Abstract

Habitat loss and fragmentation as a result of urbanization and agriculture have led to considerable declines in populations of many North American native bee species. This decline has inspired the development of solutions intended to reduce pollinator habitat disruption, including incorporating plant species shown to enhance pollinator abundance into landscape design. The ability of heterogeneous landscapes to promote native bee abundance has been well studied; however, the complex nature of plant-pollinator mutualisms suggests that pollinator recruitment and reproductive success can be heavily influenced by the structure and density of floral neighborhoods. In the summer of 2015, pollinators were studied in a newly installed native plant habitat featuring herbaceous perennials native to the western North Carolina region or their cultivars. Visitor category, visit frequency, and visit duration were recorded and used to infer population-level demographic patterns regarding foraging behavior and plant preference with in an artificial habitat. Field sampling time totaled 2,640 minutes in which visitor observations (n=2061) were made on six plant species Asclepieas tuberosa (butterfly milkweed), Coreopsis verticillata (whorled ticseed), Helianthus flexuosum (purple-headed sneeze weed), Monarda fistulosa (wild bergemont), Penstemon digitalis (foxglove beardtounge), Sympheotrichum oblongifolium (aeoromatic aster ‘Raydons favorite’) from four families (Asteraceae, Apocynaceae, Lamiaceae, Plantaginaceae) in the summer of 2015. Visitor frequency and duration data were used in statistical analyses to assess visitor diversity and interaction strength across the six plant species. Monarda fistulosa received the highest diversity and abundance of total visitors, generating the highest relative interaction strength with bumblebees and butterflies among all visitor categories. Penstemon digitalis and Coreopsis verticillata generated stronger relitive interaction strength with sweat bees and halictid bees among all vistior catagories. Observations of visitor abundance were highly skewed towered bumblebees, while Monarda fistulosa received the most frequent and diverse visitor interactions of the six plant species. Summary statistics for Monarda fistulosa were generated using SAS showing significant differences in average foraging times in four out of 11 visitor categories, indicating weighted differences in the utilization of floral resources by the artificial habitat insect community assemblage. Developing methods such as these may illuminate the presence of a quantifiable optimum in keystone resource usage by insect pollinators, improving the effectiveness of small-scale pollinator refugia at promoting pollinator abundance in the wake of habitat fragmentation.

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