|熊蜂。圖片來源：William Warby。（CC BY 2.0）
歷史上，許多熊蜂物種都曾是常見物種，例如鏽補丁熊蜂（the rusty-patched bumblebee），是70年代至80年代初期南安大略第四常見的熊蜂。
Bumblebees are disappearing from North America and Europe due to climate change, according to a study by Canadian scientists published in the current issue of the journal “Science.”
“Pollinators are vital for food security and our economy, and widespread losses due to climate change will diminish both,” said Jeremy Kerr, lead researcher and professor at the University of Ottawa’s Department of Biology. “We need to figure out how we can improve the outlook for pollinators on continental scales. But the most important thing we can do is begin to take serious action to reduce the rate of climate change.”
Bumblebees are losing large sections of the southern portion of their ranges, but unlike other species, which are compensating by moving further north as the climate warms, bumblebees are not heading north. Instead, their range areas are shrinking, causing their populations to decline.
“The fact that at the northern edges of their ranges they are not moving north as the climate changes is actually really quite worrying.” says York University Professor Laurence Packer, an expert on bees and a co-author on the study.
For this study, researchers looked at museum records of 67 species of bumblebees in North America and Europe over the past 110 years.
Packer insists this kind of research would be impossible without access to vast collections of curated specimens in museums, as well as in labs such as his, the Packer Lab at York University, which holds hundreds of thousands of bees.
“Museums hold the basic biological information that tells us about the history of our impact on the world. They also contain the specimens that everything ultimately has to be compared to in order for identifications to be reliable,” he said.
“For the North American species that I work on, we know that about a third of them are in decline and in some cases this has been quite dramatically, more than 90 per cent,” said co-author York University environmental studies Professor Sheila Colla.
Historically, many species of bumblebees were quite common, including the Rusty-patched Bumblebee, which was the fourth most common species in southern Ontario in the ’70s and early ’80s, says Colla.
She has only seen two in 10 years despite extensive searching throughout the range of the Rusty-patched Bumblebee in Canada and the United States.
“That’s an indication that there’s something going on with some species of bumblebees throughout their large ranges even for species which historically had been doing quite well,” she said.
“One of the scariest parts of the work that I’ve done is just realizing how quickly the situation is changing,” said Colla. “The bumblebees that are in decline were doing fine 50 years ago. We’re talking about large changes in community composition of essential pollinators over just a few decades.”