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Report of February Meeting 2019

Chronic Bee Paralysis Virus (CBPV) – A talk by Clare Densley, Manager of Buckfast Abbey Apiaries

What is CBPV?
CBPV mainly attacks adult bees and causes two forms of ‘‘paralysis’’ symptoms. The most common form is characterised by an abnormal trembling of the body and wings, an inability to fly leading to crawling on the ground, bloated abdomens, and dislocated wings. The other form is identified by the presence of hairless, shiny black bees that are attacked and rejected by guard bees at the entrance to the colony. Both forms of symptoms can be seen in bees from the same colony.

Diagnosis of CBPV

Bees infected with CBPV
Bees infected with CBPV  *

The virus multiplies to millions within the bee affecting most organs with little chance of the individual bee surviving. In addition to the signs above you may find, on the top bars, slow, slightly shaky bees which do not react to smoke.
Check all the symptoms before deciding the cause of dead bees inside and/or outside the hive. Do not assume that many dead bees means pesticide poisoning. CBPV is, as its name suggests, a chronic problem. Not all bees will die at once, stress can accelerate the spread of infection or improving conditions can cause it to clear up.

In Clare’s experience queens often seems to remain unaffected and can carry on laying as long as they are well fed. This has also been noted by Giles Budge. Advice from older books and the NBU suggest re-queening with a queen from a less susceptible strain of bee. Clare found that re-queening made no difference to a colony which was suffering badly. Also removing a queen from an infected colony and introducing her to a healthy colony did not cause disease to develop.

What is a virus?

Hairless, shiny bees
Hairless, shiny bees  *

A virus is a small infectious agent that replicates only inside the living cells of other organisms. Viruses are basically parasites. They invade an organism, take over their cells and turn them into factories for producing more viruses. There are 23+ viruses that affect honey bees. Viruses normally range from 30 to 100 nanometres (1 nanometre = 1 millionth of a millimetre).

How does CBPV infect bees?
Infection often initiates when the colony is stressed (overcrowding, nutritional stress, but not via varroa infestation). Usually passed from bee to bee with a few virus particles entering the cuticle where hairs are broken off. By comparison, transmission by feeding requires hundreds of virus particles.

CBPV can also infect some ant species which act as a reservoir in the wild.

Drifting has been implicated in spreading the disease between colonies.

How does the virus act?
Infected bees contain millions of viral particles, half of which concentrate in the head causing the symptoms associated with the nervous system. Many more accumulate in the hind gut adding to viral load inside the hive.

‘Good’ gut bacteria are important in bee health, helping to fight pathogens by blocking entry into bee cells. Good nutrition is therefore essential for fighting the disease.

Treating CBPV

Bee with the virus
Bee with the virus *

The NBU recommends that in strong colonies showing signs of CBPV, beekeepers ensure there is plenty of room by adding supers or an extra brood box and also that colonies are well fed.

Clare doses the bees with 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.

Infected colonies may be short of readily available food due to a lack of foragers and will benefit from feeding direct to the comb in the brood area. Spray or pour liquid feed onto an empty brood frame and put it next to brood. Dribble syrup onto the bees as well. These methods work better than feeders.

Clare uses garlic powder and probiotic capsule powder added to the syrup which prompts an immediate feeding response. See below for Clare’s recipes for a Fondant Recipe for Bees and a Garlic Syrup for Bees

Clean up dead bees inside and outside the hive.

Don’t overcrowd your apiaries. If hives are badly infected, set up a new apiary and move the affected hives.

Practice good apiary hygiene.

A mixture of normal and affected bees

* Images courtesy of The Animal and Plant Health Agency (APHA), Crown Copyright

Clare’s Fondant Recipe for Bees
Icing sugar- 1kg
Water- 100 ml
Garlic powder (optional)- 1tsp
Honey or invert sugar (ambrosia)- a dashMethod
Empty the icing sugar into a clean washing up bowl and add the garlic powder and honey or ambrosia.
Add the water and mix with your hands until you are able to knead the mixture like dough.
Put into a greaseproof wrapping or a plastic bag so that it doesn’t dry out.
Place over the feed hole on the crown board of the hive.
Clare’s Garlic Syrup for BeesMethod
Make up 2:1 sugar syrup (or use Ambrosia)
2 heaped teaspoons of pure garlic powder (not garlic salt) should be placed in a large mixing jug.
Add a tiny bit of syrup so that you can mix it to a paste (as you would cocoa or custard powder).
Then dilute this mixture with a little more syrup.
Stir thoroughly so that it all amalgamates.
Do this again.
Continue this process until the mixture is liquid enough to pour freely.
When you get to this point you can add more syrup until you have 5 litres in all.
Mix thoroughly and pour the solution into bottles or a canister.

With thanks to Clare Densley for sharing her recipes for use in combating CBPV.