Azaleas (Rhododendron spp.) are popular as ornamental shrubs in the southeastern U. S. where their large, colorful flowers form spectacular displays in early summer. Azaleas are becoming an increasingly important crop to nursery growers accounting for nearly 100 million dollars in annual sales. Hybrids of several azaleas used by nursery growers (Sweet Azalea, Rhododendron arborescens and Swamp Azalea, R. viscosum) occur naturally on the grassy balds of the Great Smoky Mountains National Park (GRSM). These open, high elevation, grassy areas have an aesthetic appeal, and offer spectacular views of surrounding peaks normally obscured by tree covered ridges. Gregory Bald differs from other balds in the large number of hybrid azaleas present. The azalea species involved in the hybridization are R. arborescens, R. viscosum (both with white flowers and strong fragrance), and R. cumberlandense (orange to red flowers, slight or absent fragrance). Observations of insect visitors to flowers of hybrid azaleas on Gregory Bald were made on 11, 15, and 18 June 2,000 between 10AM and 3PM. Insects were collected into individual 3½ dram vials; flower color and observed insect activity were recorded. In the laboratory, specimens were pinned, labeled, and identified. Results reveal the presence of nectar thieves, pollen robbers, and a few species of pollinators. Only the bumblebees, Bombus affinis, B. maculatus, and B. sp? nr. vagans, were observed gathering pollen in a manner suggesting flowers were pollinated during their visits. In other studies, bumblebees have been used effectively as pollinators under controlled field conditions. Because their colonies are small (30-150 workers) bumblebees are conducive for pollinating in small enclosed areas. Thus, the beauty and vigor of azalea hybrids may be improved by using bumblebees as a cost effective pollinator to obtain desired crosses.
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA