by John R. Platt / Scientific American
Long live the queens. A species of bumblebee that went extinct in its native Britain decades ago now has a second chance, as several short-haired bumblebees (Bombus subterraneus) were released June 3 in a restored habitat on the southeastern corner of England. This is the third phase in a multi-step effort to both bring back the species and teach the public about the value of the U.K.’s declining bees, some species of which have decreased by 80 percent or more in recent years.
Short-haired bumblebees, like many other British bee species, started losing habitat after World War II. Massive increases in industrial agriculture during the 1950s and ’60s wiped out 97 percent of England’s wildflowers, which the bees depended on. Increased pesticide use also took a deadly toll. Short-haired bumblebees were last seen in the U.K. in 1988 and were declared extinct in 2000. Most of the U.K.’s other bee species suffered great losses at this time as well.
Although the short-haired species had died out in the U.K., it wasn’t completely wiped off the face of the Earth. Some remain in other parts of Europe, where populations still face declines today. But amazingly a small fragment population descended from the British bees lives today in New Zealand. The bees were originally carried halfway around the globe more than a century ago to pollinate crops of red clover (Trifolium pratense), which itself had been transplanted to the Pacific island nation.
Scientists tried importing several New Zealand bumblebees in 2009. That didn’t work out too well. The first bees brought back to the U.K. didn’t adapt to the reversed seasons between the Southern and Northern hemispheres and died shortly after import. Scientists later examined the dead bees and found low levels of genetic diversity as well as evidence of inbreeding, effectively ending the hopes of sourcing further bees from New Zealand.
At this point the organizations behind the short-haired bumblebee partnership—Natural England, the Bumblebee Conservation Trust, Hymettus and the Royal Society for the Protection of Birds (RSPB)—turned in 2011 to Sweden, the only country with a robust and healthy population of the species. The team found several suitable locations there where some insects could be collected without weakening local populations. They applied to the Swedish government and received permission to take up to 100 queens a year for four years. Collection would take place after the queens had mated but before their underground hibernation period, so they would emerge in the U.K. and lay their eggs, hopefully establishing a new, self-sustaining population.
Meanwhile, hard work was underway in England to make sure the reintroduced bees would have a good place to take up residence. The RSPB runs a reserve in Dungeness, in the county of Kent, where the organizations have spent the past four years restoring wildflowers and moving livestock to new pastures to create a hospitable four-hectare habitat for incoming bees. Last year they collected their first batch of 89 queen bees from multiple locations in southern Sweden. The collected bees were checked for diseases and mites before being flown to England. After a period of quarantine the strongest 51 bees were released in May 2012.
Nikki Gammans, who is in charge of the project, told the BBC that the team hasn’t found any of last year’s bees yet because their favorite flower, white dead-nettle (Lamium album), has only just started to bloom. She reported the project hopes to do at least five total re-introductions, and “then the numbers will pick up and we’ll start to see them again.”
Even as they were awaiting the first year’s transplants to emerge from hibernation, the project’s volunteers returned to Sweden last month to collect 100 more queens, some of which were released this week. As Gammans wrote on the project’s blog last month, “We don’t expect to release 100, as many of the queens will have diseases and parasites which we do not want to introduce into the U.K. with the queens. So the healthy queens will be released and able to forage on white dead-nettle, comfrey, yellow flag iris and ground ivy. This year’s spring has been slow in coming so the red clover is a bit further behind, but over the next week we expect it to start flowering.”
No matter what happens next, the restored habitat has already proved itself. Two rare bee species that long since disappeared from the Dungeness region have now returned, and the reserve has served to raise public awareness in the U.K. about the plight of bees. That improved awareness could be coming right in time: Of the U.K.’s 25 native bees, two species (including the short-haired bumblebee) have gone extinct and seven more face declining populations. Hopefully the returned queens can help to reverse that trend.