Associate Certified Entomologist (ACE) Practice Exam

What does cross resistance refer to?

1. Resistance to multipleiate agents

2. Resistance to a selection agent and other insecticides with the same mode of action

3. Resistance that develops from low pesticide application

4. Resistance that occurs in the absence of pest management

The correct answer is: Resistance to a selection agent and other insecticides with the same mode of action

Cross resistance specifically refers to the phenomenon where a pest that has developed resistance to one insecticide also exhibits resistance to other insecticides that share the same mode of action. This means that if a particular pest has adapted to survive exposure to a specific chemical compound, the genetic or physiological changes that confer that resistance may render the pest less susceptible, or completely resistant, to other compounds that act in a similar manner. This concept is critical in pest management, as it informs strategic choices about which insecticides to use. If multiple insecticides work in the same way, relying on them interchangeably can lead to widespread resistance, ultimately diminishing their effectiveness. The other options do not accurately capture the definition of cross resistance. For instance, resistance to multiple agents refers to a broader type of resistance that does not necessarily relate to the mode of action. Resistance resulting from low pesticide application might contribute to some aspects of resistance development, but this does not specifically relate to the concept of cross resistance. Lastly, resistance occurring in the absence of pest management does not address the specific interaction between resistance to similar acting compounds.