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Raphael Thys
A breathtaking, new report is enough to prompt a cry of not the bees!
Bee populations are in rapid decline — even more so than previously realized. According to a study published Friday in the journal Cell Press, 25 percent of known bee species have disappeared from the public record since the 1990s.
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Bees are often vilified in pop culture for their terrible stings (remember My Girl?), but they actually serve a vital purpose in our ecosystem — pollinating everything from household flowers to essential crops.
Reports of bees' decline — alongside the decline of insects in general — are alarming. However, previous reports were largely region-centric or species-specific, focusing largely on honeybees from North America while ignoring bee populations elsewhere. This report demonstrates the global nature of this problem, suggesting a worldwide decline in wild bee populations.
How they did it — Researchers combed through bee data recorded by the Global Biodiversity Information Facility, which includes everything from museum specimens to smartphone photos shared by amateur naturalists.
It can be hard to put together an accurate description of bee species diversity from the hodgepodge of data in the repository.
"Figuring out which species are living where and how each population is doing using complex aggregated datasets can be very messy," explained first author Eduardo Zattara in a statement. Zattara is a biologist affiliated with the National University of Comahue in Argentina.
"We wanted to ask a simpler question: what species have been recorded, anywhere in the world, in a given period?"
The information they gathered from this simple question alarmed the researchers.
A bee pollinating a flower. The study found an alarming drop in global bee records since the 1990s.
What they found — The team formulated a hypothesis: If there really has been a global decline in bees, then we would see a drop in the total number of bee species being recorded in the scientific database.
The researchers confirmed there was indeed a drop in the number of bee species recordings in every continent except Oceania.
"These results suggest that the number of species among bee specimens collected worldwide is showing a sharp decline," the scientists write.
The study's two main findings:
- The total number of bee species has declined since the 1990s
- A 25 percent drop in recorded bee species between 2006-2015 compared to before the 1990s
"With citizen science and the ability to share data, records are going up exponentially, but the number of species reported in these records is going down," Zattara said.
This decline has rapidly intensified in the last two decades. The study notes an 8 percent decline in recorded bee species during the 2000s, followed by a sharp 22 to 26 percent reduction in the 2010s.
The research team can't definitely confirm global populations are declining — but it seems likely.
Michael Orr is a postdoctoral fellow and bee researcher at the Institute of Zoology, Chinese Academy of Sciences. He was not affiliated with this report. Orr tells Inverse bees do appear to be in decline, but future studies are needed to know the details.
"Regarding their conclusions, I suspect that some bees are in decline, especially true where humans have highly modified environments via agriculture for instance," Orr explains.
"Much more work is necessary to be sure and to know the extent and proximal drivers of any declines."
Loss of habitat, agricultural practices, biodiversity loss, and parasites are all theorized to drive bee loss.
Digging into the details — The suggested decline in bee species is not uniformly distributed across species, or across the globe.
The study notes reports of halictid bees — the second most common bee family — have declined by 17 percent, but the much rarer Melittidae family declined by as much as 41 percent.
According to the study, it's possible some rare bee species are declining more rapidly, while a smaller number of more common bee species are declining more gradually — or perhaps "even increasing in abundance."
There are significant limitations with the information in the global database. The greatest number of recordings are sourced from North America, and we see the steepest drop in bee reports from this continent since the 1990s.
But this may not paint an accurate picture. Rather than more species declining in North America, it could be a case of more people recording bee data.
"There are a lot of data for North America and a decent amount for Europe, but for the rest of the world, we know much less about where bees live when using public data, much less where they may be declining," Orr says.
'This [report] is more about decline in places with data, like North America and Europe, and we can't say for sure that this is also the case in Asia or much of Africa since there are so few data points."
Why these findings matter — Due to their significant role as pollinators of plant life, bees have an outsized impact on the global ecosystem.
The study notes the roughly 20,000 bee species are "are the most important group of insect pollinators" on Earth, contributing to the pollination of 85 percent of all cultivated crops.
As a result, the decline in global bee species spells trouble for the planet — and the survival of people.
"Insect decline is a hot topic now and bees are widely recognized as one of the most important pollinator groups," Orr says.
A figure from the study showing a decline in global bee recordings since the 1990s.
What's next — Due to shortcomings in the global database, we have far more data on bee species in North America and Europe, but not enough representing Africa and parts of Asia.
The researchers call for a national bee monitoring program in the U.S. to serve as a global model.
Orr agrees, arguing we need better funding and a comprehensive dataset to get a more accurate picture of bee species — and how fast they really are declining.
"Here in China, we're starting to build monitoring networks to keep better track of pollinators," Orr says. "But we're going to need a lot more funding for basic research to support these efforts if we want to know what's going on worldwide."
If the data does demonstrate a rapid decline in global bee species we must act quickly.
The study points out a few steps humans can take:
- Reversing destruction of bees' habitats
- Devising sustainability programs in cities and in agriculture
- Creating programs to "reflower our world"
"Something is happening to the bees, and something needs to be done," Zattara said.
"The next step is prodding policymakers into action while we still have time. The bees cannot wait."
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