The pink bollworm has brought down India’s cotton production by a quarter in the last decade. While a few seed companies have developed new genetically modified hybrids resistant to the dreaded insect pest, regulatory barriers are coming in the way of their commercialisation.
India’s cotton economy isn’t in great shape.
This, despite the advantage the country has as a producer of the natural fibre and its textile exports facing only 27% duty – as against China’s 54%, Vietnam’s 46%, Bangladesh’s 37%, Indonesia’s 32% and Sri Lanka’s 44% – under US President Donald Trump’s “reciprocal tariff” policy.
The cause for concern is production.
India’s cotton output in the 2024-25 marketing year (October-September) is projected at just over 294 lakh bales (lb; 1 lb=170 kg), the lowest since the 290 lb of 2008-09. Production has been on a declining path since the peak of 398 lb in 2013-14 (see chart 1). A fall from almost 400 lb to under 300 lb can even be termed catastrophic.
The cultivation of genetically modified (GM) cotton hybrids – incorporating alien genes isolated from a soil bacterium, Bacillus thuringiensis or Bt – had led to not only a near-trebling of production (from 136 lb to 398 lb), but also a 139-fold jump in exports (from 0.8 lb to 117 lb), between 2002-03 and 2013-14.
A different bollworm
The above production slide, and India turning from a large cotton exporter to a net importer, is mainly courtesy of the pink bollworm (PBW). This is an insect pest, whose larvae bore into the bolls (fruits) of the cotton plant. The bolls contain seeds from which the white fluffy cotton fibres or lint grow. The PBW caterpillars feed on the developing seeds and the lint, causing yield loss as well as lint discolouration.
The GM cotton now grown in India have two Bt genes, ‘cry1Ac’ and ‘cry2Ab’, coding for proteins toxic to the American bollworm, spotted bollworm and cotton leafworm pests. The double-gene hybrids initially provided some protection against the PBW too, but that effectiveness has dissipated over time.
The reason for it is that the PBW is a monophagous pest, which feeds exclusively on cotton. This is unlike the other three pests that are polyphagous and survive on multiple host crops: The American bollworm larvae infest even maize, jowar (sorghum), tomato, bhindi (okra), chana (chickpea) and lobia (cowpea).
Being monophagous enabled the PBW larvae to gradually build resistance to the toxins from the existing Bt cotton hybrids. The PBW population that became resistant from continuously feeding on these plants eventually overtook and replaced the ones that were susceptible. The pest’s short life cycle (25-35 days from egg laying to adult moth stage), allowing it to complete at least 3-4 generations in a single crop season of 180-270 days, further accelerated the resistance breakdown process.
A recent article in the Nature scientific journal showed the PBW developing resistance to both cry1Ac and cry2Ab toxins by 2014, about 12 years after Indian farmers began cultivating Bt cotton.
The incidence of the pest crossing the “economic threshold level” – where the value of crop damage exceeds the cost of control – was recorded from 2014 in the central (Maharashtra, Gujarat and Madhya Pradesh), 2017 in south (Telangana, Karnataka, Andhra Pradesh and Tamil Nadu) and 2021 in north (Rajasthan, Haryana and Punjab) growing zones.
Not for nothing that all-India per-hectare cotton lint yields, which increased from an average of 302 kg in 2002-03 to 566 kg in 2013-14, have plunged to 436-437 kg during the last two years.
Deploying new genes
Leading Indian seed companies have developed GM cotton hybrids deploying new genes from Bt, which they claim confer resistance to PBW.
The Hyderabad-based Bioseed Research India, a division of DCM Shriram Ltd, is conducting confined field trials of hybrids based on its proprietary ‘BioCotX24A1’ transgenic technology/event expressing the ‘cry8Ea1’ gene found in Bt.
The Ministry of Environment’s Genetic Engineering Approval Committee (GEAC) had, in late-July 2024, permitted Bioseed to undertake Biosafety Research Level-1 (BRL-1) trials of its event at six locations in MP, Karnataka and AP. The trials, in isolated plots of not more than one-acre size each, are meant to evaluate the expression of the new alien genes and the agronomic performance of the hybrids/lines into which they are introduced. BRL trials also entail generation of data on food and feed toxicity and environmental safety (residue analysis, pollen flow studies, etc).
