Past Agricultural Research Service work to control Russian wheat aphids may pay off again, this time against a new biotype of the insect.

Russian wheat aphids are major pests of cereal crops. The original biotype has cost American wheat and barley farmers billions of dollars in losses since first appearing in the United States in 1986.

The new biotype, first spotted in Colorado last year, overcomes the genetic defenses of many wheat and barley lines developed to combat the original aphid. These lines were developed at the ARS Wheat, Peanut and Other Field Crops Research Unit in Stillwater, Okla., and at the Small Grains and Potato Germplasm Research Unit in Aberdeen, Idaho.

In Stillwater, entomologist James Webster and geneticists Cheryl Baker and Dolores Mornhinweg reacted to the discovery of the first aphid biotype by screening 30,000 wheat and 24,000 barley germplasm accessions for resistance traits for incorporation into new crop lines. Most of that germplasm was obtained from the Aberdeen unit's National Small Grains Collection.

That work led to identification of more than 300 resistant wheat germplasm lines and 40 promising barley germplasm lines.

Now, the new biotype has led Baker and Mornhinweg to re-examine breeding lines they developed during the first crisis. Mornhinweg tested about one-third of the barley lines found to be resistant to the original aphid and discovered they were resistant to the new type. Also, four breeding lines of winter barley and three feed barleys set to be released within the next few years show resistance to both aphid biotypes.

Baker has found strong candidates among the advanced wheat lines, including a promising one derived from a wheat-rye line she received from South Africa.

Read more about the research in the April issue of Agricultural Research magazine, available on the World Wide Web at: http://www.ars.usda.gov/is/AR/archive/apr04/aphid0404.htm