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Jan 052011

By Barbara Kessler
Green Right Now

Wait! Don’t squash that baby bumblebee. You could be hurting a struggling species. Several varieties of bumblebees, which help pollinate major fruit and veggie crops, are in serious decline in the U.S., according to just published research.

A survey of bumblebees undertaken by University of Illinois-Urbana/Champaign entomologist Sydney Cameron, shows that the nation has simply “lost a lot of bees” in recent decades.

“There are whole regions where we can’t find them any more,” Cameron told Science magazine online.

Bumblebees are losing range, and some populations are declining (Photo: Johanna James-Heinz)

Cameron’s research, published this week in Proceedings of the National Academy of Sciences,   compared current populations of bumblebees — 16,788 bees collected recently from across 40 states — with species preserved in museums to determine which varieties were diminishing.

He and a team of colleague researchers found that some species that used to be common have become rare, such as the Bombus occidentalis, which accounted for about 20 percent of the museum bees, but only1 percent of the bees recently collected.

The team found three other subspecies that had dramatically declined, and had lost large swaths of habitat. Four other subspecies, however, had shown population fluctuations but were not consistently declining.

The reason for the losses is still in question. The declining populations of bees had a higher infection rate from a pathogen called Nosema bombi. But whether that infection was the underlying cause of the bees’ decline or a symptom could not be determined.

Researchers studying the recent honeybee decline have confronted a similar dilemma. Many honeybees are found to be infected with a virus; but it is not known if this is a symptom, trigger or cause of the mass die offs.

Recent hypotheses about the death of honeybees in the U.S. increasingly mention pesticides as a potential underlying cause.

One explanation for honeybee decline; could the same thing bee fumbling up bumblebees?

In December, new information surfaced that buttresses theories pesticides are causing major U.S. honeybee losses. The evidence came from a leaked document showing that the EPA knew the pesticide clothianidin could harm honeybees when it approved it for use on crops years ago.

The document, leaked to a Colorado beekeeper, showed that the EPA had ignored warnings that “nontarget insects” like honeybees could be harmed by the pesticide clothianidin, which received conditional approval from the U.S. EPA in 2003.

Researchers have suspected that this class of pesticide, which is taken up systemically by crop plants (clothianidin, made by Bayer CropScience, was developed to protect corn, canola and other crops from pests), can be lethal to bees.

Some researchers have been calling for a ban of the compound since Germany and France banned clothianidin in 2008. These scientists (read about one of them here) are convinced that such neurotoxin pesticides, which came into use in the last decade, are behind Colony Collapse Disorder (CCD), which began killing honey bees in large numbers in the last decade.

CCD is characterized by the bees’ disorientation, followed by their sudden abandonment of the hive — as if affected by a neuro-impairment — and their mass death.

The leaked document details current EPA concerns about the potential harm to honeybees as it responds the Bayer’s request to expand the use of the pesticide to mustard and cotton crops:

Clothianidin’s major risk concern is to nontarget insects (that is, honey bees). Clothianidin is a neonicotinoid insecticide that is both persistent and systemic. Acute toxicity studies to honey bees show that clothianidin is highly toxic on both a contact and an oral basis. Although EFED does not conduct RQ based risk assessments on non-target insects, information from standard tests and field studies, as well as incident reports involving other neonicotinoids insecticides (e.g., imidacloprid) suggest the potential for long-term toxic risk to honey bees and other beneficial insects.

The document goes on to say that an earlier study of the effects on bees was “deficient” and that another study is warranted “to evaluate the effects of clothianidin on bees through contaminated pollen and nectar. Exposure through contaminated pollen and nectar and potential toxic effects therefore remain an uncertainty for pollinators.”

The lengthy EPA response memo also considers the potential harm to birds that might eat clothianidin-coated seeds and the aquatic life that could be affected by runoff.

Some crops, like almonds, rely almost exclusively on pollination by honeybees. Bumblebees help pollinate tomatoes, pumpkins and other produce.

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