Today I'd like to share with you this abstract of a recent study called Patterns of widespread decline in North American bumble bees. I edited it very slightly for clarity.
Bumble bees (Bombus) are vitally important pollinators of wild plants and agricultural crops worldwide. Fragmentary observations, however, have suggested population declines in several North American species. Despite rising concern over these observations in the United States, highlighted in a recent National Academy of Sciences report, a national assessment of the geographic scope and possible causal factors of bumble bee decline is lacking. Here, we report results of a 3-year interdisciplinary study of changing distributions, population genetic structure, and levels of pathogen infection in bumble bee populations across the United States. We compare current and historical distributions of eight species, compiling a database of >73,000 museum records for comparison with data from intensive nationwide surveys of >16,000 specimens.
We show that the relative abundances of four species have declined by up to 96% and that their surveyed geographic ranges have contracted by 23–87%, some within the last 20 years. We also show that declining populations have significantly higher infection levels of the microsporidian pathogen Nosema bombi and lower genetic diversity compared with co-occurring populations of the stable (nondeclining) species. Higher pathogen prevalence and reduced genetic diversity are, thus, realistic predictors of these alarming patterns of decline in North America, although cause and effect remain uncertain.
You may be wondering if you read that correctly. You did—the abundance of four of the species surveyed (Bombus occidentalis, B. pensylvanicus, B. affinis and B. terricola) have declined up to 96% and their ranges have contracted between 23 and 87%, and some of this took place in only the last 20 years.
CNN provided some additional details in Several bumblebee species in big trouble, U.S. study finds, which included these statements—
"They could potentially recover; some of them might. But we only studied eight. This could be the tip of the iceberg," [lead author] Sydney Cameron said.
Populations of some bumblebee and honeybee species have reported to be on the decline in North America and elsewhere for years, but until now, no evidence for large-scale range reductions of bumblebees had been collected, the authors wrote.
"The wide-scale reductions in range and abundance of North American species, which also confirm earlier studies of decline at local levels, are striking and cause for concern," the authors wrote.
The researchers counted bumblebees of eight species at 382 U.S. sites from 2007 to 2009 and compared the count to historical data that was collected from 1900 to 1999 and held by natural history museums across the country.
Cause for concern? Ya' think? The UK newspaper The Guardian also provided a number of details about the role of bumblebees as crucial pollinators of "wild plants and agricultural crops around the world, including tomatoes and berries." This bumblebee die-off revelation comes on the heels of some other Good News we received about viruses spreading among different pollinator species as reported by National Geographic—
Viruses that could play a role in the recent decline in honeybee colonies may be spreading through flower pollen, new research finds.
What's more, a number of wild pollinators, such as bumblebees, yellowjackets, and wasps, can also become infected with viruses in the pollen.
In hives affected by colony collapse disorder—a phenomenon that surfaced in U.S. honeybee colonies in 2006—worker bees vanish en masse. Some studies have suggested that Israeli acute paralysis virus (IAPV), first identified in 2002, may be contributing to the bees' demise.
Scientists knew that several viruses that infect honeybee colonies are transmitted from one bee to another within the hive through the bugs' saliva or from an infected queen to her eggs. But how the viruses moved from hive to hive was relatively unknown, said study leader Diana Cox-Foster, an entomologist at Pennsylvania State University.
"People suspected the viruses were being transmitted by bees visiting other colonies, but no one really knew there was evidence for the virus moving into other [insect] species," she said.
What's the upshot of this new research?
The research may suggest that as honeybees continue to decline, turning to other species for pollinating crops in the U.S. is not the best alternative.
Bee pollination accounts for $15 billion in added crop value, particularly for specialty crops such as almonds and other nuts, berries, fruits, and vegetables, according to the U.S. Department of Agriculture.
"People thought, The honeybees are disappearing, let's just use a different species" for pollinating plants, Cox-Foster said.
But the new research shows that the viruses can spread to other pollinators—"and they're likely exposed to the same stressors."
Well — that's not good! I first talked about die-offs among pollinators in Honeybees Are Still Dying. If you care about these issues, I recommend that you read it. Here's a quote—
Honeybees are dying of everything, just like AIDS sufferers with weakened immune systems. This points to environmental stress as the primary cause of the ongoing demise of A. mellifera. If we continue to degrade the environment, the stresses on bees will increase. This will further weaken the bees, which will result in more die-offs, which will increase the probability of extinction over time. Barring extinction, honeybee population declines could easily be severe enough to preclude industrial scale pollination for the various fruits and nuts we eat.
So, what's the meaning of it all? As Sydney Cameron said, this could be the tip of the iceberg. I think one thing is clear—this used to be a pretty nice planet to live on.
Add to that the White Nose Syndrome that is destroying entire bat colonies and it spells trouble.
Posted by: Remi | 01/05/2011 at 10:44 AM