Buzzing into Summer

Summer is a season brimming with life and activity. Gardens burst into vibrant colors, crops ripen under the sun, and flowers bloom in full glory. Amidst this seasonal activity, an essential group of workers buzzes tirelessly – native bees. These pollinators play a crucial role in maintaining healthy ecosystems and ensuring food security, making them indispensable during the summer months.

When we think of bees, the image of the honeybee often comes to mind. However, native bees, which includes bumblebees, mason bees, carpenter bees, and sweat bees, are even more important. Unlike honeybees, native bees have evolved alongside the local flora and fauna, creating mutually beneficial relationships with native plants and maintaining biodiversity. As they pollinate plants, they help propagate a wide range of species, from trees and shrubs to wildflowers and grasses. This, in turn, supports other wildlife, including birds, butterflies and mammals, which depend on these plants for food and habitat.

Importance of Native Bees

Native bees as a group exhibit incredible diversity, with more than 4,000 species in North America and around 500 species in the state of Illinois. This diversity includes varying sizes, shapes and behaviors, which allow different species to pollinate a wide array of plants. Some native bees have specialized relationships with certain plants, including some important summer garden helpers. For example, the squash bee (Eucera pruinosa) is a specialist pollinator of squash, pumpkins and gourds, while blueberry bees (Colletes validus) are vital for blueberry crops.

Diverse bee populations are also indicators of a healthy ecosystem. A decline in native bee numbers often signals broader environmental issues, such as habitat loss, pesticide use and climate change. Protecting native bees, therefore, means protecting the broader ecosystem and the multitude of species that inhabit it.

Reasons for Bee Declines

Habitat loss and fragmentation has been determined to be the most prominent cause of decline in population and abundance of bees (LeBuhn et al 2021, Olynyk et al 2021, Winfree et al 2016). However, habitats surrounded with differing adjacent habitats have been known to host more diverse species. Bee species abundance, diversity and successful pollination has often been associated with nest proximity to wetlands (Evans et al 2018, Vickruck. et al 2019). Low rates of success of restoration are present when it comes to constructing mitigation wetlands, resulting in fragmentation, degradation and destruction of the landscape (Craft 2022).

Bee Diversity in Wetlands

Wetlands are important ecosystems that provide many services and benefits to humans and wildlife, including providing habitats for threatened and endangered species and protecting our river communities from flooding. However, wetlands have also been declining rapidly. The long-term loss and conversion of wetlands is 54 to 57 percent on average but could be as high as 87 percent since 1700. Wetland restoration has been used as an attempt to mitigate these losses. Restored wetlands perform better than degraded wetlands but worse than natural wetlands in supporting and regulating ecosystem services (Meli et al. 2014), which are basic ecosystem processes such as primary productivity and services that maintain characteristics of the environment such as air quality, respectively (Mitsch et al. 2015). Additionally, restoration increases the biodiversity within the wetland (Meli et al. 2014).

The purpose of the ongoing bee surveys is to quantify and compare the taxonomic diversity and functional trait diversity, measured through intertegular distance (see Figure 1), of bees found in natural, restored and managed wetlands. To do this, we visited six wetlands in Illinois and Missouri – two natural wetlands to serve as our reference sites, two restored wetlands and two more actively managed wetlands – on a weekly basis in the summer. While only one and a half summers into our study, we can see some interesting trends in the data and think about how wetlands may support differing communities of bees.

Firstly, all wetlands exhibited a diverse assemblage of native bees. However, we collected the greatest number of bees in the natural wetlands and the lowest number of bees in the restored wetlands. The natural wetlands also had the greatest diversity using the Shannon Diversity Index (a popular metric used in ecology for estimates of species diversity). However, despite having the lowest number of bees, the restored wetlands had greater diversity than the managed wetlands.

The size of bees within the three wetland types were significantly different. One reason this is important is because bee size correlates with flight distance. Bigger bees can fly farther to access more nutrients, nest sites or mates. Smaller bees do not fly long distances and can be limited in the forage or nest sites available to them. This is important when considering the floral diversity of a site, and how that supports the diversity of bees that are there.

Natural wetlands supported the greatest range of sizes, and the largest mean size. Restored wetlands had a greater mean size than the managed wetlands, but the managed wetlands had a greater range of sizes than the restored wetlands.

While more years of surveys will give more definitive conclusions on the influence of varying wetlands on bee communities, we can see that wetlands do support a diverse assemblage of native bees. However, it is not the same bee community across all wetlands, and there is a significant relationship between wetland type and bee size. Overall, protecting a variety of wetland types with a diversity of native plants will support a variety of native bees.

Literature Cited

Craft, C. (2022). Creating and restoring wetlands: from theory to practice. Elsevier.

Evans, Elaine, Matthew Smart, Dan Cariveau, Marla Spivak. (2018). Wild, native bees and managed honey bees benefit from similar agricultural land uses. Agriculture, Ecosystems & Environment, Volume 268, Pages 162-170, ISSN 0167-8809, .

Meli, P., Rey Benayas, J. M., Balvanera, P., & Martínez Ramos, M. (2014). Restoration Enhances Wetland Biodiversity and Ecosystem Service Supply, but Results Are Context-Dependent: A Meta-Analysis. PLoS ONE, 9(4), e93507.

Mitsch, W. J., Bernal, B., & Hernandez, M. E. (2015). Ecosystem services of wetlands. International Journal of Biodiversity Science, Ecosystem Services & Management, 11(1), 1–4.

Olynyk, Marika, A Richard Westwood, Nicola Koper. (2021). Effects of Natural Habitat Loss and Edge Effects on Wild Bees and Pollination Services in Remnant Prairies. Environmental Entomology, Volume 50, Issue 3, Pages 732–743.

Winfree, Rachael; Aguilar, Ramiro; P. Vázquez, Diego; LeBuhn, Gretchen; A. Aizen, Marcelo (2016). A meta-analysis of bees’ responses to anthropogenic disturbance. Wiley. Collection.

Vickruck, Jess L., Lincoln R. Best, Michael P. Gavin, James H. Devries, Paul Galpern. (2019). Pothole wetlands provide reservoir habitat for native bees in prairie croplands. Biological Conservation, Volume 232, Pages 43-50, ISSN 0006-3207.

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Jenny Mullikin is an Assistant Scientist in Wetlands Ecology at the National Great Rivers Research and Education Center in East Alton. She studied native bees, specifically the wetland specialist the hibiscus bee, for her PhD at St. Louis University. She loves hiking and exploring the natural areas of Missouri and Illinois.