Tonight I dusted off the beekeeping books and my notes from the classes, the exam is approaching rapidly. Flash cards on diseases were written with the intention of learning, but there is one card I feel I could write without consulting notes; varroa destructor.
For a couple of weeks we have been noticing a few dead bees on the ground in front of the hive. With a population in the thousands, maybe tens of thousands at the moment, a few casualties in the game of life are expected. However, the numbers of dead bees has steadily increased to more than to be expected; not good. Some of the bees have deformed wings caused by a virus called…..wait for it…..deformed wing virus. And a few seem to have just decided to give up, with pollen or honey interesting them no more. These dead bees have been coupled with an increased count of a devastating little nasty that sometimes drops to the hive floor where it can be see. Varroa destructor.
an amazing picture of the varroa mite by Gilles san Martin
Varroa destructor is a tiny mite than has never been seen by the European honey bee in the hundreds of thousands of years that it has gone about its honeybee business. Then man introduced the mite to the bee accidentally and it has been a downhill story from there. Varroa destructor is said to be the reason why the wild population of honeybees in Ireland has been reduced to zero. The mite pushed the bees to extinction by attaching itself to the bee and sucking its blood. Then it reproduces and brings up its little baby mites in the bees larval stage by…sucking its blood. If this was not bad enough, it also is a host to all sorts of nasty viruses including… deformed wing virus.
I dusted off my old microscope and took my own image
nasty
The only way beekeepers can keep the mite in controllable numbers is to intervene with an arsenal of chemicals and methods that try and maintain a minimal population. The population of mites in our hive was minimal when we got them and minimal for the first few weeks, then it exploded. Its just one of those things.
Yesterday I got a delivery of one of the few viable treatments for this time of year (some treatments can ruin any possible honey harvest). I myself am also infected with a virus and was in no mood for doing any sort of beekeeping last night. I do not have deformed wings but a cold, and the vector was not a mite but the little man and the nursery he attends. Luckily the hive treatment required nothing more than opening the hive and dropping two strips of medicine into it. I added a bit of sniffing, snorting and sneezing that was not required.
the hive floor debri scooped up and still alive with mites – the stuff of nightmares
Today I pulled out the hive floor to see if the treatment had any effect, it did. I estimated* 2237.29 about 2200 mites were on the hive floor in both dead and half dead states. It seems to be quite a serious infection. We are not hoping for honey this year, in our minds it was always a possibility, but only a bonus. We didn’t even want to keep bees to help with pollination. To be honest, Bumble bees are far better pollinators than honey bees in Ireland. We just wanted to keep bees for the joy and fascination.
*If you were wondering if I counted all the mites on the floor of the hive you would be wrong. Like any good scientist I took a couple of 10 by 10cm squares and counted the mites in these with a magnifying glass. Then I measured the total area of the floor and extrapolated. Although I did once do a bit of silly counting. A couple of months ago I was waking around the garden and thought that there was a ridiculous amount of daffodils. I wondered how many there were and then a little inner voice said, “Don’t ask the questions unless you are prepared to find out the answers”. So I counted them and there were seven hundred and twenty three daffodils in the garden that day. Sometimes I catch the lovely Sharon looking at me with a look of curiosity mixed with unease and I don’t need to ask her why; I know she is remembering the day I counted the daffodils.
this teacher's life 
May 17, 2011 at 11:26 pm
I didn’t realise that we didn’t have honey bees in Ireland…so there you go/
This is more related to the daffodils but I was wondering the other day why so many of our wildflowers are yellow? Maybe I’m just imagining that
May 18, 2011 at 4:28 am
Good luck with your exam and I hope your cold gets better soon!
Impressed by your microscope image of the evil varroa mites. Your poor bees really do have it bad if you’ve got thousands dropping down. Maybe you could do some drone trapping too?
May 18, 2011 at 8:43 pm
Thanks Emily. I think I am going to have to Drone cull, and treat with acid in the winter if I am going to give them a chance to make it through the winter. I might even give up on the prospect of honey (the weather if preventing that anyway) and treat with something different after the apistan. I will have to keep a wee eye on them and see. I did stumble upon a brilliant book that is giving me a bit of confidence with the bees: Keeping Healthy Honey Bees by David Aston. You probably already have it but I think it is worth a look if you don’t.
May 19, 2011 at 5:35 am
Oxalic acid worked really well for me in December. I was getting hundreds of mites on the monitoring board each week but after doing the acid that really dropped.
We can’t use Apistan here in London as the local mites are pyrethroid resistant. I’ve been using Apiguard after the supers come off in August.
Haven’t got that book, will look out for it, thanks!
May 18, 2011 at 8:44 pm
Yellow flowers…. I remember reading about this once. As far as I am aware, and it is a vague memory so forgive me if I am wrong, it is yellow that is the easiest colour to spot on a green background in low light levels. It seems that all our early spring wild flowers are yellow (apart from snowdrops, but there area always exceptions to the rule). These flowers have to be visible in short hours of daylight and to as wide a range of pollinators as possible as it is still too cold for a lot of insects. The other colours don’t seem to begin to show until late spring and the summer when the light is much better. I wonder if something similar is happening to the flowers that seem to be flowering for long periods of the year like gorse, tormentil and dandelion. I know they have their time of blossom but you can always find flowering examples all summer. Maybe they are yellow so they can again be seen by a wide range of pollinators. Of course the perception of colour is a very weird thing to think about when we do not actually know what insects perceive. I always hit this philosophical wall when I teach Ultra Violet and Infra Red; no matter how many times I try to explain, they keep saying, “but what do the other colours look like?”. To top off all this I just read the other day that honeybees see in colour when they are slowly flying to the flowers and in black and white when they are flying faster back to the hive.
May 19, 2011 at 12:27 am
cool…this was the first year that I noticed how yellow our native spring flowers. I suppose yellow and blue are the two colours beside green on the colour wheel so…..I’m not really sure…umm….anyway.
Bee’s are amazing. I’m pretty sure my uncle’s used to have some type of converted cattle trailer hive contraption for keeping bees,I must ask him if he’s still got it next time I see him