India’s falling cotton production

The pink bollworm has taken a toll on cotton production, even as new “mating disruption” technologies to control the pest are showing promise.

About Cotton:

• Cotton, like coconut, is a source of all the three Fs: Food, Feed and Fibre.
• The white fluffy fibre or lint constitutes about 36% of kapas.
  • Kapas is the raw un-ginned cotton harvested by farmers.
  • The seed (62%) and wastes (2%) are separated from the lint during ginning.
• Cotton seed contains 13% oil used for cooking and frying.
  • After extraction of oil from the seed the residual cake which is a rich in protein becomes feed ingredient for livestock and poultry.
• It is mostly sown in May-June in black soil of states like Punjab, Haryana, Rajasthan, Uttar Pradesh, Maharashtra, Gujarat.

Market share of Cotton in India:

• Cotton has around 2/3^rd share in India’s total textile fiber consumption.
• Cottonseed is country’s third largest domestically-produced vegetable oil (after mustard and soyabean) and second biggest feed cake/meal (after soyabean).

The Bt Cotton revolution:

[ref-IndianExpress]

• Bt Cotton are Genetically-Modified (GM) cotton hybrids incorporating genes isolated from a soil bacterium Bacillus thuringiensis or Bt.
• The Bt genes is encoded for proteins toxic to the American bollworm insect pest.
• This technology resulted in India’s cotton productionrising from 140 lakh to 398 lakh bales of 170 kg each.
  • There was a rise in output of oil and cake to nearly 1.5 million tonnes (mt) and 4.5 mt respectively.
• As the share of Bt hybrids in the country’s area sown under cotton touched 95%, average per-hectare lint yields more than doubled from 278 kg in 2000-01 to 566 kg in 2013-14.

What lead to fall in production?

• The gains didn’t last, both production and yieldsfell after 2013-14, to 343.5 lakh bales and 447 kg/hectare in 2022-23.
  • The reason for that had primarily to do with the pink bollworm.

About Pink bollworm:

• Pink bollworm is a monophagous pest that feeds mainly on cotton.
  • American bollworm is polyphagous, with alternative hosts from arhar (pigeon pea), jowar (sorghum) and maize to tomato, chana (chickpea) and lobiya (cowpea).

The new problem:

• The Bt toxins were supposed to provide protection against both the American bollworm and pink bollworm caterpillars that burrowinto the bolls or fruits of the cotton plant in which the lint and seeds grow.
  • However, Bt cotton has retained its effectiveness only against the American bollworm due to it being polyphagous.
• PBW earlier typically appeared in the crop’s later stages after the first picking, while being confined only to central and southern India.
  • But now, the infestation has started as early as 40-45 days after sowing at the initiation of flowering.

What went wrong?

• Pink bollworm is monophagous, which enabled its larvae to develop resistance to Bt proteins over time.
• The pink bollworm population that became resistant from continuously feeding on Bt hybrids gradually overtook and replaced the ones that were susceptible.
• The pest’s short life cycle (25-35 days from egg laying to adult moth stage), is conducive for it to complete at least 3-4 generations in a single crop season (180-270 days), this further accelerated the resistance breakdown process.

How to control Controlling Pink bollworm?

• The conventional route of spraying insecticides has had limited efficacy against the pink bollworm larvae.
  • Pink bollworm larvae feed on the cotton bolls as well as the squares (buds) and tender flowers, affecting lint quality and yields.

Mating disruption:

• It deploys Gossyplure, a pheromone signaling chemical that is secreted by female pink bollworm moths to attract male adults.
  • The pheromone is artificially synthesized and filled into pipes or lures.
• The male adult moths are, attracted towards the lures and do not mate with females during their 7-10 days’ time.
• This leads to the event, where eggs aren’t laid and they don’t grow into larvae.
• Mating disruption products for controlling pink bollworm:
  • PBKnot is a dispenser having a 20-cm hollow polyethylene pipe, into which 140-160 mg of Gossyplure is filled.
  • SPLAT-PBW, a flowable emulsion formulation technology for delivering Gossyplure.

Ref: Source