Even on Farms, Bees Look For a Balanced Diet

Managed bees provide a critical service to crop growers, providing pollination as the bees search for nectar and pollen for their own needs. But many crops cannot provide for all the nutritional needs of bees. In those cases, bees begin searching for alternative sources of food.

This means that beekeepers and farmers may need to find ways to provide alternate food sources for their bees—while the bees will still be attracted to crop pollen and nectar, it won’t be an exclusive relationship. But, in turn, the bees will likely be healthier. To find out how managed honey bees (Apis mellifera) and bumble bees (Bombus impatiens) seek out a balanced diet, a group of researchers from Michigan State University looked at pollination and feeding behavior of bees around blueberry crops in that state.

The team, led by Kelsey Graham, Ph.D., a research associate at Michigan State’s Entomology Department at the time of the study and now at the U.S. Department of Agriculture’s Agricultural Research Service, determined what plants managed honey bees and bumble bees visited during high bush blueberry pollination season. They found that the most pollen collected was from plants other than blueberries, even though the blueberry bushes were the most abundant resources during the study. They also found that honey bee and bumble bee collection behavior varied a lot. Their results were published in July in Environmental Entomology.

In 2018 and 2019, the team collected pollen from bee colonies at 14 blueberry farms in Michigan. At each field, they used a 10-frame pollen trap immediately before the start of blueberry blooming (in early or mid-May) and collected samples through the end of the bloom (early to mid-June). At the same time, the researchers placed bumble bee colonies at the margin of each site, far enough away from the honey bee colonies to prevent raiding and robbing. The team used microscopes to identify the plant sources of the pollen.

Perhaps typical for them, bumble bees collected pollen from a wider range of plant species than did honey bees. Honey bees collected 21 pollen types in both 2018 and 2019. Bumble bees, however, collected 29 types in 2018 and 52 pollen types in 2019.

Source: entomologytoday.org

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