Summary: Insects with super fast genetic mutations sounds like the stuff of science fiction, but insects are very adaptable to external pressures and can develop pesticide resistance in just a few generations. Ironically, the more effective a pesticide, the more quickly a pest will develop resistance to it.
When we think of genetic mutations we often think of the extremes. Extra pairs of arms or eyes, maybe something gigantic or, perhaps, developing the ability to fly are some mutations found in comic books. Insects are almost like super heroes anyway. They can fly, survive extreme conditions, and are renowned for their super strength. Resistance to chemicals meant to poison them can be added to the list of amazing insect abilities.
Individual insects do not develop resistance to insecticides. If an individual insect is not resistant to an insecticide, it will die when exposed to it. However, insects began developing resistance to insecticides in the 1950s when DDT was commonly being used to treat all kinds of pests, including mosquitoes. Large areas of land were sprayed with DDT and, at first, the insecticide exceeded expectations, being very successful in controlling insect populations. Shortly thereafter, however, people started noticing that the chemicals were having less and less effect.
It turns out that the pesticides were successful in controlling insect populations because the insecticide killed all the individuals that had no resistance to the pesticide. However, some insects survived. They were naturally resistant to the chemicals.
Usually, resistance to a pesticide comes from an enzyme that breaks down the active ingredients and renders it harmless. Some insects naturally produce these enzymes. When one type of pesticide was used frequently, more and more naturally resistant insects survived and reproduced even more resistant offspring.
Estimates of between 500 and 1000 insect species have developed resistances to pesticides. To combat this growing phenomenon many political action groups have been formed such as the Insecticide Resistance Action Committee and the National Agricultural Pesticide Assessment Program. The goal of the groups is to mitigate the resistance insects have to pesticides. They advocate applying pesticides only when necessary, using pesticides that have different modes of killing action and rotating the pesticides that are applied.