Parnopes grandior is a species that until recently was on the brink of extinction in Poland. Current data, however, indicates that it is expanding north-westwards. Most records of this species come from after the year 2000, primarily in northern Poland, especially in the north-eastern part of the country. Simultaneously, our research has shown that anthropogenic habitats like sand quarries and military training grounds are optimal sites for P. grandior.
Although research into alien species usually focuses on their negative aspects associated with their penetration into native ecosystems, their influence is much more complicated. This study investigated the pollinators of Bryonia dioica, an invasive climber in the temperate zone. Flowers of this plant in two cities in western Poland (Bydgoszcz and Poznań) were visited by 27 bee species, the most frequent ones being Apis mellifera and Andrena florea. Until recently, the latter was regarded as rare and threatened in Poland. Our results indicate that the spread of Bryonia dioica into urban areas has enabled large and stable populations of Andrena florea to flourish there. This study investigated the daily and seasonal dynamics of its activity. A positive relationship was found between the spread of Bryonia dioica and the presence of its obligatory pollinator Andrena florea. Alien plant species are thus not only an additional source of food for local pollinators but also may favour the occurrence of otherwise rare species with specific food requirements, such as A. florea.
This study complements earlier research on wild bees (Apiformes) in the “Góra Gipsowa” steppe reserve and other habitats near the town of Kietrz (SW Poland), close to the Czech border. It also attempts to reassess the opinion of some researchers about the Moravian Gate as a migration route of southern species to Poland. 109 bee species were recorded at the study sites, including 10 red-listed ones; southern species accounted for 16.5% of this number. The hypothetical route of migration of thermophilous bees through the Moravian Gate to Poland was analysed and the species composition of southern species at either side of the Moravian Gate compared. The results of this study indicate that at present the Moravian Gate plays no part in the migration of southern bee species to Poland.