What surface film agent can be used to block breathing trumpets in pupae?

What surface film agent can be used to block breathing trumpets in pupae?

• A. Mineral oil
• B. Soap solution
• C. Water
• D. Detergent

Answer: (A)

Pupae breathe through small trumpets at the water surface, so blocking that surface access can halt their respiration. A thin layer of mineral oil forms a stable, inert film on the water that surrounds and covers those breathing openings, preventing gas exchange and causing the pupae to suffocate. Soap solution or detergent are surfactants that may disperse or emulsify, not create a reliable, persistent barrier, and water provides no surface film at all. Mineral oil is effective because it stays on the surface and blocks the air intake without altering the water chemistry.

Pupae breathe through small trumpets at the water surface, so blocking that surface access can halt their respiration. A thin layer of mineral oil forms a stable, inert film on the water that surrounds and covers those breathing openings, preventing gas exchange and causing the pupae to suffocate. Soap solution or detergent are surfactants that may disperse or emulsify, not create a reliable, persistent barrier, and water provides no surface film at all. Mineral oil is effective because it stays on the surface and blocks the air intake without altering the water chemistry.