In late 2006, honeybee keepers across the United States began reporting inexplicable behaviour in their colonies: for no apparent reason, bees were leaving their hives and never returning.
Puzzled scientists and worried beekeepers were anxious to figure out what caused the bees to act so strangely. Hypotheses about the cause of the die-off, dubbed Colony Collapse Disorder (CCD), soon began to surface. Theories blamed everything from mites to pesticides to cell phones but the only point of agreement was that bees were vanishing, at least until recently. A study in the journal Science points to Israeli Acute Paralysis Virus (IAPV) as the most likely cause of CCD. Researchers compared genetic samples from beekeeping operations that had reported CCD with samples from unaffected operations. They found the virus in all of the CCD stricken colonies and only one of the healthy colonies. As well, it was found that IAPV caused an increase in a hive’s risk of CCD. The researchers propose that Australia is the source of the virus, as they found relatively high concentrations of IAPV in a sample of imported Australian bees.
Dr. James Thomson, a professor of ecology and evolutionary biology at the University of Toronto, has been studying bees for 30 years and was not involved in the study.
“This [study] to my mind is a pretty good smoking gun for [CCD] being a viral disease and that’s more or less what people were saying,” said Thomson. “It had to be some infectious disease that would move around quickly.”
The researchers point out that, due to the infancy of their research, they have not explicitly proven that IAPV is the cause of Colony Collapse Disorder. They do, however, maintain that IAPV is a very good indicator that a honey bee operation may develop a disease.
Some scientists have taken a different approach to the CCD problem. Instead of seeking the cause of the bee disappearance, they are trying to find a means of pollination that could be used in its place. Currently used for the commercial pollination of certain crops, solitary bees and bumblebees offer a prospective solution.
In a study published late last year in the Proceedings of the National Academy of Sciences, two researchers from the University of California showed that honeybee sunflower pollination efficiency can increase when wild bees are also present. “We found that behavioral interactions between wild and honeybees increase the pollination efficiency of honeybees on hybrid sunflower up to five-fold,” wrote Sarah Davis and Claire Kremen.
Kremen also worked on a study that looked at the relationship between wild bees and watermelon pollination. The study, published in Ecology Letters, proposed that watermelon farmers might be able to use wild bees instead of honeybees to propagate their crop.
Using wild bees to supplement honeybees is not as easy as replacing one with the other, however. Honeybees are convenient pollinators for large-scale, conventional agriculture because they live separate from the crop site, allowing for large quantities of pesticides to be used on crops without worrying about killing the bees.
“You can create a biological desert in your fields and then just truck in honeybees for the week that you need pollination,” explained Thomson. “Then they get trucked somewhere else and pollinate for someone else and you don’t have to create a healthy ecosystem that can support wild bees throughout the year.”
As well, many people raise honeybees for a living, either as pollinators or as honey producers. Wild bees do not make marketable quantities of honey. “A big bumblebee nest might give you a teaspoon full on a good day,” said Thomson.
Investigations regarding the disorder are still in their early stages and there is a lot of research to be done concerning the root of CCD. One thing is certain: more hard evidence is needed about both CCD and wild bees before anyone can be sure of the severity of the bee die-off.
Further information is needed about colonies that have suffered from CCD, especially concerning the magnitude to which their corresponding bee operations have been affected. Until a greater sampling of CCD-affected hives has been tested for IAPV, no one can be sure that it is the cause of the bees’ mysterious behaviour. It is also unclear how much of the honeybees’ work wild bees could do. This stems partly from the fact that the ecology of most wild bees has not been studied in depth enough to accurately predict how much of the load they could bear.
“There is some redundancy and some ability in the system to be resilient and to take up slack,” said Thomson. “But clearly it’s deeply worrying when we see species winking out across the landscape—especially when we don’t know why.”
