Abstract: For the past 80 years, chemicals have played an important role in vector control programs. Indoor residual spraying and the use of insecticide-treated nets are the main strategies for malaria vector control and they rely heavily on the use of insecticides. However, the development of resistance to the various classes of insecticides has resulted in a reduction of the efficacy of these interventions. Resistance to all classes of insecticides has been found on the African continent, with some insecticide resistance reported from Asia, and Central and South America. The development of resistance to insecticides is mainly due to the fact that public health insecticides are reformulations of insecticides that were previously used for agricultural purposes. The rapid spread of insecticide resistance is a major problem in vector control programs where there are only a finite number of insecticides to select from. The problem is exacerbated by cross resistance between various groups of insecticides which further limits the choice of effective insecticides. In order to identify the earliest emergence of resistance, there needs to be monitoring of resistance on a continual basis. Resistance monitoring is necessary to ensure that effective insecticides are being used and to ensure that changes to insecticide policy are based on sound scientific data. Resistance management strategies need to be implemented from the outset because methods for delaying resistance becomes less effective as resistance becomes common. The advent of resistance has resulted in programs undergoing a paradigm shift from spraying single insecticides to using insecticide combinations and rotational spraying. The main impact of resistance on disease control programs has been the way in which insecticides are applied. Increasing resistance to insecticides has generated an interest in finding new chemical compounds that insecticide vectors are susceptible to. Control programs are now moving to an integrated method of control where chemical and nonchemical measures are being used as complementary measures. However, for the moment, chemicals will continue to be used for vector control but they need to be used with caution and in a manner that does not promote the development of resistance.
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