What does pesticide cross resistance refer to?

• A. Using product at label rate
• B. Resistant to a class of pesticides, leading to resistance of other classes
• C. Resistant to the same class
• D. Chemical has the same MOA

Answer: (B)

Cross resistance happens when a pest population that has become resistant to one pesticide also shows resistance to other pesticides, often from different chemical classes. This occurs because the resistance mechanism—such as enhanced metabolic detoxification or a changed target site—affects multiple compounds, not just the one that initially selected resistance. So, control that works on one pesticide may fail on others as the pest carries a broad defense. It’s not about applying the product at label rate, and it’s broader than resistance to a single class. While sharing the same mode of action can contribute, the defining idea is the pest’s broad ability to withstand multiple pesticides across classes.