Chronic Bee Paralysis Virus

By Clare Densley, Manager, Buckfast Abbey Bee Depatment

 and Martin Hann, Seasonal Bee Inspector, NBU

Experience and Management of CBPV at Buckfast Abbey. Reported and discussed at DARG meeting on 14th January 2018

Chronic Bee Paralysis Virus

This virus has become a lot more common over the last five years or so. Many beekeepers are reporting its incidence, so much so, that the national bee unit are starting to monitor it officially and record when, where, and under what circumstances it pops up. Strangely it is one of the few viruses which doesn’t seem to have an association with varroa (yet)!

We have quite a bit of experience with this rather ugly and distressing disease. None of the literature I can find about it suggest any kind of treatment for it, they simply say that either your colony will die or it will recover. However after some educated and earnest trial and error we have come up with a care plan for colonies afflicted with it which appears to work provided the virus is spotted early.

It seems that if you recognise the symptoms before the devastating mass die off of bees you have got a chance to pull the colony through with a bit of vigilant T.L.C.

This virus can occur at any time of the active season from early spring to late autumn. Probably it is present in the colony most of the time but expresses itself when certain external/internal conditions and stress levels tip over a threshold.

The initial symptoms are quite difficult to notice if you are not specifically looking for them and unless you have experience of them they may slip you by unnoticed until the more obvious mass death of bees shocks you into action.

This is what I am always conscientious about when I am inspecting a colony:

Black shiny or dull looking bees. There may be just one or two of these initially and they never really reach epic proportions.

Apart from these there may be the odd normal looking bee which appears to be a bit shaky or slow. These can be noticed on the top bars of the frames when you have smoked the bees. They seem unable to react to the smoke and almost look confused and are immobile and or shaky whilst the rest of the bees have scuttled down between the frames.

One or two dead bees on the varroa mesh floor. This number can rise to thousands if the virus affects more of the population. You may see the undertaker bees trying to remove them from the hive but at some point they will be overwhelmed by the quantity that they need to evict. Also they may succumb to the virus themselves and so the dead start to pile up

Dead bees outside the hive entrance at different stages of decomposition. There may also be dying bees amongst the dead which crawl and shiver with their wings spread out from their bodies.

It is a natural mistake to confuse CBPV with pesticide poisoning. A pile of dead bees outside the hive can look so alarming that you almost need to pin the deaths on some kind of understandable and beastly reason.

Inside the hive the brood may look normal and the queen will seem to be laying as usual

Food may seem short. I think that a colony afflicted with the virus will not be able to replace food eaten and used to feed the larvae on a daily basis quick enough so supplies dwindle quickly and the colony becomes nutritionally compromised. Possibly robbing may have occurred too. They do not seem to respond to food put into a feeder.

Sometimes there is a dark brown poo on the floor and on the top bars of the frames. Some bees will have distended abdomens because the honey stomach swells up.

All of these things can be noticed if you are a vigilant beekeeper. When you take off the roof take a moment to observe the bees’ behaviour on the crown board and likewise the top bars when you have removed this. The healthy bees will shun the diseased ones, sometimes you can see them attacking or nibbling at them whilst others become exiled either outside of the hive or at its extremities (above the crown board).

What conditions spark off CBPV?

Most often we have experienced this virus getting a hold when the colony becomes over crowded. This can happen for a number of reasons: a classic example is when a colony builds up lovely and strong in the spring but then the weather changes and the large population is confined to the hive for a period of time. These bees are all at home, cooped up and are rubbing up against each other so that their protective exoskeleton gets damaged and viral particles can gain access to the bees’ cells. Typically this is because the body hairs are snapped off at their base. The virus enters a naïve bee via these entry points in the exoskeleton and becomes established in the cytoplasm here. It can also be transferred by feeding, trophallixis and by the removal of infected poo. Research has shown that many more viral particles are passed on via cuticle damage than through food or faeces.

We have noticed on several occasions that colonies have come down with symptoms of CBPV due to the temporary overcrowding which sometimes occurs when you have a virgin in a colony.

Have you ever noticed, particularly during patchy weather conditions, that the colony with a virgin (waiting to mate) fills up with drones?  The virgin inside has reached sexual maturity but the weather isn’t really conducive to a decent drone congregation area. Drones from everywhere pile into that colony. We have seen them literally bouncing off the hive front because there were so many trying to get in. Then, I presume, when there is a brief window in the weather she flies out and is followed by the accumulated boys to mate somewhere not so far away. This is often called apiary vicinity mating.

However: whilst the bees are waiting for the virgin to fly the hive is very overcrowded and CBPV can get a hold. There is some research which says that CPBV has a high incidence in drones.

CBPV does seem to be very contagious in an apiary and is probably spread by drifting bees. If you have two colonies next door to each other where one is visibly infected it is likely that you may see signs of the disease in the neighbouring hive. This “secondary infection” may not be as bad as the original sick colony but should not be ignored and treated in conjunction with the source colony.

I have seen it in early spring during the first proper colony inspection. Signs then were not as overt as in the case of a large or overcrowded colony. Probably the symptoms were more dead bees than expected on the mesh floor with some lingerers outside the entrance. One or two shaky or dull looking bees on the top bars. The infection had more of a “chronic” or gradual feel to it rather than the acute or startling death toll of a full on overcrowding die off. Never the less this type of infection can linger on and the colony never really develops properly.

Possibly the infection may have been caused by robbing? A weaker colony being robbed would suffer damage to the exoskeleton during fighting and so be more prone to the virus (just guessing!)

Lesley Bailey cites too many bees in an area as being a significant factor in the incidence of CBPV. I’m not sure about the mechanisms inferred here but I think that nutritional stress must play a part in the equation. Maybe this is why feeding helps and why smaller “unovercrowded” bees succumb to it (with the help of robbing). Thinking this through a little: if poor diet in people can cause rickets surely a poor diet in bees would affect the strength and quality of an exoskeleton?

What can be done about it?

Some colonies will seem to just shake it off if the weather conditions become good and allow for frequent flying and foraging. Others will struggle and the death toll will be so great that the colony will simply collapse. Others seem to try and replace the queen by supersedure and often this doesn’t work and the colony becomes a drone layer. I don’t know if the supersedure process is because of the condition or if this is just coincidental.

We have found that you can nurse a colony through, especially if she is a strong one and that she will have a productive life with no future problems. It all depends if you think that she is worth it.

What we do

First and foremost is hygiene. Clear up as many of the dead bees as you can and take them away to dispose of (burn or double bag them; don’t just chuck them in the hedge) It is hard cleaning dead bees up out of grass in front of the hive entrance but if you leave them there they become smelly which can’t be very nice for the colony which is already struggling.

Place a piece of plastic (a varroa monitoring tray is perfect) or a kitchen tray in front of the hive entrance so that the dead and dying bees can be easily swept up and removed as regularly as you can manage.

Clean your hive tool and hands between colonies

I douse the bees in Varromed (formally Hive Clean) right from the outset. This seems to activate not only the grooming process but also seems to encourage the bees to clear out their dead. There is some research which suggests that bees will use venom to coat themselves with as part of their microbial defence system? If grooming includes this behaviour then it can only be good.

Take the hive body off the mesh floor and clean out as many of the dead and dying bees from here also. Likewise any from the crown board. Bees which are sick and infected aren’t going to get better so if your conscience pricks about removing still live but sick you can bag them up and stick them in the freezer for a more humane death.

Make sure that the colony is not congested and if so give them room to spread out (give them super, or take away the QE so that they aren’t inhibited from using it).

Feed sugar syrup or ambrosia in a way which is directly accessible to them. Very often sick bees will not come up to a rapid feeder placed above the crown board so some more direct feeding methods are definitely better. A shallow dish placed directly on the top bars filled with syrup and straw works well. I also dribble syrup onto the bees themselves and into any empty combs as close to the brood nest as possible. Be careful about flooding any cell with eggs in. This latter method is a bit of a fiddle and can take a bit of time and patience but you will find that the bees start to feed/tidy it up immediately.

I add garlic powder and probiotic capsule powder to my syrup. I think that this helps (debateable). It certainly does no harm and it makes me feel like I’m being Nurse Nancy. They do love the garlicky syrup and start to slurp it up straight away.

The point about the feeding is that often a colony with CBPV becomes hungry very quickly. You are not going to make sick bees any better but you need your queen to keep laying so that you continue to have young bees coming through to replace the dying ones.

The queen doesn’t seem to suffer from CBPV because she appears to acquire an associate virus which contains proteins which protect her from it.

I have tried whipping out the queen in the past and requeening and this has no affect at all. Also Segundo took the queen I whipped out (he wouldn’t let me kill her because he is a Buddhist) and introduced her to a colony of his at home and they did not develop the disease!

Giles Budge doesn’t reckon that any particular race or sub race of bee is more or less susceptible to the disease  than others.

Feed regularly like this and you will notice that over a period of about 2 to 3 weeks that the dead being chucked out onto your monitoring tray will become less and less until there are none!

It really is spoon feeding and TLC but it can be done.

Move the bees. There is anecdotal evidence that some sites are more prone to the disease than others. We have tried this and it did seem to work although I have no idea why! Declan seems to support the idea and has recommended that we move the bees out of the Home Apiary for a year to rest the site before moving them back. I have asked for clarification on how this might work but no word yet. Could the soil and grass be a reservoir for the disease? Maybe there are too many bees in the area (and there are a lot round and about) and so the bees are nutritionally stressed? There is evidence now that some viruses can be passed on via inanimate objects?

Other things to consider not tried by us but by others:

If they are strong enough you might consider a shook swarm. This has worked for a guy called Chris Neal (Bee Farmer).

Kill the colony to stop the spread of infection. This would never be my choice although I can kind of see the logic behind it.


Beyond the Antipredatory defence: Honey bee venom function as a component of social immunity

David Baracchi a,*, Simona Francese b, Stefano Turillazzi a,c

a Università degli Studi di Firenze, Dipartimento di Biologia Evoluzionistica “Leo Pardi”, Via Romana 17, 50125 Firenze, Italy

b Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, UK

c Centro di Servizi di Spettrometria di Massa, dell’Università di Firenze, Viale G. Pieraccini, 50139 Firenze, Italy

Bailey, L, et al (1983). Honey bee paralysis: Its natural spread and diminished incidence in England and Wales

Journal of Apicultural Research, 22(3), 191–195


Ribière, M, Olivier, V and Blanchard, P (2010). Chronic bee paralysis: a disease and a virus like no other?

Journal of Invertebrate Pathology, 103, Suppl 1, S120–131.

The History and biology of a honey bee disease Chronic Bee Paralysis

Giles Budge and Kirsty Stainton

National bee unit download

Chronic Bee Paralysis: Past, Present and Future

Dr Giles Budge, senior lecturer at Newcastle University and Crop and

Bee health lead at Fera Science Ltd, with an update on research initiatives

(Article from Bee Farmer Magazine)


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