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A viral disease that causes honey bees to experience intense trembling, not flying and dying within a week is spreading exponentially in Britain.
Chronic Bee Paralysis Virus (CBPV) was only recorded in Lincolnshire in 2007. A decade later, it was found in 39 out of 47 English counties and six out of eight Welsh counties, according to data collected from visits to more than 24,000 beekeepers.
In addition to struggling to fly, affected bees develop shiny, hairless abdomens. Scores of dead people are found outside the hives, with entire colonies frequently wiped out by the disease.
A team of scientists led by Professor Giles Budge of Newcastle University identified clusters of the disease, and the cases were concentrated among apiaries led by professional beekeepers rather than amateurs.
In the study, published in Nature Communications, the scientists used data from 130,000 imports of honey bees from 25 countries to show for the first time that the disease was almost twice as likely in apiaries owned by beekeepers who imported honey bees. Professional beekeepers bring queens of honey bees to replenish their hives every few years.
Another way that commercial beekeeping could be contributing to the spread of the disease is because they tend to handle large colonies, and the virus seems to spread rapidly in densely populated hives.
But Budge said it was not clear that the disease was imported through queens and that it was “unfair” to claim that the disease was caused by industrial beekeeping.
“Beekeepers in this country tend to be quite small. A standard beekeeper could have 100 to 200 colonies. In the United States, they have up to 10,000. Even in Germany there will be large-scale beekeeping, “he said.
According to Budge, professional beekeepers can have problems in Britain because they are very successful in bringing bees during the winter and building colonies in the spring to take advantage of the first flowers, such as rapeseed. If the weather becomes humid, these large colonies are limited to one hive. “You can’t socially distance yourself in a hive that easily, but you can manage it by increasing the space there,” Budge said.
Viral disease has been around for centuries, its symptoms were first described by Aristotle, but researchers are eager to discover whether a new, more virulent strain is behind its global rise. In the United States, the prevalence of CBPV was 0.7% in 2010, but reached 16% in 2014. The prevalence in Italy doubled from 5% to 10% between 2009 and 2010. In China, the prevalence increased from 9% to 38%.
Infected adult bees carry the virus for up to six days without showing symptoms, and can spread it to other colonies where different bees forage for food.
But honey bees generally do not feed more than 10 km in Britain, and the study found significant clusters of the disease up to 40 km away. A quarter of beekeepers have multiple sites, so they could be helping the spread of the disease.
Although the disease appears to be “running out” in Britain and does not recur at critical points between seasons, it eventually returns to the country elsewhere. The disease has also been found in populations of bumble bees and wild ants, but the direction of transmission is unclear.
Rob Nickless, president of the Bee Farmers Association, who supported the study, said: “This is the type of research that brings practical benefits to the industry: helping grassroots beekeepers to improve the health of bees and increasing UK honey production. “
The researchers will continue to examine the genetics of the disease to determine if there is a new strain and try to discover if imported queens are bringing the disease to Britain, or if those queens are simply more susceptible to the virus that is already here.
