Which outcome indicates successful IGR activity in a treated site?

Which outcome indicates successful IGR activity in a treated site?

• A. Increased adult emergence
• B. Immediate kill of adults on contact
• C. No effect on larval development
• D. Decreased emergence due to disrupted larval development

Answer: (D)

Insect Growth Regulators disrupt development of immature mosquitoes, not kill adults outright. When an IGR is working, larvae can’t properly molt into the next stage or reach the pupal-to-adult transition, so far fewer mosquitoes successfully emerge as adults. This results in a lower adult population even though you may not see immediate death in larvae. So, the indicator of effective IGR activity is decreased emergence due to disrupted larval development. Immediate adult killing or no change in larval development would not reflect IGR action, and increased emergence would be the opposite of what an IGR is designed to do.

Insect Growth Regulators disrupt development of immature mosquitoes, not kill adults outright. When an IGR is working, larvae can’t properly molt into the next stage or reach the pupal-to-adult transition, so far fewer mosquitoes successfully emerge as adults. This results in a lower adult population even though you may not see immediate death in larvae. So, the indicator of effective IGR activity is decreased emergence due to disrupted larval development. Immediate adult killing or no change in larval development would not reflect IGR action, and increased emergence would be the opposite of what an IGR is designed to do.