YSM Issue 86.1

BY KATIE LEIBY
What if the most important cells
in your body were not your own
but rather those of bacteria?
Researchers continue to uncover evidence
that communities of bacterial symbionts
within the gut play important roles in the
health of their hosts. Nancy Moran, the
William H. Fleming, M.D. ’57 Professor of
Biology in Yale’s Department of Ecology
and Evolutionary Biology, studies these
bacteria and their influence on not humans
butbut the health of honey bees.
Until now, few have taken an interest
in understanding the nature of the honey
bee gut microbiota. A strong link exists
between honey bees and the bacteria intheir
guts; each organism depends on the other,
yet the precise nature of this relationship
is still largely uncharted. The remarkable
community consists predominately of eight
bacterial species found only in honey bees
and some bumblebees. Moran says, “I feel
like we’re really studying something that is
part of the bee.”
An Important Pollinator on the Decline
Honey bees are nature’s primary pollinators:
at least 80% of agricultural crops, from
almonds to avocados and, soybeans, andto
sunflowers, depend on them for growth.
Approximately one-third of everything we
eat has in some way benefited from honey
bee pollination. Honey bee-pollinated crops
are worth $15 billion in the United States
annually, in addition to the value of the honey
produced. Increasingly, the bees we depend on
for pollination are managed by beekeepers and
transported across the country to pollinate
specific crops. The number of wild bees is
decreasing: fewer than 20% of honey bees
today are feral with almost none in heavilyfarmed
regions.
The number of managed honey bee
colonies has decreased from 4 million in the
1940s to 2.5 million today. In recent years, this
decline is due in part to a phenomenon termed
Colony Collapse Disorder (CCD). During
the winter of 2006–2007, beekeepers began
experiencing unexplained losses of 30–90%
of their hives. Adult worker bees would suddenly
disappear, with no dead bee bodies in
or near the hive. Although the queen would
still be alive, colonies were often reduced to
fewer than the 10,000 bees needed for colony
survival.
Each winter between 2006 and 2010, honey
bee populations fell 33% with one-third of
those losses contributable to CCD. CCD is
thought to result from a multitude of interacting
factors, including habitat loss, insecticide
use, parasites, stress due to managed pollination
migrations, and the quality of available of
food and water. Managed bee losses during
the winter of 2011–2012 were only 22%,
which may represent a decline in CCD or
may merely be the consequence of changing
environmental conditions is unclear.
Beneficial Gut Communities Revealed
The great diversity of bacteria that make
up the gut community of host organisms,
www.yalescientific.org
January 2013 | Yale Scientific Magazine 17