Expert Commentary

Genetically modified corn and effects on nearby crops

2010 study in the journal Science examining the impact of genetically modified corn on neighboring un-modified crops.

The use of genetically modified corn seeds has been the subject of much debate, as questions persist over cost-effectiveness, yield, long-term effectiveness and the impact on non-GE plants. The controversy runs deep enough that some countries continue to ban genetically modified crops, yet they make up the majority of corn, soybeans and cotton grown in the United States.

A 2010 study published in the journal Science, “Areawide Suppression of European Corn Borer with Bt Maize Reaps Savings to Non-Bt Maize Growers,” explores the impact of genetically modified crops on the health of neighboring crops in U.S. agriculture. The researchers tested the impacts specifically from corn genetically modified to make insecticidal proteins derived from bacterium Bacillus thuringiensis (Bt), referred to as Bt corn.

The study’s findings include:

  • The damages from European corn borers decreased significantly in both Bt corn and the non-Bt corn that was planted nearby. This “halo-effect” was attributed to the way female corn borers lay eggs indiscriminately on Bt or non-Bt crops.
  • Though Bt corn seed is more expensive, planting a mix of Bt corn and non-Bt corn yielded enough of a benefit that it outweighed the increased seed costs.
  • Mixing Bt corn with non-Bt corn should increase the length of time it takes for corn borers to develop a resistance to the pesticide.
  • Over a 14-year period, Illinois, Minnesota and Wisconsin have seen an estimated $3.2 billion benefit for corn growers; $2.4 billion of that has accrued to non-Bt corn growers. Iowa and Nebraska saw an estimated $3.6 billion in benefits, with $1.9 billion for non-Bt corn growers.

The study has implications for farms throughout the developing world, the researchers say, where yields, cost-effectiveness and sparse arable land are pressing concerns. Previous studies have concluded that pest-resistant corn helps neighboring non-genetically modified crops, but it was believed that the increased cost of the genetically modified seed would outweigh the financial benefits in overall crop yield.

Tags: technology

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