Scientists Hopeful Cause Of CCD Identified

By Nancy K. Crevier

Colony Collapse Disorder (CCD) of honeybee colonies worldwide has been an issue since 2006, when the phenomenon was first identified. Characterized as “sudden colony death with a lack of adult bees in or in front of the dead-outs” by the Mid-Atlantic Apiculture Research and Extension (MAAREC) consortium in 2007, the MAAREC website added, “Honey and bee bread [pollen mixed with honey and present in the comb] are usually present and there is often evidence of recent brood rearing. The queen and a few young bees may remain, as well, and even though the hive is unprotected, other colonies do not rob the hive, nor are there signs of pest infestation. Bees disappear quickly, with some hives losing an entire squadron of worker bees in just a few days, unlike with a spring or fall ‘dwindling’ disease when hive populations slowly lose force. Because a pathogenic agent has not been identified as the source of the problem, CCD is not considered a disease.”

The disappearance of honeybees is of great concern. Honeybees are vital to crop pollination. As large numbers of bees succumb to the disorder, agricultural yields drop dramatically, creating the potential for a scarcity of many agricultural products.

Since the disorder was identified, there have been numerous hypotheses as to what was causing the mysterious disappearance of bee colonies. Early research at Washington State University and Penn State University suggested that high levels of pesticides contributed to weakening of colonies. Beekeepers and scientists around the world considered the loss of foraging grounds; exposure to pathogens; overexposure to improperly applied pesticides used by homeowners; viruses and parasites; single crop farming; contaminated feed supplements; or the intermingling of bees trucked by commercial beekeepers for crop pollination to all be possible contributing factors to CCD. Still, why CCD occurs has not been identified and the losses have continued, with 2010 being one of the worst since 2006 for commercial beekeepers.

A study released in October on PLoS One, an international, peer-reviewed online publication for scientific research, however, offers hope. The study, supported by various foundations concerned with the preservation of the health of honeybee colonies, the California Beekeepers Association, and the Montana Agriculture Experiment Station, in conjunction with the US Army Medical Research and Material Command, indicates findings that “implicate co-infection by IIV [invertebrate iridescent virus] and Nosema [ceranae] with honeybee colony decline, giving credence to older research pointing to IIV, interacting with Nosema and mites, as probable cause of bee losses in the USA, Europe, and Asia.”

According to the study, “Co-occurrence of these microbes consistently marked CCD in (1) bees from commercial apiaries sampled across the US in 2006-2007, (2) bees sequentially sampled as the disorder progressed in an observation hive colony in 2008, and (3) bees from a recurrence of CCD in Florida in 2009. The pathogen pairing was not observed in samples from colonies with no history of CCD….”

“We need to wait and see if others can confirm this study in other bee populations,” cautioned Connecticut Agricultural Experiment Station (CAES) assistant agricultural scientist Kimberly Stoner. “There have been other scientists over the years who have said ‘We know now why CCD occurs.’ That’s the way science works; we’ll need to be asking, does that answer continue to be valid?” she said.

While the new study is of interest, in Connecticut, said Ms Stoner, the CAES has not been able to confirm a specific case of CCD in the state. “It does seem that while smaller beekeepers in some parts of the country are getting CCD, it is a larger problem for the commercial beekeepers,” she said.

That does not mean that there are not die-offs in Connecticut, and because there have been, the CAES has been testing bees for the new Nosema microbe. Managing mites remains the greatest challenge faced by backyard beekeepers, she said, and keepers struggle constantly with ways to do so without endangering the hive. Treatment for Nosema ceranae holds the same challenges, said Ms Stoner.

Despite the difficulties of keeping a healthy colony of honeybees, Connecticut has actually seen an uptick in the number of new beekeepers registered in the state, according to CAES records. “There are more people interested, and that’s a phenomenon seen across the country. It’s great that people are concerned, and doing something,” Ms Stoner said. As of April of this year, the CAES had 679 beekeepers registered in Connecticut, up from 400 just three years ago.

The findings of this study mean that, if positively identified as the cause for CCD, management practices can be developed that will prevent further loss of honeybee colonies.