Genetically modified (GM) crops such as Bt cotton were introduced in India with the promise of reducing pesticide use. But over time, they became part of a farming model that made insecticide applications more widespread. A new study has investigated the paradoxical and often devastating consequences of GM agriculture — particularly Bt cotton in India.
Drawing on data from four GM crops — Bt cotton, herbicide-tolerant (HT) soybean, HT and / or Bt maize and HT rapeseed (canola) — the researchers underscored that GM crops, despite their early promise, had only deepened agriculture’s dependence on chemical inputs over the last three decades.
Genetically modified (GM) crops such as Bt cotton were introduced in India with the promise of reducing pesticide use. But over time, they became part of a farming model that made insecticide applications more widespread. A new study has investigated the paradoxical and often devastating consequences of GM agriculture — particularly Bt cotton in India.
The study, published on April 14, 2025 in the Journal of Agrarian Change, found that GM crops designed for greater chemical input efficiency actually contributed to higher pesticide use through the “input-intensive monocultures in which they are embedded”.
The study was done by researchers from Purdue University, Washington and Lee University and the International Cotton Advisory Committee in the United States.
In the case of Bt cotton, pesticide use initially fell, and farmers saw a drop in input costs. This, along with government support, accelerated its adoption. However, the reductions were short-lived. By around 2010, resistance among pests and the emergence of new ones reversed these gains. Insecticide applications increased significantly after that.
“By 2018, Indian cotton farmers were spending 37 per cent more than the pre-Bt high,” said the study.
What began as an individual advantage — spending less on inputs — turned into a collective burden. As more farmers planted cotton and pest resistance grew, insecticide use soared.
The researchers found similar patterns elsewhere. The complex effects of Bt cotton meant that in several countries, pesticide use either rebounded or surpassed previous levels.
GM crops also promised greater labour efficiency — particularly by reducing the time spent managing weeds, as well as economic efficiency by allowing expensive herbicides to be replaced with less expensive ones.
The soybean-glyphosate dilemma
HT crops were marketed as allowing the use of cheaper, broad-spectrum herbicides like glyphosate in place of older, more expensive alternatives. While this was initially true, the widespread adoption of glyphosate-resistant crops led to a “dramatic escalation” in glyphosate use.
The study revealed how among US farmers, who grow the majority of HT crops globally, soybean acreage treated with glyphosate jumped from 9.2 million acres in 1994 (before HT crops) to 113 million by 2018.
“During this time, the number of soybean hectares rose from 24.9 million to 36.1 million, and the percentage of area treated with glyphosate rose from 15 per cent to 87 per cent,” the paper said.
Monsanto (now part of Bayer) had claimed that the complex mode of action of glyphosate would make resistance unlikely. However, resistance has evolved in dozens of weed species since 1998.
In South America, too, soybean growers dramatically increased herbicide applications as GM crops expanded. In Canada, similar increases were seen with HT maize, sugar beet, and rapeseed (canola).
“As predicted, a technology that purports to reduce the consumption of a resource through efficiency actually increases it. However, these crops also intensified the use of other agrichemicals such as fertilisers and fossil fuels because they are integral to the input-intensive monocultures that are supported and protected by powerful agrochemical companies and national policies,” the research stated.
Reported by downtownearth