With no clear cause, after two decades beekeepers across North America report losing up to 90 percent of their hives.
Although the alarming losses of the 2006-7 season have not repeated, since then, experts consistently track higher than normal winter losses among honeybee colonies, according to the U.S. Environmental Protection Agency (EPA).
A survey by the University of Maryland University of Maryland found 40% of US honeybee colonies died between April 2018 and April 2019.
While most Americans associate the insects with one of humankind’s oldest sweet treats - honey - they might not realize honeybees are actually an invasive species that can end up competing for resources with indigenous “pollinators” such as bumblebees.
“Worldwide, there are over 20,000 species of bees,” said Cynthia Maples, the lead beekeeper and apiarist at Zoo Knoxville. “About 265 of those are bumble bees. In North America, there are 46 bumblebee species. In the southeast, we have about 15 bumble species with at least six of those in decline.”
Maples explained all bees are part of the order Hymenoptera, which also includes ants and wasps.
“Native pollinators would classify as those species naturally occurring in a particular area, not introduced. Honeybees are technically an invasive species to North America. They were brought over from Europe by humans,” she said.
“In the past few years the narrative has made a switch from keeping honeybees to help native pollinators to the realization that honeybees may be stealing resources from native pollinators,” she continued. “Honeybees are still very important as agricultural pollinators, but protecting native pollinators is also very important.”
While Maples doesn’t know if local bee populations are on the ropes, she said the Xerces Society for Invertebrate Conservation (an international nonprofit group) has formed regional “community science groups” as part of a widespread effort to track bumblebee species.
“It’s really hard to say specifically if there has been a decline in local insect populations since insects are very difficult to track,” she said. “I took part in the training for the southeast bumble bee atlas earlier this year. The hope is that this atlas will give scientists a better idea of population numbers.”
It’s important that scientists understand any threats to the health of the world’s bee populations as the insects are vital to humankind’s ability to survive.
Bees — both domesticated and wild — are responsible for pollinating 71 of the 100 crop species that provide 90 percent of the global food supply, according to experts from greentumble.
Without bees, for instance, there would be no apples, avocados, onions, cucumbers, oranges or almonds.
“Pollination is defined as the act of transferring pollen grains from the male anther of a flower to the female stigma,” Maples explained. “When bees go from flower to flower collecting pollen, they are also depositing pollen grains onto the flowers, thus pollinating them. Not all plants rely on insects to reproduce; for example, some are wind pollinated.”
“The bees benefit because nectar and pollen are their food source. Nectar is an energy source and pollen is a protein source for them. Many agricultural plants are pollinated by bees, hence their importance for us. Roughly one in three bites of food are pollinated by bees, plus another 25 percent of animal feed stuffs. Almonds are 100 percent honeybee pollinated.”
It’s not entirely clear why bee populations appear to be shrinking, but Maples said there’s no shortage of possible explanations.
“As with many species in decline, there are a number of reasons behind it,” she said. “Habitat loss is a big one. Our culture has taught us that we should have pristine lawns without ‘weeds,’ but letting your yard — even in part — grow wild would be a huge step in creating more resources for pollinators. Dandelions and clover can be a haven for pollinators.”
Poisons used to control unwanted animals and insects are another factor.
“Pesticides have a huge impact as well, especially though containing neonicotinoids,” she said. “Pesticides rarely distinguish between beneficial invertebrates and those that cause harm.”
This summer’s historic heatwaves in the Northern Hemisphere may also be playing a role, but Maples cautioned that it’s too early to know for certain what the impact is.
“Climate change may also be playing a role,” she explained. “It isn’t clear if bumblebees are adapting to changing temperatures within their normal ranges.”
Those interested in helping researchers to track bee populations can go to Xerces and learn about taking part in one of the organization’s community science groups.