Date of Award

Spring 2017

Document Type


Degree Name

Master of Science (MS)


Biological Sciences

Committee Director

Lisa Horth

Committee Member

Lytton Musselman

Committee Member

Eric Walters


Colony Collapse Disorder has greatly reduced honey bee populations in the last decade. Native bees have been largely neglected in research, and their floral preferences may have agricultural implications because native bees ameliorate the demand to rely solely on non-native bees. In this work, pollinator visitation to flowers with manipulated ultraviolet floral patterns was monitored. Populations of wild showy golden-eye in Colorado, plus cultivar populations of black-eyed Susan and lawn populations of buttercups in Virginia were monitored for pollinator landings to compare preference for unmanipulated ultraviolet-absorptive floral guide preferences. Another number, a proxy for pollen load, was manipulated on strawberry flowers to determine whether this treatment affected mason bee visitation frequency. Three mason bee densities (three, six and nine bees in ≈2.33 m2) were compared in three greenhouses, each stocked with 10 strawberry plants. Bee visitations were monitored and berry size and symmetry were measured. Mason bee emergence rates were compared in two environments (natural conditions and temperature-controlled conditions) for cocoons. Field surveys was conducted to evaluate which native pollinators naturally recruited to field blackberries. Higher visitation rates were found for flowers with larger ultraviolet-absorptive floral guides and stamen manipulations. Mason bees did visit flowers but did not demonstrate any preference for flowers with more stamen. Bee density did not affect berry weight or berry symmetry. High emergence rates were observed in both natural and controlled environments and more bees emerged in the controlled environment. Sweat bees and bumble bees were the major visitors to blackberry flowers but honey bees were not present. This work builds upon earlier findings that pollinators prefer larger ultraviolet patterns and supports a more generalizable phenomenon. This study further suggests that mason bees may be commercially valuable given their peak of in mid-summer, coinciding with the pollination period of fruiting crops. Native pollinators may play an important role in blackberry pollination because of their relatively high abundance relative to honey bees.


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