Focus: GS-III Science and technology, Agriculture
Introduction
- Cotton fabric from around 3,000 BCE has been excavated from the ruins of Mohenjo-daro show that cotton was used in the subcontinent as far back as 5,000 BCE.
- Indian cotton fabrics dominated the world trade during the succeeding millennia and were exported to many places, including Greece, Rome, Persia, Egypt, Assyria and parts of Asia.
- Cotton suffers from plenty of infestation from moth pests (Lepidopteran) such as the Pink Bollworm (PBW) and sap-sucking (Hemipteran) pests such as aphids and mealy bugs.
- Much of the cotton cultivated until the 20th century was of the indigenous variety Gossypium arboreum.
- From the 1990s, hybrid varieties of G. hirsutum were promoted which cannot resist a variety of local pests and require more fertilizers and pesticides.
- Bt cotton was introduced in India in 2002 to help farmers deal with the increasing use of synthetic pesticides.
What are GM Crops?
- Genetically modified crops (GM crops) are plants used in agriculture, the DNA of which has been modified using genetic engineering techniques. More than 10% of the world’s crop lands are planted with GM crops.
- In most cases, the aim is to introduce a new trait to the plant which does not occur naturally in the species like resistance to certain pests, diseases, environmental conditions, herbicides etc.
- Genetic Modification is also done to increase nutritional value, bioremediation and for other purposes like production of pharmaceutical agents, biofuels etc.
Bt cotton
- Genetically modified (GM) cotton, the plant containing the pesticide gene from the bacteria Bacillus thuringiensis (Bt), has been grown in India for about twenty years.
- Strains of the bacterium Bacillus thuringiensis produce different Bt toxins, each harmful to different insects.
- Most notably, Bt toxins are insecticidal to the larvae of moths and butterflies, beetles, cotton bollworms and ghtu flies but are harmless to other forms of life.
- The gene coding for Bt toxin has been inserted into cotton as a transgene, causing it to produce this natural insecticide in its tissues.
- According to the Ministry of Agriculture, from 2005, adoption of Bt cotton rose to 81% in 2007, and up to 93% in 2011.
The important advantages of Bt Cotton are briefly:
- Increases yield of cotton due to effective control of three types of bollworms, viz. American, Spotted and Pink bollworms.
- Insects belonged to Lepidoptera (Bollworms) are sensitive to crystalline endotoxic protein produced by Bt gene which in turn protects cotton from bollworms.
- Reduction in insecticide use in the cultivation of Bt cotton in which bollworms are major pests.
- Potential reduction in the cost of cultivation (depending on seed cost versus insecticide costs).
- Reduction in predators which help in controlling the bollworms by feeding on larvae and eggs of bollworm.
- No health hazards due to rare use of insecticides (particularly who is engaged in spraying of insecticides).
Arguments against Bt Cotton
- In India, Bt cotton has been enveloped in controversies due to its supposed failure to reduce the need for pesticides and increase yield.
- The link between the introduction of Bt cotton to India and a surge in farmer suicides has been refuted by other studies, with decreased farmer suicides since Bt cotton was introduced.
Argument for Indigenous variety
- The cost of ignoring indigenous varieties for decades has been high for India.
- These varieties resist many pests and don’t present the problems faced with hybrids.
- Research suggests that with pure-line cotton varieties, high density planting, and short season plants, cotton yields in India can be good and stand a better chance at withstanding the vagaries of climate change.
- But government backing for resources, infrastructure and seeds is essential to scale up indigenous varieties.
-Source: The Hindu
