Background and Alternatives

The development of anticoagulant resistance is one of the most important challenges to the sustainable use of anticoagulants around the world. In other pest control disciplines, for example insect pest control, several different insecticide modes of action are available and novel active substances come into use. This is not so for rodent pest control; in fact the opposite is the case. There is almost complete reliance on anticoagulants and we are losing effective chemical interventions rather than gaining them. In some countries, such as the UK and perhaps in some other European countries, anticoagulant resistance is extensive and established and it is too late for real consideration of the prevention of resistance. But in other countries, where resistance is not yet so widespread, the prevention of resistance must be a high priority. There are a number of actions that should be taken by pest managers to prevent the development of anticoagulant resistance.

Anticoagulant resistance only develops where anticoagulants are used. Therefore, any suppression of rodent populations that can be undertaken by other means provides a way to avoid resistance development. For example, modification of habitats to ensure that they are not conducive to the establishment and growth of rodent infestations, by the removal of food and harbourage, will reduce the numbers of rodents present. This in turn reduces the quantities of anticoagulants required for their removal and, thereby, the probability of resistance development. The use of traps and glue-boards imposes no selection towards the development of genetically-resistant rodents and is therefore a positive way to prevent their evolution. The same can be said for the use of non-anticoagulant rodenticides, where these remain or may become available. The use of these interventions within integrated pest management programmes is particularly to be promoted because programmes that exert a range of different genetic selection pressures are less likely to promote resistance development.

Ideally, where effective alternatives to anticoagulants are available, the occasional use of different modes of action should be considered.

Even when there is no resistance suspected, occasional use of one of the most potent anticoagulants may prevent the potential selection of a few resistant animals.