The lifespan of lab-raised bees today is half of what it was fifty years ago, according to a new study, which researchers say could be a sign that environmental stress is not the only factor affecting the world’s bee population.
The insects aren’t exactly known for their long lifespans, but beekeepers have seen disproportionate declines and high colony turnover rates for years, the researchers note, with Canadian beekeepers seeing average losses of nearly 45% of their bees last winter and some reporting losses. up to 90% of their bees.
Factors such as climate change and parasitic mites that target bees have been noted as contributors to the problem, but this new research shows that even with these confounding factors removed, a concerning pattern persists.
The study, published in early November in the peer-reviewed journal Scientific Reports, looked at the lifespan of bees kept in a controlled laboratory environment and found that their lifespan was 50% shorter than it is. was in the 1970s.
The researchers say this is the first study to show a marked decrease in bee lifespan independent of environmental stressors.
“We isolate bees from colony life just before they emerge as adults, so anything that reduces their lifespan happens before that point,” said Anthony Nearman, a holder of a doctorate. student in the Department of Entomology at the University of Maryland and lead author of the study, said in a press release. “This introduces the idea of a genetic component. If this hypothesis is correct, it also points to a possible solution. If we can isolate certain genetic factors, we may be able to breed for longer-lived bees.”
In order to isolate the bees from external factors, the researchers collected bee pupae from honey bee hives within 24 hours of the bees emerging from the individual honeycomb cells that they slowly developed from eggs into larvae into pupae.
The bees were placed in an incubator until they had finished developing, then were placed in special cages to keep them isolated.
Part of the study was originally to examine the diet – whether supplementing the bees’ diet with sugar water with plain water would create a diet closer to their natural conditions and a longer lifespan – but then Nearman realized that the lifespans of his bees were significantly shorter than those in similar lab experiments conducted decades ago, regardless of diet.
Caged honey bees that were offered water in addition to sugar water lived longer than those given only sugar water, two to five times longer.
Yet Nearman’s bees only lived about 17.7 days, down from 34.3 days in the 1970s.
As he delved deeper into other laboratory studies over the past 50 years, an unexpected trend emerged.
“When I plotted the lifetimes over time, I realized, wow, there’s actually this huge time effect going on,” Nearman said. “Standardized protocols for keeping honey bees in the lab weren’t really formalized until the 2000s, so you’d think the lifespan would be longer or unchanged, because we’re getting better at it, n “Right? Instead, we saw a doubling of the mortality rate.”
The researchers acknowledge that this is a laboratory study, so the results are not directly applicable to bees kept by beekeepers or in wild colonies, but previous studies have shown that there is a duration similar lifespan between beekeeper colonies and the lifespan of laboratory bees.
And a shorter lifespan impacts the ability of bees to produce honey. According to the statement, other studies have shown that there are lower honey yields and less foraging time in bees with shorter lifespans.
So taking that into account, what would it look like if this decline in lifespan seen in this lab study were true for the wider bee population? The researchers estimated this would mean a bee colony loss rate of around 33%, similar to the average loss rates reported by beekeepers over the past 14 years.
If bees have shorter lifespans regardless of other factors, that means there could be a genetic component, the researchers say, something that could help beekeepers in the future selectively breed more resilient bees. with longer life.
The researchers added that more research needs to be done to determine the full extent of these trends to see if they exist in the United States and other countries in order to identify contributing factors and improve lifespan. life of bees.
The study also noted that their data on caged bees living longer when offered water with sugar water should inform best practice for how bees in laboratory studies are raised. . This change, the researchers say, would not only ensure less stress for the bees, but better study results, because studies looking at bee health won’t be confounded by poor nutrition leaving them undernourished.
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