Insecticide resistance is defined as what?

• A. A heritable change in pest sensitivity resulting in repeated failure of a product to achieve expected control
• B. A temporary tolerance that disappears after several generations
• C. A behavioral change that reduces exposure to insecticides
• D. A genetic modification of pests by the insecticide to enhance susceptibility

Answer: (A)

Insecticide resistance occurs when a pest population accumulates heritable genetic changes that lower their sensitivity to a chemical, so repeated applications fail to achieve the expected level of control. Because these changes are passed from one generation to the next, the reduced susceptibility persists and the problem tends to get worse with continued use of the insecticide. This definition centers on genetic, enduring changes rather than temporary effects, which is why a temporary tolerance that fades over generations isn’t the right fit. Behavioral changes that reduce exposure can contribute to control failures, but the core idea here is the heritable change in sensitivity, not behavior alone. And insecticides don’t genetically modify pests to become more susceptible; they select for individuals with resistance traits, leading to increased resistance in the population.