Field Evaluation Of Two Single Feeding Anticoagulant Rodenticides Against Mus Musculus In A Confined Swine Facility

Abstract:
Three commercial rodenticide bait blocks were tested at a confined swine facility in Lafayette, Indiana to compare efficacy for control of the house mouse (Mus Musculus). The three products were Talon® Ultrablok rodenticide (brodifacoum 0.005%), Final® All-Weather Blox™ (brodifacoum 0.005%), and Contrac® All-Weather Blox (bromadialone 0.005%). Pretreatment monitoring with non-toxic bait blocks and tracking pads determined that mouse populations were equivalent in the three buildings used as treatment sites. Each building was treated with toxic bait for 15 days. Bait consumption and tracking pad activity were monitored. After a three-day rest period the sites were monitored again with non-toxic bait and tracking pads for eight days. Following the monitoring, multi-catch mouse traps were placed in each building to trap mice remaining in the building. Consumption of Contrac bait (7136 grams) was significantly greater than for Talon (2454 grams) and Final (1094 grams). Consumption of Talon brodifacoum was significantly greater than Final. Following the 15 day toxic baiting period, bait consumption and tracking pad activity were significantly lower for the Talon treatment, (1% bait consumption and tracking pad activity), than for the Final (38 % bait consumption, 27% tracking pad activity) and Contrac (91% bait consumption and 78% tracking pad activity). Trap catches following baiting were 6 mice for Talon, 44 mice for Final, and 57 mice for Contrac. Results indicate that there was probably bait aversion to the Final bait and rodenticide resistance to bromadialon, the active ingredient in Contrac. DNA analysis showed that 67% of the trapped mice were homozygous for Y139C mutation for anti-coagulant resistance, and 33% were heterozygous for the same mutation. In addition 33% of the mice were homozygous for L128S mutation for anti-coagulant resistance. The test confirms the presence of single feeding anticoagulant resistance in a house mouse population in the United States.