Final answer:
It is true that pesticides can become less effective when exposed to sunlight due to photodegradation and pest resistance development.
Step-by-step explanation:
It is true that when pesticides are exposed to sunlight, their pest-eliminating abilities may be altered or hindered. Pesticides can lose their effectiveness over time due to several factors, including photodegradation, which is the breakdown of pesticides through exposure to light, particularly ultraviolet (UV) radiation from the sun. This process can lead to the formation of new compounds that are less effective at controlling pests, or even completely inactive.
Additionally, the development of resistance by pest populations can render pesticides ineffective. This evolution of resistance is an example of microevolution, where small changes occur in a population, such as insects adapting to the presence of pesticides and passing these traits to their offspring.