DOBSON, HEIDI E. M.* AND MANFRED AYASSE. Department of Biology, Whitman College, Walla Walla, WA 99362; Department of Evolutionary Biology, Institute of Zoology, University of Vienna, Vienna 1090, Austria. - Does larval pollen diet influence host-flower selection in solitary bees?
A fundamental question in bee-flower associations is whether flower
selection and specialization in bees is determined by genetically
based preferences or by the chemical imprinting of bees to odors of
their larval pollen provisions. To evaluate the role of imprinting to
pollen chemicals, females of two solitary bee species were forced to
provision their nests with pollen of Brassica
napus(Brassicaceae) and females of the next generation were tested
for their preferences to flowers. In these multiple-choice behavioral
experiments, bees were offered flowers from eight species and their
responses to each were compared in terms of number of visits, duration
of visits, and sequence of visits. In the pollen-generalist
(polylectic) bee Osmia rufa (Megachilidae), no imprinting
effect was observed. These findings will be compared to experiments
conducted on a pollen-specialist (oligolectic) bee, Chelostoma
florisomne (Megachilidae), and the implications on the development
and evolution of flower/pollen specialization in bees will be
discussed.
Key words: Brassica napus, chemical imprinting, flower selection, oligolectic bees, pollen odor, solitary bees