Meeting Abstract
We analyzed natural nectar dynamics, removal effects, and floral visitors of Convolvulus arvensis on the eastern Greek island of Lesbos. To determine nectar reward to pollinators, we measured nectar dynamics of individual flowers, in anthesis, in June and July at several field sites. Nectar flow and standing crop differed among collection times and different sites. In general, flowers produced the most nectar volume at the beginning of the day, which gradually decreased thereafter. Nectar flow and standing crop available to pollinators differed in their responses to visitation. Nectar flow displayed interactive effects between Site and Time, whereas standing crop displayed a Site effect and a Time effect. Nectar flow was not consistently higher than standing crop, as we hypothesized. However, we correlated temperature, pollen availability, and visitation rates of primary pollinators as factors affecting nectar reward. A post-hoc hypothesis for the different response of nectar flow and standing crop to visitation is nectar reabsorption by C. arvensis. Systropha curvicornis and Lasioglossum malachurum primarily visited C. arvensis as abundant pollinators during our studies. In a nectar removal experiment, L. malachurum harvests the pollen and not the nectar of C. arvensis but the specialist, S. curvicornis;, harvests both pollen and nectar of C. arvensis. Therefore, the foraging behavior of these two species should be taken into consideration when examining the nectar dynamics of C. arvensis in the Mediterranean ecoregion.
