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Last Updated: Monday, 5 July, 2004, 11:22 GMT 12:22 UK
Sticky bees combat insect pests
Bee hives, BBC
The mites have killed off many colonies
A powder that exploits a bee's natural stickiness could help beekeepers tackle a devastating insect pest.

The Varroa mite is endemic in British hives and in large numbers can sap a bee colony's strength.

The powder sticks strongly to the bees and allows the insects to spread the powder and its key ingredient throughout the hive.

The Exomite powder gives beekeepers an alternative which may help to prolong the usefulness of other products.

Mite damage

A Varroa species of mite was first discovered in Britain in 1992 but was thought to be present in hives long before then.

The first outbreak devastated honey bee numbers, with many keepers losing up to 75% of their colonies.

Varroa mite, Horticulture Research International Association
Varroa destructor: Mites make bees susceptible to disease
Chemical controls known as pyrethroids have proved effective in controlling Varroa but lax use has produced mites resistant to them.

Beekeepers fear this means mite numbers are set to boom again leading to more lost colonies.

But now Southampton-based Exosect has developed a novel way of distributing another preparation around hives.

The Exomite system uses a powder that can be made to stick to the bee by exploiting its natural electrostatic charge.

The wax powder being used as a carrier medium is a harmless food grade substance.

The charged powder can be combined with ingredients used in other mite products, but at much smaller quantities.

In this case it is combined with thymol, a component of thyme oil.

Varied attack

Georgina Kemp, spokeswoman for Exosect, said that because the powder stuck to the bees it got spread all over the hive, including inside comb cells where bees develop.

"When the mites are actively developing, they do so in the brood cells where the bee larvae are growing," she added.

"One of the problems with other products is that they rely on vapour action so once the brood is capped they are no longer effective."

By contrast, she said, the powder got right into the brood cells.

Worker bees spend 12 days of their 21-day development period in a capped brood cell.

To get the powder on to the bees, Exosect has produced traps that fit into the entrance of hives. When the bees walk through the trap they pick up some of the powder which is then spread around the hive.

Trials of Exomite carried out in the hives of members of the Meridian Beekeepers Association showed that it did a good job.

The Exomite powder also used much less thymol than existing Varroa products.

"We want people to use different products and leave the pyrethroids until they really need them," said Ms Kemp.

The British Bee Keepers' Association recommends that Varroa products be rotated to ensure that the mites have little chance to develop resistance.

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