Analysis of the current status of anticoagulant resistence in Norway rat (Rattus norvegicus) in italian populations

The norway rat, Rattus norvegicus, as well as other synanthropic rodent species, is an important pest and it is essential to find efficient strategies to control wild populations. The introduction of the anticoagulant compounds in the early 1950s produced a significant change for rodent control practices. However, after some years, first resistance events were observed in wild rodent populations. In the norway rat, anticoagulant rodenticide resistance is mainly associated with mutations in the third exon of the Vitamin K epoxide reductase complex subunit 1 (VKORC1) gene. Because of these mutations, rats may lose their susceptibility to rodenticides and become resistant. The identification of the resistant wild populations is very important to improve the control practices and to limit the damages due to a not adequate use of the anticoagulant rodenticide. Studies on anticoagulant resistence in wild populations have been made in many European and extra-European countries, but are completely lacking for Italy. In this preliminary work, the anticoagulant resistence in the Italian wild populations of R. norvegicus is tested searching mutation (SNPs) of the third exon of the VKORC1 gene known to be associated with the anticoagulant resistance (resistance SNPs, r- SNPs). We obtained sequences of the third exon for 25 norway rats from seven italian regions (Abruzzo, Calabria, Campania, Lazio, Piemonte, Toscana and Sicilia) and San Marino Republic. We didn't find r-SNPs in any individual. The work is yet very preliminary to make any hypothesis and will be continued increasing the number of individuals for each region. Furthermore, we are planning to sample norway rats from areas of use/not use of anticoagualnt rodenticides to understand if there is a relationships with the use/not use of those compounds and the presence/absence of the mutations known to confer the resistance. This work was partially supported by A.N.I.D., Associazione nazionale delle Imprese di Disinfestazione