The intensive use of chemicals through decades has been selecting resistant populations of several insect species to distinct classes of insecticides, like neurotoxics, insect growth regulators, and toxins derived from bacteria. Insecticide resistance is nowadays a huge challenge for control programs of pests of rural practices and principally to the management of arthropod vector-borne diseases. Several behavioral, physiological, and molecular mechanisms can be selected for avoiding toxic effects of insecticides in the insect organism. These changes are genetic traits that arise randomly and spread throughout the population along time, under an environment with insecticide selective pressure. However, new rapidly achieved characteristics can present a fitness cost to their harbors, with negative effects in development and reproductive aspects. In this way, in the absence of insecticides, susceptible individuals may present reproductive advantages and then the population resistance levels would tend to decrease. If the selection pressure persists, however, compensatory genes known as modifiers can be selected, ameliorating the negative effects caused by the resistance genes themselves or their pleiotropic effects.
Part of the book: Insecticides Resistance