Mus musculus populations in Western Australia lack VKORC1 mutations conferring resistance to first generation anticoagulant rodenticides: Implications for conservation and biosecurity

From chip to SNP: Rapid development and evaluation of a targeted capture genotyping-by-sequencing approach to support research and management of a plaguing rodent

The management of invasive species has been greatly enhanced by population genetic analyses of multilocus single-nucleotide polymorphism (SNP) datasets that provide critical information regarding pest population structure, invasion pathways, and reproductive biology. For many applications there is a need for protocols that offer rapid, robust and efficient genotyping on the order of hundreds to thousands of SNPs, that can be tailored to specific study populations and that are scalable for long-term monitoring schemes. Despite its status as a model laboratory species, there are few existing resources for studying wild populations of house mice (Mus musculus spp.) that strike this balance between data density and laboratory efficiency. Here we evaluate the utility of a custom targeted capture genotyping-by-sequencing approach to support research on plaguing house mouse populations in Australia. This approach utilizes 3,651 hybridization capture probes targeting genome-wide SNPs identified from a sample of mice collected in grain-producing regions of southeastern Australia genotyped using a commercially available microarray platform. To assess performance of the custom panel, we genotyped wild caught mice (N = 320) from two adjoining farms and demonstrate the ability to correctly assign individuals to source populations with high confidence (mean >95%), as well as robust kinship inference within sites. We discuss these results in the context of proposed applications for future genetic monitoring of house mice in Australia.

Widespread resistance to anticoagulant rodenticides in Mus musculus domesticus in the city of Barcelona

Control of rodent populations is a big challenge because of the rapid evolution of resistance to commonly used rodenticides and the collateral negative impacts that these products may have on biodiversity. Second-generation anticoagulants are very efficient but different single nucleotide polymorphisms (SNPs) in the Vkorc1 gene may confer resistance in rodents. We sequenced exons 1, 2 and 3 of the Vkorc1 gene from 111 mice (Mus musculus domesticus) captured across the city of Barcelona and found SNPs associated with resistance to first- and second-generation anticoagulants in all of them. Although most of the SNPs were associated with resistance to bromadiolone, we also found SNPs associated with resistance to brodifacoum. Out of all the individuals analyzed, 94.59 % carried mutations associated to introgression events with Mus spretus, a sympatric rodent species. Currently most of the chemical products for rodent control commercialized in the area are based on bromadiolone, although recent public control campaigns have already shifted to other products. Thus, the widespread occurrence of resistant mice to bromadiolone represents a challenge for rodent control in Barcelona and may increase the risk of secondary poisoning of animals preying on this species. Public health managers, pest control companies and citizens should be aware that the use of bromadiolone based products is ineffective and represents a risk for the environment, including human and animal health.