Russian wheat aphid (Hemiptera: Aphididae) reproduction and development on five noncultivated grass hosts

The Russian wheat aphid, Diuraphis noxia (Kurdjumov), is a small grains pest of worldwide economic importance. The Russian wheat aphid is polyphagous and may encounter differential selective pressures from noncultivated grass hosts. Aphid biotypic diversity can disrupt the progress of plant breeding programs, leading to a decreased ability to manage this pest. The goal of this research was to quantify Russian wheat aphid biotype 2 (RWA2) reproductive and development rates on five common noncultivated grass hosts to gain information about host quality, potential refuges, and sources of selection pressure. First, RWA2 reproduction was compared on crested wheatgrass (Agropyron cristatum, (L.) Gaertn.), intermediate wheatgrass (Elytrigia intermedia, (Host) Nevski), slender wheatgrass (Elymus trachycaulus, (Link) Gould ex Shinners), western wheatgrass (Pascopyrum smithi, (Rydb.) A. Love), and foxtail barley (Hordeum jubatum, (L.) Tesky) at 18-24A degrees C. Second, RWA2 reproduction was compared on intermediate and crested wheatgrass at three temperature regimes 13-18A degrees C, 18-24A degrees C, and 24-29A degrees C. At moderate temperatures (18-24A degrees C), the intrinsic rate of increase values for all five hosts ranged from 0.141 to 0.199, indicating the possibility for strong population sources on all tested hosts. Aphids feeding on crested and intermediate wheatgrass at the 13-18A degrees C temperature had lower fecundity, less nymph production days, longer generational times, and lower intrinsic rate of increase than aphids feeding at the 18-24A degrees C temperature regime. Aphids feeding at 24-29A degrees C did not survive long enough to reproduce. The positive intrinsic rates of increase in Russian wheat aphid on the wheatgrasses suggest that these grasses can support aphid populations at moderate to low temperatures.