Kakugo virus was described in research into the defensive behaviour of bees. It is closely related to deformed wing virus.

The observation

The virus was found in the brains of bees performing guard duty and defending. That raised the question of whether there is a link between infection and aggressive behaviour.

What that does and does not mean

Establishing an association is not the same as demonstrating a cause. Finding the virus in defending bees leaves open whether:

• The virus influences the behaviour
• Defending bees become infected more often for other reasons
• Both are determined by a third factor

This is an area where research is ongoing. No practical recommendations follow from it.

The relationship that does matter

The virus belongs to the same group as deformed wing virus — the most important virus in beekeeping.

The same principles therefore apply: it is transmitted by Varroa, the mite introduces it directly into the haemolymph, and the burden depends on mite pressure.

What a beekeeper gains from it

Little, and saying so is more honest than pretending a measure follows.

What does hold is what holds for all bee viruses: no product acts on the virus, and the only genuinely effective measure is keeping Varroa under control.

If a colony is defensive

Look to the known factors before thinking of a virus:

• The age and genetics of the queen
• Queenlessness
• Robbing or sustained disturbance
• Weather and dearth
• Alarm pheromone in clothing and gloves

Requeening is the measure that almost always works for defensiveness.