Kashmir bee virus was first identified in the 1970s in the Asian honey bee, Apis cerana. It was later found in the western honey bee and is now reported in many parts of the world.

It belongs to the same family as acute bee paralysis virus and Israeli acute paralysis virus, and the three are closely related.

Usually silent

Like most bee viruses it is generally present without symptoms. Colonies can carry it for long periods with no visible effect.

It becomes active when the balance is upset — above all under Varroa pressure.

When it is activated

Once activated it can kill both adults and brood within a short time. It is described as one of the more rapidly lethal bee viruses under experimental conditions.

What is seen in the field:

• Sudden loss of adult bees
• Dead brood in the cells
• Colony collapse over a short period
• No distinguishing sign

The problem of identification

Kashmir bee virus cannot be told apart from acute bee paralysis virus or Israeli acute paralysis virus in the field. The three produce the same picture.

Distinction requires molecular analysis — and for practical purposes it rarely changes what the beekeeper does.

The role of Varroa

The mite injects the virus directly into the haemolymph, bypassing the barriers of the digestive tract. It also suppresses the bee's immunity.

Both effects turn a silent infection into an active disease. This is why the level of this virus tracks the mite load.

What to do

There is no treatment acting on the virus. The measures are indirect:

• Keep Varroa under control. The single most important measure
• Keep nutrition strong. Varied pollen supports immunity
• Do not buy colonies from unknown sources
• Attend to equipment hygiene
• Work with lines showing strong hygienic behaviour
• Requeen a weakened colony

Practical position

Knowing the name of this virus gains a beekeeper little. What matters is that it is one of the reasons a high mite load leads to sudden collapse.