Submitted to: Journal of Agricultural and Urban Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 21, 1999
Publication Date: N/A
Interpretive Summary: The Russian wheat aphid is a serious pest of wheat, barley, and cool-season grasses. Plant introductions of crested wheatgrass were evaluated for resistance to the Russian wheat aphid. Several of the plant introductions were identified as resistant to the Russian wheat aphid. The most resistant plant introduction entries (PIs 281862, 297869, 325180, and 439912) were not damaged from aphid feeding, sustained low aphid populations, and the leaves did not curl. When they were given free choice, the resistant plant introductions were the least preferred over the most susceptible plant introductions and susceptible wheat. The resistant plant introductions can be used in developing improved resistant forage grasses.
Technical Abstract: The Russian wheat aphid, Diuraphis noxia (Mordvilko), is a recently introduced pest that is an economic threat to wheat, Triticum aestivum L., and barley, Hordeum vulgare L., production. Crested wheatgrass, Agropyron cristatum (L.) Gaertner, is an important alternative summer host of the aphid and provides a food source for Russian wheat aphid populations between spring harvest and fall planting of cereal crops such as wheat and barley. Experiments were conducted in the greenhouse to identify Russian wheat aphid-resistant crested wheatgrass plants obtained from the Western Regional Plant Introduction (PI) Station, USDA-ARS, Pullman, WA. PIs 281862, 297869, 325180, and 439912 were highly resistant to leaf chlorosis and leaf curling caused by aphid feeding. Further tests were conducted to characterize the plant components (antibiosis, antixenosis [nonpreference], and tolerance) contributing to resistance of the resistant PIs. Resistant PIs had high levels of antibiosis, demonstrated by Russian wheat aphid s reduced rates of fecundity compared with susceptible genotypes. When infested with Russian wheat aphids, the resistant PIs had reduced dry mass foliage loss compared with susceptible PIs, denoting acceptable levels of tolerance. A strong antixenosis (nonpreference) resistance component existed in the resistant PIs when aphids were given a choice of several genotypes. PIs 281862, 297869, 325180, and 439912 are new sources of resistance for germplasm enhancement efforts.