THE BEE BOX
32
Almond Facts
MARCH | APRIL 2016
The Bee Box
CHRISTI HEINTZ
& TARA McCALL
“This could be a game changer for honey bee
colony health,” says Grass Valley beekeeper
and biologist Randy Oliver. “Dr. Stephen Martin
(Salford University, UK) may have hit the jackpot.”
What is all the excitement about?
DeformedWingVirus
andVarroa
Professor Martin and his team have recently published
several articles in scientific journals with research, in part,
funded by Project Apis m (PAm). Dr. Stephen Martin
wrote recently in the
American Bee Journal
(November,
2015), “It is now becoming clear that the role of a small
group of viral pathogens, especially Deformed Wing Virus
(DWV), lies at the very heart of the Varroa problem.”
The Varroa mite, of course, is the number one pest of
the honey bees that are so
important
to the pollination of
California’s almond crop. The mite itself is dangerous
enough, its offspring developing in honey bee brood and
then growing up to pierce the exoskeleton of adult honey
bees to feed off the honey bees’ hemolymph and possibly
fat bodies as well. If that weren’t enough, the Varroa
infects the bee with deadly viruses as well.
DWV is one of several viruses linked to Varroa mite
infestations and is tied to winter colony mortality. While
the disease can be found in colonies not infected with
Varroa, it is generally more common and more damaging
in colonies where mites are present. In heavily Varroa-
infested colonies, almost all of adult workers may be
infected with DWV and many will have the deformed
wings typical of this virus.
To analyze the interaction between DWV and Varroa,
Dr. Martin and his team traveled to a remote island in
Brazil to study populations of European honey bees that
appear to be resistant to Varroa. Varroa originally was
a pest of the Asian honey bee,
Apis ceranae,
and jumped
species to the European honey bee,
A. mellifera
, when
A.
mellifera
was imported to Asia. Unlike Asian honey bees,
European honey bees are not resistant to the Varroa mite -
except for the anomaly in Brazil. On the Brazilian island,
despite high Varroa mite levels in European honey bees
(fluctuating seasonally between 2,000-5,000 mites during
the year without Varroa treatment), colonies are healthy
with no reports of deformed wings or death due to DWV.
Dr. Martin used next-generation sequencing to define
three variants of DWV. DWV type A, found to be the
lethal variant, is most likely the culprit bringing down our
honey bees in the U.S. When DWV type B, a non-lethal
variant, becomes established in colonies, the lethal type
A DWV variant will not persist. In other words, DWV
type A leads to colony death, but there are no reports of
type B being linked to colony death or type A occurrence
when type B is present. Scientists are hoping to use this
information about the host-pathogen relationship to
develop an effective treatment that minimizes colony
losses in the future.
The third variant is DWV type C, which appears to have
diverged from type A and type B some time ago. At this
Randy Oliver, a Grass Valley beekeeper and Project Apis m. scientific
advisor, has been instrumental in supporting and sourcing funding for
Dr. Stephen Martin’s landmark Deformed Wing Virus research.
