AN OVERVIEW - RESISTANCE TO THE RUSSIAN WHEAT APHID (HOMOPTERA, APHIDIDAE) WITHIN THE PERENNIAL TRITICEAE

Introgression of valua le gene(s) for insect resistance has been achieved bv interspecific hybridization between the perennial Triticeae species and the cultivated cereals. We relate Russian wheat aphid, Diuraphis noxia (Mordvilko), resistance to the newly defined and realigned genera of the perennial Triticeae based on genomic composition. Possible sources of Russian wheat aphid resistance in the perennial Triticeae are reported for the first time. We could not correlate the degree of Russian wheat aphid resistance with the genomic system of classification. However, genera within the tribe Triticeae can be loosely grouped into three categories: (1) moderately resistant: Leymus and Elytrigia; (2) tolerant to moderately suseeptible: Agropyron, Pseudoroegneria, Elymus, and Pascopyrum; and (3) susceptible: Hordeum and Thinopyrum. Within the tribe Triticeae, the genera Leymus and Elytrigia are the best sources of resistance. However, within each species, extensive variation for resistant types occurs.