Ábrahám Levente: Biomonitoring a Dráva folyó magyarországi szakasza mentén 2000-2004 - Natura Somogyiensis 7. (Kaposvár, 2005)

Ábrahám, Levente.: Biomonitoring of the butterfly fauna in the Drava region (Lepidoptera: Diurna) - Nappali lepkék biomonitoring vizsgálata a Dráva mentén (Lepidoptera: Diurna)

ÁBRAHÁM L.: BIOMONITORING OF BUTTERFLY FAUNA 65 Apatura metis is a highly hygrophilous species. The size of the relative population was investigated in the soft-wood open woodlands of the riverbank near Bélavár, Vízvár, Babócsa és Őrtilos. The species of Lycaena dispar, Maculinea teleius, Maculinea nausithous are less hygrophilous. These populations were measured on wetlands and oligotrophic humid grasslands near Babócsa and Gyékényes. The species of Euphydryas maturna is tightly associated with the edges of hardwood forests. In 2001, its populations were found in the Palina forest, near Bélavár, and in the Lankóci forest, near Gyékényes. Although Parnassius mnemosyne is considered to be a mesophilous type, its populations were researched near Péterhida and Bélavár on similar type of habitats. The investigation of Zerythia polyxena would not fit into this hydro ecological gradient line, but it has environmental protection significance to keep track of this potentially endangered monophag population. A transect line estimation on the relative populations of certain species was carried out mainly in accordance with the methods recommended by NBmR (RONKAY 1997). Table 1.: Paramètres of the transect line method applied in the fieldwork species number of transect/site long x wide of transect controU time/transect number of sampling days/year A. metis 6 100x20 m 20 min 9+7 P. mnemosyne 3 100x20 m 20 min 6 E. maturna 6 100x20 m 20 min 6 M. teleius 9 50x10 m 20 min 9 M. nausithous 9 50x10 m 20 min 9 In the case of Zerythia polyxena, we carried out a caterpillar count. Regarding the collecting sites, this method gives an absolute population estimate as each induvidual was counted on certain sampling occasions. The investigations were carried out at different collecting sites from April to mid September on a yearly basis. Results During the course of the biomonitoring survey a transect line estimation on butterflies was carried out* The relative population sizes were analyzed per species with regard to the years of research. Apatura metis The figures of five research years show similar time trends (Fig. 2-3) at the four collecting sites alongside the entire length of the river. The figures show the highest relative size of population of the investigated species in the first year of the research, in 2000. This figure dropped to a half/third in 2002, while later showed a minor increase in 2003 (in comparison with the two previous years). In 2004, the size of the first generation population almost reached the relative population size we got in the first year of the research. The time trend can be seen especially clearly in the first generation where the transect line number of individuals is always higher than in the second generation. Similar trends can be detected in the case of the second generation at all of the three collecting sites