LAUSR

ABSTRACT Globally, urbanization and other forms of land use change have been implicated in widespread pollinator declines and disruptions to plant–pollinator interactions. A growing body of literature, however, suggests that urban habitat fragments can provide oases for both plant and insect diversity. A micro-ecosystem on our college campus was created to represent the longleaf pine savannas (sandhills) that once dominated upland ridges throughout the Southeast. To assess the ability of this site to support wild insect pollinators, from May through August for three years (2016–2018) we compared visitation to two abundant flowering plant species, Bidens alba (a generalist-pollinated composite) and Chamaecrista fasciculata (a specialist-pollinated legume), between the campus micro-ecosystem and a nearby site within a large conservation area containing sandhill habitat undergoing restoration. We found that, for both plant species, total insect visitation rates did not differ between years or sites, suggesting that the small urban fragment is capable of maintaining abundant pollinators. The identity of generalist visitors to Bidens alba, however, differed dramatically between sites. Wild hymenopterans constituted more than two-thirds of all insect visits in the campus site but less than half in the conservation area, where butterflies, flies, and beetles were also common visitors. The high density of flowers in the campus site is likely at least partially responsible for the high abundance of hymenopterans, a result consistent with that of many other studies showing that hymenopterans are less sensitive to urbanization than are other insect groups.