Tóth Sándor: A Bakony természettudományi kutatásának eredményei 25. - A Bakonyvidék zengőlégy faunája (Diptera, Syrphidae) (Zirc, 2001)

HOVERFLY FAUNA OF THE BAKONY REGION (SUMMARY)

north and north-east, and by the Kisalföld on the west and north-west. Regional division of the mountains based on geography has gone through some modification during the past. Earlier divisions (BULLA 1962, PÉCSI and SOMOGYI 1967) were supplemented with new results by JUHÁSZ (1975). An ecological division was made in the recent past (DÉVAI et al. 1992) which differs from the traditional one mainly because it places the northern shore of Lake Balaton and most of the Tapolca basin (with the exception of the remnant hills of the basin) into the Balaton basin. Natural factors have been of basic importance for the development of the hoverfly fauna of the region. Primarily geographical location, climatic factors which are depending on the former one and vegetation are the key elements which influence to a smaller or bigger extent the qualitative and quantitative composition of the recent fauna. In the present volume composition of the hover fly fauna is examined based on the traditional division of the region into small units. Brief characterization of hoverflies Hoverflies (Syrphidae) represent one of the biggest families of dipterans (Diptera). Number of described species of this family amounts to over 5000. App. 1600 species are known from the palearctic region and 800 from Hungary. In Hungary at present 367 species are registered. In the Bakony, which is relatively well investigated in comparison to other regions of Hungary 340 species have been found. Most of the adult hover flies feed on pollen and nectar but they also consume honeydew, plant sap and some species even feed on leaking saps of injured trees. Despite adults, feeding habits of larvae are much more diverse. Three main groups can be distinguished: (i) herbivores (phytophags), (2) detritivores (saphrophags) and (3) predators (zoophags).Within these groups some intermediate types may occur, and there are species whose life type is not quite clearly or less known. App. 40% of the species falls to the category of predators. Among them many are useful, aphydophagous organism. Most of the adult hover flies play an important role in the pollination by their feeding, similarly to bees and other, flower-dependent insects. 446 such plant taxa are known from the mountains on which at least one hoverfly species has been found to feed. List of these plants (with Latin and Hungarian names) is published at the end of this volume in the index, in alphabetical order and with serial numbers. When characterizing those hover flies that have a wide range of plants, only the serial number of actual plants are shown (to save some space). Number of plants visited by hoverflies is highly varying. The block diagram (Fig 8.) illustrates the number of plant taxa on which some relatively frequent hover fly species feeding on flowers (or partly on flowers) could be collected or at least seen in the mountains. As we can see, Eristalis tenax is the first (242 plant taxa), Eristalis arbustorum is the second (237 plant taxa) and Sphaerophoria scripta is the third (218 plant taxa). Materials and methods For collection of hoverflies, in addition to the modified butterfly net which was the main equipment, the Malaise trap was successfully used as well, mostly for occassionally collections, having lasted for some hours. In some cases on selected spots a special version of this trap was also used for longer time, which was made of plastic mosquito net, being more tolerant to weather conditions.