Collateral damage is a wonderful word discovered to justify damages to the civilian populations trapped between two fighting forces in a battlefield situation. Recent sufferings of civilian population in the war of attrition between Sri Lankan Army and LTTE fighters are fresh in the memory of the world. All wars are undesirable and from Lord Buddha to Mahatma Gandhi realized the foolishness of war and violence for attaining any goal. Probably Kurukshetra War in Hindu mythology deserves the credit for recognizing the futility of wars, as felt by Pandavas after their pyrrhic victory over Kauravas. One may wonder what this has got to do with the consumer of to day who has plenty of other issues to be worried about. No matter how much one abhors war, the ground reality is that life is a series of mini wars between the consumer on one side and a host of day to day problems on the other side.
One such war is of some importance in the lives of people, especially in India where mosquito based diseases are on the increase lately. Dreaded diseases like Filaria in the south-west coastal areas, Malaria in certain areas near the forests and many others like Dengue, Chikungunya, Encephalitis, Lymes disease, Yellow fever, Bubonic plague, West Nile Virus and many viral fevers are spread by these winged creatures and their control is paramount in protecting the vulnerable population from them. During fifties and sixties of the last millennium, governments in the states used to have regular programs of spraying and fogging pesicidal preparations in the vicinity of affected areas to control breeding of mosquitoes in stagnant waters which seem to have become a part of history. The hapless citizens are left to fend for themselves to escape from the dangers posed by these winged army. Their shrill 'music' ( from their 'wing' instrument!) delivered directly to the ears once the lights are switched off and the sharp stings to suck out blood from the victim are common place occurrence in millions of homes across the country. One can ignore these signals only at one's own peril!
There are over 3500 species of mosquitoes( meaning small fly in Portuguese or Spanish) is estimated to be 170 million years old and most of them are benign to human beings, only a small percentage spreading diseases. They have a pair of scaled wings which are moved 1000 times a second generating the "music" sound, so annoying during sleeping time. Their most lethal weapon is the proboscis, the antenna like structure containing two tubes, one to inject its saliva and the other to suck out the blood from capillaries of the victims. The saliva contains a mixture of chemicals including some unique anticlotting, antiplatelet and vascodilatory agents to increase the fluidity of the blood for easy suction. Potential for extraction of anticlotting drugs beneficial to man from mosquito saliva is being explored. Measuring no more than 1/4-3/4 an inch, a mosquito can suck blood 1-1.5 times its weight which is less than 0.01 ml! It is a little known fact that mosquitoes love foods like nectar for regular consumption but will have to get blood for conceiving and laying their eggs. While loss of blood is not very insignificant, the transfer of infection through its proboscis from one person during its previous visit to another during the next visit is of a serious concern with epidemic potential. While in captivity mosquitoes can live for a month, under open environment its life is limited to 1-2 weeks.
Here comes the valiant 'private' generals offering socour and solace to the victims of the unwelcome nocturnal visitors with their mats, coils and vaporant bottles which come in many variants. In western countries mosquito killing gadgets can be as costly as $ 5000 a piece incorporating modern technology of attracting the mosquitoes and killing them. The simplest electrical device costing about Rs 100-150 in India is the electrical zapper, looking like a tennis racquet which needs to be swished around for the catch, which electrocutes the flying creature on contact. Imagine every consumer emulating the feats of the all time great champion tennis player Roger Federer in using the zapper every night to score aces against these winged opponents! The sonic gadget using high frequency sound waves which looks simple is not often effective. Fogging machines containing pyrethrins, permethrins or/and piperonyl butoxide preparations are recommended for use during dawn and dusk in the gardens, the preferred visiting time of these "uninvited guests" to control their population around buildings.
DEET (N, N Diethyl-m-toluamide), essential oils of lemon, eucalyptus ( (p-menthane-3,8-diol or PMD), Icardin or Picardin, Napelactone, citronella oil, neem oil, Bog Myrtle etc are known mosquito repellents in use. Plants like citronella, marigold, ageratum and catnip possess repelling properties because of their content of some active constituents. Generally people with high cholesterol, uric acid, CO2 emission, lactic acid levels attract mosquitoes more than others while women are more preferred choice for these predators. They are believed to be most active during full moon periods and are more attracted towards incandescent lights. Mosquito species Toxorhynichitis are effective natural predators for the house mosquitoes, each of their larva able to gobble about 5000 larvae of smaller mosquitoes during their development cycle. Dragon Fly can eat mosquitoes but their population itself is being threatened due to many environment problems.
In India approved fumigant materials work either through smoke generated when they are burned or vapors generated when indirect heat is applied on to the absorbed mats or by evaporation of the liquid fumigant. These contraptions are supposed to work for 8-10 hours spewing out the vapors against the hardly visible enemy and give a sound sleep to the beneficiary. Such gadgets help to continuously emit the anti-mosquito substances in a closed environment as the effect of repellents lasts only for about 30 minutes to 2 hours on a single application. Electronic gadgets are being marketed that can control the time of fumigation with auto shut off in 8 hours after switching on before going to sleep. Normally a 35 ml bottle is rated to work for 30 days but high pressure promotion and fierce competition in the market are driving manufacturers to claim up to 90 days life for the same volume of fumigant. How this can be accomplished is any body's guess! What effect these fumigants have on the health of the unsuspecting sleepers also is an unknown factor. "Sleep well and regret later" may be the ultimate slogan if this industry, which is currently the winner raking up huge profits (courtesy the dreaded winged army), is allowed to grow indiscriminately without any strong scientific foundation, so critical for ensuring consumer safety in the long run.