Clumping Hives Can Reduce Hive Exposure to Pesticide Drift

According to a presentation at the 2024 Oregon Blueberry Conference, collaborative research is showing that aggregating hives 80 feet from a blueberry field can reduce honey bee hive exposure to pesticide drift and actually improve visitation to blueberry flowers. The findings go against traditional thought that bees need to be close to blueberry plants for pollination.

“A lot of growers have told us that the reason they placed their hives close to the field edges is because honey bees have low attraction to blueberry blossoms and weather can be marginal,” said Lisa Wasko DeVetter, an associate professor at Washington State University who leads the statewide small fruit horticulture program. “So, they’re trying to place their hives close to the crop to keep those bees from going elsewhere and keep them in their blueberry fields. But this really isn’t a data-driven practice.”

The research showed that under ideal conditions, or 55 degrees Fahrenheit or better and partial to full sun, honey bee visitation was actually improved when clumping hives and placing them 30 feet or greater away from the field edge in comparison to placing hives along the field edge. Under less than ideal conditions, bee visitation was similar whether hives were clumped or spread out at the end of rows.

Wasko DeVetter added that researchers didn’t find any difference in fruit set, berry size or seed count, which are indicators of pollination success, between the different placement strategies.

Researchers tested exposure to pesticide drift by placing silicone bands on the exterior of hives for the duration of bloom. The bands indicate when pesticide residue is present. Data showed that clumping hives reduced the levels of pesticide residue on the silicone bands.

“I want to point out that less residue doesn’t necessarily mean that we are going to have healthier bees,” she said. “We are measuring exterior pesticide concentrations, not the concentrations in the hive. But I think the take away is that distance and clumping might be a way to reduce (pesticide) exposure levels.”

Follow-up work showed that hives 80 feet or further from the field edge had significantly less pesticide residue than hives placed on the field edge. “Distance does seem to have an effect on reducing pesticide exposure to the exterior of those hives, Wasko DeVetter said. “We plan to work a little bit more within that 0- to 80-feet range and understand more about where that decay curve is.”

Wasko DeVetter noted that beekeepers prefer to clump hives rather than spread them out along a blueberry field, not only because of the reduced risk to pesticide exposure, but also for ease of management.

“From the beekeepers perspective, clumping, or aggregating, hives away from the field edge is much more efficient when it comes to deployment, management in the field, as well as removal,” Wasko DeVetter said.