siphon

QUESTION

Where do Anopheles mosquito lay their eggs?

ANSWER

Female Anopheles mosquitoes lay their eggs in standing, often stagnant, pools of fresh water. These larvae can be identified in ponds and puddles because unlike other mosquito larvae, they position themselves parallel with the surface of the water, allowing them to breathe air despite not having a respiratory siphon (instead, they have spiracles on their body).

Different species of Anopheles can tolerate very different larval habitats, including very brackish water (high salt content) in mangrove swamps and estuaries to pristine freshwater and also varying degrees of sun exposure and vegetative cover. Many different fish and aquatic invertebrates can predate on mosquito larvae, many of which have been used in attempts to control mosquito populations throughout the world.

QUESTION

What are mosquito larvae?

ANSWER

Larvae are one of the life stages of mosquitoes; they are baby mosquitoes, if you will. Adult mosquitoes lay eggs as a “raft” on the surface of a body of fresh water—they prefer still and stagnant pools. These eggs then hatch into the mosquito larvae, which live in the freshwater pool until they form a pupa, just under the surface. These pupae then hatch into adults again, completing the life cycle.

Mosquito larvae are omnivorous, eating algae and small organisms also living in the water. Despite living immersed in water, they require oxygen to breathe, which they inhale using two different methods: Aedes and Culex mosquitoes (the vectors of a number of diseases, including West Nile disease, dengue fever, yellow fever, encephalitis and filarisasis) have a specialised breathing organ, a bit like a snorkel, called a siphon, which they use to suck in air, whereas Anopheles mosquitoes (the main vectors of malaria) lack this organ and so have to lie next to the surface to take in air. The larvae moult four times while they live in water; after the fourth time, they are ready to pupate and become adults. The entire larval stage of a mosquito’s life usually take between one and two weeks, depending on the ambient temperature.