Abai, MR

6th International Congress of DipterologyFauna and Abundance of Non-Chironomid Dipterans(Insecta: Diptera) in the Littoral Zone of Small Lakes inNorthwestern RussiaPrzhiboro, A.Laboratory of Freshwater and Experimental Hydrobiology, Zoological Institute, RussianAcademy of Sciences, Universitetskaya nab. 1, St.Petersburg 199034, RussiaFaunal composition, habitat distribution and abundance of Dipteraexcepting Chironomidae were studied in the upper littoral zone of six smalllakes (from lower border of the eulittoral zone to depth 1-1.5 m). The lakesconstitute three pairs: northern (66°21'N 33°35'E), central (60°18'N29°17'E), and southern (56°12'N 28°40'E).The study first combined quantitative assessment (numbers and biomasses)of immatures in all families during the season, and reliable identificationbased on mass rearing to adults using three methods (rearing from separatelarvae and pupae, laboratory rearing from substrata collected in eulittoralzone, and field emergence traps; over 2500 adults were reared).A total of 59 species in 13 families develop within the littoral zone ofstudy lakes. The numbers of species and families increase more than twicefrom northern to southern lakes.Larvae of 4 families, Ceratopogonidae, Limoniidae, Tabanidae andEphydridae were abundant and occurred in most habitats. Non-chironomidDiptera are represented mainly by insectivorous predators (all lakes),detritivores (northern and southern lakes) and phytophages of emergentmacrophytes (central and southern lakes). However, Palpomyiinae(Ceratopogonidae) were only non-chironomid dipterans abundant in alllakes. All taxa except Ceratopogonidae and Dicranota bimaculata areconfined only to stands of emergent macrophytes. A tendency to thedecrease of species number from oligotrophic to eutrophic waterbodies, aswell as with pH decreasing, was not expressed.Two peculiar habitats are formed by dense stands of emergent macrophytesin southern lakes, dense turf of monocotyledones’ roots and the layer nearthe water surface filled with plant remains. These habitats are populated,200