| Description |
The north-western part of the Czech Republic, including the environs of Bílina and Duchcov (Bílinsko Area) has been one of the major coal mining regions in then Czechoslovakia. Extensive surface and underground mining made the Bílinsko Area one of the most antropogenously devastated regions in Central Europe. However, a secondary succession took place on the created harsh areas. Coal mining in the study area stopped during the second half of the 20th century. Restoration took place mainly by planting the very resistant canadian tree species Pseudotsuga menziesi, which can live also on a completely sterile soil. In fact, the restoration was based on giving support to a natural autosuccession with minimal antropogenous interference. Traces of pollution still exist in study area., both in soil and water. The study area of about 48 sq. km is situated between the villages of Osek, Štépánov and Braňany. About 60 percent are taken by the urban-industrial area and the opencast Bílina mine. The greatest part of the studied region geographically belongs to the Podkrušnohorská pánev Basin, the southern part is situated on the edge of the České středohoří Mts. Biomonitoring project included 28 localities, biting midges were recorded on 8 of them: loc. 1. Duchcov, loc. 6. Chloumek, loc. 7. Jirásek III, loc. 8. Štěpánov, loc. 18. Lom, loc. 21. Vršíček, loc. 25. Holibka, loc. 28. Radovesice The processed material was collected during 1998-1999 using Malaise traps, Emergence traps, Yellow Pan Water Traps, and some adults were collected from decomposed wood. From the collected material have been prepared about 400 microscope slides (248 females and 149 males) and determinated 65 species, what represents 41.4 % of the total Czech fauna (157). Altogether 13 species (20 %) have been recorded for the first time in the Czech Republic: Nilobezzia posticata (Zetterstedt, 1850), Clinohelea unimaculata (Macquart, 1826), Atrichopogon alveolatus Nielsen, 1951, A. epicautae Wirth, 1956b, A. meloesugans Kieffer, 1922, A. muelleri (Müller, 1905), Ceratopogon communis Meigen, 1804. Forcipomyia phlebotomoides Bangerter, 1933, F. frutetorum (Winnertz, 1852), F. radicicola Edwards, 1924, Dasyhelea flavoscutellata (Zetterstedt, 1850), D. arenivaga Macfie, 1943 and D. ermeri Remm, 1967. This result might be due to the fact, that the area hosts a young biocoenosis developing towards a climax. In the final stage of developement the number of species would be probably lower. Remarkable is the occurrence of Atrichopogon epicautae known from North America only and recorded in the Czech Republic for the first time. The found species excludes biting midges with a crepuscular and nocturnal activity, because used collection methods are only appropriate for biting midges with diurnal activity. To obtain a complete spectrum of species it would be necessary to collect also at dusk or at night using some kind of light trap or emergence traps (with CO2, nulliparous females) at the peak of their activity. The locality hosting the most diverse ceratopogonid species spectrum appears to be Holibka (29 spp.), followed by Jirásek III and Lom (both 24 spp.) and a floodplain forest near Duchcov (21 spp.) The most common species in the study area were as follows: Atrichopogon meloesugans (found in 7 localities), Forcipomyia velox, F. tenuis (both found in 6 localities), F. bipunctata, F. tenuisquama and F. ciliata (all found in 5 localities).
|