Scientists aim to halt honey bee decline by targeting deadly mite

Honey bee populations in the UK have fallen by 23 per cent since 1992 with a tiny insect, the deadly Varroa mite, blamed for much of the decline.

However, York-based scientists have helped to develop a pioneering treatment that may halt global honey bee losses by forcing the Varroa mite to self destruct.

The blood-sucking Varroa, a crab-like mite, is the biggest killer of honey bees worldwide and is particularly deadly during the winter when depleted bee colonies lack the warmth generated when bees huddle together.

The mite has also developed a resistance to beekeepers' medication but researchers from the Government's National Bee Unit – based at the Food and Environment Research Agency (Fera) at Sand Hutton, near York – and Aberdeen University have worked out how to effectively "silence" natural functions in the mites' genes to make them self destruct.

If successful the treatment could help stem the decline of the number of UK bees and the massive contribution they make to the country's ecology and economy.

Dr Giles Budge from the National Bee Unit at Fera said: "This cutting edge treatment is environmentally-friendly and poses no threat to the bees.

"With appropriate support from industry and a rigorous approval process, chemical-free medicines could be available in five to ten years."

Varroa mites began their destruction of bee colonies on Asian honey bees before jumping to their European relatives, thought to have poorer natural defences.

By injecting a virus which suppresses a bees natural immune system it weakens the bee before feasting on its blood. If untreated just 1,000 mites can kill a colony of bees as large as 50,000.

The process uses the Nobel Prize-winning theory called RNA interference.

So far the "silencing" has worked with a neutral Varroa gene, which has no significant effect on the mite.

Scientists now need to target a gene with the specific characteristics that are perfect to force the Varroa to self destruct.

Tests by other scientists have shown the treatment can be added to hives in bee feed.

The bees move it into food for their young, where the Varroa hides.

Dr Alan Bowman from the University of Aberdeen said: "Introducing harmless genetic material encourages the mites' own immune response to prevent their genes from expressing natural functions. This could make them self destruct.

"The beauty of this approach is that it is really specific and targets the mites without harming the bees or, indeed, any other animal."

The Varroa mite entered the UK in 1992 and since then the number of UK bee colonies has fallen from 151,924 to just over 116,000.

Environment Minister Lord Henley said: "Bees are essential to putting food on our table and worth 200m to Britain every year through pollinating our crops. This excellent work by UK scientists will keep our hives healthy and bees buzzing."

As well as crops such as oil seed rape, bees are essential to the pollination process of strawberries, raspberries, onions, broccoli and carrots.

Last year scientists began attaching micro ID tags to bees in order to track their progress as part of a project to research possible links between pesticide use and bee deaths,

Some environmental groups are calling for all neonicotinoid insecticide products to be banned, claiming they are to blame for the loss of bees. However, opinions, about the safety of the pesticide vary widely. Wet summers in recent years have exacerbated the decline in numbers of bees, according to experts.