Saturday 25 April 2015

CHAPTER 5 : MOSQUITOES

Types of Mosquitoes
Aedes, Anopheles, and Culex


There are approximately 2, 700 species of mosquito in the world; the three most significant genera are the Aedes, Anopheles, and Culex, as these types of mosquitoes are responsible for transmitting various diseases that are hazardous to mankind.

The Aedes Mosquito
As one of the most dangerous types of mosquito, the Aedes is anthropophagic, that is, it feeds on the blood of humans. Only the female mosquito bites. It transmits among humans menacing diseases such as yellow fever and dengue fever, and can also cause lymphatic filariasis, an illness that can trigger elephantiasis in certain cases.

MosquitoMost species of Aedes can be found in the tropical and subtropical zones of the world. Recently, the genus has been discovered in more temperate regions, and its presence can now be anticipated on every continent except Antarctica.

The female Aedes mosquito lays its eggs on the surface of water; adulthood is reached within approximately six to seven days. The mature Aedes mosquito breeds, feeds, and dies within a week or two, which is the life cycle of most mosquitoes.







The Anopheles Mosquito
The Anopheles is different from other types of mosquitoes as it is the genus most accountable for spreading malaria to humans. Malaria can be fatal; its typical symptoms include fever, headaches, chills, and general flu symptoms. The species of Anopheles known as Gambiae is infamous for transmitting plasmodium falciparum, the most threatening form of malaria in the world.

The Anopheles mosquito is generally located near bodies of water, such as ponds, swamps, marches, ditches, and rain pools. The Anopheles female favors laying its eggs in fairly still water that is oxygenated, and where there is an abundance of wild plant life. Some species enjoy the shady areas, while others prefer sunlight.







The Culex Mosquito
The genus of mosquito known as the Culex can be considered the least dangerous of the three major types of mosquitoes due to the fact that humans are not their preferred blood meal. Instead, most species of Culex are partial to biting birds rather than humans. Despite this inclination, the Culex female mosquito is nevertheless recognized as spreading diseases such as the West Nile virus, malaria, filariasis, and encephalitis.

The Culex, like the Anopheles, tends to favor standing water to lay its eggs; however, unlike the Anopheles, it does not necessarily opt for plant and wild life surroundings. Instead, it often breeds in the outdoor objects on your property, such as barrels, cans, garden pots, used tires, as well as other places where stagnant water can collect.





LIFE CYCLE


Like all flies, mosquitoes go through four stages in their lifecycles: egg, larva, pupa, and adult or imago.

The first three stages—egg, larva, and pupa—are largely aquatic. These stages typically last five to 14 days, depending on the species and the ambient temperature, but there are important exceptions. Mosquitoes living in regions where some seasons are freezing or waterless spend part of the year in diapause; they delay their development, typically for months, and carry on with life only when there is enough water or warmth for their needs. For instance, Wyeomyia larvae typically get frozen into solid lumps of ice during winter and only complete their development in spring. The eggs of some species of Aedes remain unharmed in diapause if they dry out, and hatch later when they are covered by water.

Eggs hatch to become larvae, which grow until they are able to change into pupae. The adult mosquito emerges from the mature pupa as it floats at the water surface. Bloodsucking mosquitoes, depending on species, gender, and weather conditions, have potential adult lifespans ranging from as short as a week to as long as several months.


TYPES OF LARVAE





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