Parasite Tied to Global Bee Deaths

Published July 1, 2009

The sudden collapse of honeybee colonies around the world, a condition identified in 2004, is most likely caused by the parasite Nosema ceranae, not the human causes alleged by environmental activist groups, Spanish researchers have reported in Environmental Microbiology Reports, a journal of the Society for Applied Microbiology.

The researchers reached their conclusion after studying a large number of affected colonies and finding Nosema ceranae as the only common thread among them.

Since 2004, honeybee populations around the world have been succumbing to Colony Collapse Disorder, characterized by worker bees leaving their hives and dying off without returning. Loss rates have varied from 30 percent to 90 percent of regional colonies.

With no known cause to account for the die-offs, environmental activists blamed everything from pesticides to cell phones to global warming.

Single Common Link

In April, Dr. Mariano Higes, lead researcher at the Bee Pathology Laboratory in Spain, announced scientists had found the likely cause. The parasite Nosema ceranae was found in all the bee populations they studied.

Once that was discovered, the Spanish science team introduced fumagillin—an antibiotic—into the affected bee colonies. It cleared the parasite and halted colony collapse. Many colonies began to rebuild their numbers shortly thereafter.

Activist Theories Refuted

Higes had hypothesized pesticides were responsible for Colony Collapse Disorder, but his early research convinced him his hypothesis was wrong. For many of the affected colonies, no significant amount of pesticides could be found. The signatures of other asserted factors, such as cell phones and global warming, were likewise missing from many affected colonies.

While the study has brought promising results in Europe, North American colonies have yet to be studied or treated for Nosema ceranae. The European and North American parasites are somewhat different, though in Canada colonies treated with fumagillin have seen recoveries.

“Now that we know one strain of parasite that could be responsible, we can look for signs of infection and treat any infected colonies before the infection spreads,” Higes said in a media statement.

Media ‘Strangely Silent’

“This is the same thing that happened with frogs when amphibians were declining,” said Sterling Burnett, a senior fellow at the National Center for Policy Analysis. “The environmental activists were quick to point their finger at global warming, pesticides, and other human activities, when it turned out entirely natural factors were the cause.

“Of course, after the activists’ media allies sounded the alarm that pesticides and global warming are killing frogs and bees, they became strangely silent about reporting the exculpatory evidence that natural factors are to blame,” Burnett added. “The general public has no idea that humans in fact were not to blame, unless they subscribe to and read academic journals.”

E. Jay Donovan ([email protected]) writes from Tampa, Florida.

For more information …

“Honeybee colony collapse due to Nosema ceranae in professional apiaries,” Higes et al., Environmental Microbiology Reports, 2009: 1 (2):