A survey of VKORC1 missense mutations in eleven Italian islands reveals widespread rodenticide resistance in house mice

• Published in: The Science of the total environment Vol. 953; p. 176090
• Main Authors: Gallozzi, Francesco, Attili, Lorenzo, Colangelo, Paolo, Giuliani, Davide, Capizzi, Dario, Sposimo, Paolo, Dell'Agnello, Filippo, Lorenzini, Rita, Solano, Emanuela, Castiglia, Riccardo
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 25.11.2024
• Subjects: Anticoagulant rodenticides; House mouse; Island conservation; Mus domesticus; Resistance; VKORC1; VKORC1; Resistance; House mouse; Anticoagulant rodenticides; Mus domesticus; Island conservation
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.176090

To protect native wildlife, more than one hundred rodent eradications have been attempted in the Mediterranean islands by using anticoagulant rodenticides (ARs). Despite their high efficiency, resistance to ARs has been observed in many countries and it is mostly related to missense mutations (SNPs) in the VKORC1 gene. The presence of resistant individuals reduces the efficiency of rodent management, leading to an excessive use of ARs. Thus, the risk of poisoning in non-target species increases. In this study, the first survey of ARs resistance in the house mouse Mus domesticus covering multiple islands in the Mediterranean was performed. Tissue samples of eighty-two mice from eleven islands in Italy were analysed and eight missense SNPs were found. In addition to some well-known missense mutations, such as Tyr139Cys, six new missense SNPs for the house mouse were discovered, four of which were new even for any rodent species. Furthermore, the frequency of Tyr139Cys significantly increased in Ventotene Island after a four-year long rat eradication. This could be due to the selective pressure of ARs that allowed the mice carrying the mutation to survive. This study demonstrates once again the importance of assessing resistance to ARs before undertaking rodent eradications. Indeed, this would allow an informed decision of the most effective AR to use, maximizing the success rate of the eradications and minimizing secondary poisoning and other deleterious effects for non-target species and the environment. [Display omitted] •Anticoagulant rodenticides (ARs) are commonly used in the Mediterranean islands.•Almost no knowledge about ARs resistance is available for this area.•The VKORC1 gene was sequenced in 82 house mice from 11 islands in Italy.•Resistance to the most used ARs is widespread in the study area.•Different types of ARs should be adopted to reduce impacts on non-target species.