[Development of resistance in health pests including ectoparasites-- definition and present situation]

The increasing formation of resistance of ectoparasites and other pests may only delayed if the causes and mechanisms of this development are recognized. On the basis of the genetic classification (definition) of resistance formation, concrete measures to achieve a delay (slow-down) of this process may be taken in the control of different pests and parasites, such as the regular exchange of certain agents or the coordination of measures. The scope of such measures will depend on the concrete resistance situation at the site in question related to the pest species to be controlled, and if necessary, even on the target strain. A survey of the factors to be taken into consideration as well as the present resistance situation of individual European species is presented.