Answer:
This phenomenon will be explained as the adaptation to Environment.
Step-by-step explanation:
Adaptation is a process of natural selection where an organism changes its functional or structural parts to best fit in an environment. Adaptation is the basic concept of Darwin's theory of Natural Selection. It explain that why Organisms tend to change with the changing environment. In the given example, Although pesticides can improve the crop production however, eventually Pests developed resistance to the Pesticides and no longer got effected by them. So we can say that Pests have adapted themselves to survive in the presence of Pesticides.