Minimum size threshold of visiting bees of a buzz?pollinated plant species: consequences for pollination efficiency

PREMISE Flowering plants with poricidal anthers are commonly visited by buzzing bees, which vibrate flowers to extract pollen. However, not all flower visitors in fact pollinators, and features such as body size duration of visits important factors determining pollination effectiveness. We tested whether bee-to-flower relationships predict the effectiveness a buzz-pollinated species (Chamaecrista ramosa, Fabaceae). METHODS sorted 13 bee taxa into three groups: smaller than, equivalent (“fit-size”), larger than herkogamy (spatial separation between stigma). expected latter two groups touch stigmas, would be an indicator effectiveness, more frequently first group. To test this hypothesis, we assessed contact foraging behavior, for bees. RESULTS Our data reveal that small bees scarcely touched while large fit-size were most efficient achieving high stigma-touching rates, conducting much shorter visits, visiting conspecific at rates during bouts. CONCLUSIONS The results did show size-matching among flowers, expected, but rather minimum threshold pollinators. finding is nonarbitrary approach predicting herkogamous anthers.