About five species of mosquitoes are important to human beings as pests, as vectors spreading deadly diseases like Malaria, Filaria, Dengue, Chikungunia, Yellow fever and Encephalitis claiming many lives and infecting thousands. The trail grows wider as every successive year the microorganisms causing the disease mutate to more virulent form. Although malaria has been around for centuries, dengue and chickungunia are relatively new. In spite all our efforts the best remains that control of vector in all possible way is the nearest solution.

The Deadly enemy:

1. Pests - Mosquitoes undoubtedly cause the greatest suffering, both to man and animals. Besides sucking blood, they inflict painful and irritating bites. After each bite, a residue of saliva left beneath the skin vexes the victims with itching welt, resulting in sleepless nights with constant irritation.

2. Vectors - The mosquito serves as transmitting agents or vectors for some of the deadliest diseases of man and animals. The main diseases of man transmitted by the mosquitoes are – malaria, filariasis, dengue fever, yellow fever and encephalitis.

a. Malaria/Brain malaria- Most dreadful all these disease, caused by the species of the protozoan, Plasmodium vivax/falciparum i.e. transmitted by female Anopheles. Symptoms include recurrence of fever every third and fourth day/continuous high fever.

b. Filariasis or elephantiasis- This is caused by a parasitic roundworm- Wuchereria bancrofti. It is carried by Culex fatigans. The disease begins with a slow inflammatory swelling of the limbs, scrotum or mammae. If left unattended, the swelling can grow to elephantine proportions.

c. Dengue/Chikun fever- These are caused by a virus and spread by Culex fatigans and Aedes aegypti. Symptoms are aching limbs, high temperature and minute rash.

d. Yellow fever -It is caused by a virus and spread by Aedes aegypti. Symptoms include high fever, internal bleeding, anemia and destruction of liver. It is not reported form India, although its carrier mosquito is found in this country. Although, now limited to Africa and South America, yellow fever is still deadly.

e. Encephalitis- This disease is caused by a virus and spread by various species of Culex and Aedes. It can kill its victims or cause them permanent brain damage. Common birds make up the main “reservoir” or the disease.

Further, the scientists at the Jawahalal Nehru Institute for Post-Graduate Education and Research (JIPMER) at Pondichery have reported that leprosy can be spread by Indian mosquitoes.

Mosquito control

(I) Elimination of breeding places- Elimination of breeding places like drains and septic tanks must be properly maintained. Swampy areas, marshes and stagnant waters, such as cesspools, ponds, pits and open ditches must be drained off. Water should also be prevented from standing in gutters, drains, tree-holes and other depressions. The domestic species can be largely controlled by eliminating receptacles that hold water such as tin-cans, buckets, cisterns, barrels, an old tire, etc. the bushes and shrubs should be cleared off. Open drains should be closed or made under-ground.

(II) Destruction of larvae and pupae-  It is easier and more convenient to kill the aquatic larvae and pupae than the adults of the mosquitoes.

1. Proper drainage- The young stages of mosquitoes can be prevented by not allowing the water to stand in gutters, drains, streams, ditches, etc. By their occasional cleaning, a speedy flow of water can be maintained so that the developing stages get washed into large streams and rivers, where they generally die.

2. Oil screens- The larvae and pupae may be killed by covering or spraying the surface of water with petroleum or paraffin oil and crude oil or kerosene oil. These substances produce a thin film of oil on the surface, so that the larvae and pupae die due to suffocation or lack of respiration.

3. Chemical larvicides- Oil solution or emulsions of DDT, DDD and Benzene Hexa-Chloride are effective larvicides. Dusts containing Paris green, DDT or BHC are effective in the control of surface feeding anopheles larvae.

4. Biological methods. Larvicide fishes like sticklebacks, minnows, trouts, “guppy” and “gambusia” etc., should be introduced in the ornamental fountains, ditches, ponds, lakes, canals, tanks etc. Aquatic nymphs and adult insects (dragonflies), which are natural enemies of mosquitoes, should be encouraged. Aquatic insectivorous plants, such as bladderwort (Utricularia) can also devour the larvae and pupae of mosquitoes.

(III) Destruction of adult mosquitoes

1. Killing by hands. The mosquitoes which approach for bite may be killed by hands.

2. Traps. These are small boxes made of wire gauze and internally lined by black paper or cloth. The mosquitoes tend to enter the boxes and can be killed by closing them.

3. Fumigation. Sulphur, pyrethrum, cresol or other derivatives of naphtha are burnt to produce poisonous fumes. All the openings of the fumigated room are closed but a window-pane is left uncovered for light to come in. the smoke of garlic / neem leaf is now considered to be effective in driving the mosquitoes out.

4. Spraying. Mosquitoes can be killed inside human dwellings by using mosquito bombs or by occasionally spraying them and the adjoining lands with DDT, flit, gammexane, pyrethrum and methanine.

5. Sterilization. Male sterile technique is very effective in controlling mosquito population.

6. Genetic control. Inter specific cross is also another way of controlling mosquito.

(IV) Defence against mosquito bites

(1) Houses built on high grounds with drainage and away from vegetation and marshy places.

(2) Mosquito-proof houses by adequate screening the doors, windows and ventilators etc.

(3) Mosquito-nets should be used, especially at night.

(4) The exposed parts of the body may be protected by the use of veils, gloves, and boots, etc., or by the application of repellents, such as anti-mosquito creams, mustard oil, mixture of kerosene oil and eucalyptus oil.

(V) Conclusion:

Proper awareness and community effort is a must to control mosquitoes.