Sunflower pollen protects bees from disease, study finds

Sept. 26 (UPI) -- Great access to sunflowers and their pollen could help keep vulnerable bee populations pathogen-free.

In experiments carried out by researchers at North Carolina State University and the University of Massachusetts, Amherst, scientists found bees fed sunflower pollen enjoyed lower rates of infection by two common pathogens.

Bumble bees, Bombus impatiens, on the sunflower pollen diet were less likely to test positive for, Crithidia bombi, a common bumble bee parasite. European honey bees, Apis mellifera, fed sunflower pollen, were less likely to test positive for the parasite Nosema ceranae.

Both pathogens have been linked with slower colony growth and greater rates of mortality among infected bee populations.

Bumble bees fed sunflower pollen enjoyed a lower mortality rate than control groups. Colonies of sunflower pollen-feeding bumble bees showed signs of improved health and growth rates.

"We've tried other monofloral pollens, or pollens coming from one flower, but we seem to have hit the jackpot with sunflower pollen," Rebecca Irwin, a professor of applied ecology at NC State, said in a news release. "None of the others we've studied have had this consistent positive effect on bumble bee health."

The benefits for honey bees weren't as pronounced. The bees perished at the same rates as those fed a non-pollen diet. They were also four times more likely to die than bees fed buckwheat pollen.

While sunflower pollen provides medicinal and protective benefits, it is low in protein and some amino acids, which may explain why honey bees experienced increased mortality. Sunflowers shouldn't be used as the main source of a honey bee's diet, but as an addendum.

"Sunflower could be a good addition to a diverse wildflower population for bees," Irwin said.

Honey bees and bumble bees are generalists. They do best when they have access to a diversity of flowers. Unfortunately, industrial monoculture farming has stifled plant diversity, harming bee health.

Scientists published the results of the bee diet experiments this week in the journal Scientific Reports.

In future tests, Irwin and her colleagues plan to measure the effects of sunflower pollen on other species of bees.