August 31, 2011


Monsanto's high-tech corn affected by pests



Monsanto Co.'s genetically modified corn plants initially created to thwart a voracious bug are losing resistant to that same pest in a few Iowa fields currently.


This is the first time a major Midwest scourge has developed resistance to a genetically modified crop.


The discovery raises concerns that the way some farmers are using biotech crops could spawn superbugs.


Iowa State University entomologist Aaron Gassmann's discovered that western corn rootworms in four northeast Iowa fields have evolved to resist the natural pesticide made by Monsanto's corn plant. This could encourage some farmers to switch to insect-proof seeds sold by competitors of the St. Louis crop biotechnology giant, and to return to spraying harsher synthetic insecticides on their fields.


"These are isolated cases, and it is not clear how widespread the problem will become," said Gassmann. "But it is an early warning that management practices need to change."


The finding adds fuel to the race among crop biotechnology rivals to locate the next generation of genes that can protect plants from insects. Scientists at Monsanto and Syngenta AG of Basel, Switzerland, are already researching how to use a medical breakthrough called RNA interference to, among other things, make crops deadly for insects to eat. If this works, a bug munching on such a plant could ingest genetic code that turns off one of its essential genes.


Monsanto said its rootworm-resistant corn seed lines are working as it expected on more than 99% of the acres planted with this technology and that it is too early to know what the Iowa State University study means for farmers.


The discovery comes amid a debate about whether the genetically modified crops that now saturate the Farm Belt are changing how some farmers operate in undesirable ways.


These insect-proof and herbicide-resistant crops make farming so much easier that many growers rely heavily on the technology, violating a basic tenet of pest management, which warns that using one method year after year gives more opportunity for pests to adapt.


Monsanto is already at the centre of this issue because of its success since the 1990s marketing seeds that grow into crops that can survive exposure to its Roundup herbicide, a glyphosate-based chemical known for its ability to kill almost anything green.


These seeds made it so convenient for farmers to spray Roundup that many farmers stopped using other weedkillers. As a result, superweeds immune to Roundup have spread to millions of acres in more than 20 states in the South and Midwest, according to scientists.


Monsanto said it generated world-wide sales of US$4.26 billion from corn seed and biotechnology traits, about 40% of its overall sales, in its latest full year.


Until insecticide-producing corn plants arrived, Midwest farmers typically tried to keep pests like the corn borer and the rootworm in check by changing what they grew in a field each year, often rotating between corn and soybeans. That way, the offspring of corn-loving insects would starve the next year.


The US government requires that farmers who plant the genetically modified corn take certain steps aimed at preventing insects from developing resistance. Farmers are told to create a refuge for the bugs by planting non-modified corn in part of their fields. The refuge, which can be as much as 20% of a farmer's field, is supposed to reduce the chances that two toxin-resistant bugs mate and pass along that trait to their offspring.


The US Environmental Protection Agency said it is too early to comment on any implications arising from Gassmann's paper.

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