How Fall-Blooming Plants Can Support Wild and Managed Bees in Urban Environments
In the United States, nearly 4,000 native bee species play a crucial role in pollinating agricultural, urban, and natural landscapes. However, managed honey bee populations, which are not native to the U.S., have sparked concerns about their potential impact on wild bees. The fear is that competition for resources and the spread of pathogens from managed honey bees could harm native bee populations.
A recent study by Penn State researchers sheds light on this issue. While some native bee species are negatively affected by the presence of honey bees, the findings reveal that only a small number of bee genera face significant challenges. The research is now published online and will appear in the November issue of Science of The Total Environment.
Impact of Managed Honey Bees on Wild Bees
The study, the largest of its kind, examined 33 genera of wild bees and found that six were affected by the presence of managed honey bee apiaries or urban land development. These bee genera, including long-horned bees (Svastra and Florilegus), green bees (Agapostemon and Augochlora), and sweat bees (Lasioglossum), exhibited reduced populations where honey bee colonies or urban development were prevalent.
Interestingly, the bees most affected tended to nest in the ground, forage later in the season, or specialize in certain types of flowers. The greatest challenge for these bees, according to lead researcher Gabriela Quinlan, is the difficulty in finding suitable nesting grounds and floral resources in urban environments, which are often dominated by asphalt, concrete, and other hard surfaces.
The Role of Urbanization and Apiary Density
The researchers sought to understand the relative impact of urban land development and apiary density. For example, long-horned bees like Svastra were most affected by high concentrations of apiaries, while urbanization had the greatest negative impact on Florilegus. Ground-nesting bees, like many in these genera, struggle to find suitable bare ground in cities, and the intense competition with honey bees for floral resources adds to their stress.
In contrast, some wild bee species appear less affected by the presence of honey bees, suggesting that the impact of honey bee competition varies across species. However, as Quinlan explained, many wild bees forage later in the season when honey bee colonies are at their peak, leading to increased competition for dwindling floral resources.
Solutions for Supporting Bee Populations
The researchers emphasize that urban gardens can play a vital role in supporting both wild and managed bees. Planting fall-blooming plants and providing bare ground for nesting are simple but effective ways to reduce the pressure on native bee species. These measures can help mitigate the effects of urbanization and honey bee competition on at-risk bees.
Additionally, beekeepers can support their colonies and minimize their impact on wild bees by managing pests and diseases more effectively. This can reduce the likelihood of honey bees spreading pathogens to wild bee populations.
Insights into Bee Interactions and Future Research
One of the unique findings of the study was how interconnected different bee species are. For example, the cuckoo bee (Triepeolus), which parasitizes the nests of long-horned bees, also showed reduced populations in areas with high apiary densities. The decline in long-horned bees like Svastra likely contributed to the decline in Triepeolus, illustrating the complex relationships between different bee species.
The researchers hope that future studies will explore these dynamics in other regions of the U.S., further investigating how honey bees affect wild bee populations on a species-specific level. Penn State’s new INSECT NET graduate program is working on nonlethal, automated monitoring systems to help advance this research.
The Importance of Native Plants and Public Involvement
For those interested in helping bees, both wild and managed, planting native flowering trees, shrubs, and fall-blooming plants is an effective way to provide essential resources. Penn State’s Beescape decision-support tool can also help the public understand local bee resources and the risks posed by pesticide use and climate variation.
Supporting bee populations, whether in cities or rural areas, requires a collective effort. Adding fall-blooming plants and creating bee-friendly environments in urban areas can contribute to the long-term survival of both wild and managed bees.
FAQs
1. How do honey bees affect wild bees?
Honey bees can negatively impact some wild bee species through competition for floral resources and the transmission of pathogens. However, only a small number of wild bee genera have been found to be significantly affected by managed honey bee populations.
2. Why are ground-nesting bees more vulnerable in urban environments?
Ground-nesting bees struggle in urban settings because hard surfaces like asphalt and concrete reduce available nesting sites. Additionally, limited floral resources in urban areas make it difficult for these bees to forage effectively.
3. What can be done to help wild bees in cities?
Planting fall-blooming plants, providing bare ground for nesting, and reducing pesticide use are key strategies for supporting wild bee populations in urban areas. These measures can alleviate the stress caused by urbanization and competition with honey bees.
4. How does apiary density affect wild bee populations?
High concentrations of managed honey bee colonies (apiary density) can increase competition for floral resources, negatively affecting certain wild bee species. This impact varies depending on the bee genera, with some being more vulnerable than others.
5. What is the Beescape tool, and how can it help?
Beescape is an online tool developed by Penn State that helps people understand the availability of bee resources in their area, as well as the risks bees face from pesticides and weather conditions. It provides valuable insights for those looking to support bee populations.
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#Pollinators #UrbanBees #BeeConservation #WildBees #HoneyBees #NativePlants #FallBloomingPlants #Biodiversity
