What does pest resistance refer to?

Pest resistance specifically refers to pest populations that have developed the ability to survive exposure to pesticides. This phenomenon occurs when a segment of the pest population possesses genetic traits that enable them to withstand the effects of the chemicals used against them. Over time, repeated applications of pesticides can lead to a selection pressure, where the susceptible individuals are killed off, while those with resistance traits survive and reproduce. As a result, the overall pest population becomes increasingly resistant to the pesticide, making it less effective.

In contrast to the chosen answer, the other options do not accurately capture the concept of pest resistance. The ability of pests to thrive in adverse conditions does not directly relate to pesticide tolerance. Eliminating pests completely with chemicals is often unrealistic, as complete eradication is extremely difficult to achieve and doesn't reflect the changing dynamics of pest populations. Similarly, although new pests can emerge in an area, this is not a definition of resistance but rather a consequence of environmental changes, pest movement, or shifts in agricultural practices.