Pink Bollworm is wreaking havoc on cotton fields

Subject : Geography

Section: Economic geography

Context: Pink ballworm has caused widespread damage in Haryana and Punjab

Pink ballworm (PBW):

It is one of the most destructive pests of cotton.

Distribution: Originally native to India, it is now recorded in nearly all the cotton-growing countries of the world.

Features

The adults are small moths about 3/8 inch long and are dark brown with markings on the fore wing.
The larval stage is the destructive and identifiable stage.
The larvae have distinctive pink bands and can reach a length of ½ inches right before they pupate.

Ecological Threat:

Adults lay eggs on cotton bolls; once hatched, the larvae eat the seeds and damage the fibers of the cotton, reducing the yield and quality.
When the larvae mature, they cut out the boll and drop to the ground and cocoon near the soil surface.
It has also been observed to attack hibiscus, okra, and hollyhock plants.
The PBW larvae burrow into the developing fruits (bolls) of cotton plants, and the damage affects both the weight and quality of the harvested bolls containing the lint fibre and seeds inside.

Symptoms of Damage

Rosetted flowers.
Excreta observed at the point of bore holes by larval feeding. .
Interlocular boring and formation of double seeds.
The attacked buds and immature bolls drop off. Discoloured lint and burrowed seeds.

Cotton

Cotton is the most important commercial crop of our country contributing upto 75% of total raw material needs of textile industry and provides employment to about 60 million people.
India has the largest area under cotton cultivation with relatively low productivity primarily due to the large area under rainfed cultivation with inadequate supply of inputs.
Area wise, India ranks first in world, whereas, it ranks second in production next to China.
Only in India, all the four spinnable fibre yielding species of Gossypium viz., Gossypium hirsutum, G. barbadense, G. arboreum and G. herbaceum are cultivated commercially.
Hybrid cotton cultivation in about 45% of total cotton area contributing 55% of production is a significant milestone achievement in Indian Cotton scenario.
Cotton is attacked by several insect pests reducing the crop yield to a greater extent. The insect pests that attack cotton crop may be classified into sap sucking insects (Aphids, Jassids and White fly) or chewing insects (Bollworms, leaf eating caterpillars etc.). Of the total pesticides used in Indian Agriculture, about 45 per cent is sprayed on cotton crop alone. To reduce pesticide usage in cotton, several strategies like use of Genetic Resistance to insect pests, Integrated Pest Management (IPM), Insecticide Resistance Management (IRM) etc. are advocated. In recent times, Bt cotton technology is found to be one of the best strategies to manage bollworms, the most important pest of cotton.

The Need for Bt cotton

The genetic resistance, one of the important pest management strategy, is available in cotton gene pool against the sap sucking pests such as jassids, whitefly etc and using this several resistant / tolerant varieties and hybrids have been developed and released in India. However, such kind of known resistance is not available against the bollworms. Hence, an alternate strategy is explored to circumvent this problem by cloning and transferring the genes encoding the toxic crystal δ – endo toxin protein from the soil bacterium Bacillus thuringiensis. The Bt transgenic cotton (Bollgard of Monsanto) has thus been developed successfully in USA, which has the ability to control the bollworms at the early stages of crop growth (upto 90 days) effectively.
The first commercial Bt cotton variety was released in USA by M/S. Monsanto (Bollgard), which contains Cry 1Ac gene of Bacillus thuringiensis. Bt cotton is commercially grown in several countries like China, Australia, Mexico, South Africa, Argentina, India, Indonesia etc. World wide the area under Bt cotton keep increasing year by year. Overall, about 12% of the world cotton is now planted with Genetically Modified varieties / hybrids (GMO) and ICAC has estimated that his may rise to 50 % in 5-7 years.