Evaluation of secondary poisoning of difethialone, a new second-generation anticoagulant rodenticide to barn owl, Tyto alba Hartert under captivity.

Secondary toxcity of difethialone to Barn owl (Tyto alba) has been investigated. Difethialone was fed to owls for successive periods of 1 (phase 1), 3 (phase 2) and 6 (phase 3) days via-rodenticide dosed rats. The owls survived after the treament of rodenticide on phase 1 and phase 2 experiments but they died during phase 3 experiment. The results suggest that the difethialone could cause more secondary toxicity to owls.

Studies on Merops orientalis Latham 1801 with special reference to its population in Mayiladuthurai, Tamil Nadu.

Role of habitat-structure and climatic factors in the population dynamics of the small green bee-eater Merops orientalis was evaluated in three habitats viz., agricultural lands, river banks and human habitations during 1991-1993. The river banks supported relatively high population of bee-eaters (157/Km2) followed by the agricultural lands (101/Km2) and human habitations (58/Km2). Bee-eater populations showed year-wise variations in river banks and human habitations having high values during 1992 (123/Km2) and 1993 (43/Km2) respectively. Agricultural lands showed a significantly low mean density in 1991 than other years. Seasonal variations in the bee-eater densities among the habitats were also recorded. Vegetation structure, food (insects) availability, climatic conditions and human disturbance were the casual factors for variations in bee-eater populations.

Field evaluation of difethialone, a new second generation anticoagulant rodenticide in the rice fields.

A new second generation anticoagulant rodenticide, difethialone (0.0025%), was evaluated in the rice fields at three different cropping stages, viz. Milky, Panicle formation and Panicle maturation, during Kuruvai and Thaladi seasons. The difethailone (0.0025%) yielded satisfactory control success suggesting a great potential as a rodenticide especially in the early stages of rice.

Evaluation of two rodenticides in the paddy fields during Samba and Thaladi seasons.

The single dose anticoagulant rodenticide, bromadiolone (0.005%) and the acute rodenticide, zinc phosphide (2%) were evaluated in the paddy fields during Samba and Thaladi seasons for two crop stages, viz. 20 and 40 days after transplantation. Three baiting methods namely, burrow, station and burrow+station were adopted for both rodenticides. Both the rodenticides were exposed for one and two days in the partitioned plots. In the plots with 20 days after transplantation, the two day exposure of both rodenticides in burrow+station baitings during both seasons cleared cent percent rodent population. The cost-benefit ratio of the employed rodenticides favoured zinc phosphide than bromadiolone. Thus, zinc phosphide is deemed to be an economic rodenticide than bromadiolone and it can be suggested for the control of rodent population with two day exposure by burrow+station baiting methods preferably 20 days after transplanted paddy fields in both seasons.