Suction air traps vs. crops in monitoring Russian wheat aphid, Diuraphis noxia (Kurdj.) in Central Europe (Hom., Aphididae)

The Russian wheat aphid (=RWA), Diuraphis noxia (Kurdj.) is an exotic expansive aphid on the small grains determined in the Czech republic since 1993 (1995). Determination of RWA flight patterns by suction air traps (=SATs) between 1994-1998 indicated some banker, less important, or indicated RWA distribution areas. A comparison of the RWA monitoring by SATs and by crop samples in areas more or less distant from individual SAT locations manifested a high similarity of RWA evidence in its overall distribution and area-influence population numbers. Owing to geographic area - dependent features of its life-cycle (holocycly) and host plant preferences, RWA seems to be most injurious to spring barley. In spite of the role of SATs in aphid forecasting, RWA samples are recommended to be taken also from the crops at the early ripening stage as the respective SAT evidence reflects only the emigration of the alate aphids originating from the decreasing populations. In general, RWA detection by SATs was either simultaneously or successively found to reflect the RWA presence in the more or less distant crops. The 30 km perimeter of a SAT is agreed to be representative for monitoring RWA populations in a sampled area.