1998 2ND PLACE

Introducing a bee bug

By Ashley Payne

In the cold winter, many of us dream of summer, soaking up the sunshine in gardens blossoming with scented flowers, lulled to sleep by the hum of honeybees...this summer, the flowers will blossom as normal, and the sun may appear, according to our fickle climate. The bees may not. An insidious threat has brought the honeybee in Britain to the brink of extinction.

The varroa mite, varroa jacobsoni, is a small red-brown parasite that lives exclusively on honeybees, feeding from the blood of the bee. Its natural host was the Asian honeybee, apis cerana, but since the 1970s it has spread across the world to honeybees in North and South America, and North Africa. In Europe only Ireland remains free from the plague. Individual bees infested by varroa mites normally survive but are weakened, and may be deformed, due to viruses transmitted by the puncturing mouthparts of the mite. Low levels of infestation may go unnoticed by a beekeeper, but the mites breed incredibly rapidly, feeding on developing bee larva. One new model, by Dr Stephen Martin of the National Bee Unit predicts an 800 fold annual rise in the mite population in a single hive.

The first discovery of varroa in Britain, was in Devon in 1992. It was probably brought into the country with a queen imported by an unscrupulous beekeeper. It rapidly spread throughout England and Wales, and is currently spreading through Scotland, despite a ban on movement of bees issued by the Ministry of Agriculture, Fisheries and Food. How has varroa spread so quickly? Bees are not always busy and hardworking. When a colony has few bees, perhaps due to varroa, it becomes vulnerable to robbing. Other bees enter the hive and steal some honey. Bees can simply enter the wrong hive by mistake. The end result is the same, they carry the mite back to their own hive, a happy hunting ground for the parasite. However, over longer distances, varroa is spread by the movement of bees by beekeepers. Our own honeybee, apis mellifera, has no defences against this invasion.

Bees are incredible, beautiful creatures with a complex social organisation. A worker bee may live for only six weeks but learns to speak in a language of dances. The females do all the work in the bee hive, which can contain up to 80,000 bees: industrious workers, sleek-bodied drones, and, of course, the queen. The overall effect of varroa on a colony of bees is startling. If left untreated over two years, the numbers of mites become such a drain on the society in the hive that it disintegrates into anarchy. The colony collapses and the bees become refugees, and fly to other hives.

There are many treatments suggested for infested hives, but most reek of arcane witchcraft. Lactic acid, marjoram oil, formic acid and thymol are some ingredients recommended by sage old beekeepers. One treatment is to shake icing sugar over the bees, which causes the bees to groom and so remove the parasites. These treatment can leave chemical residues in the honey and none are very effective. The difficulty lies in finding a pesticide that is strong enough to kill varroa, without killing the bees it is trying to protect. The government has approved only one medication, Bayvarol, a pyrethroid compound impregnated onto plastic strips. When hung in an infested hive dead mites shower down, like tiny ugly crabs, 20,000 to a hive. Unfortunately, the more conservative beekeeper (there are quite a few) is unwilling to change methods or is tempted to save money and so doesn't treat his bees often enough. This leads to a reinfection of those bees in the area that have been treated.

Varroa cannot be eradicated and will eventually spread to every honeybee colony in Britain. Already some mites have been discovered that are resistant to the pesticides used to control them. If honeybees become extinct in Britain, honey and beeswax could well be imported, but the biggest problem will be the pollination of flowering plants. Ruin for beekeepers could mean ruin for farmers. Some attempts are being made to selectively breed bees capable of resisting varroa. The Asian honeybee has developed its own natural defences against varroa, grooming itself regularly. Many beekeepers feel that the only way to continue beekeeping will be to introduce Asian honeybees to Britain. But like rabbits in Australia, some introduced organisms cause nothing but trouble.