Hoverflies (Syrphidae: Diptera) in areas contaminated with heavy metals (Cd, Zn, Pb)

The aim of the research was to study the diversity of hoverflies (Syrphidae: Diptera) living in areas under the influence of heavy metal emissions (Cd, Zn and Pb). Although the area of the Olkusz Ore-bearing Region (OOR), where the research was partially conducted, belongs to the contaminated regions, where a relatively high species richness of Syrphids has been noted. During the research period, a total of 1,180 syrphids, belonging to 165 species were caught, which constitutes 39.76% of all the Polish Syrphidae fauna. These species represented all the trophic groups with the dominance of zoophagous species (48.48%); however, the most numerous (quantitatively abundant) were saprophagous. Among the collected syrphids, common and numerous species, such as: E. arbustorum (LINNAEUS, 1758), E. tenax (LINNAEUS, 1758), Episyrphus balteatus (DE GEER, 1776) and S. pipiens (LINNAEUS, 1758), as well as rare species such as Callicera aenea (FABRICIUS, 1777) (NT), Chalcosyrphus piger (FABRICIUS, 1794) (DD), Epistrophe ochrostoma (ZETTERSTEDT, 1849) (VU), Orthonevra geniculata (MEIGEN, 1830) (DD), Rhingia rostrata (LINNAEUS, 1758) (DD), Sphegina sibirica STACKELBERG, 1953 (LC) and Spilomyia diophthalma (LINNAEUS, 1758) (NT), were noted. Eleven of the collected species have been included in the Polish Red List of Endangered Species. Melangyna ericarum (COLLIN, 1946) is recorded as a new one among the Polish fauna. Numerous observations did not indicate that the area covered by the study was characterised by a significantly lower species diversity compared to other sites. In fact, the samples taken were usually characterised by a relatively high biodiversity. The obtained results may suggest that anthropogenic activities, including those leading to environmental pollution with heavy metals and to a strong transformation of natural habitats, do not completely destroy biodiversity, and in some cases leave space for nature to create habitats where even rare species of organisms such as Syrphidae can develop.