A new study has once again sparked controversy over the use of agenetically modified crop. At issue is Bt corn – a corn grown by manyfarmers in the Great Lakes region – and its effect on the monarchbutterfly. The Great Lakes Radio Consortium’s Dale Willman reports:
A new study has once again sparked controversy over the use of a genetically modified crop.
At issue is Bt corn – a corn grown by many farmers in the Great Lakes region – and its effect on
the monarch butterfly. The Great Lakes Radio Consortium’s Dale Willman reports.
Bt corn is a corn genetically engineered to contain a naturally occurring insecticide.
The corn accounts for just 19-percent of all corn grown in the country right now – that’s
about one out of every five acres of corn. But its relatively small share of the market hides
its apparently remarkable potential for causing arguments. Especially when it comes in contact
with one of America’s most endearing symbols, the Monarch butterfly.
It was just a year ago that scientists at Cornell University in New York led a study that found
Bt corn to be toxic to the larvae of Monarchs under laboratory conditions. For months, those
results were debated and criticized for not involving a real-world test of the corn. The
scientists were accused of feeding butterfly larvae levels of Bt pollen much higher than those
actually found in farm fields.
This latest study though has moved the lab a bit closer to the field. Iowa State University
researcher John Obrycki says the two-year project used milkweed plants. They placed those potted
plants out in Bt and non-Bt cornfields.
“And allowed pollen to be naturally deposited on these
milkweed plants. Then we took those leaves, brought them
into the lab, counted the densities, the amount of pollen on
the leaves, then exposed those to monarch larvae.”
And the results, says Obrycki, were startling.
“And we observed significantly higher mortality when we
exposed those larvae to the Bbt corn pollen, as compared to the non-Bt corn pollen.”
In fact, about 20-percent of the larvae eating the Bt leaves died from the insecticide, while
almost all the larvae that ate the non-Bt leaves stayed alive. This is troubling, says Obrycki,
because milkweed plants are the only thing the Monarch larvae will eat. And milkweed plants are
often found within, and around, cornfields. So the Monarchs attracted to those plants near Bt
corn could face a much greater risk. Val Giddings is a Vice President at the Biotechnology
Industry Association, a Washington-based trade group for biotech companies. He says it’s true
that some strains of Bt corn, under the right conditions, could indeed kill Monarchs.
“I’m willing to concede that, you know, what they have found,
that pollen of this particular variety, if monarch larvae are
exposed, would have some probability of a negative impact.”
However, the devil he says is in the details. He says the actual amount of exposure the larvae
might get to Bt corn pollen is slight.
“The amount of time that corn pollen is present overlaps with
only a very small fraction of the amount of time that
monarch larvae are present, so most monarch larvae are unlikely ever to encounter any corn
pollen in the field.”
And Giddings says the alternative to Bt corn could be much worse. Right now, he says Bt is one
of just two options available to farmers to control corn-boring caterpillars. That pest causes
an estimated one billion dollars worth of crop damage each year. The other option is the spraying
of broad-spectrum pesticides, which are quite effective against the caterpillars. But the
pesticides have some major drawbacks not found in Bt corn.
The results of the study, if confirmed by other scientists, could be especially significant for
Midwestern farmers and butterfly lovers. As much as half of the Monarch butterfly population
makes its way across the Midwest during its annual migration.
Even the study’s co-author says this is not the last word on Bt corn. John Obrycki says more
studies must be done before the full effects of this transgenic crop are understood.
In the meantime, the fight against Bt corn will continue. Environmentalists say it’s simply the
latest battle in a larger war against all bioengineered crops.
For the Great Lakes radio Consortium, I’m Dale Willman.