Research Finds Southwestern Michigan Abuzz With Native Bee Species

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Julianna Tuell and Rufus Isaacs found 166 native bee species in southwestern Michigan. (view larger image)

How many kinds of bees can the average person name? Most folks throw in the towel after spelling, quilting, honey and bumble. Julianna Tuell, postdoctoral researcher who works with MAES entomology scientist Rufus Isaacs, can name a far greater number, but even she was surprised at what she found in the blueberry fields of southwestern Michigan.

As is the case for all horticultural crops, pollination is a critical step in blueberry production. Typically, domesticated honeybees are put on the job. Growers rent hives that are placed near fields, giving the insects access to the flowers from which they gather nectar and spread pollen from blossom to blossom, fertilizing the year’s crop.

Blueberry growers have been concerned about the loss of wild honeybee colonies, which made them more dependent on rented colonies, and wanted to learn more about what other bees help pollinate their crop.

“They were concerned that honeybees weren’t interested in some cultivars, and they wanted to know what other options there were,” Tuell said.

To help answer the questions, she led a research team that collected, counted and categorized bees found in blueberry fields for 3 years on 15 southwestern Michigan farms. The scientists knew they would find native pollinators in the fields they studied because blueberries are native to North America. What they didn’t expect was the sheer number of bee species buzzing in the blueberry blossoms.

“We found 112 species during blueberry bloom, and 166 species overall,” Tuell said. “They aren’t all visiting blueberries, but at least half of them are contributing to pollination. There’s a really wide diversity of bees across the season, with some that provide pollination during bloom and are also active later in the season.”

The team found seven bee species that had never been found as far north as Michigan. These findings, published in the Annals of the Entomological Society of America, describe a more diverse ecosystem in managed blueberry fields than scientists had imagined and also mean that growers may have more pollination options than they thought.

“If you have a small field, you’re likely to have a large number of these native bees that can provide a portion of the pollination work,” Tuell said. “In large fields, growers are more dependent on honeybees because there isn’t the density of native bees to do the pollination.”

Native bees are active in the fields before, during and after blueberry bushes bloom. Farmers who time pesticide applications to avoid flowering and who don’t spray during the day or when it’s windy can help these bees survive and be around for the next season.

Tuell and Isaacs are using the research results to help growers time spray applications so natural pollinators aren’t affected.

“This research fits with the MSU Extension programming we’ve done to talk to blueberry growers about conservation strategies they might implement to make their fields more sustainable for native bees,” Isaacs said. “We call it the closing of the circle. We got the input from the growers, we did the research, and then the results go back to the growers through workshops and a bulletin to put the information into their hands.”

Besides the MAES, the research is funded by Project GREEEN (Generating Research and Extension to meet Economic and Environmental Needs), the plant industry initiative at MSU; MBG Marketing; and a C.S. Mott predoctoral fellowship in sustainable agriculture.

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