Where Have All The Bees Gone?

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Honeybee populations are decreasing due to a number of factors. Image by Annie Cavanagh

In the past 5 years, much attention has been devoted to the topic of Colony Collapse Disorder (CCD), a mysterious ailment that first appeared in 2006, affecting European honeybee colonies in the United States and Europe.  This disorder manifests as a sudden sharp decline (30-90%) in the number of worker bees in the colony as they fly away from the hive to forage, never to return.  This syndrome even appeared at the beginning of M. Night Shyamalan’s 2008 movie, The Happening, when Mark Wahlberg’s character, science teacher Elliot Moore, discussed it and its possible causes with his students.  It’s interesting that one of his student’s responses that CCD is “an act of nature, and we’ll never fully understand it” has until recently proven more prophetic than anyone might have predicted.

Honeybee Background

The common honeybee, Apis mellifera mellifera, is actually not native to North America.  Prior to the arrival of Europeans, pollination in the Western Hemisphere was largely accomplished by native species of solitary bees.  When European settlers started transporting non-native plant species to North America for cultivation, they also brought hives of European honeybees with them, the first of which arrived in the New World in what would eventually become Virginia around 1622.

Varroa destructor mite on bee nymph: Image by Gilles San Martin

After 5000 years of breeding for domestication, it should come as no surprise that geneticists have recently discovered that bees no longer have the normal genes responsible for detoxification and immunity that many other insects have.  This deficiency has left European honeybees vulnerable to a vast array of pathogens (mostly viruses) and parasites (mostly mites).  In addition, there are many environmental factors that may contribute to CCD by increasing stress and decreasing fitness of the bees including: pesticides, transgenic plants, hive migration (the practice of moving hives to bring bees in contact with different crops throughout the year), competition, climate change, and even cell phone radiation (this last one has been disproven). In any case, no single factor has been demonstrated to be sufficient on its own to cause colonies to completely collapse as with CCD.  Current consensus among entomologists is that CCD is due to a lethal combination of multiple pathogens/parasites and environmental factors that collectively stress and weaken the bees’ immune systems, making them even more susceptible to additional pests and pathogens until the colony reaches a tipping point and crashes.

Bees Are Disappearing: Does it Matter?

Honeybees serve a critical purpose for many plants. Image by Mamboman1

Now, you may be asking yourself “Why should I care?”  Consider this:  According to the USDA, more than 25% of plants making up the human diet require honeybee pollination services, which are also responsible for generating $15 billion in revenue annually in the U.S. alone.  Add to that bee pollination of forages such as clover and alfalfa which form the foundation of the diet of many domesticated livestock, and the potential economic impact of honeybee declines becomes even more obvious.

A quote famously (and falsely) attributed to Albert Einstein states that:

“If the bee disappears from the surface of the earth, man would have no more than four years to live.”

Although there is a grain of truth to it, that’s probably a little unrealistic.  Nevermind the fact that Einstein never said it.  I personally prefer May Berenbaum’s summary of the problem:

“To illustrate how pervasive the honey bee is, consider a Big Mac. All beef patties, the pickles, onions, lettuce, the cheese, the sesame seeds on the bun – that’s a lot.”

In other words, you’d just be left with an empty bun.  Think about that the next time you find yourself questioning whether you should be concerned about bees and their decline.

Sources

Associated Press. 2007. Declining honeybees a ‘threat’ to food supply. Last accessed: 10/1/2011.

USDA-ARS.  2008. Colony Collapse Disorder: A Complex Buzz. Last accessed: 10/1/2011.

USDA-ARS. 2011. Questions and Answers:  Colony Collapse Disorder.  Last accessed: 10/1/2011.

Zeder, M.A. 2008. Domestication and early agriculture in the Mediterranean Basin: Origins, diffusion, and impact. Proceedings of the National Academy of Sciences 105(33):11597-11604.

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