Field trials of WBA 8119 (PP 581, brodifacoum) against warfarin-resistant infestations of Rattus norvegicus

Abstract

SUJMMARYBaiting with medium oatmeal or soaked wheat containing 0-002, 0*001 or 0 0005 % brodifacoum completely controlled infestations of warfarin-resistant rats on farms when the poisoned baits were maintained until rats ceased to feed on them. The concentration of brodifacoum did not affect the duration of these treatments which lasted from 11 to 25 days.Poison baiting with 0002 % brodifacoum for only 1, 4 and 7 days achieved, respectively, only about 41, 51 and 68 % control ofsimilar farm infestations, and so emphasized the need to continue baiting for longer periods.

Field trials of second-generation anticoagulants against difenacoum-resistant Norway rat populations

“…brodifacoum on nine farmsteads in Powys and Shropshire, the bait-take frequency decreased by almost 90 % (as against 40 % here) in 11 days, and virtually complete control was obtained in 11-25 days, even when the concentration was reduced to 5 p.p.m. (Rennison & Dubock, 1978).…”

“…Remarkably little is known, however, of the amounts of bait ingested by individual rats during treatments. Rennison & Dubock (1978) suggest that many individuals eat little or no bait during the first week or so of a typical anticoagulant treatment and bait consumption may therefore often be closer to the minimum required for success than is generally believed.…”

“…The resistance is potentially a serious problem since difenacoum, introduced in 1975, is now the compound most commonly used in Britain for the control of rodents resistant to warfarin and other long-established anticoagulant rodenticides. More recently, two potent new anticoagulants, brodifacoum and bromadiolone, have been introduced for the control of warfarin-resistant infestations (Rennison & Dubock, 1978;Richards, 1981) and these two compounds, together with difenacoum have come to be known as the 'second-generation' anticoagulant rodenticides.…”

Comparative effect of the three rodenticides warfarin, difenacoum and brodifacoum on eight rodent species in short feeding periods

“…Such laboratory findings cannot always be transferred to the field situation as has recently been demonstrated by Rowe, Swinney & Plant (1978) in house mice and by Rennison & Dubock (1978) in brown rats, due to the behaviour and the social structure of the populations. The results obtained with microtine rodents may be of particular interest, as these species generally prefer herbs to seeds and grain.…”

Field trials of flocoumafen against warfarin-resistant infestations of the Norway rat (Rattus norvegicus Berk)

“…Stabilized medium oatmeal was used as the bait base at the beginning of each treatment but, occasionally, it was necessary to change to soaked wheat when it became apparent that the dry bait was proving insufficiently attractive. The 12 farms used in the study were selected so that they were similar to those employed in previous investigations (see, for example, Rennison & Dubock, 1978;Richards, 1981) and were neither too lightly nor too heavily infested (Rennison, 1974). Before each trial began, the farm was surveyed by an experienced operator to determine the extent and intensity of the rat infestation and clean wooden bait trays were put down where rat activity was apparent (Tables 1 and 2).…”