What is a key limitation of using IGRs like methoprene in mosquito control?

• A. They kill adults immediately.
• B. They have no effect on larvae.
• C. They may require sustained exposure and do not provide rapid short-term reduction in biting.
• D. They completely prevent oviposition.

Answer: (C)

IGRs like methoprene work by disrupting mosquito development rather than killing larvae outright. They mimic juvenile hormone, so larvae can’t properly mature into adults. Because of this, there’s no rapid, short-term drop in biting: adults will still emerge gradually as exposed larvae progress through development, and you need sustained exposure across all breeding sites for a noticeable effect. In practice, this means IGRs provide long-term suppression of adult emergence only if larval habitats are consistently treated, rather than offering immediate control of the biting population. They’re most effective as part of an integrated strategy rather than a quick fix for reducing mosquito bites.