Know great about Mosquitoes its causes and varieties

Mosquito, a two-winged ‘little fly’ is a menace to humankind. It causes blood loss, transmits diseases like malaria, filaria, dengue, chikungunya, and Japanese encephalitis. There is incredible diversity in the mosquito family. Weighing only about 2.5 milligrams, mosquitoes have survived through the ages. Fossil and zoogeographic evidence suggest that these insects evolved during the dinosaur period of Jurassic Age around 250 million years ago. Though dinosaurs are long gone, these small winged creatures have adapted and evolved to produce extensive taxonomic, genetic and ecological diversity.

Where are they found?

Mosquitoes are found throughout the world except in places that are permanently frozen. They are found amply in the tropics and subtropics. The largest population of individual species occurs in the Arctic Tundra. Out of the 3500 mosquito species, about 350 species have been reported in India.

The diseases they transmit

It is estimated that over 700 million people are affected by the diseases transmitted by mosquitoes. Some of the major diseases are: malaria, filaria, dengue, chikugunya, Japanese Encephalitis (JE), yellow fever, Western Nile Fever (WNF), Western Equine Encephalitis (WEE), Eastern Equine Encephalitis (EEE), Venezuelan Equine Encephalitis (VEE), and California Encephalitis (CE).

Varieties of Mosquitoes Anopheles

Anophelinae comprises 450 species. Sixty-six of these are medically crucial for their plasmodium-carrying capacity. In our country, 58 Anopheline species have been recorded of which 10 are known to be malarial vectors.

How to identify Anopheles

Anopheles can be identified by the three to four black spots on the upper edge of the wing. It has grayish brown body and pale bands on maxillary pulp. Male mosquitoes have antennae that look like brush. In females, antennae do not have such dense hairs. The Primary vector An Culicifacies has widespread distribution and can efficiently transmit both ordinary and cerebral malaria. It breeds proficiently during monsoon and causes incidence of malaria intensify.

The other varieties are: An. Stehensi, an urban vector; An.fluviatilis that inhabits hilly regions; An.minimus found in tea garden belts and foothill regions; An.dirus, mainly confined to the forest and forest fringe areas; An.minimus, dirus and fluviatilis maintain stable malaria in the northeastern states. An.Sundaicus is at present restricted to Andaman Nicober islands, though it was earlier prevalent in Odisha. Besides malaria transmission An.gambiae, An. Funestus etc. carry the filarial parasite in some parts of the world including East Africa, Papua New Guinea. An.barbirostris and An.hycranus can transmit Japanese encephalitis virus also.

Why they feed on: Major Anopheline vectors are anthropophilic and feed on the blood of humans inside the house. The biting hours vary through night (depending on the species) with a flight range of two to three kilometers. Their flight sound is not audible.

Where they breed: Anopheles breed in fresh water bodies like riverside, lakes, cisterns, wells, paddy fields etc. But few species can breed even in foul water, muddy ponds and marshlands.