On-going expansion of Russian wheat aphid, Diuraphis noxia (Kurdj.) in central Europe (Hom.: Aphididae)

A supplementary research on Russian wheat aphid (= RWA), Diuraphis noxia (Kurdj.) between 1998-99 documented the pest distribution all over the Czech republic already. RWA abundance was proved to be significantly area-dependent within the state. The banker areas are in southern Moravia (district Znojmo, the frontier area near Austria) up to central Moravia. The determined RWA distribution area is much broader than presumed on grounds of climatic characteristics. The abundance of RWA generally decreases from the SE to the NW and N direction, as well as with the increasing altitude within the area. The highest altitude a.s.l. of RWA occurrence in the crop was 762 m. The re-classified main expansion route was determined to follow two directions (sourcing from Hungary and Austria) to southern-central-northern Moravia, and to southern Bohemia and further on to the central Bohemian lowland. The field information indicated the development of preference of RWA for barley.