A study from 2002 documented the occurrence of natural enemies (parasitoid wasps, predatory fl ies, entomopathogenic fungi) associated with colonies of the Russian wheat aphid, Diuraphis noxia (Kurdjumov, 1913) (Sternorrhyncha: Aphididae), in the spring barley fi elds in Slovakia. Parasitization by wasps was low (<5.5%) with Diaeretiella rapae (McIntosh, 1855) the dominant hymenopterous parasitoid (91% of emerging wasps). The remaining parasitoid guild
comprised of Aphidius ervi Haliday, 1834 Aphidius rhopalosiphi DeStefani, 1902, Aphidius picipes (Nees, 1811), Ephedrus plagiator (Nees, 1811), Praon volucre (Haliday, 1833) (Hymenoptera: Aphidiidae) and two hyperparasites Asaphes suspensus (Nees, 1834) (Hymenoptera: Pteromalidae) and Lygocerus spp. (Hymenoptera: Ceraphronidae). Predaceous midges (Diptera: Cecidomyiidae) were consistently found with densities ranging from 0.1 to 2.5 larvae per
aphid colony. The most abundant predaceous midge was Aphidoletes aphidimyza (Rondani, 1847), while Lestodiplosis sp. was recorded infrequently. Four syrphids, Episyrphus balteatus (De Geer, 1776), Melanostoma mellinum (L., 1758), Sphaerophoria rueppellii (Wiedemann, 1830), Sphaerophoria scripta (L., 1758) (Diptera: Syrphidae) and one pathogenic fungus, Pandora neoaphidis (Remaudière et Hennebert) Humber, were recorded.
