The stop-feed effect of cholecalciferol (vitamin D) and the efficacy of brodifacoum combined with cholecalciferol in Y139C-resistant Norway rats ().

Second-generation anticoagulant rodenticides potentially build persistent residues in animals and accordingly pose a risk of secondary poisoning. We examined the effect of a low concentration of cholecalciferol in brodifacoum bait on bait consumption by Norway rats ( Berkenhout 1769) and on the control success in a laboratory study and in field trials. Additionally, the efficacy of both baits was determined against resistant Y139C rats.

Anticoagulant rodenticide blood-clotting dose-responses and resistance factors for Tyrosine139Cysteine (Y139C) heterozygous- and homozygous-resistant house mice (Mus musculus).

Background: The house mouse (Mus musculus) is a globally distributed rodent pest species against which anticoagulant rodenticides are widely used for the protection of human and animal health and the conservation of threatened wildlife. Anticoagulant-resistant house mice have been known for more than half a century. A house mouse strain was developed in the laboratory that was homozygous resistant for the single nucleotide polymorphism (SNP) Tyrosine139Cysteine (Y139C) and, subsequently, heterozygous resistant animals were produced from this strain by crossing with the homozygous susceptible strain.

Effects of anticoagulant rodenticide poisoning on spatial behavior of farm dwelling Norway rats.

Commensal rodent species cause damage to crops and stored products, they transmit pathogens to people, livestock and pets and threaten native flora and fauna. To minimize such adverse effects, commensal rodents are predominantly managed with anticoagulant rodenticides (AR) that can be transferred along the food chain. We tested the effect of the uptake of the AR brodifacoum (BR) by Norway rats (Rattus norvegicus) on spatial behavior because this helps to assess the availability of dead rats and residual BR to predators and scavengers.

The potential of coumatetralyl enhanced by cholecalciferol in the control of anticoagulant-resistant Norway rats (Rattus norvegicus).

Background: We evaluated the potential of cholecalciferol as an enhancer of the first-generation anticoagulant coumatetralyl in the Westphalia anticoagulant-resistant strain of the Norway rat (Rattus norvegicus Berkenhout), characterised by the Tyr139Cys polymorphism on the VKOR enzyme. Because today only the most potent, but also most persistent anticoagulant rodenticides of the second generation remain available to control this strain, new rodenticide solutions are required.

Results: Feeding trials in the laboratory confirmed a significant level of efficacy, which was corroborated by field trials in the Münsterland resistance area.

Resistance testing and the effectiveness of difenacoum against Norway rats (Rattus norvegicus) in a tyrosine139cysteine focus of anticoagulant resistance, Westphalia, Germany.

Background: Anticoagulant resistance in Norway rats at foci in Belgium, Denmark, France, Germany, the Netherlands and the United Kingdom is genetically characterised by the same single nucleotide polymorphism (SNP) and consequent amino acid exchange from tyrosine to cysteine at location 139 of the vkorc1 gene (i.e. tyrosine139cysteine or Y139C).

Vkorc1 variation in house mice during warfarin and difenacoum field trials.

Background: Field studies guided by genetic monitoring of Vkorc1 need to be done to implicate mutations conclusively with rodent control problems due to the presence of animals resistant to anticoagulant rodenticides. Rodent control success in relation to Vkorc1 genotypes in house mice (Mus musculus domesticus) was studied on two farms (I and II) in Germany. Tests were carried out to determine whether certain resistance profiles and Vkorc1 genotypes displayed dynamics over the course of sequential treatments with warfarin and difenacoum that were consistent with single nucleotide polymorphisms (SNPs) in Vkorc1 as indicators of resistance.

Resistance tests and field trials with bromadiolone for the control of Norway rats (Rattus norvegicus) on farms in Westphalia, Germany.

Background: The aim of this study was to determine the incidence and the level of resistance to bromadiolone among rats on farms suspected of being foci of resistance by using the international normalised ratio (INR)-based blood clotting response (BCR) test. Whether the level of reduced susceptibility constitutes 'practical resistance' was subsequently determined in field trials.

Results: The 2.

Vitamin K requirement and reproduction in bromadiolone-resistant Norway rats.

Background: Nucleotide polymorphisms in the VKORC1 gene can be linked to anticoagulant rodenticide resistance in Norway rats (Rattus norvegicus Berkenhout). This provides a fitness advantage to rats exposed to anticoagulant actives, but may also cause fitness costs. The vitamin K requirement and reproductive parameters of bromadiolone-resistant rats (Westphalian resistant strain; VKOR variant Tyr139Cys) and bromadiolone-susceptible Norway rats were compared.

Adaptive introgression of anticoagulant rodent poison resistance by hybridization between old world mice.

Polymorphisms in the vitamin K 2,3-epoxide reductase subcomponent 1 (vkorc1) of house mice (Mus musculus domesticus) can cause resistance to anticoagulant rodenticides such as warfarin [1-3]. Here we show that resistant house mice can also originate from selection on vkorc1 polymorphisms acquired from the Algerian mouse (M. spretus) through introgressive hybridization.