Pollination Biology of <i>Ailanthus altissima</i> (Mill.) Swingle (Tree-of-Heaven) in the Mid-Atlantic United States
To date little information has been collected on the pollination biology of Ailanthus altissima (Mill.) Swingle (tree-of-heaven), an invasive exotic in the U.S. This study was conducted to determine the insect pollinator fauna visiting A. altissima and to study general pollinator visitation patterns associated with the tree's nectar profile. A list of taxa visiting trees within each of three sites was developed from collected insects. Overall, visitor assemblage was dominated by the soldier beetle Chauliognathus marginatus with large numbers of ants in the genera Formica, Prenolepis, and Camponotus. No major diurnal pattern was found for visitation of insect pollinators using instantaneous counts. The nectar composition, concentration, and amount of total sugars in the flowers of A. altissima and how these are related to tree gender and time of day were determined. Nectar was found to be sucrose-dominant with lower, but nearly equal amounts of fructose and glucose. Total amounts of sugar in male and female blossoms were not statistically different, however higher concentrations of sugar were found in males (40.7%) than in females (35.3%). No difference was found over time. Nectar production and removal in trees was studied by comparing bagged flowers with flowers open to insect visitation. Bagged flowers were higher in overall sugar than open flowers, however, this was not constant across all times and gender.