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United States Department of Agriculture

Agricultural Research Service

avidin attack on pests

The graphic shows Dr. Watts, and an intro to the story that reads: Scientists have some 'egg-citing' news.

"Egg-
citing !!"

Animated graphic of an egg that falls and cracks open.Graphic of DNA, a molecule on which an organism's genes reside--in this case, chicken genes for making the egg protein avidin.



Photo of a field of wheat, a crop whose grains are eaten by insects mentioned in this story.



A photo of a pair of tweezers holding a kernel that's been chewed on by an insect.




Photo of flour beetles nibbling on pet food. These insects also are serious pests of cereals made of grains.




Photo of a lesser grain borer climbing on a grain.




































Animated graphic of 3 colored balls that are used for page design purposes.Animated graphic of 3 colored balls that are used for page design purposes.Animated graphic of 3 colored balls that are used for page design purposes.

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Here's some food for thought: Agricultural Research Service scientists have discovered how to use eggs to protect certain grains from gnawing bugs--without chemicals.

Photo of Karl Kramer at computer keyboard and lab technician Thomas Morgan, who is looking into a microscope.Here are more details on this "egg-citing" news: Egg whites have a protein called avidin. ARS chemist Karl Kramer and other scientists showed that avidin blocks insect growth by tying up a vitamin called biotin. If the bugs can't get their biotin, they can't grow, says Dr. Kramer, at the ARS Grain Marketing and Production Research Center in Manhattan, Kansas.

Each year, insects cause millions of dollars of damage by chewing on stored products like corn, wheat, rice and grain sorghum. ARS scientists are working to find ways to control these insect pests without chemicals. One way is to change the plant's genes with "resistance traits"--so the plant can resist the insect without help from chemicals.
Sometimes two or more headsAnimated graphic of cartoon scientist who sips from a beaker and changes into different types of characters, including a bunny, a clown, and a frog. are better than one when it comes to fighting a common enemy--pests! So Dr. Kramer's team joined up with researchers from two private companies: Pioneer Hi-Bred International, Inc., in Johnston, Iowa, and ProdiGene, Inc. of College Station, Texas. Together, these scientists are able to stay one step ahead of the insects.
There are many different kinds of stored-grain insects. Some, like the sawtoothed grain beetle and the confused flour beetle, get into food containers in home cupboards through cracks and holes. Others--like the lesser grain borer, warehouse beetle, and even one called the cigarette beetle--actually chew holes in plastic or cardboard packages.

Scientists at the biotechnology companies found a way to give corn plants a little "something extra"--the egg gene that helps produce avidin. This borrowed gene helps the corn fight off attacks by insects, even when it's stored in grain bins or kitchen cupboards for months.

Scientists have used this idea of borrowed genes before. They put the genes for a substance from Bacillus thuringiensis (Bt) bacteria into corn plants. But Dr. Kramer thinks that putting avidin into corn is even smarter, because avidin can kill more kinds of insects. Bt mainly kills moths and only a few beetles.

In lab experiments, scientists found that most insects stopped growing and developing when they ate corn with 100 parts per million (ppm) of avidin. (One hundred parts per million is equal to one dollar in a pile of $10,000.) Only about half the insects died when they ate corn with only 30 ppm of avidin.

You can learn even more about avidin from a longer story in the August 2000 issue of Agricultural Research magazine. Click here to read it on the World Wide Web.



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By Linda McGraw, Agricultural Research Service, Information Staff

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Last Modified: 2/14/2011
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