USC 1233 RS2GP, INRAe, VetAgro Sup, Univ Lyon, F-69280 Marcy l'Etoile, France.
SEOR, 13 ruelle des orchidées, 97440 Saint André, La Réunion, France.
Sci Total Environ. 2021 Jul 20;779:146287. doi: 10.1016/j.scitotenv.2021.146287. Epub 2021 Mar 11.
The Réunion harrier is an endangered raptor and endemic species to the Réunion Island. Second generation anticoagulant rodenticides (SGARs) are widely used pesticides on the island in order to control rodent populations. The latter are responsible for the transmission of leptospirosis to humans, the damage of sugarcane crops, and the decline of endemic endangered birds. SGARs are very persistent chiral pesticides and consequent secondary exposure or poisoning of the Réunion harrier has been observed (73% of prevalence in a group of 58 harriers). Commercial formulations of SGARs are a mixture of trans- and cis-diastereoisomers. Both diastereoisomers of all SGARs have been shown to inhibit coagulation function with the same potency. On the other hand, they have been shown to have a significant difference in terms of tissue-persistence. This difference has led to residue levels in rats with a significantly lower proportion of one of the isomers compared to the bait composition. In this study, residue levels of the diastereoisomers of all SGARs were evaluated in the livers of 58 harrier carcasses. The respective concentrations and proportions of cis- and trans- diastereoisomers of all SGARs are presented. cis-Brodifacoum and trans-bromadiolone had the highest concentrations (up to 438 and 573 ng/g ww respectively), while trans-brodifacoum was less than 46 ng/g and cis-bromadiolone was barely detected. cis-Difenacoum showed the highest prevalence and the highest concentration was 82 ng/g ww, while trans-difenacoum was never detected. This study demonstrated that only cis-brodifacoum and trans-bromadiolone (and cis-difethialone, but with a low prevalence) had hepatic concentrations above a toxic threshold. The cis- and trans-diastereoisomers of SGARs had differential bioaccumulation in the food chain of the Réunion harrier compared to commercial baits. This suggests that a change of the proportions of SGARs diastereoisomers in baits could reduce the risk of secondary poisoning of predators, but maintain primary toxicity.
留尼汪岛猎隼是一种濒危猛禽，也是该岛的特有物种。第二代抗凝血灭鼠剂（SGARs）在该岛被广泛用作杀虫剂，以控制鼠类种群。鼠类会传播钩端螺旋体病给人类，破坏甘蔗作物，并导致当地濒危鸟类数量减少。SGARs 是非常持久的手性杀虫剂，因此已经观察到留尼汪岛猎隼出现二次暴露或中毒的情况（在 58 只猎隼中，有 73%的患病率）。SGARs 的商业制剂是 trans-和 cis-非对映异构体的混合物。所有 SGARs 的这两种非对映异构体都被证明具有相同的凝血功能抑制作用。另一方面，它们在组织持久性方面表现出显著差异。这种差异导致在大鼠中的残留水平与诱饵组成相比，其中一种异构体的比例明显降低。在这项研究中，评估了 58 只猎隼尸体肝脏中所有 SGARs 的非对映异构体的残留水平。介绍了所有 SGARs 的顺式和反式非对映异构体的浓度和比例。顺式溴敌隆和反式溴鼠灵的浓度最高（分别高达 438 和 573ng/g 湿重），而反式溴敌隆低于 46ng/g，顺式溴鼠灵几乎检测不到。顺式氯丹的检出率最高，浓度最高可达 82ng/g 湿重，而反式氯丹从未检出。本研究表明，只有顺式溴敌隆和反式溴鼠灵（以及顺式氯丹，但检出率较低）在肝脏中的浓度超过了毒性阈值。与商业诱饵相比，SGARs 的顺式和反式非对映异构体在留尼汪岛猎隼的食物链中有不同的生物累积。这表明改变诱饵中 SGARs 非对映异构体的比例可以降低捕食者二次中毒的风险，但保持初级毒性。
