Associate Certified Entomologist (ACE) Practice Exam

Which of the following statements about insect population dynamics and pesticide resistance is accurate?

1. A large proportion of the population should be unexposed to the insecticide

2. A large proportion of the population must be exposed to the insecticide

3. Resistance occurs only in populations with low reproductive potential

4. Resistance develops regardless of the population's genetic structure

The correct answer is: A large proportion of the population must be exposed to the insecticide

A large proportion of the insect population needs to be exposed to the insecticide for resistance to develop and become evident. When a significant number of insects are exposed, those individuals that carry advantageous genetic traits conferring resistance can survive and reproduce. This selective pressure allows the resistant individuals to pass on their genes to the next generation, leading to an increase in the frequency of resistant traits within the population over time. Resistance development is driven by the concept of natural selection, where only the insects that can withstand the effects of the pesticide survive, leading to a greater representation of those resistant individuals in future generations. If a small proportion of the population is exposed, the chance of resistance development is significantly reduced because there may not be enough genetic variation or individuals with resistant traits to propagate. Insecticide resistance is not directly associated with the reproductive potential of the population, nor does it solely depend on the genetic structure of the population. While reproductive potential can impact population dynamics overall, resistance can emerge from various population structures as long as selection pressure from the pesticide is present.