The effect of coumatetralyl on rat abundance and reduction in crop damage in ricefield

Abstract

The effects of coumatetralyl, a first generation anticoagulant rodenticide in controlling rats was investigated in a rice-field area at Selising, Kelantan. Two plots were established; one baited with coumatetralyl and the other serve as a rodenticide free plot. Six replicates were randomly selected for both treatments. Three baiting campaigns were carried out; the first baiting was conducted ten days before transplanting; the second, three weeks after transplanting and the third six (6) weeks after the tillering stage. The effects were evaluated based on two parameters, i.e. rat damage assessment and rat abundance. Damage was estimated by counting the proportion of cut tillers at tillering, booting and maturing stages. Rat abundance was indirectly compared by the amount of bait taken in both treatments. Rat damage and abundance were calculated and significance between means were established by unpaired t-test. Rodent activity was measured at prebaiting and on two occasions post baiting. Coumatetralyl significantly reduce rat number by up to 61% based on the acceptance of plain bait measurement. This indicated an approximate reduction of rat population density presumably due to mortality after consumption of coumatetralyl baits. Incidence of rat damage in both the control and coumatetralyl plot was less than 5% at all rice plant growth stages. There was significant difference between the treatment and control plot for all stages of rice crop combined (p>0.05). The mean percent rat damage level for three growth stages in coumatetralyl baited and control plot were 0.65% and 3.49% respectively, being significantly different (p>0.05). Mean damage at coumatetralyl baited plot remained less than 1% throughout this indicated that coumatetralyl was effective in suppressing rat number and thereby reduced crop damage at all stages of rice growth.