Cotton; the white gold, has been the backbone of the economy of many countries. It supports a large number of populations from the small farmers and tenants to the grand textile and oil producing companies. Lint, yarn, textile, and on the other hand, edible oil industries, all depend upon cotton production. Yield of cotton has mainly been affected by the cotton leaf curl virus (CLCV) and it has given rise a lot of boll worms attacking the cotton crops i.e. pink boll worm, spotted boll worm and American boll worm. Different insects attack has drastically increased the use of broad spectrum pesticides on cotton crop. This has increased the production cost of cotton as well as threat for the beneficial insects and environment.
After a long period of disappointment and unfruitful attempts, after all an American company Monsanto has been able sort out a better solution against CLCV vector i.e. white fly; of cry1gene from a soil dwelling, gram positive bacteria, Bacillus thuringiensis. This gene has ability to produce cry toxin, responsible for damaging the membranes of insect gut and eventually causing the death of insect. This cry1 gene been incorporated in the cultivated Gossypium species which enables every part of plant making the cry toxin, thus the plant is available with in-plant resistance to all chewing and sucking insects. This is supposed to be the best possible resistance of today to the insects.
When we talk about the benefits of Bt., we see it in terms of its environmental, economical and social impacts on specific industry. Not only the yield of cotton, Bt. cotton has far much better effects on cotton linked industries. Use of Bt. Cotton variety reduces the use of broad spectrum pesticides, in effect, it saves the predator and pollinator insects, increasing the impact of these beneficial insects on nature as well as study of their role in contorling harmful insects are possible. The less the use of pesticides, the less would be the soil contamination, danger to peasants' health, use of machinery and air pollution due to burning of fuel. Thus the Bt. Cotton is referred as environmentally friendly.
Bt. Cotton has been grown over large areas of the world. Firstly, it was grown in US and then was introduced to Brazil, Mexico, Argentina, South Africa, Australia and China and then it was introduced all over the world, gradually. Use of Bt. Cotton has increased 5% yield of cotton lint and has imposed positive effects on GOT. It is an estimation that, increase in 1 million bales of cotton alleviates the GDP of that country as much as half percent. Thus reducing the pest attack ultimately increases the yield and quality of cotton by many folds.
Millions of small and big landholder, tenants, daily wages workers, businessmen, stake holders, ginners are directly or indirectly dependent upon the failure or progress of this single crop. After the introduction of CLCV, the cotton crop has continuously been declining but, Bt. Cotton has given a ray of hope to all the individuals who are dependent upon this crop.
Although the explorer of Bt. Technology claims it to be environmentally friendly but, still there are also many expectations regarding to the unseen threats of genetically modified crops that their ultimate hazards would be on humans. The α-toxins may cause allergies, burns and many unseen skin diseases as it has ability to degrade the cell membrane. Any mutation in cry1gene may show hazardous effects as one cannot differentiate between the Bt. and conventional varieties by seeing. Moreover, as the cry1 gene produces α-toxin in all parts of plant. So, the plant part, which has not been harvested and decomposes in the soil, adds a great amount of α-toxins to the soil which is not readily degraded by bacteria nor escapes out of the soil and increases the selection pressure on the soil dwelling microbes.
No doubt, still there is need for some more and targeted research on risk/benefit evaluation of Bt. cotton in order to make its use more effective and widespread. Research and documentation on effects of Bt. cotton on small and often neglected issues regarding to the environment, insect populations, worker's health and the long term effects of α-toxin on environment and human would make all the Bt. crops more popular among growers.
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