| Abstract: | The traditional technique of applying anticoagulant rodenticides, as shaped by long experience in the use of low-toxicity, first-generation anticoagulants such as warfarin, aims to maximize treatment efficiency by maximizing the rate of bait consumption by the target rodents. This is done, somewhat laboriously, by laying surplus amounts of bait initially, and maintaining this surplus throughout the treatment by repeatedly replenishing the bait placements. The suggestion that the high toxicity of the second-generation anticoagulants should enable a more efficient baiting system to be designed is examined experimentally in this field study of the control of Rattus norvegicus on British farms. Bait toxicity, infestation size and the incidence of complete takes of bait were found to be independent and highly significant determinants of treatment duration whilst, in comparison, the size and density of bait points and the frequency with which the bait was replenished were found to be relatively unimportant. However, bait size and, more especially, replenishment frequency had detectable secondary effects, apparently through partial relationships with the incidence of complete takes and infestation size. The results indicate, in relation to the control of commensal infestations of R. norvegicus on British farms, that the use of high-toxicity bait formulations and frequent replenishment schedules increase the speed of control, whilst the number and size of bait placements are relatively unimportant; they also suggest that reductions in the frequency of bait replenishment made in order to save labour could be compensated for by increasing the toxicity of the bait and taking other steps to reduce the incidence of complete takes of bait. The results are discussed in relation to the concept of ‘pulsed baiting'. |
