ABSTRACT
The Insecticide Resistance Action Committee (IRAC) denes insecticide resistance as a heritable change in the sensitivity of a pest population that is reected in the repeated failure of a product to achieve the expected level of control when used according to the label recommendation for that pest species (www.irac-online.org). True resistance does not occur unless a structural genetic change that is heritable occurs. Therefore, insecticide resistance is an evolutionary phenomenon, resulting from the presence of new biocides in the environment of such populations. Insecticide resistance is different from insecticide tolerance. Tolerance is the natural ability of a population to withstand the toxic effect of a particular insecticide. It can be developed within one generation as a result of physiological adaptation, for example, enzyme induction. In this case, tolerance is lost when insects are no longer exposed to a chemical (i.e., inducer).
