A pest is any species or organism which competes with the plant/ animals or human beings, and causes economic damage to us for food, destroys woods in houses, spreads disease, or just conflicts with a man's welfare, convenience, and profits. Agricultural pest includes animals, insects, fungi, and bacteria that cause the crop and crop yield reduction from the potential yield that could be obtained in the area without pests. Pest may be observed in both fields during a crop's lifecycle or storage at post-harvest life of crops in agriculture. It is estimated about 70,000 pest species damage agricultural crops which include about 9,000 species of insects and mites, 50,000 species of plant pathogens, and 8,000 species of weeds and only 10% of this pest are considered as major pest. Pest has been a major devastating problem for crop production since the starting phase of agriculture, and still today it remains the same. Crop lost by the insect and pest can be considered one of the serious problems existing today as human beings on the earth are 7.674 billion. From 2018-2019 the number of undernourished people increased by 10 million and increased 60 million more undernourished people than in 2014. This is the reason why pest control is important for the agriculture industry to improve the food security level.

Pest control can be defined as the management or regulation of pest species to maintain them below the economic injury level so that the economic damages caused by insect pests remain minimum. The pest control methods include natural control, mechanical control, physical control, cultural control, biological control, and chemical control. Natural enemies like predators, parasites, and disease organisms can control about 50-90 % of the pest population in the natural ecosystem. Monoculture is the more preferred cultivation practice which has already upset the natural balance; hence we require a new set of practice to control the pest in the monoculture which is served by chemical control.

Chemical control is based on the substances that are toxic to the pests. These chemicals are often called pesticides and insecticides. According to Pesticides Act, 1991; the poisonous medicines used for killing or destroying the harmful pest that appears in seeds, plants, trees, animals, etc. are pesticides. To add the desired results and improve physical and chemical properties some auxiliary substances are added to the processing or use of pesticides. These substances are known as pesticides additives, e.g. synergists, solvents, diluents, surfactants, stickers, etc.  Increasing agricultural productivity and safeguarding public health is the major goal of pesticides. But with time, the adverse effects of overusing chemical pesticides on human health and the environment are known. 

About 60.4% of the population in Nepal is engaged in agriculture and contributes 27% to GDP . It hasn’t been so long that people in Nepal started using chemicals in order to increase agricultural productivity. People were unaware of modern chemical pesticides till the 1950s. They were dependent on the traditional organic methods for killing pests. For the first time ever, in 1952 chemical pesticides was introduced in Nepal for the control of Malaria. Paris Green, Gamaxone, and Nicotine were imported from the United State of America for malaria control program. DDT was first introduced in 1952 by the MOH. After the 1960s, other chemical pesticides were also introduced rapidly for the agriculture sectors. Since then the number of farmers using pesticides has been increasing rapidly.

About 25-35% yield loss in Nepal is caused by insects and pests. There are 3,035 types of pesticides available by trade name whereas 170 types of pesticides available by common name. The number of the vegetable farmers increased from 7.1% in 1991/92 to 16.1% in 2001/2002 who use pesticides for growing vegetables. About 80% of pesticides are used in vegetables. Fungicides are the dominant form used. The proportion of pesticide users in the last three censuses for maize commodity were 0.9, 2.8 and 4.2% respectively. Total active ingredients used in the pesticides during 2011/12 were about 345,000 kg or liters. Mainly used pesticides in Nepal are organo-phosphate, carbamates, bio-pesticides, synthetic pyrethroids, fungicides, herbicides, rodenticides, botanical pesticides, and pesticides used in public health.

Most of the farmers are unaware about the banned pesticides and apply the pesticide whatever the agro-vet suggests. A survey conducted in four municipalities of Bhaktapur to know farmers’ pest management strategy knowledge on pesticide safety and practice of pesticide use at Bhaktapur district in 2018, reported that only 12% of farmers knew about the banned pesticides whereas over 90% of farmers did not know about the class of pesticides, only 27% of farmers followed the waiting period, and 18% know about the natural enemies. Further they reported 12% of respondent used cultural method, 13% used biological control, 35% used chemicals with other methods and 28% used chemicals only for the pest management.

The use of pesticides has made the farmers dependent upon these chemicals and ignore other better alternatives. Majority of farmers in the developing countries like Nepal had lack of knowledge about the proper use of the pesticides. They use pesticides without proper information against the insect whether it is beneficial or harmful and the population of the insects or pest. It was estimated that, 26 million human pesticides poisonings with 220,000 deaths per year worldwide, about 72 million bird die due to the use of pesticides. Similarly, other animals belonging to mammals, birds, fishes, reptiles are also adversely affected. This is due to the pesticides residue which remains for the long period of time causing health problems to the consumers. In the fiscal year 2016/17, Rapid Bioassay Pesticides Residue(RBPR) analysis unit tested 1903 samples. The result shown that out of total, 5 need to be quarantined and 22 samples need to be disposed. A research conducted for analyzing residue of pesticides on 75 samples of 13 different vegetable shown that 58% of the vegetable samples contained no detectable level, 38% of sample contained trace level of pesticides residue while 4% of the sample contained above maximum residue limit.

Use of pesticides has led to development of resistance on the target organism creating the superbugs while decreasing the numbers of beneficial and non-targeted insects and microorganisms. High cost of production, decreasing level of soil fertility, environmental pollution, negative health impacts are some of the major problems of using chemical pesticides. An example of the health impact of pesticides residue is the Endosulfan tragedy in Kerala which existed for many years.