Associate Certified Entomologist (ACE) Practice Exam

What must be present in a population for resistance to develop against an insecticide?

1. High reproductive potential and short generation time

2. No exposure to the insecticide

3. Low genetic diversity

4. Consistent environmental conditions

The correct answer is: High reproductive potential and short generation time

For resistance to develop against an insecticide, a population must exhibit high reproductive potential and a short generation time. This is crucial because it allows for rapid reproduction, which means that any individuals with a genetic mutation or trait that confers resistance to the insecticide can proliferate quickly within the population. In environments where insecticides are used, if some individuals have a natural resistance, they will survive the application and reproduce more than susceptible individuals. Over multiple generations, this leads to an increase in the proportion of resistant individuals in the population, effectively rendering the insecticide less effective. The other options do not support the development of resistance. For instance, if there is no exposure to the insecticide, resistant traits cannot be selected for as there would be no selective pressure influencing the population. Low genetic diversity would typically limit the number of potential resistant individuals, reducing the chances of resistance developing. Lastly, consistent environmental conditions do not inherently lead to resistance; rather, it is the interaction with the insecticide and the resulting selection pressure that facilitates this process.