Loss of Honeybee Biodiversity: What is Killing Them?
By Daniel Straub
A recent TED conversation and trip to the University of
Oregon’s Urban Farm made me aware of an alarming fact, and I must believe many
others, were not yet aware of. This is the fact that bees are dying at a
terrifying rate. This got me extremely interested in what exactly this was and
why it is happening. Colonies of bees are suffering from what is called Colony
Collapse Disorder (CCD). CCD was first
noticed in 2006 when beekeepers observed a disappearance of their worker
honeybees that would later be found dead, or most often, not at all (Walsh
2013, Kaplan 2013). CCD can result in the loss of 30-90 percent of a particular
colony dying (Kaplan 2013). Honeybees are extremely vital to our agriculture.
They are responsible for about one third of pollination in the United States
agriculture business; pollinating a lot of good and healthy food such as
apples, melons, onions, almonds, and broccoli to name a few (Holland 2013).
What is also truly scary, is the fact that no one knows what is causing CCD to
happen. However, over the past few years, through research, a few ideas have
come to the forefront on what might be causing CCD. In this blog post I intend
to summarize my findings from what is available and causing this devastating
destruction to our bees.
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| Figure 1: Typical Honey Bee (Apis Mellifera) Photo Credit: John Kimbler. National Geographic |
Through researching many articles it seems that a very
talked about cause of CCD is the use of pesticides, specifically, the
neonicotinoid family. I should say this is talked about for most people in the
scientific community however, not the US government (Ullrich 2013, Kaplan 2013).
In a recent study, experimenters exposed honeybees to what is thought to be the
leading culprit, neonicotinoid pesticides. They found that not only did the
honeybees that were exposed to the pesticides have higher mortality rates but
that their memory and learning abilities were also impacted, compared to those
not exposed (Williamson and Wright. 2013). Honeybees must perform very elaborate
behaviors for finding food and for signaling the other bees of the colony where
the food is. If their learning and memory is affected by these pesticides then
not only is the individual at risk, the whole colony could be at risk as well.
Another study also found that bees exposed to neonicotinoids were more easily
infected with the gut parasite Nosema (Holland 2013). The European Union has
implemented a two-year ban on such neonicotinoids to investigate the pesticide
and its effects. While it took a lawsuit filed against the EPA to accelerate
its research into this category of pesticides (Walsh 2013, Holland 2013).
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| Figure 2: Farmers with Insufficient Bee Coverage on Hive from CCD Photo Credit: vanEnglesdorp et al. 2009. PLoS ONE |
Another highly investigated topic is the role of pathogens
and parasites in CCD (vanEnglesdorp et al. 2009, Kaplan 2013 and Walsh 2013).
Dennis vanEnglesdorp (who gave the below TED talk) and his team of
experimenters conducted a study where they looked at the virus load (amount of
viruses present) of different hives that were experiencing CCD and compared
those to control hives that did not experience CCD. What they found was that
the bees that had experienced the CCD had higher amounts of virus loads,
particularly the parasite Nosema spp. (a parasitic fungus) and Israeli Acute
Paralysis Virus (a deadly virus)
(vanEnglesdorp et al. 2009). The
study found, and the USDA agrees, that there is no specific pathogen or
parasite that was found with enough frequency to be the specific cause of CCD.
The study goes on to state that pathogens play a crucial but secondary role in
CCD, finding the primary factor is the holy grail. They believe that the higher
viral loads and the co-infection with other disease agents (i.e. Nosema and
Israeli Acute Paralysis Virus) seen in the CCD hives shows that this is
something that cannot be ignored. The study along with the USDA states the lack
of knowledge in this area and the further need for research. Since this study,
not much more has been found that widely differs from this in role of pathogens
and parasites other than the parasite, Varroa mites, which also have been known
about for sometime (Comman et al. 2012). Not much is known yet about these
mites, which are found in the honeybee hives and may play a role in CCD and
which little is known and like the other pathogens/parasites, more
investigation is needed (Kaplan 2013).
A study that I found extremely interesting that related to
the class was a study about the microbes that are associated with honeybee CCD
(Cox-Foster et al. 2007). The study
looked at the bacteria that were found on honeybees over a three-year period.
They looked at hives that had been affect with CCD and used those that had not
been affected by CCD as the control. The study found that the bacteria that
were found on the CCD hive and the non-CCD hives differed (Figure 3). Also,
they found that the non-CCD hives had higher amounts of new bacteria that were
not present at the beginning of the experiment (Figure 3). This led the
researchers to the conclusion that the different bacteria and different amounts
of bacteria found on the non-CCD were doing something to protect them from
diseases that the CCD colonies were unable to do. The CCD colonies were found
to have high amounts of Israeli Acute Paralysis Virus.
| Figure 3: Different Bacteria Found On Bees Photo Credit: Cox-Foster et al. 2007. Science |
The USDA and National Geographic articles also bring up the
new stressors that the honeybees now face as a factor of CCD. The USDA breaks
the stressors into two categories. First, is management stressors; these are
caused by poor-nutrition due to overcrowding and new migratory stressors they
now face. The second is environmental stressors; these are caused by lack of
diversity of pollen/nectar, availability of pollen/nectar and the availability
water. All of these could be factors that have a role in CCD and in which there
is little knowledge of how these stressors may affect honeybees.
From what I have found, this seems to be where the current
state of the troubled honeybee is. Still, colonies are collapsing and still we
do not know why. The one bright spot seems to be that this issue is gaining
momentum. Though we still do not know why this is happening to the bees, it
appears there is a narrowing of ideas and researchers are targeting specific
areas. From certain reoccurring pathogens and parasite to a family of
pesticides to the bee’s own microbiom, it seems that research is heading in the
right direction. However, more still needs to be done. The importance of bees
cannot be understated, as I have recently learned. Bees are vital for
agriculture, being responsible for pollinating one third of crops, valued at
200 billion dollars (Walsh 2013). This problem is not only one seen blaring
here in the United States but the disappearing of honey bees is happening
globally as well, further adding to the importance (Holland 2013). Good ideas
for the future have been put forth like the urban beehives as we have
discussed. But to me this does not fix the problem at hand. It seems paramount
that we figure out what is causing CCD so we can save future honeybee
generations and our food.
Video: Dennis vanEngelsdorp Ted Talk. Good Summary About The Plea For Bees
Credit. TED.com
Primary Literature
Cox-Foster, Dianna, S. Conlan, E. Holmes, G. Palacios, J.
Evans, N. Moran, P. Quan, T. Briese, M. Hornig, D. Geiser, V. Martinson, D.
vanEngelsdorp, A. Kalkstein, A. Drysdale, J. Hui, J. Zhai, L. Cui, S.
Hutchison, J. Simons, M. Egholm, J. Pettis, W. Lipkin. A Metgenomic Survey of
Microbes in Honey Bee Colony Collapse Disorder. Science. (2007) 10. (1126). 283-284.
Williamson, Sally, G. Wright. Exposure to multiple
cholinergic pesticides impairs olfactory leaning and memory in honeybees. The Journal of Experimental Biology.
(2013) 216 (10). 1799-1821.
vanEngelsdorp, Dennis, J. Evans, C. Saegerman, C. Mullin, E.
Haubruge, B. Nguyen, M. Frazier, J. Frazier, D. Cox-Foster, Y. Chen, R.
Underwood, D. Tarpy, J. Pettis. Colony Collapse Disorder: A Descriptive Study. PLoS ONE. (2009). 4(8) e6481
Comman, Scott, D. Tardy, Y. Chen, L. Jefferys, D. Lopez, J.
Pettis, D. vanEngelsdorp, J. Evans. Pathogen Webs in Collapsing Honey Bee
Colonies. PLoS ONE. (2012). 7(8)
e43562
Popular Media
Walsh, Brian. Beepocalypse Redux: Honeybees Are Still
Dying-and We Still Don’t Know Why. Time.
May 07, 2013. http://science.time.com/2013/05/07/beepocalypse-redux-honey-bees-are-still-dying-and-we-still-dont-know-why/
Holland, Jennifer. The Plight of the Honeybee: Billions of
dollars-and a way of life-ride on saving pollinators. National Geographic. May 10, 2013.
Ullrich, Christy. Are Honeybees Losing Their Way? National Geographic. February 13, 2013. http://news.nationalgeographic.com/news/2013/13/130213-honeybee-pesticide-insect-behavior-science/
Kaplan, John. Honeybees and Colony Collapse Disorder. United States Department of Agriculture
(Agriculture Research Division). 2013. http://www.ars.usda.gov/News/docs.htm?docid=15572
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