Sunflower pollen good for bees; has medicinal and protective effects

Honey bees that were kept on a diet of sunflower pollen showed dramatically lower rates of infection by a specific pathogen. | Credit: Jonathan Giacomini, NC State University

It has been worrying at how fast the bee populations are declining all over the globe, but a new study offers a glimmer of hope. The study suggests that for promoting bee health and well-being, bees should be given more access to sunflowers. The study was published recently in the journal Scientific Reports.

The study was conducted by researchers at North Carolina State University and the University of Massachusetts Amherst. It shows that two different species of bees, who were fed a diet of sunflower pollen had drastically lower rates of infection by specific pathogens. on this sunflower diet also benefited Bumble bees , as they showed better colony health than bees fed on diets of other flower pollens.

The study has demonstrated that sunflower pollen led to a significant reduction in infection caused by a particular pathogen (Crithidia bombi) in bumble bees (Bombus impatiens). Sunflower pollen also acted as a protector for European honey bees (Apis mellifera) from a different pathogen (Nosema ceranae). These pathogens have been involved in slowing down bee colony growth rates and increasing bee death.

However, the study also suggests that the sunflower diet had a deleterious effect as honey bees on this diet had mortality rates that were roughly equivalent to that honey bees not fed a pollen diet and four times higher than honey bees who were fed buckwheat pollen. But this mortality effect was not seen in bumble bees.

Jonathan Giacomini, a Ph.D. student of applied ecology at NC State, who is also the corresponding author of a paper describing the research, said that  these bees already seem to have been adept at collecting sunflower pollen. Annually, nearly two million acres in the United States and 10 million acres in Europe are devoted to sunflowers, he explained, which makes sunflower pollen a ready and relevant food source for bees.

“We’ve tried other monofloral pollens, or pollens coming from one flower, but we seem to have hit the jackpot with sunflower pollen,” said co-senior author Rebecca Irwin, who is a professor of applied ecology at NC State. “None of the others we’ve studied have had this consistent positive effect on bumble bee health.”

Sunflower pollen is also quite low in protein and some amino acids, and therefore should not be considered as a standalone meal for bees, Irwin said. “But sunflower could be a good addition to a diverse wildflower population for bees,” she added, particularly generalists like bumble bees and honey bees.

The next step for NC State researchers would probably be to follow up on the study to find out whether other species of bees also show the positive effects of sunflower pollen and to determine the mechanism behind the mostly positive effects of sunflower pollen.

“We don’t know if sunflower pollen is helping the host bees fight off pathogens or if sunflower pollen does something to the pathogens,” Irwin said.

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