Eugenics and Birth Control

Some control tactics are designed to suppress a pest population by altering its genetic makeup and/or reducing its reproductive potential. As a group, these tactics are frequently known as genetic controls because they affect the accuracy or efficiency with which a pest species passes its genetic material (DNA) from one generation to the next. Genetic control usually works in one of two ways: either by causing (inducing) reproductive sterility, or by incorporating new and potentially deleterious genes (or alleles) into the genetic makeup of a pest population. In effect, some members of a pest species are transformed into biological time bombs that eventually destroy other members of their own species. Because of the self-destructive nature of these tactics, they are sometimes called autocidal control.

Insects can be sterilized by exposing them to certain chemical agents (chemosterilants) or to non-lethal levels of ionizing radiation (X-rays or gamma rays). Chemosterilants are really a form of chemical control. They usually work by blocking the onset of sexual maturity, by inhibiting the production of eggs and/or sperm, or by damaging the chromosomes. These compounds will be covered more fully in the section on semiochemical insecticides.
Exposure to radiation also damages chromosomes (usually by breakage or mutation). Since cells with damaged chromosomes cannot divide correctly, they do not form normal gametes or produce viable offspring. Although the susceptibility of each insect species is different, a proper dose of radiation administered at an appropriate stage of development (usually to pupae) can often induce sterility without causing other deleterious side effects. Sterile individuals, reared in large numbers and released into the environment, can mate with "normal" individuals but they produce no viable offspring. The more sterile individuals released, the fewer "normal" matings are likely to occur