Subject: FW: Bacteria, Fungi May Be Crucial in Weed Biocontrol

From: Lon J. Rombough <[email-masked]>
Date: Fri, 09 Jul 1999 07:55:49 -0700

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From: "ARS News Service" <[email-masked]>
To: "ARS News List" <[email-masked]>
Subject: Bacteria, Fungi May Be Crucial in Weed Biocontrol
Date: Fri, Jul 9, 1999, 7:11 AM

STORY LEAD:
Bacteria, Fungi May Be Crucial in Weed Biocontrol by Insects

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ARS News Service
Agricultural Research Service, USDA
Kathryn Barry Stelljes, (510) 559-6069, [email-masked]
July 9, 1999
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Microorganisms that live in the guts of insects and in the soil may be keys
to enlisting Mother Nature against weeds, scientists with the Agricultural
Research Service are reporting this week at an international meeting in
Montana.

Many scientists around the world study and import natural insect enemies to
combat invader weeds, such as leafy spurge or spotted knapweed. Since 1865,
the approach has been used against at least 118 weeds in 55 countries.

But consistent success has been elusive. Microbes may be part of the reason,
according to scientists with the ARS Northern Plains Agricultural Research
Center in Sidney, Mont. They are reporting their findings this week at the
"Biological Control of Weeds --X International Symposium," held July 4-9 at
Montana State University in Bozeman.

ARS microbiologist Barbara A. Frederick has discovered that several insects
used as biological control agents for leafy spurge and spotted knapweed
harbor bacteria known as Wolbachia. The bacteria affect sperm in the
insects, causing offspring to be up to 90 percent female. The skewed gender
ratio may reduce the insects' ability to reproduce.

But other microbes are valuable insect allies. ARS plant physiologist
Anthony J. Caesar has found that flea beetles imported to control leafy
spurge have been most successful where naturally present soil-borne bacteria
and fungi also feed on spurge. The microbes invade roots via wounds
inflicted by insect larvae when they feed.

Both findings suggest useful tactics for mass laboratory rearing of insects
that would be released to attack weeds. Scientists are working on artificial
diets to increase the insects' populations. In the future, they may try
including in these diets a compound to rid the insects of undesirable
bacteria. Or, they might add beneficial microbes to a diet, so the insects
would transport them directly to the weeds.

ARS is the USDA's chief scientific agency.

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Scientific contacts: Barbara A. Frederick or Anthony J. Caesar, ARS Northern
Plains Agricultural Research Center, Sidney, Mont., phone (406) 482-2020,
fax (406) 482-5038, [email-masked] or
[email-masked].
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