Honeybees are dying off at an alarming rate. For several years, scientists have been looking at a number of factors that may be influencing their survival. Now, a University of Idaho scientist has found a working model that may explain why honeybee colonies collapse.
UI professor Brian Dennis built a mathematical model that shows the size of the beehive may be the critical factor in colony collapse disorder. That’s when too many bees in a hive die or disappear and the hive falls apart.
Dennis has seen hundreds of studies on different environmental factors blamed for hive death. One recent review paper looked at 60 different factors, pesticides, viruses, parasites and so on.
“And no single factor emerged as a convincing leading cause of bee colony decline.”
His model shows hives are highly structured and need a certain number of worker bees to survive. When the hive is stressed, by a virus or pesticide, that number can drop below the critical level. If the queen can’t produce more workers fast enough, the hive falls apart. There has to be enough worker bees in each hive.
“And so if there aren’t enough adult workers to help recruit more adults, faster than adults die off, then that hive will be in trouble.”
Under the right environmental conditions, that critical number can be as low as 1,000 bees. But once the hive is stressed, by say pesticides or parasites, that number goes up. More bees are needed to replace those that die.
Dennis says, in effect, the tightly organized society of the honeybee doesn’t respond well to human interference, like pesticides and viruses. Dennis says queen bees can’t lay eggs any faster, so in order to save beehives from collapsing, humans will have to adapt, if we want to keep honeybees around, by figuring out bee stressors and working to stop them. One way is to manage regions of agriculture cooperatively. When parasites hit one area, humans will have to work together with the USDA to protect the bees where they live.
His work was recently published in the science journal PLOS One.
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