THE EFFICACY OF A TRACKING-EDIBLE ZINC PHOSPHIDE/MOLASSES GEL DELIVERY SYSTEM FOR CONTROLLING ROOF RATS COMPARED WITH A TRADITIONAL METHOD

The present study was carried out as an attempt to overcome bait shyness developed by rats when they ingest sub-lethal doses of rodenticides. It depends on incorporating a rodenticide with a gel contaminant. Contaminated rodents would then ingest the toxicant during grooming and die. The efficacy of a tracking-edible zinc phosphide/molasses gel delivery system was tested through non-choice and free-choice laboratory feeding tests. In non-choice tests, the results indicated that the consumption of plain molasses gel equals 6.6% of the average individual body weight, while the consumption of the toxicant/gel bait equals 7.5% of that weight. The average daily amount of zinc phosphide ingested, in the form of toxicant/gel bait, was 68.4 mg/ a rat. Rat mortality was 75% over 2 days. In freechoice tests, the average daily consumption of plain molasses gel was 48.7% of that of crushed maize, and its acceptability was 32.9%. The average daily consumption of the toxicant/gel bait was 56% that of crushed maize. The daily mount of zinc phosphide ingested by individual rats was 21 mg/individual rat. This amount was sufficient to kill 50% of tested caged rats. The acceptability of the gel/ toxicant bait was 36.2%. The average daily consumption of 0.5% zinc phosphide/crushed maize bait was lower than the average daily consumption of plain crushed maize. The acceptability and mortality were 19.3% and 33.3%, respectively. The results of the present study indicate that the acceptability, against plain crushed maize, of the toxicant/gel was about twice that of the toxicant/crushed maize and that the mortality among rats exposed to the toxicant/gel bait was higher than that among rats exposed to toxicant/crushed maize bait.