Which would decrease the likelihood of pesticide resistance?

• A. Using pesticides with a single site of toxicity
• B. Rotating pesticides with different modes of action
• C. Using pesticides with multiple sites of toxicity
• D. Applying at higher rates

Answer: (C)

The key idea is making it harder for pests to survive pesticide exposure by targeting them in more than one way. A product that has multiple sites of toxicity affects several different biological targets in the pest, so an organism would have to develop multiple, independent resistance mechanisms at once to survive. That combination is much less likely to occur and spread, so resistance develops far more slowly.

If a pesticide acts on a single site, a single genetic change can confer resistance, and that trait can spread quickly through the population. Rotating pesticides with different modes of action helps delay resistance by not placing continuous pressure on one mechanism, but pests can still accumulate resistances to the various modes over time if rotations aren’t managed carefully. Applying at higher rates intensifies selection, promoting faster evolution of resistance.