Resistance in <i>Triticum aestivum</i> , <i>Triticum monococcum</i> and <i>Triticum turgidum</i> to <i>Rhopalosiphum padi</i>

The bird cherry-oat aphid Rhopalosiphum padi (L.) (Hemiptera: Aphididae) is a cosmopolitan species that attacks all the major cereals, causing the yield loss directly by removing nutrients and indirectly by vectoring plant virus diseases. The study aimed to explore the potential antixenosis and antibiosis resistance to R. padi in nine cultivars of different wheat Triticum L. species and subspecies. The content of phenolic acids and flavonoids in the leaves of wheat cultivars was also determined. The wheat cultivars studied differed in susceptibility to R. padi: Triticum turgidum subsp. turanicum “Khorasan” (highly susceptible) > T. turgidum subsp. dicoccum “Bondka” > T. turgidum subsp. dicoccum “Lamela” and T. monococcum “Joanka” > T. monococcum “Pagatula” and T. aestivum “Torridon” > T. turgidum subsp. durum ‘Wintergold’and T. aestivum subsp. spelta “Wirtas” > T. aestivum “Galerist” (partially resistant). Neither of the studied wheat cultivars possessed antibiotic resistance to R. padi. No correlation occurred between the content of phenolic compounds and aphid performance and probing behaviour. The differences in aphid performance and settling and probing behaviour on wheat cultivars can be attributed to antixenosis factors, probably of a chemical nature, in mesophyll and/or phloem and/or the variation in nutritional quality of the phloem sap.