ABSTRACT
Resistance is a genetically based decrease in susceptibility of a population to an insecticide. As resistance entails changes in allele frequencies in a population, by definition, it is an evolutionary phenomenon. Insects are known for their ability to develop resistance to certain insecticides rapidly. Resistance occurs particularly when insecticides are used repeatedly and at high concentrations leading to intensive selection pressure on insect populations. More than 500 species of insects and mites are known to have developed resistance to insecticides and miticides (Georghiou and Lagunes-Tejeda, 1991).
