Global warming threatens vital bees

Global warming could silence the summer buzz of the bumblebee forever unless urgent action is taken to save the insects, scientists have warned.

New evidence shows warmer temperatures are having a devastating effect on the heavyweight bees that play a vital role as wild pollinators.

Unlike other insects, such as butterflies, bumblebee are not migrating further north in search of cooler places to live, say experts.

Instead, their range areas are being squeezed and their populations dwindling.

The study of 67 species shows that, over the past 110 years, bumblebees have lost about 300km from the southern edge of their living space in Europe and North America.

Southern bee populations are disappearing as conditions become too warm for them, but there is no corresponding shift northwards. The northern boundary of the bees’ territory is not moving, the study shows.

A strong correlation was found between what was happening to the bees and climate change.

Lead scientist Jeremy Kerr, from the University of Ottawa in Canada, said: “Global warming has trapped bumblebees in a kind of climate vice. The result is dramatic losses of bumblebee species from the hottest areas across two continents.

“For species that evolved under cool conditions, like bumblebees, global warming might be the kind of threat that causes many of them to disappear for good.”

It may be necessary to help bumblebees establish new colonies further north by physically moving them, say the researchers.

So-called “assisted migration” is controversial among conservationists but gaining support in a warming world.

Bumblebees may be unusually vulnerable to climate change because, unlike many other insects with tropical origins, they evolved in the ‘Palearctic’ ecozone that encompasses Europe, northern Asia, and northern Africa. For this reason, they may not be so able to adapt to warmer temperatures, according to the experts whose findings are reported in the journal, Science.

British co-author Sheila Colla, from the University of York, said bumblebee species that once were quite common were now becoming rare. A third of North American species were in decline and some populations had crashed by more than 90%.

One, the rusty-patched bumblebee, was the fourth most common species in Southern Ontario, Canada, in the 1970s and 1980s. Prof Colla said she had only seen two of the insects in the last 10 years despite extensive searching.

She added: “One of the scariest parts of the work that I’ve done is just realising how quickly the situation is changing. The bumblebees that are in decline were doing fine 50 years ago.”

US colleague Leif Richardson, from the University of Vermont, said: “These findings could spell trouble for many plants, including some crops like blueberries that depend on bumblebees for pollination. Bumblebees are crucial to our natural ecosystems.”


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