Buzzing Bees (Hymenoptera: Apidae, Halictidae) on Solanum (Solanaceae): Floral Choice and Handling Time Track Pollen Availability
Flower selection and pollen-collecting effort were monitored for 3 species of bees that sonicate flowers of Solanum wendlandii Hook. for pollen in southern Costa Rica. Between 0700-0900 hours, Bombus pullatus (Fkln.), Euglossa erythrochlora Moure, and Pseudaugochloropsis graminea (Fabricius) foraged more frequently at new flowers (that had opened the day of observation) than old ones (that had opened at least 1 day before observation). Between 0900-1100 hours, however, this preference was no longer evident, and all 3 species visited new and old flowers with similar frequency. E. erythrochlora and P. graminea spent more time harvesting pollen during 1) initial (first or second) visits to new flowers than initial visits to old flowers and 2) initial visits to new flowers than final (seventh or later) visits to new flowers. Similar, although not statistically significant, trends were evident for B. pullatus as well. An experiment using pollinator exclusion bags revealed that the reduced foraging effort at individual flowers was resource-dependent and was not simply a time-dependent phenomenon.