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Title: BIOTYPIC STATUS OF RUSSIAN WHEAT APHID (HOMOPTERA: APHIDIDAE) POPULATIONS IN THE UNITED STATES (MODIFY TO ADD ACCEPT DATE AND SHOW REVISED TITLE)

Author
item Shufran, Kevin
item Burd, John
item Webster, James

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: "Biotypes" are populations within an insect species that differ genetically and physiologically from other populations of the same insect species. This biotypic phenomenon allows an insect to damage crop plants that are resistant to a different biotype. Plant resistance is being developed in wheat and barley against the Russian wheat aphid, a new pest in the United States since 1986. Russian wheat aphid biotypes occur in other parts of th world and could eventually be introduced into the United States. We monitored Russian wheat aphids in the United States for biotype development, but found none. We also tested 4 resistant wheat and barley lines and found that they remained resistant when fed on by Russian wheat aphids collected from 5 western states. Therefore, crops resistant to Russian wheat aphid are not likely to be threatened by biotypes in the United States at this time. However, Russian wheat aphids should be routinely tested for biotype development.

Technical Abstract: This study reports baseline information on the biotype status of Russian wheat aphid, Diuraphis noxia (Mordvilko), populations in the USA prior to the commercial planting of resistant cereals. Eleven Russian wheat aphid clones collected from five states were evaluated for biotypic variation on four wheat (Triticum aestivum) ('Pavon', PI 372129, STARS-9302W, and STARS-9501W) and two barley (Hordeum vulgare) ('Wintermalt' and STARS-9301B) entries. Measurements of chlorosis, leaf rolling, leaf number, tiller number, plant height, shoot mass, root mass, aphid numbers, and aphid mass did not reveal the presence of any biotypic variation among Russian wheat aphid populations. Although statistical differences were detected among some clones, no clear differences in virulence properties were apparent. Host responses to Russian wheat aphid infestation among the 11 clones were similar. Ten years after its introduction to the USA, the Russian wheat aphid has not exhibited any biotypic variation prior to the commercial planting of resistant cultivars. Because of the threat of another introduction, however, Russian wheat aphid should be periodically monitored for biotypic variation, especially after the implement of resistant cultivars in the field.