In a bit of welcome news -- welcome because perhaps now we can fix the situation -- researchers at Harvard School for Public Health may have found what's been killing honey bees around the world.
According to researchers, low doses of imidacloprid, the world's most widely used insecticide, are linked to Colony Collapse Disorder, in which bees abandon their hives over the winter and eventually die. The new study also found that low doses of a second neonicotinoid, clothianidin, had the same negative effect. Both insecticides are classified as neonicotinoids, which may impair bees' neurological functions. Neonicotinoids are used in agriculture and are found in products marketed for use in gardens and on lawns and ornamental trees. (If you would like to learn which products contain neonicotinoids, a good place to start is www.xerces.org/neonicotinoids-and-bees.)
This most recent study replicated findings from a 2012 research project, also conducted at Harvard.
"We demonstrated again in this study that neonicotinoids are highly likely to be responsible for triggering CCD in honey bee hives that were healthy prior to the arrival of winter," said lead author Chensheng (Alex) Lu, associate professor of environmental exposure biology at HSPH.
At one time, scientists suspected mites as the culprit, but this most recent study concluded the insecticides might make honey bees less resistant to mites or other parasites. There was also some question about whether practices of beekeepers -- who often travel with their hives to pollinate crops around the country -- were responsible for CCD.
"The new study found that bees in the hives exhibiting CCD had almost identical levels of pathogen infestation as a group of control hives, most of which survived the winter. This finding suggests that the neonicotinoids are causing some other kind of biological mechanism in bees that in turn leads to CCD," stated a press release from HSPH.
The researchers worked with the Worcester, Mass., County Beekeepers Association and studied the health of 18 bee colonies in three locations in central Massachusetts from October 2012 through April 2013. At each location, the researchers separated six colonies into three groups -- one treated with imidacloprid, one with clothianidin, and one untreated.
There was a steady decline in the size of all the bee colonies through the beginning of winter -- typical among hives during the colder months in New England. Beginning in January 2013, bee populations in the control colonies began to increase as expected, but populations in the neonicotinoid-treated hives continued to decline.
By April 2013, six out of 12 of the neonicotinoid-treated colonies were lost, with abandoned hives that are typical of CCD. Only one of the control colonies was lost with what appeared to be symptoms of a common intestinal parasite.
The researchers are hoping that further study can pinpoint the biological mechanism that is responsible for linking the pesticides to colony collapse disorder.
According to the USDA, there were four million honeybee colonies in 1970; today there are 2.5 million.
"Hopefully we can reverse the continuing trend of honey bee loss," said Lu.
Kenneth Setzer, of the Fairchild Tropical Botanic Garden, writing for the Miami Herald, noted that before the 1600s, North America had no honeybees.
"Honeybees, like the Europeans who introduced them, were immigrants from the Old World. But there was no lack of bees here. We had bumblebees, sweat bees (often confused with flies), digger bees, mason bees, carpenter bees and leaf-cutter bees -- and still do."
But since their introduction, honey bees have become vital to production of food in America.
"If you want a price tag to convince you of their value to us, the USDA Agricultural Research Service reports that bee pollination adds about $15 billion to crop value annually. That's not including the value of the crops themselves, which is much higher," writes Setzer.
How much more would it cost if the bees were gone and we had to figure out another way to pollinate our food crops? There really is no telling, but Setzer said there are things everyone can do to help protect all the bees, and not just honey bees.
They include not indiscriminately spraying bug killers.
"Often the residual chemicals left behind will not harm your target but will kill a honeybee. If you must spray, avoid doing so at midday, when bees are out foraging for pollen and nectar."
Setzer also recommends avoiding herbicides, especially those containing atrazine (which was banned throughout Europe because it contaminated groundwater and wreaks havoc on susceptible amphibians, causing all kinds of hormonal and reproductive destruction).
Homeowners can also help out by planting flowers, especially native wildflowers. "Even planting food for yourself, like plants in the cucumber family, will produce flowers attractive to bees."
Bees such as the bumblebee, which pollinate blueberry, tomato, eggplant and peppers, need bare sandy soil for their subterranean dwellings.
"Some solitary bees will live in cavities you can create by drilling holes in a block of wood and hanging it in a tree, or try tying a clump of bamboo stems together for the same result," writes Setzer.
We would recommend doing all the things Setzer suggests, but also being more cautious about using insecticides or herbicides of any kind. Many pesticides and herbicides also pose risks to human health, especially to children and woman carrying fetuses.
Perhaps the best thing we can do is not use bug and herb killers at all. Yes, it makes working in the garden or on the lawn a little more difficult, but why does everything have to be easy? If we are concerned about our own health and the ecosphere around us, finding natural ways to combat pests, or getting down on our hands and knees to pull weeds out of the ground one by one, seems like a small price to pay.