By Adam Vaughan/London

Climate change caused by emissions from cars, factories and power plants is squeezing the habitats suitable for bumblebees to live in across Europe and North America, scientists have discovered.
As temperatures have risen over the past 110 years, the bees are being killed off by increased heat in their southern habitats. But to the surprise of researchers, they are failing to move north to cooler climes, unlike other species.
The finding matters because of the vital job the bees do as pollinators for wild flowers and other plants. Scientists consider the bees to be  a “keystone species” crucial to the health of the ecological communities they are part of. If they disappear there will be knock on effects for a wide range of other species.
They are also critical for agriculture. The bumblebees are active in spring, summer and autumn, and help to pollinate crops such as blueberries, clover and cherries. Tomatoes in particular rely on bumblebees because they, unlike honeybees, perform buzz pollination, where their vibrations on the fruit shakes loose its pollen.
The research is the first time that scientists have analysed what is happening to bees’ geographical ranges under climate change, and comes on top of substantial declines in bumblebees over the past few decades ascribed to a cocktail of factors including habitat loss, pesticide use and parasites.
Jeremy Kerr, a professor of biology at the University of Ottawa and lead author of the new research, said that given how other species have responded to warmer temperatures by moving northward, his team was “shocked” bees had not done the same.
“We thought bumblebees would do that. Our results show very clearly that generally is not what they’re doing at all, they’re not expanding their range, unlike butterflies.” The result, his study says, is that the bees’ range is being compressed across continents.
Bumblebees evolved under a cool climate, unlike butterflies which have a common ancestor in the tropics, and are relatively intolerant of heat. Extreme temperatures of 43C (109F) will kill them outright, while prolonged heatwaves can dry up the food sources they rely on.
The study, published in the journal Science yesterday, examined natural history records dating back 110 years - including around 423,000 observations for 67 European and North American bumblebee species.
The team checked to see if the bees’ movements were affected by land use or pesticide use, but found they were not. The trends were consistent in places where, as Kerr put it, “there is lots of natural habitat and in places where there is nothing but corn fields” and consistent across continents.
Kerr said he did not know why the bees are failing to move. “There is a mystery here that we need to solve quickly,” he said.
Dave Goulson, professor of biology and bee expert at the University of Sussex, who was not involved in the study, said: “Maybe the habitat further north is not suitable for them, perhaps because the plants they need haven’t themselves moved north. I’m just speculating, because we don’t really know.” — Guardian News and Media