Toxicity of Second Generation Anticoagulant Bromadiolone against Rattus Rattus: Individual and Sex Specific Variations

There are reports of development of resistance to the second generation anticoagulant, bromadiolone in rodents from several countries, but no systematic study has been carried out in India to record the status of bromadiolone resistance. To distinguish susceptible and resistant individuals of house rat, Rattus rattus, it was required to record their response towards toxicity of LD50 of bromadiolone. The Present study was carried out to determine LD50 value of 0.005% bromadiolone bait against R. rattus of both sexes. Different doses of cereal based bait of 0.005% bromadiolone were fed to different groups (5 rats per group) of male (1, 2, 4, 6, 8, 10, 16, 32 and 64 g/100g bw) and female (2, 4, 8, 16, 32 and 64 g/100g bw) rats. LD50 values were found to be 1.05 and 1.83 mg/kg bw of active ingredient corresponding to 2.10 and 3.67 g/100g bw of 0.005% bromadiolone bait for male and female rats, respectively. Female rats were found more tolerant to bromadiolone toxicity than male rats. In some cases, the mortality in rats of lower dose group was found more than those of higher dose group. Also, the groups which had consumed almost double the dose of bromadiolone from one another showed similar mortality rate. Within one group, days to death varied among individual rats. Present study therefore reports individual as well as sex specific variations in response towards toxicity of bromadiolone in R. rattus.