JoAnne Skelly: Honey bee colony counts

The Bee Informed Partnership (www.beeinformed.org) is a national collaboration of leading agricultural science universities and research labs that examines and tries to better understand honey bee declines in the United States.

Their preliminary analysis of their “2019-2020 Honey Bee Colony Losses in the United States” (https://beeinformed.org/wp-content/uploads/2020/06/BIP_2019_2020_Losses_Abstract.pdf)

reports that over the past year they surveyed 3,377 beekeepers who managed 276,832 colonies (9.9 percent of estimated 2.81 million managed honey-producing colonies in U.S.

Twenty-two percent of managed honey bee colonies were lost from Oct. 1, 2019 to April 1, 2020, a decrease from the 37.7 percent loss the previous year. “This year’s estimate is the second lowest level of winter loss reported since the survey began in 2006-2007, and it directly follows the highest loss on record that occurred during the 2018-2019 winter.”

Backyard beekeepers (managing 50 or fewer colonies) lost more colonies (32.8 percent) than commercial (501 or more colonies) beekeepers (20.7 percent).

However, during the summer of 2019 (April 1, 2019 to Oct. 1, 2019) 32 percent of managed colonies were lost in the U.S., the highest ever reported by this survey. For April 1, 2018 to Oct. 1, 2018, there was only a 20 percent summer loss. Beeinformed.org attributes this to the high losses experienced by commercial beekeepers (33 percent) over the historic average of 22 percent commercial summer loss.

For the entire year April 1, 2019 to April 1, 2020, 43.7 percent of colonies were lost, the second highest loss rate since the survey started in 2010-2011. The 2018 loss was 40.4 percent. Colonies lost include not only those that died, but those that were combined with others.

Nevada, at 65.5 percent, had the greatest loss rate of states surveyed. However, there are only 15 beekeepers reporting on 119 colonies, a rather small sample size.

Why the lower winter loss, but a higher summer loss? I’m not sure. According to the USDA National Agricultural Statistics Service who has been collecting annual data on honey bee populations for decades, “Colony losses and gains occur seasonally. The greatest losses occur in the fall and winter...” Yet the opposite is true in the beeinformed.org report.

Habitat and forage quality are critical to keeping honey bee colonies healthy. Both are declining. Bees that have high nutrition sources available are less susceptible to diseases and other stress factors. Water quality and pollutants also can impact colony health as bees bring contaminants back to the hive after foraging.

We will have to watch next year’s report and see if there is a trend.

JoAnne Skelly is associate professor and Extension educator, Emerita at University of Nevada Cooperative Extension. She can be reached at skellyj@unce.unr.edu.