(CN) – Honeybees, indispensable powerhouses of American agriculture, often suffer high casualties in cold winters – a harsh fate that could be mitigated, according to research released Monday.
New findings, publishing in the Proceedings of the National Academy of Sciences, show that prairie sites with late-flowering prairie plants can provide honeybee colonies with enough pollen to survive rough winters when food is scarce.
Honeybees build up their stores of nectar and pollen during the summer to produce enough honey to keep the colony alive during the lean winter months. In addition to providing humans with honey and beeswax, the bees are also responsible for pollinating about one-third of the crops eaten by Americans, according to the Food and Drug Administration.
While the honeybee faces a number of threats such as Varroa mites and pesticides, scientists from Iowa State University and the University of Illinois looked at the other threat of devastating winter weather. They set about to discover if there were better land management practices beekeepers could use to keep colonies alive during the winter.
They set up honeybee hives next to soybean fields and monitored the bees over the course of a year. While the hives thrived during the summer, researchers discovered the bees quickly became malnourished by mid-October as their stores of honey had been used up before winter arrived.
“We saw a feast-or-famine kind of dynamic happening, where in the middle of the summer they were doing great. In fact, the hives in highly agricultural areas outcompeted hives in areas with less soybean production,” said Iowa State University entomology professor Amy Toth.
“But then they all just crashed and burned at the end of the year,” Toth said.
The scientists continued their experiments but moved some of the hives to prairie sites with late-flowering prairie plants. They discovered the hives rebounded with access to the new sources of food and were better prepared to survive the winter months.
Adam Dolezal, entomology professor at the University of Illinois, said the findings show a more in-depth view of how agriculture affects the health of honeybees.
“There’s been a lot of interest in how bees respond to agriculture,” he said. “There’s been work on pesticides and predictions that the highly monocultured agricultural landscapes have lost a lot of floral resources.”
Dolezal said some studies have found that the bees are better off in agricultural areas than in other environments.
“One hypothesis about that is that bees near agricultural zones have more access to flowering crops and weeds like clover than those near forests, which can have fewer floral resources,” he said.
To see if their results matched the conclusions of other studies, the research team took samples of pollen spilled by the bees to determine where it came from.
“Over the entire year, more than 60% of their pollen collection was from clover,” Dolezal said.
Matthew O’Neal, entomology professor from ISU, said he was surprised by the amount of clover honeybees found in fields full of corn and soybeans.
“Most of the field edges are mowed and can contain clover,” he said. “This little bit of land could be offering a significant source of food.”
As soybeans and clover bloom until late July in Iowa where the study was conducted, however, the bees’ food supply quickly disappeared by early August.
While the scientists found that prairies were helpful in maintaining the health of the beehives, they said they don’t recommend that beekeepers move their colonies there. Instead, they are investigating the use of 5- to 8-acre strips of reconstructed prairie alongside or within agricultural fields.
The researchers said the strips could better feed bees while also reducing erosion, but more testing is needed.