Ecological notes on horse-flies of some flooded areas in the middle course of the Drava River (Diptera: Tabanidae)

The faunistical research of horse-flies along the middle course of the river Drava during 2005 resulted with 23 species of which Atylotusflavoguttatus (Szilddy 1915), Hybomitra distinguenda (Verrall 1909), Heptatoma pellucens (Fabricius 1776) and Haematopota italica Meigen 1804 were new for the study area. The total number of Tabanidae species currently known in the study area increased to 42. The results of Sorenson index indicate a rather high degree of dissimilarity between Tabanidae fauna on both sides of the Drava river. On the Hungarian side of the river Drava, 36 species were collected, while on Croatian side only 23 species were collected. The most abundant species were: Haematopota pluvialis (Linnaeus 1758), Tabanus bromius Linnaeus 1758, Hybomitra ciureai (Seguy 1937), Chrysops viduatus (Fabricius 1794), Tabanus sudeticus Zeller 1842, Tabanus maculicornis Zetterstedt 1842 and Chrysops relictus Meigen 1820. These seven species comprised 79.49% of the Tabanidae fauna of the study area. Seasonal abundance was analyzed for seven most abundant species. Ch relictus, Ch viduatus, Hy ciureai, T bromius, T sudeticus and Hae pluvialis reached their highest peak of abundance in July, whereas T maculicornis reached their maximum abundance in June. All the other species collected in this study were of sparse abundance.