Increase of Russian wheat aphid, Diuraphis noxia (Kurdj.) in hot and dry weather (2000) (Hom., Aphididae)

Two hot and dry weather periods during mid-spring and early summer caused severe drought-stress to barley groves in many districts of the Czech Republic in 2000. Although not generally taken into consideration as an injury-increasing factor, the Russian wheat aphid (= RWA), Diuraphis noxia (Kurdj.), was discovered to contribute significantly to injury in the ripening stage of spring barley as well as to the substantial decrease of yield (up to 30 – 40 % of the calculated mean, in some districts). RWA increased considerably not only in the lowland banker areas but also in the higher altitudes, values in the latter case then manifesting those found in the lowland banker areas in the previous years.