Malaria Control via Larval Elimination

Steps:

• Recall malaria transmission: Mosquitoes (Anopheles) breed in stagnant water, laying larvae that develop into adults carrying Plasmodium parasites.
• Identify control methods: Target breeding sites to reduce mosquito populations before they bite humans.
• Evaluate options: Match each to biological mechanism—larvicides disrupt larval respiration in water.
• Select match: Oil suffocates larvae by blocking air access on water surface.

Why B is correct:

• Oil forms a monolayer on water, preventing mosquito larvae from obtaining oxygen through their siphons, as per entomological larvicide principles.

Why the others are wrong:

• A: Nets physically block mosquito entry but do not kill them; they prevent bites.
• C: Anti-malaria tablets (prophylactics) inhibit parasite growth in humans, not mosquito behavior.
• D: Insecticides target adult mosquitoes or vectors, not the Plasmodium parasites inside them.

Final answer: B