The first stage are the eggs which are laid by femalemosquitos in a moist place such as: puddles or the inside of an old tire wherecondensation is found. The eggs of Culexare laid by the female mosquitos in batches of 50 to 100 in tiny clumps thatare around a quarter-inch long and tend to float together on the surface of thewater. The eggs that are white in the beginning turn to a near black within aday. Most of the times they hatch in one to three days, however it usuallydepends on the temperature. Once the eggs hatch, the mosquito larvae comes out.The larvae are the baby stage of mosquitos.
The larvae are aquatic creatures thatfeed on algae, bacteria, and other microorganisms in the water. Most of theirtime is spent hanging upside down from the surface while sucking in oxygen fromthe breathing tubes that are located in their tails. “The New South WalesDepartment of Natural Reources in Austrailia describes them as ‘hairy maggotswith siphon,’ covered on the lower half by a cocoon.” Since mosquitos arecold-blooded, they depend on external heat sources to warm their bodies due towhich the temperature plays an important role in their development. Themosquito larvae grow faster if the temperature is warmer. It takes about a weekfor most of the larvae to develop as they shed their skin four times to become mosquitopupae. The mosquito pupae do not feed at all. They tend to swim around in thewater.
The mosquito pupae have short, curved bodies with a large head at oneend and flippers for swimming at the other. They live at the surface due totheir light weight, and just like the larvae, mosquito pupae have to take inoxygen from time to time through two breathing tubes. It takes approximatelyfour days for the pupae to develop into an adult mosquito inside the cocoon,again depending on the temperature of the water. Once the pupal tissue developsinto an adult mosquito, the adult uses the air pressure to split the cocoon andemerge. Usually, the new mosquitos tend to rest on the surface to let their wingsdry out and their bodies harden. Adult mosquitos have a head with two largecompound eyes, a thorax, a pair of scaled wings and six jointed legs.
They havetwo things in mind when they come out of their cocoons: feed and mate. If theyare successful in doing both, there are more mosquitos to bother us.Now that we know about the life cycle of mosquitos. Anotherquestion that might arise in one’s mind is how have mosquitos evolved to suckon human blood? To answer this question let’s look at the “Unique mosquitothat lives in the London Underground.” There are mosquitos that live in theunderground as they have evolved to live in the unique conditions of the tubeenvironment. “Over the course of the war, almost 180,000 people sheltered inthe Underground.
” People sheltering in the Underground were pestered by allsorts of insects such as flies, ticks, lice, and fleas as they were very commonduring that time. “The London Underground mosquito is a genetically distinctsubspecies.” Katharine Byrne, a London-based doctoral student, collectedmosquitos from seven sites across the 180km network. Her results showed that thesemosquitos were essentially different from the mosquitos that lived aboveground. The very common species of mosquito, Culex pipiens that lived above-ground only bit birds, however, the Culexpipiens molestus tend to feed on human blood. “The Culex is avery common mosquito,” says biologist Bruno Gomes from the Liverpool School ofTropical Medicine. “There are hundreds or thousands of types of them and they’renot very harmful.
“Along with having different diets, the two species havedifferent behaviours as well. Culexpipiens, the above-ground mosquito, need blood to lay their eggs, hibernatein the winter, and need a lot of space to mate. On the other hand, Culex pipiens molestus does not requireany of these. There only similarity being their looks. The differences werecaused by the different lifestyles that both species are exposed to. Theunderground species adapted to their underground life: where there were nobirds to feed on so they fed on mammals that would be present in theUnderground, mostly rats and humans; they had to mate in closed areas unlikethere above-ground relatives because there were no open spaces in theUnderground; and lastly they lost their tendency to hibernate as theUnderground does not have different seasons.
This is a direct representation ofallopatric speciation as there was a physical barrier that separated them. “Afterthe London Underground system’s construction, the tunnels were largely sealedoff from the surface, and some of the mosquitos found themselves trappedunderground.” It created two different populations that are no longer able tointerbreed due to the differences in their mating behavior. The above-groundmosquitos tend to form big swarm to pair with their mating partner, however theunderground mosquitos tend to choose their mates individually. Although some may argue that the Culex pipiens molestus are their own species.
The genetic makeup ofCulex pipiens is so closely related thatit is near impossible not to say that the one species evolved from the other.