Catch the buzz – pollinator diversity, distribution, and phenology in Shenandoah National Park

Rykken, Jessica

Insect pollinators, specifically bees (Hymenoptera: Anthophila) and flower flies (Diptera: Syrphidae), are critical to maintaining functioning ecosystems in Shenandoah National Park. Despite their ecological importance and potential vulnerability to environmental threats such as climate change, the diversity of these pollinators has remained largely unknown. In an effort to establish a baseline pollinator database for the park, we conducted a survey with three main objectives: (1) to document the diversity, distribution, and phenology of bees and flower flies in selected habitats of the park; (2) to establish a series of citizen scientist-run sampling sites and develop protocols for continued monitoring of pollinators; and (3) to educate park staff and visitors about pollinators and threats to pollinator health. Between May and October, 2015, we used nets and bee bowls to collect bees and flower flies at 100 different sites in the park (including seven monitoring sites run by nine citizen scientists). Sites ranged in elevation from 336 to 1225 m, and stretched north to south from MP 2 to MP 101 along Skyline Drive. We targeted areas of high or unusual floral diversity, including: forest roads, meadows, roadsides, and rock outcrops. In all, we collected 3,387 bees and 377 syrphid flies, comprising 145 and 40 separate taxa, respectively. Among bees, this represented half the genera known from Virginia, and approximately one quarter of the bee species known from the mid-Atlantic region. Photographs of select syrphid fly and bee species can be found in Figures 1 and 2. Notable bee finds included 16 oligolectic (specialist) species, dominated by spring-active bees in the genus Andrena. A group of high elevation Appalachian species which are also found in more northern regions included several Andrena; the two bumble bees, Bombus sandersoni and B. vagans; the masked bee Hylaeus annulatus; and a rarely collected cellophane bee, Colletes aestivalis. Interesting syrphid flies included the rarely collected ant predator, Microdon ruficrus, and a single female in the genus Chalcosyrphus that is one of two very rare species in North America. The most abundant pollinator group was the social, ground-nesting bees, including Lasioglossum species and Augochlorella aurata. However, the most abundant species overall (13% of all bees) was the wood-nesting solitary bee, Augochlora pura. The syrphid catch was dominated by two species in the genus Toxomerus (57% of the total syrphid catch). Sampling effort across habitats was uneven (primarily meadows), but when this was accounted for by rarefaction curves, meadows still had the highest species richness among bees, while syrphids were most diverse in forest habitats. Standardized monthly sampling at the seven monitoring sites allowed us to track the seasonal activity of various pollinator genera, and also highlighted the need to begin sampling earlier in the season (i.e., April or May). Park visitors and staff learned more about Shenandoah’s pollinators through hands-on microscope sessions at Byrd and Dickey Ridge visitor centers, as well as one evening presentation at the Skyland amphitheater. Citizen scientists were invaluable to this inventory effort, and the development and documentation of detailed sampling protocols will allow Shenandoah to continue sampling at the established monitoring sites with the help of citizen scientists in the future if funding allows.

Catch the buzz – pollinator diversity, distribution, and phenology in Shenandoah National Park

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