A group of agricultural scientists reports in the journal Science that corn that has been genetically engineered to produce insect-killing proteins isolated from the soil bacterium Bacillus thuringiensis (Bt) provides significant economic benefits even to neighboring farmers who grow non-transgenic varieties of corn. Bt corn suppresses of corn borers, thus allowing for improved yield and higher grain quality.
The researchers estimate that farmers in Iowa, Illinois, Minnesota, Nebraska and Wisconsin received cumulative economic benefits of nearly $7 billion between 1996-2009, with benefits of more than $4 billion for non-Bt corn farmers alone. The scientists estimated that in Minnesota, Illinois and Wisconsin, borer populations in adjacent non-Bt fields declined by 28 to 73 percent, with similar reductions recorded in Iowa and Nebraska.
The researchers attribute the collateral benefits enjoyed by non-Bt farmers to area-wide suppression of corn borers stemming from long-term plantings of Bt-protected crops. Potato, green bean and other host crops also stand to benefit from area-wide reductions of corn borers, the researchers note. The team's Science report also highlights the importance of the use of refuge crops — the planting of non-Bt crops adjacent to fields of Bt crops, providing a refuge to which the pests can retreat — and other strategies to slow the corn borer's ability to develop resistance to Bt and thus maintain the insecticidal proteins' long-term effectiveness.
