Farm & Ranch News
Go Back
2011-03-31

Where have all the bumblebees gone?

By Kristina Chew Care2 Causes

The population of bumblebees has declined disastrously, according to a just-published study in the Proceedings of the National Academy of Science.
The decline in the bumblebee population is a separate issue from honeybee colony collapse disorder. The dramatic drop in population is especially being seen in domesticated bees that are useful in agriculture.
Bumblebees have long tongues; high-frequency buzzing, which helps release pollen from flowers; and a large body - all of which makes them excellent pollinators, according to USA Today as reported in the Tucson Citizen. Bees pollinate many native wildflowers and crops such as cranberries, blueberries, raspberries, squash, melons, and hothouse tomatoes, as per a study done at the University of Minnesota. In the United States, bumblebees pollinate some 15 percent of all crops grown in the nation, for a total of about $3 billion.
University of Illinois Professor of Entomology Sydney Cameron, who led the research, analyzed historical records going back to the late 1800s. He also repeated surveys of about 400 sites in the US to study the geographic distribution and genetic diversity of eight species of bumblebees.
As a result, researchers put together a database of more than 73,000 museum records, and compared these with a current sampling based on intensive national surveys of more than 16,000 specimens.
As noted in Science Daily, the researchers found that "the relative abundances of four of the eight species analyzed have declined by as much as 96 percent," while the geographic ranges of the species shrunk by 23 to 87 percent. Even more telling was that some of these changes have occurred in the last two decades. In the past 20 years, four species of bumblebees have all but shrunk in their populations to the point of being non-existent.
Declining populations of bumblebees lead to lower genetic diversity than in bumblebee species with healthy populations.
And, populations with lower genetic diversity are more likely to be infected with a deadly intracellular parasite that has affected some species in Europe, nosema bombi, a fungus has been suggested as a reason for the declining bee populations.
In an article about her study in the Jan. 6 edition of the News-Gazette, Prof. Cameron noted "People should be aware of the decline as a loss to nature and to the agricultural industry." The cause of these significant changes in this country's bumblebee population is open to speculation.
Some factors that Cameron notes are climate change, which appears to account for the declines in some bumble bee species in Europe; habitat loss; and the above-mentioned parasite, nosema bombi.
Cameron encourages people to "plant native species that can provide habitat for the big bees."So forget about those jokes about killer bees. It's really that something is killing the bumblebees.
Kristina Chew, PhD, is an Associate Professor of Classics at Saint Peter's College in New Jersey.

Courtesy Photo