I have on a few occasions (most recently on Agricultural Biodiversity Blog) been asked to give my view on various aspects of Colony Collapse Disorder, a mysterious syndrome that seems to be killing honeybee colonies primarily in the USA but possibly also in Europe. Because I’m a beekeeper, apparently my opinion is considered “expert”.

The thing is, no one really knows what CCD is all about. The symptoms include adult bees vanishing from the colony, while the queen is still present as well as brood and some food stores. Adult bees will usually not abandon a hive while there is still capped brood present, and if the colony is starving, uncapped brood are usually eaten before the adult bees start dying. Also the bees in a colony dying from starvation or disease normally die in or around it rather than simply vanishing.

CCD has only been defined in the past couple of years and has mainly been reported in the US. There are historical sources speaking of similar events in the past but the records are incomplete and, just like today, everything is mostly based on beekeepers’ own reports. In short, very little actual trustworthy data exists on the true extent of the disorder.

It gets even worse when you start looking at possible causes. Pretty much everything has been suggested and there is no conclusive evidence for anything. Varroa destructor mites, the most pervasive and destructive pest faced by beekeepers and their colonies today, appear not to be linked to the disorder. The Israeli acute paralysis virus has been shown to be correlated with incidence of CCD, but no causality is implied and it might simply be that colonies suffering from whatever is causing CCD are more receptive to the virus. Electromagnetic radiation has been implicated by the press but the one study on which the media based this ridiculous rumour had nothing to do with CCD.

Here in Sweden, most of the senior beekeepers I have spoken to are extremely skeptical about the disorder and consider it mostly a problem for American beekeepers, who tend to truck their hives around a lot during the active season as well as use antibiotics to a much greater extent than we do over here. Beekeeping is much more of an industry in the US, and that has to affect the bees in some way. In short the general opinion over here seems to be that US beekeepers had it coming, because they are exposing their colonies to stressful situations that never occur in nature, which likely weakens their immune system and generally renders them more vulnerable to all natural enemies.

In fact, there are quite a few beekeepers as well as scientists of the opinion that the recent mass-deaths of colonies in the US are within the bounds of what can be considered normal: Some years, a lot of bees simply die because of poor weather conditions.

Either way, I don’t want to pretend I know something that I can’t possibly know. There are scientists hard at work at figuring out what is causing CCD, and until they have produced some evidence in any direction, I won’t offer an opinion on the subject. I am of course very interested in seeing what will happen and hope that a cause and treatment is found soon, but meanwhile, I think I will focus on battling the Varroa in my own hives.

ETA: One possible cause I haven’t seen discussed anywhere is the possibility of genetic stress due to breeding. We already know that honeybees are very sensitive to inbreeding due to their sex determination system (I think I’ll write about this in a future post, it’s very interesting), but what if there are other, less obvious problems with the way we breed honeybees? Could it be that breeding for docility, repressed swarming behaviour and increased harvests produces other unwanted effects such as a weakened immune system?

colony collapse disorder, ccd, honeybees, beekeeping, varroa