Which stage of mosquitoes does not respond to pesticides?

Which stage of mosquitoes does not respond to pesticides?

• A. Eggs
• B. Pupae
• C. Larvae
• D. Adults

Answer: (B)

Pesticides work best when the mosquito is actively feeding or moving, because most products need to contact target tissues or be ingested. The pupal stage is a short, aquatic, non-feeding phase with very low metabolic activity. They’re largely protected inside a pupal casing and aren’t actively feeding, so chemicals that kill by disrupting feeding, nervous system activity, or metabolism don’t reach effective concentrations. For this reason, pupae are generally not affected by most pesticides. Control programs therefore target the other stages: larvae in water with larvicides that disrupt development or kill feeding larvae, and adults with adulticides that kill or incapacitate flying mosquitoes. Eggs are typically not the primary target because they’re dormant on water surfaces and chemically resistant; some interventions aim to prevent hatching, but the pupal stage itself is the least responsive to pesticides.

Pesticides work best when the mosquito is actively feeding or moving, because most products need to contact target tissues or be ingested. The pupal stage is a short, aquatic, non-feeding phase with very low metabolic activity. They’re largely protected inside a pupal casing and aren’t actively feeding, so chemicals that kill by disrupting feeding, nervous system activity, or metabolism don’t reach effective concentrations. For this reason, pupae are generally not affected by most pesticides. Control programs therefore target the other stages: larvae in water with larvicides that disrupt development or kill feeding larvae, and adults with adulticides that kill or incapacitate flying mosquitoes. Eggs are typically not the primary target because they’re dormant on water surfaces and chemically resistant; some interventions aim to prevent hatching, but the pupal stage itself is the least responsive to pesticides.