Role of hydroxamic acids in the resistance of wheat to the Russian Wheat Aphid, Diuraphis noxia (Mordvilko) (Hom., Aphididae)

Wheats and triticales resistant to Russian wheat aphid (RWA), Diuraphis noxia, contained medium to very high concentrations of hydroxamic acids. Feeding behaviour and performance of RWA in wheat seedlings differing in hydroxamic acid (Hx) levels, were determined by electrical penetration graphs, and mean relative growth rates, respectively. Higher Hx levels in the seedlings produced a delay in attaining a sustained phloem ingestion, and tended to produce lower mean relative growth rates. These facts support Hx as resistance factors in wheat towards RWA.