Honeybees Live Shorter Lives Than They Did 50 Years Ago

Honeybee life spans are dropping significantly. New research finds that their lives are 50% shorter today than they were a half-century ago.

The experiment was done in a lab, suggesting that the drop is due to something other than a change in environmental conditions.

“Honeybees are our most important pollinator and are the livelihood of many,” study lead author Anthony Nearman, a Ph.D. student in the Department of Entomology at the University of Maryland, tells Treehugger. “Researching honey bee health improves food security and allows us to help each other.”

Beekeepers are familiar with colony turnover because bees naturally age and die. But over the past decade, keepers in the U.S. have reported higher losses. That means they have to replace colonies more frequently to stay in business.

Curious about why this was happening, researchers looked at environmental stressors, parasites, nutrition, disease, and exposure to pesticides. 

But this study shows that the decline in life span may not be related to environmental conditions and instead genetics may be playing a role.

The findings were published in the journal Scientific Reports.

Studying the Past

Nearman first became aware of the diminishing life spans when working on a study about standardized protocols when caring for adult bees in a lab. The researchers repeated earlier research, collecting pupae from hives when they were close to emerging from their wax cells. The bees then completed their growth in an incubator, then were placed in cages as adults.

Nearman was studying the effects of supplementing the bees' diet with water when he noticed that no matter what the bees were fed, the median life span of the caged bees in the experiment was half that of caged bees in similar conditions in the 1970s. Then, they lived 34.3 days and now it was 17.7 days.

Intrigued by this change, Nearman reviewed lab studies published over the last 50 years.

“We sort of stumbled across the information that shows life spans have reduced while doing other research. I was writing a paper on a separate lab experiment when I noticed the bees in some of the papers I was referencing had much longer life spans than those in my experiment,” Nearman says.

“From there, I collected life span data on all the experiments I could find. Time was by far the strongest relationship to the reduction in life span, which really says something changed over time but we don't know what.”

They asked whether there was a correlation between the reduced life spans and honey production amounts, which there was. And they found that shorter life spans translate to more lost colonies.

Being in a lab is not the same as being in a colony, but the records suggested that colony bees had a similar life span as lab bees. Earlier studies showed that in the natural world, shorter honeybee lives corresponded to less time foraging and lower honey production. This study made a connection with colony turnover rates.

The team studied what a 50% reduction in life span would have on a honeybee operation; the losses were about 33%. This is similar to the average annual loss rate of 40% reported by keepers over the past 14 years.

“I'm not sure I'd say the findings are worrisome, as they just provide a possible explanation for what has already been happening,” Nearman says. “I would say the research is important because the results strongly suggest why more colonies have been lost over the years. They do not, however, suggest what is causing them to be lost.”