Selecting bait base to increase uptake of zinc phosphide and warfarin rodenticide baits

Rodent pests cause major economic losses to rice crops and inflict health risk to people and live-stock in villages. Maize-based baits were used traditionally to control ricefield rodents. This study aimed to determine if replacing maize with rice as bait base would increase uptake of zinc phosphide and warfarin wax block baits in maturing rice crops, fallow fields and villages. The study site was in lowland ricefields in Cambodia. Nineteen experimental plots were placed in the three habitats, with three/four plots treated with zinc phosphide and three with warfarin per habitat. Each plot consisted of five bait points each with rice and maize-based toxic and non-toxic baits. Mean bait uptake was increased by 65% through replacing maize with rice as the base. Such increase was greater with warfarin being the active ingredient than with zinc phosphide, but both increases were substantial (62% and 51%). The increase was high in villages (85%) and maturing rice crops (79%), and lower in fallow fields (49%). We recommend that rice be the base in both baits.