Well-fed bees fight off parasite

Photo of Honey Bee Extension Specialist Ramesh Sagili

OSU researchers Inspecting bee hives. Cooperating commercial beekeepers and farmers are key to the statewide honey bee research program. Honey Bee Extension Specialist Ramesh Sagili.
Photo by Lynn Ketchum

Many Oregon beekeepers worry that preventive antibiotic treatments—the conventional way to combat two serious parasites—might be doing their bees more harm than good.

At high levels, Nosema ceranae and a related parasite disrupt protein metabolism, weaken immune systems, and cause malnourishment in the next generation of bees. A severe infestation can deplete the population of bees within a colony and may eventually cause it to collapse.

A study of European honey bees by Ramesh Sagili, a professor and honey bee Extension specialist, and Cameron Jack, a doctoral student in horticulture, found that well-nourished honey bees are better at fighting off the parasite.

The finding suggests that giving honey bees access to a greater quantity and variety of pollen—their only source of protein—could make them more resilient against parasites and other pests, and help to stem worrisome declines in bee populations.

Bee experts have worried for some time that “working” honey bees with access only to monocultural crops are not getting enough nourishment to thrive. Some are giving their bees a few weeks’ break from work and letting them forage in uncultivated areas.

“It’s a limited menu for them,” Sagili said. “It’s as if you or I were to eat nothing but chicken for two months. We think a polyfloral diet can definitely enhance bee nutrition by providing a variety of amino acids and other nutritional elements.”

Many beekeepers already feed their bees extra rations of protein in early spring when they’re rearing new brood, and in the fall when they’re preparing to overwinter. Sagili cautions that too much protein can also be harmful to bees. “It appears that there is an optimal balance of nutrients needed for best survival,” he said. “We now need to do some trials in the field to determine how much protein is optimal.”

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