Copyright 1999 Star Tribune
Star Tribune
(Minneapolis, MN)
March 17, 1999, Wednesday, Metro Edition
SECTION: NEWS; Science; Pg. 8A
LENGTH: 463 words
HEADLINE:
NEWTON'S APPLE;
A guide to how, what and where;
The search for a natural
pesticide leads to worms that glow
BYLINE: Sharon
Schmickle; Staff Writer
BODY:
A humbling chapter in
crop science is the one now being written as pesticide companies try to mimic
nature. By giving plants new genes, these firms may curb the need for synthetic,
sometimes ecosystem-disrupting chemicals.
The bug-fighting business is coming full
circle to the strategies of the early 1900s when entomologists searched for
natural predators to help control crop pests,
said David Bowen, a scientist at the University of Wisconsin in Madison.
It's hard to imagine any chemical that could be
more artful in attacking crop-threatening insects than Photorhabdus luminescens,
a bacterium Bowen and his colleagues are studying. One hope for the research,
reported in June in the journal Science, is that genes from Photorhabdus could
be used to complement its distant cousin Bt in guarding crops against borers and
beetles.
Like Bt, Photorhabdus is as
common as dirt. It resides inside certain nematodes (a family of worm) the size
of a speck of dust. So plentiful is this duo that it probably thrives in your
back yard whether you live in Minnesota or Florida. It attacks the corn root
worm and a broad range of other insects.
From the insects' perspective,
Photorhabdus and the nematode are a nasty team. A young nematode invades an
insect, then releases Photorhabdus, which releases toxins that kill the host.
Finally, they transform the carcass into a reproduction pool and get busy making
more nematode-bacterium pairs.
Now comes
the feature that gives Photorhabdus luminescens its name: The insect corpse
becomes saturated with a soup of proteins that gives off an eerie blue glow.
It was this faint beacon that enabled
Bowen and his colleagues to start following Photorhabdus' deadly trail in 1985.
Wisconsin researchers have gathered illuminated insect carcasses from Florida,
throughout the Midwest and into Washington state.
Back in the lab, they isolated the genes
and proteins that give rise to toxins. Now vials of the protein soup glow in a
dark room adjacent to Bowen's lab. The Wisconsin Alumni Research Foundation has
obtained patents on the discoveries, and the scientists are working with
companies to translate their findings into products for the field and the home.
Still, there is much to learn. Indeed,
they don't know exactly why Photorhabdus' victims glow.
"The light may serve as a warning to repel
other insects, or it could be an attraction," Bowen said. "The take-home message
is that this is just one example of our limited understanding of the many things
that exist in nature."
_ Sharon Schmickle is a Star Tribune staff
writer. The PBS series "Newton's Apple" airs at 3 p.m. Tuesday on KTCA, Channel
2, in St. Paul. Its Web site is http://www.ktca.org/newtons.
LOAD-DATE: March 18, 1999
