DNA-based field monitoring of warfarin resistance in rats (Rattus norvegicus)

Missense mutations in a hitherto unknown gene VKORC1, have recently been shown to confer resistance to anticoagulant rodenticides in rodents. This discovery provided new opportunities for improving resistance-testing methodology by molecular-biological techniques. A PCR-based genetic test for mutations in the VKORC1 gene can successfully identify warfarin-resistant rats trapped in the field. Our investigations showed that such a test can be applied not only to rodent tissue but also to faecal pellets, allowing for a totally non-invasive sampling and testing procedure. Such genetic tests provide a simpler and cheaper methodology for monitoring the distribution of warfarin resistance in rats and mice than previous methods, thus enabling both registration authorities and users of rodenticides in their efforts to develop resistance management strategies, and helping users to avoid the use of ineffective pesticides.