In May 2009, NATURE Online asked Dennis van Engelsdorp, Pennsylvania’s acting state beekeeper, to comment on recent developments in the investigation into Colony Collapse Disorder. Here’s what he had to say. Check back later in May for a new report detailing colony losses in the U.S. for this past winter.

Q: A new study by Spanish researchers, published in the February ’09 edition of the Environmental Microbiology Reports journal, suggests that the fungus Nosema ceranae had been isolated as the cause of colony collapse in two affected beekeeper colonies in Spain. Is this fungus responsible for the Colony Collapse Disorder in the U.S.?

A: Absolutely not. We identified Nosema ceranae right from the beginning, and right away it was clear that Nosema ceranae could not, on its own, explain losses CCD losses in America. I don’t know about Spain, but there are [scientists and beekeepers] in Europe who have had high losses who are saying it’s not Nosema ceranae. What we do know is that the description of mortality described in these papers isn’t the same as Colony Collapse Disorder.   I think what’s happening is that CCD has caught people’s attention and so now everything that is a colony dying is “Colony Collapse Disorder.” And that’s not true. Colony Collapse Disorder is a very defined set of traits: a rapid loss of the adult population and no dead bees in the bee yard or in the bee colonies, and that’s certainly not what this research described.  We also know that in America, not all colonies have Nosema ceranae — colonies have a lot of viruses. So instead of having one or two viruses, they’ll have five or six viruses. We think they have something like the flu, and this flu is simply wiping through. The question is “Why suddenly are the bees so susceptible to all of these other pathogens — including Nosema ceranae but certainly not limited to Nosema ceranae.

What kind of reception is the study having with experts in Spain and Europe right now?

I work with the American group and we were at the first conference they put together to try to figure out [the causes of] Colony Collapse Disorder. We said, “well, we don’t think it’s this because half the colonies that have CCD don’t have any Nosema ceranae.” It just seems like it’s a distraction, and it’s unfortunate because surely there are people in Spain, and in America, who have a problem with Nosema ceranae, and it’s very treatable. And our recommendation is to treat for Nosema ceranae because it is another stress, and if you reduce stress you’re probably going to help your bees out. But this “Oh we found the solution” sort of dilutes the pressure that exists to make sure we have the funding and resources we need to solve this problem. And we really do need to solve this problem.

Are there any other recent developments regarding CCD in North America since we last spoke in June 2008?

We have discovered a condition we’re calling entombed pollen, where there are high levels of fungicide in some pollen that might be associated with mortality. Certainly most of the colonies that are dying are not dying from CCD. Most of them are dying from poor queen quality, which is something that’s surprising.

Could you explain what you mean by “poor queen quality”?

Every colony has a queen, and what we’re finding is that those queens are dying. And if a colony is unable to successfully replace them, or if the beekeeper is unable to identify that there’s a problem with the queen and buy a new queen to replace her, the colony dies.

Also, we’re finding that beekeepers tend to have better success keeping their colonies alive by keeping colonies as healthy as possible and by aggressively treating disease and keeping colonies well nourished.

An updated development happening in California relates to almonds. You may remember from your Silence of the Bees film that normally half the colonies in the country are needed to pollinate the almond crop.  Demand for almonds was expected to grow through 2012, and there was an expectation that there wouldn’t be enough bee colonies in the country to pollinate the almonds. With the drought in California, it appears that they are now plowing under some of the older almond orchards. That has taken some of the pressure off, and we aren’t seeing some of the pollinator shortages we expected.

In June 2008, NATURE checked in with Pennsylvania’s acting state beekeeper, Dennis van Engelsdorp, for an update on the latest details on the investigation into Colony Collapse Disorder.

Q: In Silence of the Bees, you are shown monitoring a quarantine of several collapsing hives from a Pennsylvania beekeeper. Is this monitoring ongoing?

A: All of the original colonies died by December [2007]. We now have eight new colonies at that site, and continue to sample once a week. We are watching disease growth curves, and this year we are sampling a more diverse range of bees.

What have you been hearing recently from other beekeepers?

The Apiary Inspectors of America (AIA) commissioned a survey to estimate colony losses across the country between September 2007 and 2008. The USDA-ARS Beltsville Honey Bee Lab conducted a similar survey of beekeepers pollinating almonds in California in February 2008. In total, nearly 19 percent of the country’s estimated 2.44 million colonies were surveyed. A total loss of 36 percent of managed honey bee colonies was recorded. This represents a 13.5 percent increase in total losses as compared to last year. The 327 operators surveyed lost nearly a third of their colonies, on average.

Are all of these losses attributable to CCD?

One of the symptoms of Colony Collapse Disorder is the complete absence of bees in dead colonies. The AIA survey data doesn’t differentiate between true CCD cases and other cases that share this symptom. However, the 37.5 percent of operations that reported having at least some of their colonies die with this symptom had a total colony loss of about 41 percent. This compares to the roughly 17 percent colony loss reported by beekeepers who didn’t have “the complete absence of bees.”

It’s important to keep in mind that at least 71 percent of all colony deaths can be attributed non-CCD causes. This really emphasizes the need for further research into pollinator health in general — not just CCD.

Last October NATURE Online reported the research breakthrough that Israeli Acute Paralysis Virus (IAPV) had been found in over 96 percent of bees from CCD-affected hives. This doesn’t mean that IAPV is the only — or even the main — culprit behind CCD, however. Could you tell us about what has been learned since that time about the role IAPV may play in CCD?

Research published in September 2007 showed that among known pathogens, IAPV was the most consistent indicator of CCD. And it was found in at least 19 states. However, Kashmir Bee Virus (KBV), and two microscopic spore parasites — Nosema apis and Nosema ceranae — were also found to be indicators of CCD. Also, no clear cause and effect relationship was found between IAPV and CCD. Not all colonies with IAPV die off, and it’s possible that other stress factors are needed to make IAPV deadly to bee colonies.

Besides IAPV, how has the investigation evolved since last fall in regard to the other potential causes, such as pesticides and varroa mites? What kinds of studies are going on now?

We are in the final stages of receiving individual colony analysis on pathogens and pesticides from the original data set and are analyzing and writing up these results. IAPV cannot explain CCD losses by itself, and other factors are being examined.

Last year we monitored 280 colonies as they moved up and down the East Coast. We are processing this data, to test some predictors of disease based on last year’s studies.

We’ve also discovered some new conditions that seem to be affecting survivorship, and we are trying to figure out what exactly these are.

The effort to look at the impacts of pesticides has reveled a surprisingly large number of different pesticides in pollen, wax, and the bees themselves — and some of these at high levels. These pesticides are used in agriculture and sometimes by the beekeepers themselves. We have initiated investigations into the sub-lethal effects of pesticides, potential synergistic effects of multiple pesticides, the impact of pesticides in combination with other stress factors — like IAPV or varroa mites — and the use of irradiation to mitigate pesticides residues.

In many media reports on CCD, there is a feeling of inevitability that suggests that beekeepers are just waiting for CCD to decimate their hives. What can beekeepers do now?

Beekeepers are advised to practice good hygiene with their hives. For example, they shouldn’t combine weak colonies with stronger ones or exchange colony hardware. This kind of contact can spread diseases. Beekeepers should irradiate “dead-out” equipment — or at least store it for as long as possible — before reusing it with other colonies.

There are also products that beekeepers can use to control other colony stresses, like varroa mites and other parasites. And because nutrition is a concern, beekeepers should make sure their colonies are well fed, especially with a protein supplement.

Many of our viewers are interested in doing whatever they can to help. What would you tell them?

There are many things people can do: become a beekeeper, support beekeepers by buying local honey, plant a pollinator garden, and use less pesticides.

For more information, see “How can you help the bees?“