Time Magazine: Of Corn and Butterflies
U.S. farmers are planting 20 million
acres of bioengineered corn. Will it
poison the monarchs?
MAY 31, 1999 VOL. 153 NO. 21
BY FREDERIC GOLDEN
With its flamboyant orange-and-black wings and
incredible 1,000-mile migratory flights, the
monarch butterfly is one of the world's
best-known and most beloved insects. And like a
miner's canary, it has become a kind of biological
early-warning system, succumbing to
environmental changes long before humans
notice them. Last week the monarch sounded
another alert--fanning new fears about
bioengineered crops.
In a study published in Nature, Cornell
entomologist John Losey and his colleagues
reported that pollen from corn made
pest-resistant by the addition of bacterial genes
could spell trouble for monarchs. In his
experiments, Losey scattered pollen from the
genetically modified corn onto milkweed--the
butterfly's only food during its larval or caterpillar
stage--and watched what happened with alarm.
Most of the caterpillars that ate these leaves
either died or were stunted.
The Cornell tests set off a flutter of concern not
only for the survival of the monarchs--already
threatened by logging in their winter roosts in the
mountains west of Mexico City and by pesticides
in their Cornbelt breeding grounds--but also over
our increasing dependence on high-tech,
genetically engineered food crops. "This is a
heads-up," warns entomologist Fred Gould of
North Carolina State University.
Approved by the Environmental Protection
Agency in 1996, so-called Bt corn has become
enormously popular with farmers, and now
accounts for up to 25% of the U.S. corn crop, or
about 20 million acres. By splicing DNA from the
common soil bacterium Bacillus thuringiensis
into the corn's genes, scientists have created a
plant that turns out the same toxin as the bug.
While the toxin is deadly to the corn borer, which
costs U.S. growers more than $1 billion annually,
it is harmless to humans--as well as to such
beneficial insects as ladybugs and honeybees.
Indeed, organic farmers have long used Bt sprays
as a natural pesticide.
With hundreds of millions of dollars at stake,
agritech companies aren't eager to draw
sweeping conclusions from the Cornell
experiments. "Obviously the work is preliminary
and inconclusive," says Monsanto spokesman
Randy Krotz, minimizing the possibility that corn
pollen could ever be blown far enough to affect
monarch habitats. But it was just such a
discovery--of pollen-dusted milkweed 200 ft. from
the edge of cornfields--that prompted Losey's
study in the first place. Says he: "We asked
ourselves, 'What would happen if the milkweed
would be dusted with Bt [corn pollen]?'" His
experiments quickly gave an answer: within four
days, 44% of monarch larvae placed on the
dusted leaves were dead, while controls survived
unscathed.
Losey is eager to take the experiments into the
field, to measure pollen density at various
distances from its source so as to determine risk
to monarch larvae at each site. Says Losey: "We
have to weigh the costs and benefits [of Bt corn],
then decide as a society what we want." But that
decision may already have been made. The Bt
gene is now regularly spliced into potatoes (as
protection against the Colorado potato beetle)
and cotton (against the boll weevil).
Five years after U.S. regulators approved the first
genetically altered food crop, the "FlavrSavr"
tomato, there are all manner of brave new foods
on the way: beans and grains with more protein,
caffeine-less coffee beans, strawberries packed
with more natural sugars, and potatoes that soak
up less fat during frying. At last count, says plant
ecologist Allison Snow of Ohio State University,
field trials have been conducted for some 50
gene-spliced food plants, including squash,
melons, carrots, onions, peppers, apples and
papayas.
But such tinkering can go awry. As even their
proponents concede, spliced genes, like any
other genes, can be picked up by wild species.
The fear is that they will create what geneticist
Norm Ellstrand of the University of California at
Riverside, calls "a weedier weed"--a species,
such as the superweed that turned up in France
when sugar beets crossed accidentally with a
wild relative, that is both harder to control and
more ecologically disruptive. Scientists also fear
that as use of Bt crops increases, so will
resistance in the very pests they're aimed at,
depriving organic farmers of a natural pesticide
they'd come to trust.
Measures are being considered to avert such
calamities--for example, ringing cornfields with
patches of plain, old-fashioned corn so that not
all pests become resistant. But these efforts
haven't silenced critics, especially in Britain,
where a noisy debate is raging over what the
London tabloids like to call "Frankenstein foods."
Last week the British Medical Association called
for a moratorium on commercial planting of all
transgenic crops until scientists agree on their
safety. In India, Monsanto is running into a p.r.
buzz saw in its efforts to introduce a Bt cotton
called Bollgard--even as it wrestles with
continuing protests over its stalled plans to
include in its new crops so-called terminator
technology that would compel farmers to buy
fresh seed for each planting.
Viewing the new crops as useful alternatives to
pesticides, most scientists want work on them to
continue, if more cautiously. The message from
the monarchs, meanwhile, is that even the most
well-intentioned biotechnologies are not risk-free.
END
© 1999 TIME INC. NEW MEDIA
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