Which of the following is NOT recommended to delay resistance development?

• A. Reapplying the same pesticide repeatedly
• B. Rotating pesticides to vary modes of action
• C. Monitoring pest populations and rotating accordingly
• D. Using pesticides with the same mode of action repeatedly

Answer: (D)

Delaying resistance relies on reducing constant selection pressure on pests by varying the tools used. When you use pesticides with the same mode of action over and over, you consistently select for individuals that are naturally resistant to that mode. Those survivors pass on resistance genes, and the next generations become more tolerant, making the product less effective over time. That’s why this practice is not recommended for resistance management. In contrast, rotating pesticides with different modes of action disrupts the pest's ability to adapt by forcing it to cope with multiple targets, slowing resistance development. Monitoring pest populations and rotating products accordingly helps ensure you apply effective controls only when needed and mix in different modes, further delaying resistance and preserving efficacy. So, using pesticides with the same mode of action repeatedly is the scenario that most directly undermines resistance management.