Clearly Oligolectic on Campanulaceae. Pollen samples from Germany, Austria, Switzerland, Poland, Greece and Turkey show the following plant species provide pollen forage:Campanula rapunculoides, C. persicifolia, C. trachelium, C. glomerata, C. rapunculus, C. rotundifolia and C. sibirica. (Westrich, 1989).
Pesenko in Banaszak (1995) state that this is an oligolectic species, specialising in Campanulaceae.
In Poland, it is reported to vist the following forage species (presumably for nectar): Borago officinalis (Boraginaceae); Jasione montana (Campanulaceae); Geranium pratense (Geraniaceae); Centaurea jacea (Asteraceae); Stachys sp. (Lamiaceae)(Pesenko, Banaszak et al., 2000).
Ortiz-Sanchez & Pauly (2017) report visitation to Campanula rapunculi (Campanulaceae) in Andalucia, southern Spain.