Bees are under threat from a species of mite, but beekeepers in Tipperary are breeding bees that can resist the parasite, in an effort to save the prolific pollinators from extinction, writes EOIN BURKE-KENNEDY
BREEDING COLONIES of disease-resistant superbees to safeguard the pollination of vital food crops sounds like the stuff of science fiction. However, it’s a strategy that is fast becoming a reality in some countries, and one that is soon to be adopted here.
It’s seen by some experts as the only long-term solution to a plague that is wiping out honeybee populations across the globe. Nature’s most prolific pollinators have been struggling to cope with the ravages of a tiny blood-sucking parasite known as the varroa mite. The crab-like mites attach themselves to bees, acting as vectors for several lethal viruses to enter the bee’s body and spread infection through hives.
In a little more than two decades, the mites, in combination with other viruses, have killed off up to 30 per cent of Europe’s bees, and a whopping 85 per cent of Middle Eastern bees.
In the US, mite infestation has been linked to the phenomenon of “colony collapse disorder”. It has seen bee numbers drop by more than a third, and the country’s once-robust honey industry has been decimated.
Since they arrived on these shores in 1998, the mites have almost entirely wiped out Ireland’s population of feral honeybees, leaving bees from managed hives and other pollinating insects to fill the vacuum. The sight of wild bees swarming in old tree trunks or household cavities, once a common part of summer, is now largely a thing of the past.
While managed hives can be successfully treated with bee-friendly pesticides to control the problem, the mites have become increasingly resistant to the chemicals in the pesticides, hence the need to consider more novel ways to tackle the problem.
The Tipperary-based Galtee Bee Breeding Group has begun a five-year project to develop a colony of “designer bees” which are capable of tolerating mite infestation. Micheál Mac Giolla Coda, apiary manager with the group and one of Ireland’s leading experts on beekeeping, says the plan is to harness the bee’s natural defences against the mite. Certain bee colonies, he explains, have adopted a grooming behaviour to counteract the varroa, which involves biting off each other’s mites.Similarly, other hives appear to exercise tighter hygiene controls, ridding the colony of varroa-infected larvae, which breaks the breeding cycle of the mite.
The problem is that different colonies and even individual bees within the same hive display varying levels of these behaviours. The Galtee group’s task is to select and cross-breed the bees with the most advanced grooming and hygiene habits.
In the UK, scientists, using observational hives in which bees are individually numbered, have traced superior grooming behaviours to individual drone patrilines (male lineages) using DNA markers.
The Galtee group is, however, planning a more basic screening process in simply identifying the hives with the best mite-attrition rates. This will be done, Mac Giolla Coda says, by observing the number of damaged mites and discarded mite-affected pupa parts that fall from the hive on to specially placed observation trays. By selecting for these behaviours, the group hopes to breed a strain of bees that is more adept at coping with the mite, a practice that has been successfully carried out in other countries.
When 60 per cent of the “natural mite fall” exhibits signs of having been intercepted by grooming, studies show the hive no longer needs to be treated with miticide; in other words, the bees are adequately dealing with the problem on their own.
“We hope to produce strains of disease-resistant and mite-tolerant bees which we can eventually return to the wild,” he says.