Certified Crop Advisor Practice Exam

Which of the following DOES NOT encourage pesticide resistance to develop?

1. Repeated use of the same pesticide

2. Alternating different modes of action (MOAs)

3. Under-dosing

4. Late applications

The correct answer is: Alternating different modes of action (MOAs)

Alternating different modes of action (MOAs) is a crucial strategy in pest management and actively helps prevent pesticide resistance. By using different MOAs, it reduces the selection pressure imposed on the pest population by any single pesticide. Each mode of action affects pests differently, and when pesticides with different mechanisms are used in rotation, it minimizes the chances that pests will build up resistance. In contrast, repeated use of the same pesticide can lead to resistance because pests that are susceptible will be eliminated, leaving behind those that can tolerate that specific pesticide. Under-dosing can also contribute to resistance because it may not effectively kill pests, allowing them to survive and reproduce, potentially with increased tolerance. Late applications might increase the risk of resistance as well, especially if pests have already established a strong population by that time. Therefore, the practice of alternating different MOAs is effective in managing pest populations and delays the onset of resistance.