Comparison of acceptability of three anticoagulant rodenticides by the roof rat, Rattus rattus

I evaluated the acceptability of three anticoagulant rodenticides (warfarin, bromadiolone and flocoumafen) by the roof rat, Rattus rarrus, using Acceptability-index calculated by the following formula : A-index={(X-Y)/(X+Y)}×100. X=average intake (g/day/kg) of poison bait, and Y=average intake of blank bait. The average A-index in bromadiolone (50 ppm) mixed with sunflower seeds and sesame oil was 0.5 in comparison with the blank bait and the resultant mortality was 100%. This value of the index was the highest of all three rodenticides. The index in flocoumafen (50 ppm) was -42.2, which was small but the mortality was as high as 70%. The indexes in warfarin (250 ppm) mixed with seeds and oil, and warfarin (50 ppm) were -52.9 and -37.1, respectively. Both of these values in warfarin were small and the mortalities were O%. The index in warfarin (250 ppm) without seeds and oil was -65.2, which was the smallest of all test samples, though the mortality was 20%. Therefore, bromadiolone and flocoumafen are promising agents for the control of roof rats in Japan.