B.Y.O. Bees: Managing wild bee biodiversity in urban greenspaces

Abstract

As cities become more populated and the density of urban development increases, local biodiversity is threatened. Urban greenspaces have the capacity to preserve pollinator biodiversity, but the quality of support they provide depends on greenspace landscape attributes, including the availability of pollinator habitat and foraging resources. Wild native bees provide important pollination services to urban ecosystems, yet relatively little is known about how urban landscape management influences pollinator community composition and diversity. Our study explores how wild bee communities are affected by greenspace and landscape-level features like pollinator management practices, in urban greenspaces in and around Appleton Wisconsin: a mid-sized urban community spanning more than 100 sq. km. We sampled and identified native bees periodically between late-May 2017 and mid-September of 2018 using standardized arrays of pan traps at 15 sites around the city. We classified greenspaces based on their level of development (urban or suburban) and whether they were managed or unmanaged for increasing wild pollinator diversity. We quantified floral species diversity, floral color diversity, tree species diversity, and proximity of sites to open water for each site and used remotely sensed satellite data from both the USGS National Land Cover Database (NLCD) and the Normalized Difference Vegetation Index (NDVI). All variables were tested as potential correlates of wild bee abundance and species richness. Active pollinator management sites supported higher levels of bee abundance and richness. Notably, active greenspace management (e.g. planting native wildflowers) was a stronger correlate of bee abundance and richness than greenspace size and other landscape-level attributes. Within-greenspace attributes such as floral diversity, tree diversity, and proximity to open water contributed positively to both bee abundance and richness. Based on these findings, we suggest that urban greenspaces may be managed more efficiently and cost-effectively by focusing resources on active management by planting wildflowers, removing invasive species, creating nesting habitat, and providing water resources, rather than simply expanding in area.

Insect-Mediated Pollination of Strawberries in an Urban Environment

“…Indeed, one study found that planting "bee-friendly" plants next to strawberry plants increased the yield and fruit quality in an urban area [94]. Urban conservation strategies to boost pollinator diversity, including sewing native wildflower strips, reducing pesticide use, or limiting mowing in urban green spaces [19,28], could promote pollinator diversity and the production of high-quality urban crops.…”

“…These aspects of urban landscapes can allow cities to harbour diverse pollinator communities [25][26][27]. Despite a growing interest in urban pollinator diversity [28][29][30] and their pollination services [17,21,31,32], few studies assess whether these unique urban pollinator communities can provide sufficient pollination services to support urban crop production.…”

Experimental evidence of nocturnal pollination services for berry crops

“…However, most of our knowledge about pollination and pollinators focus on diurnal activity, neglecting the contribution of nocturnal pollinators to crop production [13,28]. Night-active pollinators include vertebrates such as bats (under tropical climates) as well as invertebrates such as moths, beetles and some bee species [28][29][30][31][32][33][34][35][36]. Some studies have investigated whether nocturnal pollinators contribute to crop pollination.…”