Keeping Honey Bees Healthy in SC and NC: The Importance of Diverse Flower Planting

It’s springtime in the Carolina region, and bees are emerging to feast on flowering fields – acres upon acres of cultivated almonds, oranges and other fruits and nuts that bloom all at once for just a few weeks. Farmers raise these lucrative crops in monoculture fields, each planted with neat, straight rows of a single type of crop.

Bees’ main goal in life is to collect pollen and nectar to feed their young. But as bees forage, they are exposed to bacteria, fungi and viruses, which can spread among bees via flowers.

Honey bees really like mass-bloom events.

For humans, social interaction or touching shared doorknobs in highly trafficked office buildings can spread viruses and other pathogens. Bee scientists joke that, for bees, flowers are the dirty office doorknobs.

Artificially providing animals with food can affect the spread of diseases in two ways: It can dilute them or amplify them. When a monoculture crop blooms in a landscape that’s otherwise void of food for bees, it offers an attractive pulse of pollen and nectar. When bees cluster together, disease may be more likely to spread between infected and non-infected bees. But that’s not automatic. Flowers can feed bees and prop up their immune systems, making them less vulnerable to disease. Disease spread is also hampered if many different bee species are attracted to flowers, because not all bee species harbor all parasite species.

As the mix of bees in the community becomes more diverse, parasites are more likely to encounter unsuitable hosts, breaking up the the chain of transmission. Mass blooms could help bees under the right circumstances

Bee disease is a leading cause of bee decline.

Honey bees really like mass-bloom events. Places with historic legacies of growing flowers host more abundant bee populations than sites where flowers had been planted only recently. Even at farm sites with hedgerows, bees were consistently found foraging on sunflowers at higher numbers than on hedgerows.

But apparently, bee gluttony comes with a cost. Increases in bee abundance were subsequently associated with higher rates of parasitism. Of the individuals we screened, almost half had at least one parasite, and about a third had multiple parasites. The more bees in flower fields, the more parasites. Flower blooms were aggregating bees, which in turn was amplifying disease risk.

We also found something encouraging: When bees had access to hedgerows that contained many different kinds of flowers, they had lower rates of parasite infections. This suggests that in the presence of many flower types, bees disperse and spread across resources, reducing each individual bee’s likelihood of encountering an infected individual. Flower diversity may also provide immunity benefits to bees through other mechanisms, perhaps by enhancing nutrition.

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Credit: The Conversation via Reuters Connect

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