Do We Need Wild Bees?

By Jessica Laskowski, PhD student, Dept. of Wildlife Ecology & Conservation 

The common long-horned bee (Melissodes communis), carries crop pollen here in the Gainesville area. Photo: USGS NBIML

Do we need wild bees?

(1) Fresh squeezed OJ

(2) Farmer’s market blueberries

(3) Dinner at The Top

My favorite Gainesville, FL delicacies may all depend upon our wild bees.

Bees work hard to carry pollen from one plant to another, which is critical for fertilization and seed production on farms. Americans have largely relied upon European honeybees, which are social creatures, with excellent navigational skills that come in handy when they’re shipped out and dropped on a farm across the country. Unfortunately, European honeybee populations are declining fast due to disease and pesticide exposure. Wild bees augment honeybee pollination and may, if we learn how to manage them, provide insurance against honeybee decline. We may need these wild bees and for them, cross-country travel is not an option.

So, if we can’t transport wild bees, we have to attract them to farms.  Right now, scientists and farmers don’t understand enough about which bee species are pollinating which crops to focus on targeting certain bee species for certain farms. Instead, it might be best to cast a wide net, aim to attract many different kinds of wild bees to a farm and, chances are, pollination will increase.

For her PhD research, Rosalyn Johnson set out to understand what factors influence wild bee diversity on farms in the Gainesville area. This past Monday, Rosalyn presented her research that she conducted in Dr. Sieving’s lab in the Department of Wildlife Ecology and Conservation at the University of Florida. Rosalyn studied factors influencing wild bee diversity on ten farms surrounding Gainesville, including Swallowtail and Siembra farms. She studied the wild bee-facilitated movement of pollen of fruits and veggies you probably pick up at the farmers market. And your latest scrumptious meal at the Top, most likely prepared with ingredients fertilized by Rosalyn’s wild bees.

The Southeastern blueberry bee (Habropoda laboriosa), carries crop pollen in the Gainesville area. Photo: USGS NBIML

How do bees decide where to forage for pollen? 

Bees forage within areas where they decide to settle. Bees settle in areas that provide for their needs including food and nesting sites, not unlike how we choose where to settle. Before moving to Gainesville, most of us scoped out the supermarkets and restaurants downtown, but there were probably other important factors like housing and even potential mates that influenced our decision to settle here. Bees may be dining on the farms, but they’re nesting in the landscape around them. So, when Rosalyn thought about what factors might influence bees foraging on farms, she had to think about larger areas surrounding farms that might influence where they settle and consequently, where they forage.

Rosalyn considered many factors on the farms, such as vegetation structure and diversity, and factors surrounding farms (within a 500m radius and a 3km radius), such as urbanization and the surrounding farming practices. She measured bee diversity on farms by catching bees using nets. Rosalyn also used what she called, ‘bee bowls’ – brightly colored bowls filled with soapy water – which she systematically set out in the farms. Bees are attracted to the bowls, just as they are attracted to bright flowers. Once they enter the water, they’re trapped and sacrificed for science. Rosalyn and field assistants sampled bees at each farm twice monthly during the spring and summer growing seasons for two years.

Can North-Central Florida farmers do anything to attract more wild bees?

Factors on the farm: Rosalyn found that farms with a wide variety of types of vegetation (grasses, flowers) also had more types of bees foraging in the crop fields, providing evidence that vegetation diversity facilitates bee diversity. Rosalyn’s research suggests that flowering crops with even a small number of other crops or weeds in the mix increases wild bee diversity in fields.

Factors surrounding the farm: Rosalyn found that it doesn’t seem to matter if a farm is surrounded by more farmland or by more natural areas. If there is diverse vegetation on the farm, the bees will come.

Do certain bee species specialize and collect pollen specifically from crop vs. non-crop plants?

While Rosalyn was capturing bees on farms she collected their pollen in order to find out who carries what. Rosalyn identified 31,000 grains of pollen that she sampled from bees. She discovered types of bees that may be crop pollen specialists: bees from the families Halictidae , Hapidae and Megachildae and a couple of key species; the long-horned bee and the southeastern blueberry bee. One bee species acted like a “generalist shoppers”, as Rosalyn called it. This species (Halictus poeyi) took a little of this, a little of that, and carried both crop and non-crop pollen.

Rosalyn created a document of the wild bee pollinators she studies that included photographs of bees and pollen grains (enlarged under a microscope). For each species, she specified the proportion of different kinds of pollen they carried. In total, Rosalyn sampled 65 of the 300 wild bee species found in north-central Florida.

Rosalyn’s research is some of the first to help farmers understand how to attract more wild bees and to begin to understand the role of wild bees in pollen movement. Rosalyn hopes her work will stimulate further research on wild bees and their pollinating potential for our farms.

Blueberries, broccoli, squash, arugula,…… okra, peppers, tomatoes and eggplant; all locally grown and likely brought to you by wild bees.

Click here for more information about Rosalyn’s research.