Rodenticidal potential of bromadiolone and cholecalciferol in synergism against Bandicota bengalensis
The toxicity of standard doses of the rodenticides cholecalciferol and bromadiolone and different combinations of their use at reduced concentrations were compared against lesser bandicoot rats, Bandicota bengalensis. Mature and healthy B. bengalensis were live trapped, acclimatized, weighed and divided into groups. Cereal based baits of standard doses of cholecalciferol (0.075%) and bromadiolone (0.005%) and four combinations at lower than standard concentrations were fed to different groups of rats for 3 days in no-choice feeding tests. Rats of the control group were fed on plain food. Whole blood of treated and untreated rats was collected before treatment and 48 h of treatment to determine changes in levels of calcium and phosphorous and clotting time. 100% mortality of rats was caused at all the treatments with in 3–6 days. Acceptance of treatment baits over plain food was found to vary from 62 to 92%. A significant increase in serum levels of calcium (P ≤ 0.05) and phosphorous (P ≤ 0.05) was recorded after 48 h of treatment in groups of rats fed on bait containing the standard dose of cholecalciferol as well as the four combination baits. In groups of rats fed on the standard dose of bromadiolone as well as the four combinations, a significant increase in blood clotting time after 48 h of treatment as revealed by the increase in prothrombin time (P ≤ 0.05) and international normalized ratio (P ≤ 0.05) was observed. The consumption of treatment bait on day 3 of treatment was significantly (P ≤ 0.05) less from that consumed on days 1 and 2 of treatment. Present studies suggest the bait combination having lowest concentrations of bromadiolone (0.001%) and cholecalciferol (0.005%) to be cost effective for population management of B. bengalensis.