Viruses are the smallest of all the micro-organisms. There is debate about whether they are really alive or just tiny machine-like bundles of protein which function only in response to physical forces. They have no independent metabolism and are unable to live or reproduce on their own. Instead the modus operandi of viruses is to penetrate a cell wall of the target creature and head for the nucleus which is then hi-jacked and coerced into manufacturing more viral particles; the cell becomes a virus factory. Generally when the cycle is over, the cell will rupture and millions of new viruses will float or seep out into the environment.
The most serious thing about viruses is that once they have got inside the cell of a living creature they are out of reach of the entire range of that creature’s natural defenses and anything else for that matter. The only thing left is to kill the infected cells or wait till the viral cycle is over.
Think of cold sores, once you’ve got one of those things on your face you’re stuck with it till it’s finished with you. The best thing is not to get them in the first place – don’t go kissing people with cold sores and don’t go letting them kiss you. Which brings us to Varroa, having a hive full of Varroa means if a virus is present in just a few bees, Varroa will pick up viral particles with each bite and vector them very rapidly through the entire colony. Because of this, viruses which were never a serious problem before now have the power to destroy whole colonies.
Here is an alphabetical list of viruses known to attack honey bees:
- Acute paralysis
- Black queen cell
- Chronic paralysis
- Cloudy wing
- Deformed wing
- Invertebrate iridescent type 6
- Israeli acute paralysis
- Slow paralysis
- Tobacco ring spot virus
Fortunately for us only a few of them rear their ugly heads at this end of the world but when you start to look for the signs and symptoms of these viruses you quite quickly realise that either there are none or they are all very similar. Here are some of the more common.
Sacbrood virus affects the larvae of the honeybee. They catch it within their first 2 days of larval existence and they get it from the nurse bees who harbour it in their hypopharyngeal glands – which is where they make ‘brood food’.
The effect is to prevent them from pupating so instead of metamorphosing into a lovely baby bee they turn into a nasty little bag of slimy stuff consisting of rotten larva and zillions of viral particles but this doesn’t happen till after the cell is sealed.
- Signs that the bees have been uncapping cells.
- Dead larvae with upturned, dark and shrunken heads looking like ‘Chinese slippers’. Anyone out there with Chinese slippers? If so please send me a picture. I think they’re like a curled up winkle-picker.
Deformed wing virus
The symptoms of this disease are thought to be the result of a team effort by a number of viruses and perhaps including Kakugo virus and Egypt bee virus. On their own they would cause little effect but when in the company of a heavy Varroa load, the effects are really horrible.
Shrivelled wings and other deformities such as foreshortened abdomens. These are found in colonies which are heavily infested with Varroa – so if you see this do something about your Varroa.
Chronic Paralysis Virus
This is the one that is associated with Acarine. It affects both brood and adult bees but it is the effects on adult bees which are most draining on the colony. Despite the suspicion that this is vectored by Acarine or Varroa – there is no evidence to support the theory.
There are two types.
- Trembling of wings and abdomens
- Huddling together in sad little clusters
- Crawling – unable to fly
- K wings
There is no treatment other than to keep bees strong and employ good husbandry.
Black Queen Cell Virus
This one is commonly associated with Nosema and the reason is either that the damage done to the bee gut by Nosema facilitates the viral invasion or bees sickened by Black Queen Cell Virus are easily infected by Nosema. Although it inhabits adult workers and drones, when on its own it seems to have little effect other than to turn them into infectious carriers.
The more devastating effects are seen when it infects queen larvae then it kills the larva at the pro-pupa stage at which point it can look like sac brood but then the larvae begins to darken and so too do the queen cell walls. Eventually both cell walls and the poor dead queen become black – hence the name – she added needlessly.
- Shady looking queen cells – perhaps with a dark spot;
- Black or darkened queen cell walls and larvae;
- Remember the corrupted larva is not immediately black – it undergoes a series of colour changes – from yellow through a range of deepening browns and finally turning black;
- If you shine a torch through the other cells you should be able to see if they are ok or not.
Acute Paralysis Virus, Kashmir Virus and Israeli Acute Paralysis Virus
These 3 viruses seem to be in that category of things that are everywhere but don’t normally cause much damage – a bit like verrucas. However, when they occur in conjunction with Varroa they can be very nasty indeed – eventually killing the colony.
Israeli Acute Paralysis Virus is now considered an indicator or colony collapse disorder.
Slow Paralysis Virus
Slow Paralysis Virus is associated with the final stages of Varroaosis. It affects both larvae and adult bees and once infected it is reluctant to go away.
- Dried up larvae in sealed cells
- Paralysed adult bees
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