Compatibility of insect management strategies: Diuraphis noxia abundance on susceptible and resistant barley in the presence of parasitoids

Russian wheat aphid, Diuraphis noxia, and parasitoid abundance was monitore d on field-grown barley, Hordeum vulgare L., varying in D. noxia susceptibi lity, to address the applicability of previous laboratory assessments of ba rley seedling resistance and parasitoid compatibility. Study sites were rep resentative of the barley production region of the High Plains in the weste rn USA, where D. noxia and its parasitoids occur. D. noxia abundance on res istant barley lines, characterized as partially tolerant and antibiotic to the aphid, was lower than on more susceptible lines. Parasitism by Diaereti ella rapae, Aphelinus albipodus, and A. asychis differed in seasonal occurr ence and abundance. D. rapae mummies occurred sooner than aphelinid mummies , and there were larger increases in aphelinid mummies than in D. rapae mum mies during seed head development. But in regard to plant resistance, paras itoid abundance, relative to D. noxia abundance, was similar on resistant a nd susceptible barley lines. Based on the susceptibility of commercial barl ey to D. noxia, the seasonal abundance of D. noxia and its parasitoids, and the compatibility of resistant barley and D. noxia parasitoids, the use of resistant barley in areas of parasitoid establishment is justified.