Question

How does a pest become pesticide resistant?

Answer 1

Pests become resistant to pesticides due to natural selection.

Explanation:

Any pesticide may kill most of the pests (fleas, ticks, spiders, etc...), but not all. Some members of the same population may have genetic mutations that make the organisms resistant to the pesticide. Natural selection determines which organisms will survive. The survivors mate and produce offspring that are also resistant. Eventually, the resistant organisms make up the majority of the population, rendering the pesticide useless.