Pink Bollworm Infestation and Bt Cotton
India is the only Bt cotton-growing country facing the problem of pink bollworm infestation. Even though Bollgard 2, or BG-2, Monsanto’s second generation insecticidal technology for cotton, was supposed to protect crops against the pink bollworm, the pest has grown resistant to the toxins produced by this trait. As a result, farmers now spend more on pesticides to control infestations.
The problem is unique to India. None of the other 14 Bt cotton-growing countries have seen this resistance. China still successfully controls pink bollworm with first-generation Bt cotton. The U.S. and Australia are moving on to third-generation BG-3 without having faced this problem.
India is suffering from this unique misfortune due to
- The pink bollworm grew resistant because India restricted itself to cultivating long-duration hybrids since the introduction of Bt cotton in 2002. All other Bt cotton-growing countries mainly grow open-pollinated cotton varieties rather than hybrids.
- The introduction of the Bt gene into only one parent of Indian hybrids is itself a problem. The resulting hybrids are hemizygous, which means that they express only one copy of the Bt gene. So, they produce cotton bolls that have some seeds toxic to the pink bollworm and some that are not. This can be contrasted with the homozygous seeds of open-pollinated varieties in the U.S., China or Australia, which have 100% toxic seeds.
- The long duration of Indian cotton crops, between 160 and 300 days, allows this pest to thrive and evolve resistance more quickly than it can for short-duration crops. Contrast this with other cotton-growing countries which strictly terminate the crop within 160 days.
This has led to calls from the experts to roll back to BG-1 variety. [The Hindu]