bee biodiversity
May 12, 2014

‘Bee-odiversity’ Boosts Blueberry Crop Yields

Brett Smith for - Your Universe Online

Farmers rely on bees to pollinate their crops and increase yields, and a new study from entomologists at North Carolina State University has found the biodiversity of bees in a local ecosystem can have a significant impact on crop yield.

In the report, which was published in the journal PLOS ONE, the researchers showed that blueberry plants produce more seed and grow larger berries if they receive a more diverse range of bee species.

"We wanted to understand the functional role of diversity," said study author Hannah Burrack, an associate professor of entomology at NC State, in a recent statement. "And we found that there is a quantifiable benefit of having a lot of different types of bees pollinating a crop."

The study team said they chose to study blueberries because they are a major crop that is well understood. For the study, the entomologists selected two farms in 2010 and added a third farm in 2011.

After designating a study area, the researchers categorized their bees into five distinct groups: bumble bees, carpenter bees, honey bees, southeastern blueberry bees and a grouping of similar local bees dubbed ‘small native bees.’ When a bee from one of these groups visited a flower, it was marked with a small piece of thread designating which type of bee was observed. The researchers also caged flowers after a visitation to prevent multiple bees from visiting the same flower.

The study team discovered that for every group above one, farmers observed a raise of $311 worth of yield per acre. For instance, if two bee groups visited a crop field, the increase would be $311 per acre; for three bee groups, the increase would be $622 per acre.

"For North Carolina blueberries as a whole, we calculate the benefit of each group to be approximately $1.42 million worth of yield each year," Burrack said.

"We think the benefit stems from differences in behavior between bee groups, in part depending on the weather," added co-author David Tarpy, an associate professor of entomology at NC State.

The research team also tracked environmental conditions and found that southeastern blueberry bees actively pollinate regardless of inclement weather, while honey bees only do their best during warm, sunny days.

"This can make a big difference, since blueberries bloom in March and April in North Carolina," Burrack said. "That means the weather can swing from great to awful, as we saw this year."

While there has been some research focused on how surrounding crop fields with native flowering plants can affect crop yield – the study team said their next project will focus more on seeing how crop management strategies play a role in local bee diversity.

"We've shown that there is a real financial benefit associated with biodiversity," Burrack said. "The next step is to figure out how to foster that diversity in practical terms."