Which practice would most contribute to resistance development?

• A. Rotate pesticides with different modes of action
• B. Use more frequent applications
• C. Use the same pesticide in the same place
• D. Use pest monitoring

Answer: (C)

Resistance develops when a pest population is repeatedly exposed to the same pesticide, so the same selection pressure keeps killing susceptible individuals while those with resistance survive and reproduce. Using the same pesticide in the same place creates this constant pressure every time you spray, quickly increasing the frequency of resistant traits in the population. Over time, the pesticide becomes less effective because the surviving pests are the resistant ones.

Rotating pesticides with different modes of action helps prevent or delay resistance by changing the selective pressure, making it harder for a resistant population to take hold. Pest monitoring is useful for detecting resistance and informing management, but it doesn’t by itself drive resistance. While more frequent applications can raise selection pressure as well, the strongest/most direct contributor is repeatedly applying the same pesticide to the same location.