The estimated mean number of pollinators (± confidence intervals) recorded at flowers of I. glandulifera in the three study regions of different population age in southern Poland (Izerian Foothills, Kraków and Muszyna); groups with the same letter above the T-bars are not significantly different at p < 0.05; single records of Bombus lapidarius and Psithyrus vestalis were excluded from the analysis (see Methods).