How do insect growth regulators (IGRs) primarily affect mosquitoes?

How do insect growth regulators (IGRs) primarily affect mosquitoes?

• A. They disrupt larval development, preventing emergence as adults.
• B. They kill adult mosquitoes on contact.
• C. They sterilize eggs in females.
• D. They repel mosquitoes from treated areas.

Answer: (B)

IGRs act by disrupting the hormonal signals mosquitoes use to develop from larvae into adults. When larvae are exposed in their aquatic habitats, these compounds mimic juvenile hormone or interfere with molting, so the larvae fail to molt properly and cannot become healthy adults. That leads to a big drop in the number of mosquitoes that reach the biting, flying stage. Because the target is the immature stages, IGRs are used as larvicides in standing water rather than killing adults on contact, sterilizing eggs, or repelling mosquitoes. The key idea is that they prevent emergence by blocking larval development.

IGRs act by disrupting the hormonal signals mosquitoes use to develop from larvae into adults. When larvae are exposed in their aquatic habitats, these compounds mimic juvenile hormone or interfere with molting, so the larvae fail to molt properly and cannot become healthy adults. That leads to a big drop in the number of mosquitoes that reach the biting, flying stage. Because the target is the immature stages, IGRs are used as larvicides in standing water rather than killing adults on contact, sterilizing eggs, or repelling mosquitoes. The key idea is that they prevent emergence by blocking larval development.