BEEKEEPERS across North Yorkshire and the North East are keeping a close eye on their hives.

The Varroa mite which invaded bee hives up and down the country in 1992, wiping out thousands of honey bees, may be growing resistant to insecticides which control them.

Some beekeepers in the South West have reported mites developing resistance to the chemicals.

While at present the problem remains in the South West, beekeepers in North Yorkshire and the North-East are concerned.

John Holland, a beekeeper at Bagby, near Thirsk, explained: "It hasn't spread so far but we are watching it and being careful about it, we are hoping it won't develop any further."

Mr Holland has 12 beehives on his smallholding in Bagby, and produces up to 500lbs of honey in a good year.

Every summer, between August and September, he takes his hives up on the Snilesworth Moor on the North York Moors so the bees can feast on the heather and give the honey its distinctive taste.

However, when the bees return to Bagby, he makes sure he puts a special strip of insecticide in the hives for six weeks to kill the Varroa mites.

"Everyone in the area has Varroa mites, but we are very careful," he said.

Mr Holland explained there are a variety of ways of controlling the mites and it is very important that beekeepers do not leave the insecticide strips inside the beehives for longer than six weeks, as this enables the Varroa mites to build-up a resistance to it.

"At the moment we are OK in Yorkshire, these resistant mites have not spread here so far, but we have to be aware, because it could be transported around the country. It's the responsibility of all beekeepers."

While the Varroa mite originates from small honey bees in South East Asia, its effect on bees in the western world has earned it the nickname bee plague and apian AIDS.

If the resistant Varroa mites spread across the country, they may wipe-out the bee population, if this were to happen, British food crops would also be threatened.

Britain has more than 250 bee species that pollinate £7bn worth of food crops a year. Up to half of the food crops grown depend on bees to pollinate them.

Mr Holland, who worked for 35 years as a plant health and seed expert for the Ministry of Agriculture, said: "It could have an effect on crop production, of course it could. Bees are very efficient pollinators of crops.

"We can get large numbers of bees in to crops in a small amount of time and move them around in their hives.

"We are checking for these resistant mites, I did last year and will be doing it again this year, but so far we don't have these resistant varieties here."

The National Bee Unit, based at York, is also working hard to ensure the resistant mites do not spread.

Mike Brown from the unit said: "These medicaments are only part of the armoury to deal with Varroa, there are various integrated pest management techniques which should be used.

"We are encouraging beekeepers to do the checks for resistance, it's still limited in terms of spread and we hope it won't spread too quickly, as alternative treatments will become available.

"Defra is funding research programmes for example to see if there is a biological control method available, using fungus that might attack the Varroa, as a fungal pathogen."

Mr Brown explained that it is thought the resistant mites came about in the south west because of over exposure to the treatments.

"If you leave the strips in the hive all the time, the mites are continually exposed to it and the colony will either die out completely, or more likely, they will develop and way of dealing with the medicine in order to survive, creating this resistance."

The early detection of the resistant mites in the south has allowed beekeepers in other areas more time to be aware of the problems and manage them.

More information is available at the National Bee Unit web site at www.nationalbeeunit.com