GM crops have increased agriculture's dependence on pesticides rather than reducing it, a study published in April 2025 found.

Drawing on data from four GM crops – Bt cotton, herbicide-tolerant (HT) soybean, HT and/or Bt maize, and HT canola, the researchers – including agricultural development expert Prof Glenn Davis Stone from Washington and Lee University and Bt cotton expert K. R. Kranthi of the International Cotton Advisory Committee – traced the surge in chemical use over three decades.

They found a paradox: while GM seeds were supposed to reduce pesticide use, their introduction caused pesticide use to soar. The researchers explain this outcome using the Jevons paradox, an economic theory that dates back to 1865. British economist William Stanley Jevons argued that efficiency in resource use often leads to more, not less, consumption. The study applies this idea to GM crops, which were claimed to reduce pesticide use, but in reality have made it skyrocket.

The researchers consider the two most prevalent GM seed-pesticide technology regimes: Bt crops and herbicide-tolerant (HT) crops. Both seeds are billed as efficient technologies: HT crops are claimed to facilitate more efficient weed control, and Bt crops are claimed to control insect pests more efficiently.

However, the researchers found that, "Like other technological efficiencies… the increased use of GM crops over the past 30 years has not contributed to input reductions nor to land reclamations, but to the expansion of agricultural land and increased use of the very pesticides these technologies are purported to curtail."

This is due to the complexity of agricultural systems: "The efficiencies of GM crops not only lower the cost for individual farmers to use, in aggregate, more pesticides; they also make those pesticides ever more essential to the political economy of agriculture through the input-intensive monocultures in which they are embedded. In fact, increases in chemical usage occur throughout these GM crop systems because technological substitutions like GM seeds cannot be separated from their cascading impacts on labour, weed and pest ecology or agricultural decision-making."