Which would increase the likelihood of pesticide resistance?

Which would increase the likelihood of pesticide resistance?

• A. Rotating pesticides frequently between different chemical classes.
• B. Using biological controls exclusively.
• C. Continual use of the same pesticides or pesticides from the same chemical class.
• D. Applying pesticides only once per crop cycle.

Answer: (C)

Continual use of the same pesticides or pesticides from the same chemical class increases resistance because it keeps applying the same selection pressure to the pest population. A small number of individuals naturally carry traits that let them survive that pesticide. Each time you spray, those survivors live and reproduce, passing on resistance to their offspring. Over generations, the population becomes predominantly resistant, making the pesticide less effective.

Rotating pesticides with different modes of action interrupts that single line of selection, making it harder for pests to adapt. Using biological controls or reducing reliance on chemicals lowers the exposure of pests to pesticides in general, which also reduces the chance of resistance developing. Applying a pesticide only once per crop cycle provides limited exposure, but the most direct driver of resistance is repeatedly exposing pests to the same chemical class.