Populations of a bumblebee species living on remote Scottish islands have a lack of genetic diversity because of many generations of inbreeding, a situation that could put the region's bumblebees at risk of extinction, according to a new study by scientists from the University of Stirling in Scotland.

Penelope Whitehorn, a PhD student, presented the research at last week's annual meeting of the British Ecological Society.

The study found that moss carder bumblebees (Bombus muscorum) living on nine Hebridean islands off the west coast of Scotland are more susceptible to diseases carried by parasites than healthier populations on the mainland. Bumblebee expert Dave Goulson, a professor at Stirling, collected the data on mainland populations.

"We found that isolated island populations of the moss carder bumblebee with lower genetic diversity have an increased prevalence of the gut parasite Crithidia bombi," Whitehorn said in a prepared release. "Our study suggests that as bumblebee populations lose genetic diversity the impact of parasitism will increase, which may increase the extinction risk of threatened populations."

Other consequences of inbreeding on the Hebridean islands include an increased number of infertile males.

Whitehorn noted that the island populations of this species are a good indicator of what could happen to mainland bumblebees and honeybees—both important pollinators—as human development and climate change continue to fragment the insects' habitats.

According to the British Ecological Society, the once-common moss carder bumblebee is a coastal species that requires "linear habitats of tall, open grasslands close to seawalls and flood defenses." Officials added the species to the U.K. Biodiversity Action Plan in 2007.

Britain used to be home to 26 bumblebee species. Two have gone extinct, and six are considered endangered.

Photo: Bombus muscorum by Nigel Jones, via Flickr. Creative Commons licensed