INTRODUCTION

The word pest comes from the Latin word "pestis" which includes an animal or plant that occurs in such abundance as to present a distinct threat, economically or medically to man or his interest. A pest may be insect, fungus, weed, rodent, bacteria, virus, nematodes, acarid / mite, parasite and even animal or bird. Worldwide, about 10,000 species of insects are important as pest, out of 750,000 identified species. Over 50,000 species of fungi are responsible for some 1,500 plant diseases; Over 1,800 species of weeds out of the known 30,000 cause serious economic loss. About 15,000 species of nematodes produce more than 1,500 serious deleterious effects on plants. Over 1,00,000 species of pests destroy food which could be food for 135 million people. The word pest has no biological meaning. Pests are organisms that diminish the value of resources in which we are interested. In India, crops are affected by over 200 major pests, 100 plant diseases, hundreds of weeds and other pests like nematodes, harmful birds, rodents and the like. About 4,800 million rats cause havoc in India. Approximately, 30% of Indian crop yield potential is being lost due to insects, disease and weeds which in terms of quantity would mean 30 million tones of food grain. The value of total loss has been placed at Rs 50,000 million, represents about 18% of the gross national agriculture production. The pest wise losses are as follows:

Pest	Loss of Food Grains (%)
Weeds	28
Diseases	25
Insects	23
Storage	10
Rats	8
Others	6

Besides the agriculture, non - agriculture pests are carriers of malaria, filaria, encephalitis, typhus, plague and other dreadful diseases. About 30 household pests are worthy of attention, like files, fleas, bedbugs, lice, cockroaches, mites, termites and moths. Man's war against pests is perennial and almost eternal. No agriculture or forest crop can be grown in an insect and disease - free environment. Pests and disease are parts of natural processes that are going on since the beginning of the universe, and the biological process of evolution.Total extermination of pests is not possible and is no longer the aim of pesticide application. The control of pests is the objective and designated as plant protection. The efficient producer wants to keep loss due to pests to a minimum pest control is now the chemistry of human survival.While pest control is one of the imperative prerequisite, it bears also higher degree of negative impacts on environment. Since the chemicals which control the pest commonly known as pesticides. Pesticides are basically toxics and persistence; it can enter in food chain and causes injury to human health. It also destroys the diversity and food web and causes ecological imbalance. Pest control therefore needs regulation on the interest of human health and environment.

Pesticide Use

Pesticides are defined as the substance or mixture of substances used to prevent, destroy, repel, attract, sterilise, stupefy or mitigate any insects. Generally pesticides are used in three sectors viz. agriculture, public health and consumer use. The consumption of pesticide in India is about 600 gms. / hectare, where as that of developed countries is touching 3000 gms. / hectare. There is a wide range of pesticides found used in non-agriculture situations such as industries, public health and for a number of purposes in the home. Domestic use of pesticides is mainly as fly killer, ant killer, moth killer, repellants, rodenticides and fungicides etc. By and large industrial use of pesticide is of vital importance in the industries such as wood and carpet, wood preservation, paint industry, paper and board industry, leather industry, building industry,miscellaneous industrial application e.g. soluble cutting oils, industrial watersystems, drilling fluids etc. 

Advantages Of Using Pesticides

Pests are an ecological problem and therefore our control strategies must be ecologically sound. Basically, there are two approaches to pest control:

• Prevention
• Cure or removal of the cause.

Modern agriculture is a combination of both and human intervention is necessary, whether it be pulling out weeds by hand, use of esticides or genetic engineering. Control methods evolve over time as knowledge and techniques improve. This includes the development of chemical means of control which become very important because of a number of advantages. For example:

• Cost effectiveness. Farm chemicals are an economical way of controlling pests. They require low labour input and allow large areas to be reated quickly and efficiently. It has been conservatively estimated that for every dollar a farmer spends on farm chemicals he receives $4 return (Anon, 1990a). Production per labour unit has increased while production costs and energy inputs are lower.
• Timeliness and flexibility. A suitable farm chemical is available for most pest problems with variations in activity, selectivity and persistence. The best product can be chosen for the situation. This allows more flexibility in management options and better timeliness of pest control.
• Quality, quantity and price of produce. Farm chemicals ensure a plentiful supply and variety of high quality, wholesome food at a reasonable price. Modern society demands nutritious food free from harmful organisms and blemishes. Ornamental horticulture also requires unblemished and pest-free plants and flowers. This would be very difficult without farm chemicals.
• Prevention of problems. Farm chemicals are frequently used to prevent pest problems from occurring, e.g. preventing weeds in gardens and lawns; treatment of export and import produce to prevent the spread of pests; treatment of stored products to prevent pest attack and destruction during storage.
• Protection of pets and humans. Without farm chemicals the treatment of spiders, cockroaches, etc in houses; fleas on pets, etc, would be most difficult.
• Protection of the environment. If no farm chemicals were available to control environmental pests like noxious weeds, feral animals, etc, our environment would suffer very badly. Using herbicides to control crop weeds reduces the need for cultivation, thus reducing land degradation.

Farm chemicals are a management tool to aid in the control of pests and their continued use is supported by the conclusions of the Senate Select Committee on Agricultural and Veterinary Chemicals in Australia, and even Dr Kate Short of the Total Environment Centre states: "we do not have a problem with pesticides being used as a management tool in pest control in Australian agriculture" (Colston et al., 1990).

Potential adverse effects of pesticides

Despite their many advantages, there are some potential hazards or risks when using farm chemicals. These risks may be associated with all chemicals whether they be industrial chemicals, pesticides, household products or even natural chemicals found in the environment. Undesirable side effects of farm chemical use usually stem from a lack of understanding of the impact of the chemical on the environment, compounded by indiscriminate and overuse of the product. These side effects do not always occur when farm chemicals are used and damage does not necessarily result. Some of these effects may be:

1. Reduction of beneficial species. Non-target organisms, including predators and parasites of pests, can also be affected by chemical application. The reduction of these beneficial organisms can result in changes in the natural biological balances. Losses of honeybees and other pollinating insects can also be a problem.
2. Drift of sprays and vapour during application can cause severe damage and residue problems in crops, livestock, waterways and the general environment. Care in the methods of application and the weather conditions under which it is carried out can reduce drift. Environmental pollution from careless application and runoff can result in wildlife and fish losses. This should be a concern for all of us.
3. Residues in food for humans and feed for livestock can be a consequence of direct application of a chemical to the food source, by the presence of pollutants in the environment or by transfer and biomagnification of the chemical along a food chain. Not all residues are undesirable although good agricultural practice must be observed to prevent unnecessary and excessive levels of residues.
4. Ground water contamination by leached chemicals can occur in high use areas if persistent products are used.
5. Resistance to the pesticide used can develop in target pests due to overuse and incorrect use of the chemical.
6. Poisoning hazards and other health effects to operators can occur through excessive exposure if safe handling procedures are not followed and protective clothing not worn. Poisoning risks depend on dose, toxicity, duration of exposure and sensitivity.
7. Other possible health effects due to indiscriminate use of farm chemicals also concern many people in the community.

Problems result from misuse, abuse and overuse. Farm chemicals can be used safely and effectively without these undesirable effects although there is always a risk associated with any activity. This risk is relative, as evidenced by smoking or driving a car or a tractor. For example, in May this year, 166 Australians died in motor vehicle accidents while there are very few poisonings from farm chemicals. Many commonly used substances like aspirin or common salt are more toxic than many pesticides.

Despite the relative risks being low, all users of farm chemicals, whether on a large scale or in the home, have a responsibility to use them correctly.