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MOSQUITO

Mosquito is that pesky, dreaded insect notorious for being the deadliest animal. Mosquitoes are cosmopolitan (found world-wide). They are in every land region except Antarctica and a few islands with polar or subpolar climates. Iceland is such an island that essentially free of mosquitoes.

Mosquito is a small flying insect of the family Culicidae, known for biting and sucking blood leaving an itching bump on the skin. However, only the females of the species bites animals and humans. The adult females of most species have tube-like mouthparts (called a proboscis) that can pierce the skin of a host and feed on blood. The blood contains protein and iron the females need to produce eggs.




Mosquitoes are of great public health importance as they are known to be vectors of diseases like malaria, yellow fever, Chikungunya, West Nile, dengue fever, filariasis, Zika and other arboviruses (arboviruses are diseases caused by

arthropods). The hosts of mosquitoes are varied including ⁠— vertebrates, such as mammals, birds, reptiles, amphibians, and some fish; along with some invertebrates, primarily other arthropods. Mosquitoes cause the deaths of more people than any other animal by transmitting diseases.



Mosquitoes have a slender segmented body, one pair of wings, one pair of halteres, three pairs of long hair-like legs, and elongated, piercing mouthparts.

The slender, elongated body of the adult is covered with scales as are the veins of the wings. The feathery antennae of the male are generally bushier than those of the female. The males, and sometimes the females, feed on nectar and other plant juices.

Mosquitoes usually develop from egg, pupa, larva and adult in a complete metamorphosis.




MOSQUITO BREEDING

Mosquito species have different breeding habits, but most want to lay their eggs near water – usually in vegetation such as tree stumps and wood piles, hollow areas of a tree or in still water. Female mosquitoes can produce 100-300 eggs at one time, and the eggs hatch into mosquito larvae within 48 hours. Mosquito breeding takes place about 28 hours after the adult emerges. Often, once a female has mated, she can continue to lay eggs for the rest of her life. Mosquitoes like warm weather and require a temperature of about 500C for breeding.


TYPES OF MOSQUITOES

There are more than 3,000 species of mosquitoes. The following are the three most important genera as they are common carriers of mosquito-borne illnesses in humans:



  • Anopheles mosquitoes are the only species known to carry malaria. They also transmit filariasis (also called elephantiasis) and encephalitis. Anopheles mosquitoes are easily recognized in their resting position, in which the proboscis, head, and body are held on a straight line to each other but at an angle to the surface. The spotted colouring on the wings results from coloured scales. It usually lays its eggs in water containing heavy vegetation. The female deposits her eggs singly on the water surface. The life cycle of anopheles mosquito is from 18 days to several weeks.






  • Culex mosquitoes transmits encephalitis, filariasis, and the West Nile virus. It holds its body parallel to the resting surface and its proboscis is bent downward relative to the surface. The wings, with scales on the veins and the margin, are uniform in colour. It lays eggs on almost any body of fresh water, including standing polluted water. The life cycle of culex mosquito is usually 10 to 14 days and may be longer in cold weather.




  • Aedes mosquitoes transmits yellow fever, Zika fever, dengue, and encephalitis. Like Culex, it holds its body parallel to the surface with the proboscis bent down. The wings are uniformly coloured. Aedes maybe distinguished from Culex by its silver thorax with white markings and posterior spiracular bristles. The tip of the female’s abdomen is pointed and has protruding cerci. Aedes usually lays eggs in floodwater, rain pools, or salt marshes. The eggs are capable of withstanding long periods of dryness. The life cycle of aedes may be as short as 10 days or (in cool weather) as long as several months. A. aegypti, the important carrier of the virus responsible for yellow fever, has white bands on its legs and spots on its abdomen and thorax. This domestic species breeds in almost any kind of container, from flower pots to discarded car-tire casings. Aedes also have species in coastal areas that are prolific breeders, strong fliers, and irritants to animals, including humans.






FEEDING IN MOSQUITOES

Both male and female mosquitoes feed on nectar, aphid honeydew, and plant juices, but in many species the mouthparts of the females are adapted for piercing the skin of animal hosts and sucking their blood as ectoparasites. In many species, the female needs to obtain nutrients from a blood meal before it can produce eggs, whereas in many other species, obtaining nutrients from a blood

meal enables the mosquito to lay more eggs. Both plant materials and blood are useful sources of energy in the form of sugars, and blood also supplies more concentrated nutrients, such as lipids, but the most important function of blood meals is to obtain proteins as materials for egg production.

A mosquito has a variety of ways of finding nectar or its prey, including chemical (mosquitoes can detect organic substances such as carbon dioxide (CO2), 1-octen-3-ol - mushroom alcohol - found in exhaled breath and other compounds that make up body odour. They have odour receptors that are tuned to detecting chemicals found in perspiration. Once a female senses CO2 in the vicinity, she flies back and forth through the CO2 plume until she locates her victim), visual, and heat sensors. Among humans, the feeding preferences of mosquitoes typically include: those with type O blood, heavy breathers, an abundance of skin bacteria, high body heat, and pregnant women. Individuals' attractiveness to mosquitoes is also heritable or genetically-controlled. This means that mosquitoes prefer some people over others.

Prior to and during blood feeding, blood-sucking mosquitoes inject saliva into the bodies of their hosts. This saliva serves as an anticoagulant (to prevent blood clotting). The saliva also is the main route by which mosquito transmits pathogens to the hosts' bloodstream. A mosquito bite often leaves an itchy raised bump on the victim's skin this is caused by histamines trying to fight off the protein left by the mosquito.

Many mosquito species are crepuscular (i.e. they are dawn or dusk feeders). During the heat of the day, most mosquitoes rest in a cool place and wait for the

evenings, although they may still bite if disturbed. Some species are however known to fly and feed during daytime.



METHODS OF PREVENTING THE SPREAD OF DISEASES

It is of major public health importance to control mosquitoes since they are carriers of numerous diseases. Methods used to prevent the spread of disease (or to protect individuals in areas where disease is endemic) are:

  1. Vector control aimed at mosquito control or eradication measures including the:

  • Elimination of breeding places such as Flower pots, ponds, marshes and bogs, puddles, rainwater barrels, empty tires or debris in the yard as they can fill up with water after rain, ditches, untended yards, heavy shaded areas and long grasses,

  • Exclusion via window screens and mosquito nets,

  • Biological control with parasites such as fungi and nematodes, or predators such as fish, copepods, dragonfly nymphs and adults, and some species of lizard and gecko.

  • Another approach is to introduce large numbers of sterile males.

  • Genetic methods that have been explored include cytoplasmic incompatibility, chromosomal translocations, sex distortion and gene replacement.

2. Disease prevention, using prophylactic drugs and developing vaccines.

3. Prevention of mosquito bites, with insecticides, nets, and repellents.


Since most such diseases are carried by "elderly" female mosquitoes, some scientists have suggested focusing on these to avoid the evolution of resistance.


ANY ADVANTAGE OF HAVING MOSQUITOES AROUND US?

While mosquitoes seem to be all woeful, the design of their proboscis has provided inspiration to scientists to design less-painful hypodermic needles, examine strategies to make needle insertion easier, and create insertion guides to better place tiny electrodes into the brain. Also, it is important to know that mosquitoes do not transmit HIV nor Corona Virus. Even if a mosquito were to bite someone who is infected, it would not be able to replicate the infection and transmit it to other people."





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