Harnful Effects Of Neonicotinoids Usage In Agriculture
Indian economy has a major cornerstone in terms of agriculture, to ensure the high yield of crops and food facility for the increasing population protection from pests is necessary. Pesticides are the organic chemical substances that are premediated extensively to repel, kill any pest either acting broadly or specifically for a particular pest. These are classified on the basis of mode of action, mode of entry, type of target organism, the chemistry. On the basis of the chemical composition they are broadly classified into organophosphates, carbamtes, synthetic Pyrethroids.
Pesticides use on global scale is increasing day by day and China is one of the most extensively using pesticide country in the world. Almost 98% of these pesticides is contributing as a pollutant in various resources as they have the capability of high persistence in the soil, leaching out in the soil leads to ground water contamination and non-specific effect on the beneficial organisms.
Soil consists of various nutrients and a diversity of microorganisms that contributes in the nutrient cycling, soil fertility and various beneficial interactions with plants. There are various pesticides that have high persistence in the soil thus do not degrade easily and effect the beneficial microflora of soil leading to deterioration of soil quality by their accumulation. Neonicotinoid compounds were introduces in 1990s and now are extensively used in almost 120 countries for more than 140 different crops. They are specific in mode of action and are broadly divided into three main categories: chloropyridinyl compounds (imidacloprid, nitenpyram, acetamiprid, thiacloprid), chlorothiazolyl compounds (thiamethoxam, clothianidine) and tetrahydrofuryl compounds (dinotefuran). These are soluble in water thus absorption through different parts of the plants is easy resulting in action as systemic insecticides. These insecticides have their main target as acetylcholine receptors present in insects known as nicotinic acetylcholine receptors, that results in blockage of nerve propagation due to increase in release of acetylcholine. Similar receptors do present in mammals but the insectide do not bind with the receptors as there is difference in the subtypes of receptors.
Clothianide is in the Chlorthazolyl class of neonicotinoids do not degrade easily in the soil and having a half-life life of 3000 days in the soil, thus its high use results in its accumulation in the soil that further affect the soil microflora and nutrient cycling. Neonicotinoids are also found to have non-target bad impact on bees by disrupting their endocrine functioning, clothinidine is toxic to the worker bees thus also disturbing the natural pollination balance.
