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Sunday, September 9, 2007

On The Fate Of The Bees, Or, One Problem Down, One To Go

The survival of the honeybee, perhaps the world’s largest matriarchy, has been a matter of real concern since the announcement of Colony Collapse Disorder earlier this year.

As we discussed in an April story (On Bees, Or, An Apple A Day May Be A Thing Of The Past), the pathogenic loading seen in the few recovered bees was so dramatic and of such a great variety that it was assumed there was more than one cause for the troubles.

Recent news reports from Spain have suggested the answer may be at hand…but apparently nothing in life is that easy. We’ll talk more about the bad news-and the good-as we go on.

First the bad news: There do appear to be two different problems the bees are facing, and unfortunately we can only resolve one at the moment.

One of the most common of bee diseases is nosema, caused by a parasitic infestation (Nosema Apis, for those keeping score at home) of the bee’s gut. It is easily treated with the antibiotic Fumigilin.

The news from Spain concerns reports of another similar bee parasite, Nosema Ceranae (a third parasite of this class, Nosema Bombi, is also known to infest bees), which appears to have made the jump from infesting Asiatic honeybees (Apis Cerana) to the far more numerous and, for agriculture, more important Western honeybee (Apis Mellifera). Thanks to the work of Dr. Mariano Higes we know that the infestation is widespread in Europe, and may be present in the US.

We first became aware that N. Ceranae was a problem for Western bees because of the fact that both Western and Asiatic bees are found in Vietnam-and in 2005, it was discovered that both had the same infestation. (A quick note-we have three members of the faculty of the School of Biological Sciences, Queen’s University, Belfast, to thank for the development of a rapid-sequencing DNA screening method that made this discovery possible: Julia Klee, Andrea Besana, and Robert J Paxton, whose story we referenced above.) Further confirmation was obtained when an imported colony of Western bees was found to be infested with N. Ceranae in Taiwan.

Klee and Besana’s work can be seen here. It contains an excellent discussion of the spread of N. Ceranae, “host jump”, the technical details of bee analysis, and a thorough description of how you too can sequence DNA at home in your spare time.

They also point out that the presence of N. Ceranae in collapsed European colonies does not automatically prove it’s causing CCD-it could well be coincindental.

So we now find ourselves facing a few questions:

--Are we looking at the source of Colony Collapse Disorder (CCD)?

--Is this infestation suddenly spreading because of opportunities created by the agent that causes CCD?

--If N. Ceranae is not the cause of CCD, what effect does this infestation have on the bees?

It does not appear that N. Ceranae is the cause of CCD, according to an analysis of Dr. Higes’ work published at North Carolina State University’s website. As we had discussed in April, the sheer number and variety of pathogens found makes it unlikely that one single agent was solely responsible. At the time the thinking was that a new infection or infestation was causing immunosupression through stress, allowing the variety of other opportunistic pathogens to take hold. To quote from the analysis:

"Initial studies on bee colonies experiencing the die offs has revealed a large number of disease organisms present in the dying colonies, with most being "stress related" diseases and without any one disease being supported as the "culprit" underlying the deaths. The magnitude of detected infectious agents in the adult bees suggests some type of immunosuppression. Case studies and questionnaires related to management practices and environmental factors have identified a few common factors shared by those beekeepers experiencing the CCD; but no common environmental agents or chemicals were easily identified by these surveys. The search for underlying causes has been narrowed by the preliminary studies, but several questions remain to be answered."

As to the other two questions: is N. Ceranae spreading opportunistically because of the agent that causes CCD? We don’t yet know.

What will be the effect of the spread of N. Ceranae in Western honeybees? That is a big unknown. It appears it can be easily treated, but what is unknown is what might happen if treatments are only applied irregularly. The possibility exists of “acclimation” to our current treatments, and that is but one of many possible implications that will have to be explored-the sooner the better.

There is guarded success in the effort to deal with CCD as well.

Details are literally coming in as we speak, but on September 6th Science Daily broke the story that a US based scientific consortium had discovered a connection between the presence of the Israeli Acute Paralysis Virus (IAPV) and Colony Collapse Disorder in numerous samples collected from a variety of media-including actual dead bees and royal jelly-collected from infected colonies and non-infected colonies.

The team was able to use DNA sequencing as a tool to determine associations between many pathogenic “possibilities” such as bacteria, viruses, and fungi, which is why the work could be completed so quickly. As a result of the sequencing work, it was determined that IAPV was found in all the collapsed colonies-and none of the non-infected ones.

Does this mean we have a culprit?
Not so fast, friends.

As with N. Ceranae, association does not automatically mean causation has been established, and we are reminded to be cautious by the Mid Atlantic Apiculture Research and Extension Consortium (MAAREC) in a September 7th statement. (The statement also suggests imported Australian bees may be responsible for the infection.)

In fact, we are specifically told IAPV is likely a marker, or working with other opportunistic pathogens, and not likely to be the sole cause of CCD.

But we are again told that there is a very strong association (all the CCD colonies have IAPV present, and none of the non-infected ones do) between the two.

The statement tells beekeepers not to re-use hives, and continue to treat for Varroa and nosema as usual, and to keep hives healthy and well-fed (to maximize profits, as with any “livestock”, bees are fed exactly what they need to survive and not much more…this may also play a part in CCD).

Here’s some other possible good news: we are told that Australian bees are not affected by IAPV, and this could be because the Australian bees are immune to the virus. If so, cross-breeding is possible to eliminate the susceptibility. (It is also possible that Varroa, which is not present in Australian bees, may potentiate the virus, suggesting cross-breeding would not work.)

So that’s our story for today: the cause of CCD remains unknown, but tantalizing new information exists; a second new threat has been identified, and with any luck, our hard working friends in yellow and black (no, I don’t mean the Steelers) will be back where they belong-out hunting for your pollen.

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