Explain how insecticide resistance can arise in mosquito populations and one major mechanism.

Explain how insecticide resistance can arise in mosquito populations and one major mechanism.

• A. Random mutation only, not influenced by insecticides.
• B. Insecticides never lead to resistance; populations remain susceptible.
• C. Through selection pressure from insecticides; major mechanism includes target-site resistance (e.g., kdr) reducing sensitivity to pyrethroids.
• D. Resistance arises only through behavioral avoidance, not physiological.

Answer: (C)

When mosquitoes are repeatedly exposed to an insecticide, survival becomes non-random. Individuals with genetic traits that reduce the insecticide’s impact are more likely to live, reproduce, and pass those traits to their offspring. Over generations, the population shifts toward resistance because the resistant genes become more common. A major mechanism is target-site resistance, such as knockdown resistance (kdr). This involves changes in the insect’s nerve-cell target—the voltage-gated sodium channel that pyrethroids bind to. Mutations in this channel lessen the insecticide’s ability to affect nerve function, so mosquitoes with the altered channel survive exposure and produce resistant offspring. This exemplifies how a specific genetic change can directly diminish an insecticide’s effectiveness. Other resistance routes exist, like metabolic detoxification or behavioral avoidance, but target-site resistance is a well-documented and prominent example of how resistance can arise through selection pressure from insecticides.

When mosquitoes are repeatedly exposed to an insecticide, survival becomes non-random. Individuals with genetic traits that reduce the insecticide’s impact are more likely to live, reproduce, and pass those traits to their offspring. Over generations, the population shifts toward resistance because the resistant genes become more common.

A major mechanism is target-site resistance, such as knockdown resistance (kdr). This involves changes in the insect’s nerve-cell target—the voltage-gated sodium channel that pyrethroids bind to. Mutations in this channel lessen the insecticide’s ability to affect nerve function, so mosquitoes with the altered channel survive exposure and produce resistant offspring. This exemplifies how a specific genetic change can directly diminish an insecticide’s effectiveness.

Other resistance routes exist, like metabolic detoxification or behavioral avoidance, but target-site resistance is a well-documented and prominent example of how resistance can arise through selection pressure from insecticides.