Which option lists three biological control agents used in larval mosquito control and their mechanism?

Which option lists three biological control agents used in larval mosquito control and their mechanism?

• A. Bti toxins cause larval death; copepod predators; larvivorous fish eat larvae.
• B. Larvivorous fish eat larvae; Bti toxins kill adults.
• C. Copepods increase mosquito breeding rates.
• D. Bti toxins kill pupae; bats prey on adult mosquitoes.

Answer: (D)

Controlling mosquitoes at the larval stage relies on agents that either kill larvae directly in the water or remove them through predation. Bacillus thuringiensis israelensis (Bti) releases toxins that, when ingested by aquatic larvae, disrupt gut function and cause death, making it a direct larval killer. Copepods act as predators that feed on larvae in the water, reducing the number that survive to pupate or emerge as adults. Larvivorous fish likewise eat larvae, providing another natural check on the larval population in standing water. The idea is to pair an agent with a mechanism that targets the larval stage specifically. The alternative described—Bti killing pupae and bats preying on adults—doesn’t fit larval control, since Bti is larvicidal (not pupicidal) and bats primarily reduce adult mosquitoes, not larvae.

Controlling mosquitoes at the larval stage relies on agents that either kill larvae directly in the water or remove them through predation. Bacillus thuringiensis israelensis (Bti) releases toxins that, when ingested by aquatic larvae, disrupt gut function and cause death, making it a direct larval killer. Copepods act as predators that feed on larvae in the water, reducing the number that survive to pupate or emerge as adults. Larvivorous fish likewise eat larvae, providing another natural check on the larval population in standing water. The idea is to pair an agent with a mechanism that targets the larval stage specifically. The alternative described—Bti killing pupae and bats preying on adults—doesn’t fit larval control, since Bti is larvicidal (not pupicidal) and bats primarily reduce adult mosquitoes, not larvae.