Dr. Murai Éva szerk.: Parasitologia Hungarica 23. (Budapest, 1990)

After a certain period of time, extensively used rodenticides may provoke the development of tolerance followed by resistance, particularly if they are applied improperly. These observations, together with the finding that mice often colonize, and proliferate in, deratized areas, point to the need for new, more efficacious, so-called "second-generation" anticoagulant rodenticides (MARSH 1985; MARSH et al. 1976). Anticoagulant rodenticides of prolonged effect are known to have several advantages over preparations of acute effect. The most important advantage is that the symptoms of poisoning appear only several days after ingestion of the rodenticide, which prevents the rodents from recognizing the causal relation. Rats and mice die of haemorrhages, without spasm and pain, in 4-14 days after the first ingestion of the poison. As these rodenticides are sufficiently effective already at a very low concentration, the rodents can hardly, or not at all, perceive the presence of active ingredient in the bait; thus, bait acceptance is usually good. If the rodenticides are used as per the specifications, the uptake of sublethal doses is uncommon because of repeated rodenticide ingestion. This permits repeated or continuous use of a given preparation in the same place for long periods. A further advantage of anticoagulant rodenticides is their stability, i. e. that they do not become degraded in the bait for a long time. Their drawback is, however, that the poisoning develops only after repeated (4-5) ingestions of the rodenticide. Such repeated ingestion of the preparation is not easy to achieve in places where abundant food is available (e. g. at slaughterhouses and on farms). The greatest advantage of the newest, so-called "second-generation" anticoagulant rodenticides is that they have sufficiently high rodenticidal efficacy even after a single ingestion (8, 20). In this way the drawbacks of both the "acute" preparations and the classical anticoagulants can be eliminated (GRAND 1976; GREAVES et al. 1982; LUND 1977; MARSH et al. 1980; MEEHAN 1978; RADFERN and GILL 1980; RICHARDS and HUSON 1985; ROWE et al. 1981). Of the "second-generation" rodenticides, so far only TALON-B preparations containing brodifacoum as active ingredient have been put into circulation in Hungary. The reasons outlined above, the need to widen the rodenticide assortment and, last but not least, economic considerations have rendered it necessary to develop, by using another second-generation active ingredient, bromadiolone, a rodenticide bait which can be used widely. At the Bábolna Bioenvironmental Centre, Budapest extensive laboratory trials were conducted with the following objectives: - to determine the rodenticidal efficacy of the active ingredient bromadiolone; - to reproduce laboratory results obtained abroad; - to develop a universal formulation which is equally effective against rats and mice; - to develop a formulation which is more palatable and, therefore, more preferred by rodents than the currently available formulations.