Efficacy and environmental impact of flocoumafen (Storm) wax block baits used for rice field rat control in the Philippines
Two large (approx. 160 ha) trial sites incorporating ricefields and village housing were selected in Laguna Province, Philippines. Flocoumafen 3.5-g wax block baits (Storm®) were applied to one site, initially as two area-wide pulses of 80 to 100 blocks/ha and later as spot treatments, to areas of particularly high rat infestation. Baiting in and around the village houses was already carried out during the first two applications. On average, only 1.175 kg/ha/season of flocoumafen block bait gave good rodent control resulting in significant decreases in crop damage (% cut tillers) compared to the untreated area. The overall yield increase was estimated to be 13 t of grain, equivalent to total added benefit of P39,000 (approx US$ 1,950) or P253 (approx. US$ 13) per ha. Few domestic animals were attracted to the bait and no casualties were reported. Only one dog was seen eating bait but this animal did not develop symptoms of poisoning. None of the wild animals observed regularly during the trial showed significant decreases in numbers after baiting. With the exception of two shrews (Suncus sp.) all animal carcasses found were those of the target rodent pests. It is concluded that flocoumafen gave excellent rat control with no observable effects of non-target animals.