A multitude of bee pollinators in a phenotypic specialist - pollinator diversity from the plant's perspective

Abstract

Bilabiate flowers are phenotypically specialized and primarily pollinated by bees. However, this phenotypic specialization does not necessarily result in functional and/or ecological specialization. We use the bee-pollinated Salvia pratensis L. (Lamiaceae) as a model species to elucidate the number of pollinators, their fitting to the flower and their behavior in order to identify the best fitting pollinators and most capable foragers. Field observations at 12 localities between 2018 and 2023 revealed in total 37 bee species as pollinators. Based on morphometric and behavioral data, handling time per flower, number of flowers visited per minute and an index of the proportion of bee contacts with reproductive surfaces per flower visit, big and long-tongued bee species were identified as the best fitting pollinators and most capable foragers. We conclude that S. pratensis is a functional specialist and ecological generalist at the same time. This combination is advantageous in species assemblages with moderately specialized partners as it combines the advantages of generalization (high number of pollinator species) with those of specialization (economic pollen transfer).