Researcher Uses Natural Chemicals To Battle Major Corn Pest
Monday, July 28, 1997
Note to Editors: To arrange a visit to the corn rootworm
research project under way at Colorado State's Agricultural
Research, Development and Education Center, call Louis
Bjostad at (970) 491-5987 or Carrie Schafer in the Public
and Media Relations Office, (970) 491-6432.
FORT COLLINS--Louis Bjostad has whipped up a recipe of death
for the Colorado corn industry's No. 1 pest using an inexpensive
food processor and ingredients available at most grocery stores.
Bjostad, entomology professor at Colorado State, is testing
several non-toxic materials that target Western corn rootworm, a
pest that causes $1 billion in crop losses in the United States
each year.
After tests in the laboratory and field over the past six
months, Bjostad is confident his materials can tackle rootworm
just as effectively as insecticides, which are more toxic and
expensive.
Bjostad, who has studied the pesky bugs for more than a
decade, recently made a breakthrough that showed why rootworm
larvae only eat corn plant roots. The professor, with colleagues
Elisa Bernklau and Erich Fromm, discovered that carbon dioxide
given off by corn roots is responsible for luring larvae to their
meal.
To steer rootworms off course, Bjostad and his team of
researchers made non-toxic granules and pellets that also release
carbon dioxide. The experimental treatments, placed near the corn
seed at planting time, mix the signal that larvae rely on to find
their only source of food.
"These larvae must find the corn roots within 24 hours after
hatching or they die," Bjostad said. "We are essentially sending
them away from the plant so by the time they realize their
mistake we've dealt a lethal blow."
Main ingredients in Bjostad's treatments include baker's
yeast and a nutrient mixture, or sodium bicarbonate (the main
ingredient in baking soda), citric and other acids, combinations
of which produce carbon dioxide naturally.
In addition, the professor is on the verge of identifying
key chemicals responsible for stimulating rootworm larvae to feed
on corn roots. Once identified, Bjostad hopes to add these
chemicals to his formulas so larvae are not only attracted to the
pellets but also are tricked into feeding on the pellet itself.
The idea is to keep larvae away from corn roots as long as
possible so the plant has time to mature. Corn plants with
established root systems are less vulnerable to larvae.
Bjostad has taken his research--already being eyed by major
chemical manufacturers for future development into biological
products--several steps further. The professor's studies also
unexpectedly found that corn roots produce small amounts of
natural chemicals that, when produced in large amounts, repel
larvae. Because these repellants aren't in high enough doses in
commercial varieties of corn to thwart rootworm, Bjostad is
studying ways to isolate the natural repellants and manufacture
them in large amounts. These concentrated, natural repellents
also would be formulated into granules or pellets and applied
near the corn seed at planting time.
While biological insecticides are more ideal than toxic
chemicals available, Bjostad says the best alternative would be
to genetically engineer corn plants that produced higher
concentrations of these natural repellents so no man-made
chemicals would have to be used.
The next step, Bjostad says, is to refine these natural
insecticides so they do the best job possible for the least cost
to the farmer. Bjostad plans to conduct two more years of field
tests before deciding which compounds should be developed
further.
"The health and public safety issue is really driving this
research," Bjostad said. "The whole idea is to develop a
biological control that isn't toxic, costs less and is safer for
workers to handle."
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