Antibiosis and non-preference of Sitobion avenae (F.) (Hemiptera: Aphididae) on leaves and ears of commercial cultivars of wheat (Triticum aestivum).

Little is known on the resistance of wheat cultivars to Sitobion avenae (F.) in Brazil. The goal of this work was to assess the behavior and biology of S. avenae on four commercial wheat cultivars to verify the existence of resistance by antibiosis in leaves and ears and non-preference in the ears. The smallest net fecundity rates of S. avenae in wheat leaves have been found in the cultivars Embrapa 22 and BRS264, which did not differ between themselves. The intrinsic rate of increase of S. avenae was smaller in leaves of Embrapa 22 than in cultivars BRS254 and BRS Timbaúva. The smallest net fecundity rates of S. avenae in wheat ears were observed in the cultivars BRS254 and Embrapa 22. The intrinsic rate of increase of the aphid in the ear of cultivar Embrapa 22 was smaller than in BRS Timbaúva and BRS264, but did not differ from BRS254. The organ of the wheat plant in which the aphid was reared influences antibiosis resistance, but the cultivar BRS Timbaúva was considered susceptible and Embrapa 22 resistant to S. avenae in both plant organs tested. Ears of wheat cultivars tested did not show differences in the mechanism of resistance by non-preference to S. avenae.