Flower Constancy in the Generalist Pollinator Ceratina flavipes (Hymenoptera: Apidae): An Evaluation by Pollen Analysis

Abstract

The food habits of the solitary bee Ceratina flavipes were studied by observation on foraging behavior and identifying the pollen grains that they collected. It appeared that C. flavipes tend to collect pollen from particular species; however, they visit multiple flowering species. We analyzed pollen sources from pollen loads of dried specimens from single foraging trips (SFT) and in pollen balls created from a single foraging day (SD). The pollen from all pollen balls in a nest represented the harvest from an entire breeding season (BP). This analysis showed that each bee on average collected pollen from 3.24 (SFTs), 2.02 (SD), and 3.12 (BP) flowering species. Bees collected pollen from a total of 14 flowering plant species. Furthermore, we calculated when pollen balls were created and found no significant interaction between seasonal pollen availability and bee preferences. Moreover, bees had consistent flower preferences, even if the preferred flower was not dominant at all times. These results indicate that C. flavipes exhibits flower constancy, and therefore, the generalist pollinator C. flavipes could function like a specialist pollinator.