Field efficacy studies using three anticoagulant rodenticides were conducted on House mice, Mus musculus under a variety of conditions in 35 apartment buildings scattered over four boroughs of New York metropolitan area. Percent control successes and relative efficacies of various rodenticides and their formulations were determined by recording pre and post control census for about four years. After four monthly treatments, the control success rate of bromadialone (0.005%, meal form) was highest (94.5%) followed by brodifacoum (0.005%, pellet form, 91.23%) and diphacinone (77.72%) in the wax cake formulation. However, build-up of the residual mice population was faster in the case of bromadialone treatment when compared to brodifacoum (P < .01). Results of intermittent control operation, bi-monthly and biweekly, are compared and discussed with respect to mice population dynamics and properties of the rodenticides.

Comparative efficacy of brodifacoum, bromadiolone (second-generation single-dose anticoagulant) was evaluated in a coconut crop on Minicoy Island. Pre- and post-rodent control relative levels of rodent populations and damages were recorded as indices for assessing effectiveness of different concentrations and different bait formulations of three rodenticides. The black rat, Rattus rattus (Linnaeus), constituting a new record for Minicoy Island, was the predominant rodent species infesting the coconut crop. On an average, application of brodifacoum (.005% and .002%), bromadiolone (.005% and .002%) and warfarin (0.025% ) reduced rodent populations by 74.5, 73.58, 79.1, 69.16 and 68.44% respectively, resulting in reduction of rodent damages to nuts by 74.93, 70.26, 78.24, 69.53 and 61.9% respectively. However, brodifacoum (.005% ) impregnated with rice and coconut oil controlled rodents by 86.88% with reduction in damages by 82.85% . It was followed by bromadiolone (.005%) mixed with rice and coconut oil giving 86.48 and 83.33% control of rodents and damages, respectively. Except in the case of brodifacoum (.005%), where pulse baits were more effective than ragi baits, the effectiveness of baits followed the order of rice>ragi>pulse. Similarly, coconut oil proved to be best attractant followed by groundnut oil and palm oil. Results of these field rodent control studies are compared with field/ laboratory evaluations of respective rodenticides on Rattus rattus.

Control operations at 6-month intervals, continued for four years in crop fields, reduced the rodent population to 5.08 percent losses to agricultural production. After eight crop seasons, a significant reduction in rodent density was observed in treated areas when compared with that of the control areas (P < 0.01). Correlation between pre-treatment population index (y) and number of seasons (log of x) was found to be 0.91 (P< 0.01). A relationship was established between y and x: y = 0.804.0-0.9621 log x. From this equation, it can be inferred that rodent population will reach zero level after treating crop fields continuously for 6.85 or say 7 .0 (seven) seasons. After control, the numbers of predominant rodents, Tatera indica, Meriones hurrianae, and Rattus meltada, were significantly reduced and the residual population was composed of Mus booduga, Gerbillus spp., Rattus gleadowi, Golunda ellioti, and Funambulus pennanti.