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What’s causing CCD? A case of disappearing bees

March 24, 2010
Courtesy - Muhammad Mahdi Karim

Western Honeybee (apis mellifera) - courtest Muhammad Mahdi Karim

Blueberries. Cherries. Raspberries.

It sounds like a perfect summertime snack, but it’s also a list of what might be off the shelves if the honeybee isn’t saved.

All across Canada, western honeybees (apis mellifera) have been dying out steadily over the last few years. Even with some promising research, local beekeepers are having problems saving their hives.

Dave Gale, 51, has been working as a beekeeper for the last 27 years, 25 of which have been spent at his home-based ‘Dave’s Apiaries’ in London, Ontario.

“We’ve had losses as high as 30%. This year was good, but the last few years have all been around 30%,” said Gale.

When beekeepers open their hives in the spring they find corpses, said Dr. Ernesto Guzman, 50, Professor of Apiculture at the University of Guelph, and a member of one of the largest studies in North America that set out to identify the cause of the sudden increase in bee deaths.

Guzman said the average colony loss in Canada two years ago was 36%, and last year it was around 32%.

An average colony of honeybees can hold around 50,000 bees, and most beekeepers have multiple colonies.

In their study, Guzman and his team followed more than 400 colonies, selected from six different counties across Ontario, for almost a year.

They tested for seven different possible causes of death, including viruses, mites, and hive characteristics like population levels before the winter.

“We tried to associate some factors to colony mortality. We knew the exact conditions of each colony in the fall. In the following spring, some colonies survived and some colonies died,” said Guzman.

Guzman and his team compared the fall conditions of the colonies that survived to those that died out.

The possible cause most strongly associated with colony mortality in Southern Ontario was varroa mites (varroa destructor), said Guzman.

Varroa mites are a small red-brown mite which lives off the blood of bees. They are thought to have arrived in Canada from the United States in the 1980’s, and have been causing damage to bee colonies ever since, said beesource.com, a website for beekeepers.

The problem can’t be blamed entirely on the mites, however. Guzman thinks that agricultural practices, and even the actions of some beekeepers, might be making the problem worse.

For beekeepers like Gale, observations on the ground can help back up the researchers.

Gale thinks the bees are being stressed by the changing face of agriculture around London.

“The crops in this area have changed. There’s not as much for the bees to forage on as there was years ago. It’s mostly corn and beans in this area. There are less dairy farms and less beef cattle farms,” he said.

“When there was more dairy and beef cattle, they grew more hay, and the bees liked to forage on the blossoms from the alfalfa,” said Gale.

Guzman and other scientists say that modern agriculture is becoming increasingly reliant on monocultures – vast fields of a single type of crop.

“Normally bees would collect pollen from different sources to balance their diet. When they are subjected to a single pollen source they could suffer from malnutrition,” said Guzman.

Along with bees being improperly fed, the monoculture style of farming has other problems. When such a large area is filled with plants that need pollination, the local bee populations can’t keep up with the work.

Bees aren’t only used for making honey, they’re also one of the world’s most relied on pollinators.

According to Diana Sammataro and Alphonse Avitabile in their book The Beekeeper’s Handbook, in addition to fruit, honeybees are nearly essential to the production of almonds, avocado, garlic, asparagus, and much, much more.

Right now, over 13,000 colonies from all across Canada are in New Brunswick to help pollinate blueberries, said Guzman.

Gale said that he doesn’t take his bees on long trips, but for beekeepers that do, it’s not an easy journey.

“Those bees leave on a truck around the first of June, and they come back through Toronto on the long weekend in July. Sometimes they overheat if they get into stop-and-go traffic coming through Toronto. You can lose a lot of bees right there,” said Gale.

Guzman said a normal way of recovering from losses is for beekeepers to split their hives in the spring.  They split the colony in two, putting some bees in the old hive, and some in a new hive.

But beekeepers are stressed, and some are having problems dealing with their extra losses.

”Sometimes beekeepers split their colonies too much to try to recuperate those lost bees and fill the empty boxes. They end up having weakly populated colonies in the fall that won’t make it through the winter,” said Guzman.

Guzman pointed out that even when beekeepers split their colonies, with all the extra losses, there are not enough bees to pollinate all the crops for which we need them.

“If this trend continues, let’s says five to 10 years from now, there will be a shortage of certain products because of lack of pollination. That would result in higher prices, and the average citizen would end up paying more money for his or her food.”

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5 Comments leave one →
  1. March 24, 2010 6:17 am

    This article was from the summer of 2009, so the ‘right now’ reference may feel a little dated.

  2. March 24, 2010 8:14 am

    I found your point about the bees’ not obtaining a balance diet interesting. Humans have seen how a lack of micronutrients in their diet can cause diseases, such a scurvy and rickets. It makes sense that bees could very well be experiencing a similar result to a lack of nutrition. I have to wonder what kind of changes in plant fertilization methods might be affecting the honeybees as well. If the plants they are consuming are not receiving a balanced diet themselves, the impact would be even greater.

    • Lorraine Miller permalink
      March 23, 2011 3:31 pm

      I agree with the above comment

  3. Lorraine Miller permalink
    March 23, 2011 3:30 pm

    I think that the use of pesticides has a profound effect on the bee population. It suppresses the immune system so that the bees can not fight off any viruses or anything else that would eventually destroy them. If they are not taking in the right food sources, they will not survive. The world has to wake up and realize that chemicals of any kind be it fertilizers, sprays etc. are just poison that we can do without. Our planet and our people would all be healthier. Especially our children and grandchildren.

    • March 23, 2011 3:34 pm

      I would hazard a guess that the millions of people who are able to eat today because of pesticides and fertilizers, as well as improved farming practices and irrigation, would strongly disagree with you. An over-reliance on industrial farming techniques is I suspect a consequence of, and cause of, overpopulation.

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