et al, 2014b; Elliott et al, 2016; Smith and Shore, 2015)
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