Butterflies of the genus Phengaris have a highly specialised life cycle involving an obligatory relationship with Myrmica ants. A knowledge of the host ant specificity is essential for understanding the relationship between a particular Phengaris species and its hosts and also important for the conservation of these butterflies. Data on host ant specificity were collected in Poland, the Czech Republic, Slovakia and Ukraine. Five different Myrmica species were used by P. teleius as hosts (M. scabrinodis, M. rubra, M. ruginodis, M. rugulosa and M. gallienii) and at most localities it was not possible to distinguish a primary host - i.e. several Myrmica species were parasitized to similar extents. Three populations of P. nausithous were found in Poland and Ukraine. In every case, M. rubra was its primary host, although in the Kraków region (Poland) two nests of M. scabrinodis and two of M. ruginodis were infested by this butterfly species. P. alcon in the four populations investigated in Poland and Ukraine invariably only used M. scabrinodis as a host despite the presence of other Myrmica species. These results obtained suggest lack of host specificity in P. teleius and high host specificity in P. nausithous, which mainly uses M. rubra as its host across Europe. Moreover, the three populations of P. alcon investigated seem to be highly specific and use M. scabrinodis as a host, which confirms the high local specialisation of these populations.
Which factors influence the occurrence, population size and density of species in fragmented habitat patches are key questions in population and conservation ecology. Metapopulation theory predicts that larger and less isolated habitat patches should positively influence species occurrence and population size. However, recent studies have shown that habitat quality, human activity and permeability of the landscape surrounding habitat patches may be also important. In this paper we test the relative effects of habitat patch characteristics, human settlement and landscape permeability on the occurrence, local population size and density of the Chalk-hill Blue Polyommatus coridon a charismatic butterfly inhabiting calcareous grasslands in a fragmented landscape in southern Poland. Patch occupancy rate (corrected for the butterfly detection probability) was 0.45. Habitat patch area, proximity of human settlement and cover of larval food plants positively affected occurrence of the Chalk-hill Blue. Local population size of the Chalk-hill Blue was positively affected by patch area and proximity of human settlement, and negatively by patch isolation. Local density was higher in patches located close to human settlement. Our study is one of the few showing a positive effect of human settlement on a grassland specialist butterfly although the mechanism hidden behind this phenomenon is unknown and requires further examination. In order to maintain local populations of the Chalk-hill Blue in southern Poland, conservation action should be focused on large, closely connected calcareous grasslands. Moreover, extensive management of this habitat should be maintained by local inhabitants who are better placed to undertake such work. and Zuzanna M. ROSIN, Piotr SKÓRKA, Magdalena LENDA, Dawid MORON, Tim H. SPARKS, Piotr TRYJANOWSKI.