THE PROBLEM OF ANTICOAGULANT RODENTICIDE RESISTANCE IN THE UNITED STATES

Resistance of commensal rodents to anticoagulant rodenticides is not a new phenomenon. Its confirmed presence in several areas of northern Europe is wel1-documented (Jackson 1969, 1972; Bentley 1969; Lund 1969). Not until 1971 was a similar situation with the Norway rat (Rattus norvegicus) to be demonstrated in the United States (Jackson et al. 1971). Because it represents an initial occurrence, the site and background observations will be described in some detail. The rural area involved around Cleveland School in Johnson County is 25 miles SE of Raleigh, N. C. and about five miles in diameter (fig. 1). The typical farm is small (20-25A) and produces tobacco, corn, and cotton. Animal sheds (some left from days of mule power), small barns, tobacco sheds, and granaries are characteristic. Dirt floors and perforated foundation walls are common. Cleanliness is not a prime requisite, and considerable harborage (farm machinery and parts, lumber piles, tall weeds, junk, old cars) exists. Stored grains are easily accessible, as are dry foods, animal feed, and special supplements (table 1)