Why rotate modes of action?

• A. Increase pest kill rate
• B. Increase pesticide use
• C. Lower application rates
• D. To reduce resistance

Answer: (D)

Rotating modes of action helps manage resistance by varying the selective pressure on pest populations. If you keep using the same mode of action, any pests with a resistance mutation survive and pass that trait to their offspring, so the population becomes increasingly resistant and control fails. By switching to different modes of action, a pest that's resistant to one chemical is less likely to be resistant to the next, slowing the spread of resistance and keeping products effective longer. This approach supports integrated pest management by reducing overreliance on a single tool and can be paired with monitoring and nonchemical methods. It’s not primarily about killing more pests per application or using fewer apps; it’s about preserving effectiveness over time by limiting resistance evolution.