Question

what causes the pesticide treadmill?
pesticides exercise the pests, wearing them out, causing their bodies to become stronger.
the weakest pest individuals survive but die of starvation quickly after harvest.
pest species evolve resistance via natural selection and more pesticide must be used on them.
pests that are not susceptible to pesticides no longer reproduce because they have more resources.

Explanation:

The pesticide treadmill occurs when pests develop resistance to pesticides over time. Natural selection plays a role here: pests with genetic traits that make them resistant to a pesticide are more likely to survive and reproduce. As a result, the pest population evolves to be more resistant, so more (or stronger) pesticides are needed, creating a cycle. The first option is incorrect as pesticides don't "exercise" pests. The second option is not related to the pesticide treadmill concept. The fourth option is illogical as non - susceptible pests would likely reproduce more with more resources. Only the third option correctly explains the cause of the pesticide treadmill.

Answer:

Pest species evolve resistance via natural selection and more pesticide must be used on them.