Summer Honeybee Losses Spiked Last Year, And Researchers Aren’t Sure Why

CREDIT: Bee Informed Partnership/ARS/USDA

Honeybees are still dying and disappearing in huge numbers in the U.S., and summertime losses of bees have surged, according to a new survey.

The report, published Wednesday by the Bee Informed Partnership, Apiary Inspectors of America, and the U.S. Department of Agriculture (USDA), surveyed more than 6,100 beekeepers across the country on their experiences with bee losses over the last year. The survey found that, in total, beekeepers lost 42.1 percent of their bees from April 2014 to April 2015, though some states saw higher losses — Wisconsin and Maine beekeepers, for instance, lost an average of about 60 percent of their bees over the last year.



The survey also had some other troubling findings: for the first time, bee colony losses in summer surpassed losses in winter. According to the survey, beekeepers reported summer losses of 27.4 percent — a surge compared to summer 2013’s losses of 19.8 percent. Winter losses for 2014-2015 were reported at 23.1 percent. According to the organizations involved in the research, losses of 18.7 percent are the maximum that beekeepers consider to be economically viable.

The spike in summer losses is “extremely troubling,” said Dennis vanEngelsdorp, co-author of the report and assistant professor of entomology at the University of Maryland.

“You expect colonies to die in the winter,” he told ThinkProgress, because cold temperatures and lack of flowers magnify bees’ stress. “You don’t expect them to die during the summer, which is paradise,” with its blooming flowers and abundance of pollen and nectar, he said.

VanEngelsdorp said he and his team aren’t sure yet what’s causing the high bee losses in the summer, but thinks poor nutrition might be contributing to it. When meadows — which can contain a vast array of flowers that bees can forage from — get plowed under and replaced by crops like soybeans and corn, it can affect the total nutrition the bees in the surrounding area get. This is a problem especially in the Midwest, vanEngelsdorp said.

Pesticides have also been pointed to as a potential cause of bee losses: neonicotinoids, a class of pesticides that are used widely in industrial agriculture, have been found in studies to damage bees’ brains and contribute to bee losses, though a recent USDA study concluded that neonics aren’t the main driver in colony losses. VanEngelsdorp said these two possible causes — pesticides and reduced nutrition — need to be studied further to determine whether or not they’re contributing to summer bee losses.

As for winter losses, vanEngelsdorp said he and his team think the varroa mite — tiny parasites that attach themselves to bees and suck out their circulatory fluid (the equivalent of blood) — are contributing. The mites can spread debilitating viruses to bees, including the deformed wing virus, which causes crumpled-up, useless wings in young bees.

The surge in summer losses will affect the way vanEngelsdorp and the rest of the researchers collect data on bee losses, he said. Typically, the team surveys beekeepers on how they managed their bees throughout the summer, and compare those responses to the beekeepers’ reported winter losses. Now, the team will need to look more closely at whether there are management practices that affect bee health in the summer.

Winter bee losses are slightly lower this year than they were in 2013, and, according to a press release about the survey, this is the second year in a row that winter losses have been “noticeably lower” than the nine-year average winter loss, which hovers at 28.7 percent.


CREDIT: Bee Informed Partnership/Apiary Inspectors of America/USDA

Still, vanEngelsdorp said it’s too soon to call this decrease in winter losses a trend — typically there needs to be at least three years of data to make a trend, he said. And though this drop in winter losses is positive, vanEngelsdorp said bee losses remain a serious concern.

“We went from horrible to bad,” he said. “So instead of losing one in three, we’re losing one in five.”

One thing the researchers haven’t seen in the last few years is signs of Colony Collapse Disorder — a phenomenon in which an entire hive of bees simply disappears. Jeff Pettis, co-author of the report and senior entomologist at USDA’s Agricultural Research Service Bee Research Laboratory, said that this, compared with the lower winter losses, does paint a more hopeful picture for bees, even though the summer losses are “troubling.”

“If beekeepers are going to meet the growing demand for pollination services, researchers need to find better answers to the host of stresses that lead to both winter and summer colony losses,” he said in a statement.

There has been some progress in the quest to figure out what’s harming honeybees and what needs to be done to protect them. President Obama signed an executive order last year creating a “federal strategy” on the health of honeybees and other pollinators. The USDA has invested $3 million into an initiative to boost honeybee numbers, and the Environmental Protection Agency announced last month that it’s “unlikely” to approve new outdoor uses of neonics.