Blog Details

  • 10/27/2023


Why in news?

Recently, Indian farmers have faced consistent losses of Bt cotton crops due to pink bollworm attacks since the mid-2000s, when scientists found that the insect had become resistant to the genetically modified variety of cotton.


  • The pink bollworm is an insect known for being a pest in cotton farming. The adult is a small, thin, gray moth with fringed wings.
  • The larva is a dull white caterpillar with eight pairs of legs with conspicuous pink banding along its dorsum. The larva reaches one half inch in length.
  • The female moth lays eggs in a cotton boll, and when the larvae emerge from the eggs, they inflict damage through feeding.
  • They chew through the cotton lint to feed on the seeds. Since cotton is used for both fiber and seed oil, the damage is twofold.
  • Their disruption of the protective tissue around the boll is a portal of entry for other insects and fungi.
  • The pink bollworm is native to Asia, but has become an invasive species in most of the world's cotton-growing regions.
  • In parts of India, the pink bollworm is now resistant to first generation transgenic Bt cotton (Bollgard cotton) that expresses a single Bt gene (Cry1Ac).
  • Populations of bollworms are controlled with mating disruption, chemicals, and releases of sterile males which mate with the females but fail to fertilize their eggs.

Bt cotton

  • Bt cotton has been genetically modified by the insertion of one or more genes from a common soil bacterium, Bacillus thuringiensis. 
  • These genes encode for the production of insecticidal proteins, and thus, genetically transformed plants produce one or more toxins as they grow. 
  • The genes that have been inserted into cotton produce toxins that are limited in activity almost exclusively to caterpillar pests (Lepidoptera). 
  • However, other strains of Bacillus thuringiensis have genes that encode for toxins with insecticidal activity on some beetles (Coleoptera) and flies (Diptera). 
  • Some of these genes are being used to control pests in other crops, such as corn.