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|Title:||Patterns of Resource Utilization by Spring Bees Visiting Salix With Emphasis on Use of Pollen by Bees in the Genus Andrena (Hymenoptera: Apoidea) (Competition, Resource Partitioning)|
|Author(s):||Miliczky, Eugene Robert|
|Department / Program:||Entomology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The resource utilization patterns of native vernal bees visiting Salix (willows) were studied at a site in Champaign Co., east central Illinois during 1982-84. Hourly sweep collections of insects visiting willows and several other important pollen/nectar sources were made throughout the active seasons of the most important spring bees (late April through late June). More than 20,000 bees in over 100 species were captured. A majority were identified to species in the field and returned to the local population. The rest were processed in the laboratory. Four species of Salix were present at the study site and all were visited by bees, the most important of which were members of the large, holarctic genus Andrena and several genera in the family Halictidae. Salix rigida, S. amygdaloides, and S. nigra bloomed sequentially starting in late April and ending in late May. Each bloomed for 10-20 days with little overlap during peak bloom of temporally adjacent species. The fourth species, S. interior, had an extremely long flowering period. Beginning near the end of April and extending into July, it overlapped the other three.
Three abundant bees in the genus Andrena that are specialists (oligoleges) on Salix pollen were found to differ in seasonal phenology. Differences in daily activity periods were present but probably less important ecologically. The three oligoleges, however, showed similar preferences for concurrently blooming willows as pollen sources. Although S. rigida was used primarily as a nectar source, being the first to bloom and rare at the site, S. amygdaloides and S. nigra in turn, were preferred as pollen sources over the concurrently flowering S. interior by all three. During June, when S. interior was the only willow in flower, it was visited for pollen by the oligoleges. Many non-specialist bees (polyleges) visited the willows and showed similar pollen preferences to the oligoleges. They did not, however, use S. interior as a pollen source during June, visiting it primarily for nectar. Pollen preferences may be related to certain characteristics of the catkins and flowering phenologies of the male willows that appear to make them more attractive pollen sources.
The foraging behavior of the three Salix oligoleges on S. interior is described and evidence presented indicating that bees are important pollinators of the dioecious willows.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985.
|Date Available in IDEALS:||2014-12-16|