Spring's pollen outburst a feast for bees
Spring’s pollen outburst may be a smorgasbord of suffering for humans with allergies, but it’s a protein-packed buffet for bees.
“They are having a great time out there,” said Jon Zawislak, Extension bee specialist for the University of Arkansas System Division of Agriculture. Beekeepers dub spring the “honey flow” or the “nectar flow.”
In central Arkansas, this pollen-powered period runs from about mid-April to mid-June. In row crop areas, the honey flow can go on all summer into fall because the fields are irrigated.
Why pollen is important
Bees cannot live on honey alone. “Honey is just a carbohydrate. It’s full of energy, but it’s very low in nutrition,” he said. Pollen is very rich in protein, amino acids, vitamins, lipids and other nutrients.
“In order to raise little baby bees, they have to have a protein source,” Zawislak said. “When the bees bring the pollen back, they store it in the combs mixed with a little bit of nectar. Beekeepers refer to this as ‘bee bread’.”
The bee bread doesn’t spoil, thanks to the lactobacteria in the bees’ digestive tracts.
“These bacteria produce lactic acid, and when the bees deposit nectar and pollen, the lactic acid builds up enough to make the pollen sterile,” he said. “It also prevents the nectar from fermenting while the bees turn it into honey.”
It takes several trips for the bees to fill a cell of the comb.
Carry that weight
A good, strong bee colony “can consume up to 100 pounds or more of pollen every year,” Zawislak said. As the bees visit flowers to collect the nectar, pollen grains stick to the bees. They are covered with special feathery, or “plumose,” hairs that hold on to rough textured or spiky pollen grains.
“Stiff bristles on the bees’ front legs allow them to comb the pollen out,” he said. “Bees then add a droplet of nectar from their honey stomach, or crop, to help it stick together.”
All of that pollen is transported home as pellets on the back legs of the bees. “One segment of the back legs is very flat and wide and scooped out like a spoon, with stiff bristles on the sides that form a ‘pollen basket.’”
“Bees practice floral fidelity, only visiting one species of flower on each trip from the hive,” Zawislak said. “A bee will go from apple blossom to apple blossom to apple blossom. On the next trip from the hive, the bee may decide to start visiting another plant species.”
This high fidelity ensures those plants are pollinated.
It takes one grain of pollen transferred to a flower stigma to produce a seed.
“If you look at a peach or cherry, both fruits with one big seed, pollination was easy. Just one pollen grain was transferred,” he said. For plants whose fruit contains many seeds, such as pumpkins or squash, “bees have to transfer hundreds of grains of pollen to produce all the seeds you see in your Jack O’ Lantern.”
As for that thick layer of pollen on everything this time of year, “It’s mainly from oak trees and other wind-pollinated plants,” Zawislak said. “These trees produce such a large volume of pollen because they have to toss it out into the wind and hope that enough of it lands on another compatible member of their species.
“These plants don’t produce nectar, and therefore rely on insects like honey bees to carry their pollen directly from flower to flower, which is a much more efficient way to get the job done,” he said.