Flowers Impact Bee Foraging in Blueberries

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Just in time for Pollinator Week, I wanted to share another update on our work on pollinators in blueberries. While grad student Shelley Rogers and technician Kevin Littlejohn were collecting data on which bees are the “best” blueberry pollinators and whether bee diversity influences pollination, they observed some interesting differences in foraging patterns between some varieties of rabbiteye blueberries.

Rabbiteye blueberries represent about 20% of NC acreage and flower and fruit later in the growing season than southern highbush, which are the majority of blueberries grown in NC.

A popular rabbiteye variety, Premier, can have abnormally shaped flowers with shorten corollas as compared to other rabbiteye varieties.

Typical rabbiteye blueberry flowers (left) and malformed Premier flowers (right). Photos: Shelley Rogers

Typical rabbiteye blueberry flowers (left) and malformed Premier flowers (right). Photos: Shelley Rogers

Interestingly, it appeared that more honey bees were present at Premier flowers than at other rabbiteye varieties. Shelley and Kevin then conducted time observations of individual plants of Premier and non Premier varieties over two years to determine if this observation was correct.

They found that, on average, 19 honey bees visited Premier plants in 15 minutes, while only 5 honey bees visited other varieties in the same time period. In addition, only 1 wild bee visited Premier plants in 15 minutes, but 10 wild bees visited visited other varieties.

We suspect that the malformation of Premier flowers may act similarly to carpenter bee slits on intact flowers, and that honey bees are taking advantage of easier access to nectaries.

It is unclear if these differences in foraging activity are problematic. Rabbiteye blueberries do benefit from cross pollination between varieties, so it is possible that if honey bees only forage on Premier flowers, cross pollination may be reduced. However, it is also possible that honey bees are able and willing to visit more Premier flowers, perhaps making them better single-visit pollinators.

We will be sharing the results of this project as a poster at the North American Blueberry Research and Extension Workers Conference in Atlantic City next week.

More information

View a copy of our poster.

Blueberry pollination postsEntomology Portal