Which genus is characterized by crepuscular or nocturnal activity and breeding in stagnant water with organic matter?

Which genus is characterized by crepuscular or nocturnal activity and breeding in stagnant water with organic matter?

• A. Aedes – Day-biting and container breeding.
• B. Anopheles – Night-time biting, malaria vector with resting posture.
• C. Culex – Breeding in running water with little organic matter.
• D. Culex – Crepuscular/nocturnal, breeding in stagnant water with organic matter.

Answer: (D)

The trait being tested is how habitat and activity patterns distinguish mosquito genera. The genus that fits being active at dusk or night and breeding in stagnant water rich in organic matter is Culex. These mosquitoes tend to bite in the crepuscular hours or after dark, and their larvae develop in water that contains organic material—detritus, mud, or polluted, slow-moving water. This contrasts with Aedes, which are usually day-biting and breed in clean water in artificial containers, and with Anopheles, which bite at night but prefer cleaner, more aerated water for breeding. The description of running water with little organic matter doesn’t match Culex, while the crepuscular/nocturnal habit plus organic-rich stagnant water does.

The trait being tested is how habitat and activity patterns distinguish mosquito genera. The genus that fits being active at dusk or night and breeding in stagnant water rich in organic matter is Culex. These mosquitoes tend to bite in the crepuscular hours or after dark, and their larvae develop in water that contains organic material—detritus, mud, or polluted, slow-moving water. This contrasts with Aedes, which are usually day-biting and breed in clean water in artificial containers, and with Anopheles, which bite at night but prefer cleaner, more aerated water for breeding. The description of running water with little organic matter doesn’t match Culex, while the crepuscular/nocturnal habit plus organic-rich stagnant water does.