Bromadiolone susceptibility in Mus musculus (house mice) of Argentina

Mus musculus (house mouse) is a serious rodent pest in poultry farms of Argentina. In these habitats, bromadiolone is the most frequently used anticoagulant. In spite of this control, more than 90% of the farms are infested with rodents. The frequent application of anticoagulants and the permanent presence of M. musculus suggest that there are resistant rodent populations. The goal of this study was to assess bromadiolone susceptibility through a blood clotting response (BCR) test in M. musculus populations inhabiting poultry farms of Exaltacion de la Cruz, Buenos Aires, Argentina. Results showed that 56.6% of wild M. musculus were responders to the BCR test. We found non-responder individuals in all the poultry farms studied. Non-responder females had at least one non-responder offspring. Since the percentages of resistant animals per poultry farm were high and considering that bromadiolone is extensively used for rodent control in these habitats, there is a potential risk of an increase in the proportion of resistant individuals and a decrease in the effectiveness of bromadiolone through time in the study area. Besides, our results suggest that this resistance has a genetic basis because non-responder mothers had non-responder offspring.