I’ed like to discus two scientific articles on the possible cause of colony loss over the winter period (referred to as colony collapse disorder (CCD) in English speaking countries). The first article was published in the peer reviewed online publication PLOS ONE this month.
In this study the researchers (and the beekeepers) collected and analysed data from a total of 86 colonies using the following scheme (abbreviated copy from the article); continue reading
I’ve been wanting to move the bee blog to my own domain for a while. Registering a new domain only for the bee-blog is perhaps a little to much, but I finally got round to making a sub-domain for the bee-blog. The hosting company I use has a really easy way to install WordPress, which I finally got round to using to creating a new blog on a subdomain; bees.millar-knorr.nl.
So I think from now on I will be posting new blog posts only on that domain. Perhaps I will continue with the Dutch version of the blog on apiarists.wordpress.com. I will keep the apiarist4en.wordpress.com online for the foreseeable future, I will just updating that blog. Perhaps I will post links to the new domain on that site but that is about it I think.
American foulbrood has been identified in two places near the city where I keep my bees, the hives infected have been cleared and there is a ban in place on moving bees within a 3 km (1.8 miles) radius around the effected hives. A little over a week ago the first two hives with AFB were found and yesterday a second outbreak was identified in a hive close to (but outside the 3 km “exclusion zone”) of the first effected hive. I read somewhere that all the hives in the apiary with an infected hive should be cleared but I can’t find clear information on this happening in these cases.
I never paid much attention to the mad cow disease and swine flue scare, but now that it actually concerns animals in which I am invested and have a vested interest I do care. Perhaps a little hypocritical of me but that is just how it is.
American foulbrood is a disease caused by the spore forming bacteria; Paenibacillus larvae, which can stay dormant in your hive for years before it becomes active. I haven’t found what can instigate an outbreak but perhaps as with DWV which will only effect hives that have been weakened by say Varroa. A healthy colony with a healthy grooming propensity can be a carrier of the disease without being effected by it.
The spores produced by this bacteria don’t effect adult bees but to young brood it is devastating. Larva can be infected by food that contains spores. Larva younger than a day are easily effected, but 4 day old larva are orders of magnitude less likely to get an infection from the spores.
Finding a weakened colony with very little open brood can indicate that the colony is infected with this disease. The hive will seem lifeless and the caps on the closed brood will have holes or tears. The “matchstick test”, poking in a cell with a torn cap, will produce a yellow brownish goo (as seen in the image at the top).
In The Netherlands informing the authorities of an AFB suspicion is mandatory. Although it is unclear to me how many beekeepers stick to that rule. I guess all the beekeepers here in the north of the country are on alert.
Addition1: I visited the bees today and there was no sign of AFB in either hive, I did see a DWV bee walking on the frame in Artemis. This might be a sign of Varroa infection but I began my treatment against Varroa when this bee was perhaps a larva (bees with DWV don’t tend to live long, they will be removed from the hive by other bees). So this is not a sign of the actual Varroa pressure at this moment, I hope. Sif which does have a bottom board to catch the mite drop did have some mites in the three weeks it was under the hive but not a ridiculous amount. Not like the first time I treated Sif a little over a year ago (no pictures).
I also did a quick assessment of the stores of both colonies to get an impression of how much I will have to feed them. I think they have about 7 frames of honey between them, Sif a little more than Artemis but I will divide the honey evenly and feed them both the same amount of sugar syrup. I expect that about 10 kilogram sugar each should be enough to get them through winter. I’ll post new AFB developments here.
Postscript: I talked to a more experienced beekeeper at the apiary yesterday (21/09/14) and he told me that a colony with AFB isn’t necessarily lost. What you can do, according to him, is make a “Shook Swarm” of the entire colony then leave the colony in a ventilated box for an extended amount of time till the first bees start dying from starvation.
You do this because the AFB spores live in honey surrounding the brood nest and to be sure the spores are gone the bees in the shook swarm need to burn through all the honey they have in their stomach. Then the bees will be free of AFB and you can put them into a clean hive.
This method seems somewhat iffy to me as it seems easy to either kill the colony or still leave them with honey infected with AFB, I hope I never get the opportunity to try this method.
Addition2: (07/09/14): There has been a second outbreak of AFB in a town called Exloo, which is about 50 kilometers (≈30 miles) form my home town. For me in the right direction compared to the last case which was about 16 kilometers (10 miles) away.
Addition3: (19/9/14): A third AFB outbreak has been found, this time in a Town called Stadskanaal, again about 50 k from my bees, close to the last outbreak. Still not free from the AFB scare…
Because of the nice weather in winter and spring the varroa populations have exploded. Winter treatment against varroa using oxalic acid is used during winter because that it is the only time that the colony is not expected to have any brood. A single treatment should impact all varroa as there should be no varroa protected inside caped brood cells.
But because of the mild weather this winter there is a good chance that the bees did have capped brood, most likely filled with varroa. And then there was the mild spring which gave the mites a head start in the bee season letting their population grow to new heights. That is why this year the varroa treatments here in western Europe are especially important. Varroa can be a major cause in colony death over winter. More so than lack of food or extreme cold.
The local apiarists organisation in the Netherlands has published an article on the explosive varroa population growth. A beekeeper counted 4 times the varroa he would count in an average year. You can view a translation of the article by following this next link (in all honesty the translation isn’t all that good, but kind of readable).
I’m not sure how the varroa population is going in my hives. I’ll check the mite drop after the 5 weeks of apiguard treatment tomorrow and update this post accordingly (if the weather allows, lot of rain here lately).