Context

• Indian farmers have faced consistent losses of Bt cotton crops due to pink bollworm attacks.

Bt cotton

• GM crops are derived from plants whose genes are artificially modified, generally by inserting genetic material from another organism, to give it new properties, such as improved nutritional value, increased yield, resistance to disease or drought, etc
• Bt cotton has been genetically modified (GM) by inserting one or more genes from Bacillus thuringiensis, a soil bacterium.
• The insertion of B. thuringiensis genes causes cotton plant cells to produce crystal insecticidal proteins known as Cryproteins.
• These proteins are effective in killing some of the most damaging cotton caterpillar pests, such as tobacco budworm and bollworm larvae.

Pink bollworm

• The pink bollworm (Pectinophora gossypiella) is a significant agricultural pest that primarily infests cotton crops. 
• It is named for the pink color of its larval or caterpillar stage. 
• Unlike the American bollworm which feeds on multiple plants, pink bollworm is monophagous, meaning it feeds only on cotton crops.
• The pink bollworm has developed resistance to several chemical insecticides used for its control. This resistance has posed challenges for traditional pest management strategies.

Major concerns over Pink bollworm

• 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.
• Bacillus thuringiensis (Bt) cotton, or Bollgard-I, was introduced to protect the crop against all three species of bollworms (American, spotted and pink bollworms) as it was encoded with Cry1Ac toxin.
• In 2009-10, scientists confirmed pink bollworm’s resistance to Cry1Ac gene in four districts of Gujarat.
• In 2017-18, widespread pink bollworm infestation was reported in Maharashtra and the southern states.
• By 2023, resistant populations of pink bollworm to Bt cotton were established in the North Zone including north Rajasthan districts.

Causes for increased resistance in pink bollworms

• Early sowing of cotton, done by farmers coincides with the time when the worm comes out of winter hibernation (known as diapause stage). The cotton plants are at bud or flowering stage, during which the pink bollworm’s search for food begins. Therefore, it starts feeding on bolls during the larval stage.
• Early sowing also means the pest has access to food for a longer time. This leads to more breeding and population growth.
• The Cry gene, which Bt cotton is encoded with to prevent pink bollworm from attacking the seeds, wears off during the end of the cotton plant’s life cycle. If these pests survive these plants after exposure to small quantities of these toxins, they develop resistance to it.
• Farmers have not been following the advise of  planting indigenous, hybrid varieties of cotton alongside Bt cotton to prevent the pests from developing resistance. This is important as the cross breed of pests from different varieties of plants would have helped in preventing the development of resistance.
• Even pesticides are of limited use in the case of pink bollworms as the pest is protected inside the bolls and damages the crop from the inside.

Conclusion

• Efforts to control the pink bollworm involve a combination of biological, chemical, and cultural strategies. Sustainable and integrated pest management practices are essential to minimize the impact of this pest on cotton production and protect the livelihoods of cotton farmers.