Bee discovery suggests the importance of urban gardens in a changing world

Abstract

The diversity and distribution of wild bees are dramatically changing due to habitat fragmentation, agricultural intensification and climate change. In cities, urban gardens are proposed ‘island’ habitats for bees offering floral and nesting resources. Yet, it is largely unclear how gardens play a role in changes in species diversity and distribution. This paper reports on the discovery of a bee species to our knowledge previously undocumented in the region of Berlin, Germany. We discovered Lasioglossum limbellum in a community garden created on concrete slabs of annual and perennial vegetation. As a cavity nester in soft rock cliffs—a natural habitat functionally not existent in urban areas—the life history of this species makes this discovery particularly interesting, and an opportunity to explore the role of urban gardens in biodiversity change. This report aims to spur future research, reporting and discussion on the changes in diversity and distribution of wild bees specifically in urban areas.

Vegetation complexity and nesting resource availability predict bee diversity and functional traits in community gardens

“…We documented 24 wild bee species that are on Berlin's Red List, including Anthophora aestivalis (Category 1) and the corresponding cuckoo (cleptoparasitic) bee Melecta luctousa (Category 2). In addition, we documented a species previously undocumented in Berlin, Lasioglossum limbellum , that is usually found in southern Europe in sandy coastal habitats (Egerer, 2022a). The majority of species exhibited solitary behavior and endogeic nesting behavior, have one generation a year, and are polylectic pollen gatherers.…”

“…This included Lasioglossum limbellum, documented here for the first time in Berlin in a garden created on concrete slabs of raised beds with annual and perennial plants. As a cavity-nesting species that nests in soft rock cliffs (Scheuchl & Willner, 2015)-a natural habitat usually functionally nonexistent in urban areas-the traits of this species make this discovery relevant to the role of urban gardens as hotspots for common, rare, and specialized species (Egerer, 2022a). Furthermore, the documentation of Anthophora furcata is noteworthy because it is the only digger bee that is oligolectic on Lamiaceae with a strong preference for Stachys species-planted in gardens for diverse medicinal qualities-which it exploits using a special T A B L E 3 Summary of RLQ statistics from combined RLQ and fourth-corner analysis.…”