From: Kim Flottum [mailto:[log in to unmask]]
Sent: Thursday, May 08, 2008 12:03 PM
This ezine is also available online at
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CATCH THE BUZZ
This information was gleaned from Eric Mussen's UC Davis Newsletter.
Information below on how to subscribe. It is one of the best there is.
This article has good information on treating Nosema cerane. You need to
know this.
Colony Collapse Still Around
Stories of collapsing colonies are still coming in. As in the
previous year, they started in late summer and continued right through
almond bloom. Involved beekeepers varied from some who never had
problems before to others who were hit hard two years in a row.
As in previous years, samples taken after the collapse don't tell us
too much, because whatever happened occurred earlier. What we see is
empty hives with no sample bees left to take.
Something that quite a number of beekeepers have noticed is that
Nosema infections are much higher than they anticipated. When I arrived
fresh from the University of Minnesota, I really emphasized the
necessity of controlling nosema disease, especially if a beekeeper was
going to sell queens and bulk bees to other beekeepers. That made quite
an impact, especially on our
Bee Breeders. Sales of fumagillin rocketed up in California.
Our Bee Breeders have been using fumagillin for decades to control
Nosema apis with very good results. They had their treatment schedules
worked out and samples sent to me for spore counts were nearly always ND
(not detected).
This year, Dr. Marla Spivak and her crew began a project, with the
assistance of Sue Cobey, to help the Bee Breeders select breeder queens
whose workers demonstrated elevated hygienic behavior. Marla was
pleasantly surprised to observe how well that trait already is
established in many of the stocks.
During those visits to the beekeeping outfits, samples also were taken
of worker bees and analyzed for Nosema spores. A few years ago, ND was
the norm. This year, ND was a rare exception. Most colonies had levels
of infection that required treatment, according to the old guidelines.
Some counts were as high as we see in laboratory studies of caged bees.
How did this happen? Did our old friend, Nosema apis, become
resistant to the fumagillin? I doubt it. The few studies that have
been conducted over time showed no problem of that sort.
Perhaps this isn't Nosema apis. It is likely to be Nosema ceranae,
according to verbal reports of the CCD researchers. The European
studies suggest that N. ceranae is susceptible to fumagillin, but they
use it at dosages up to four times stronger than we use for Nosema apis.
The Bee Breeders are not the only ones to see increased Nosema
infections this year. Other California beekeepers are reporting high
spore counts. Some are reporting globs of bee feces on the fronts of
hives and on the ground in front of the colonies. Last fall, Randy
Oliver was taking some samples from his colonies. He found that
returning foragers, captured around noon and especially if they were
writhing around on the ground, had elevated levels of spores. However,
workers taken from the brood nest (nurse bees?) did not have
demonstrable spores.
This follows the pattern that Dr. Higes presented at our MegaMeeting
in Sacramento a few months ago. He stated that the nurse bees would
appear to be uninfected during the spring and summer, but as late summer
and fall approached, the bees inside the hive would start top build up
spore levels, as well as the foragers. When nearly all the "house bees"
were infected, the adult population would abandon the hive. Is this
what we call CCD?
As our beekeepers try to resolve this nosema disease problem, they
have to con-sider three important factors. The first is that worker
honey bees infected with Nosema ceranae apparently will not take feed,
either syrup or patty. Thus, the bees have to have the medicated syrup
applied onto their bodies to force them to clean themselves off and take
their medicine. Since you can only apply a small amount of syrup per
treatment, the researchers in Spain suggest four treatments at one week
intervals.
The second difference between treating Nosema apis and N. ceranae
concerns the dosage of the medication. Without saying much about
experimental trials, the Spanish have decided that the dosage should be
about 2.5-3.0 times higher than that used for N. apis. Thus, they would
mix the 95 gram bottle into 40 gallons of syrup, instead of into 100-120
gallons.
The third interesting factor is the formulation of the fumagillin that
now is available to us. Fumagilin-B(r) is imported into the Unites
States from a Canadian company, Medivet. The product is not
"registered" as such, but the FDA has worked out a type of memorandum of
understanding so that the product can be imported and used in the U.S.
The numbers on the label differ from those on the label of the old
Fumidil-B(r), but the mixing instructions are the same for Nosema apis.
However, since it is not likely that we have Nosema apis in our bees
anymore, you should pay attention to the instructions for use against
Nosema ceranae.
The Medivet label divides its instructions into fall and spring uses.
Fall isn't difficult, because they are the same instructions as for the
old Fumidil-B in the fall. It is the spring use that demands careful
study.
The instructions say to feed "at a rate of 30 mg fumagillin activity
per colony, 4 times at 1 week intervals." For our purposes, the next
set of instructions is better. "Dissolve 454 g Fumagilin-B (one large
bottle) in 40 US gallons of sugar syrup and feed each colony 1 pint
(treats 320 colonies). Repeat 3 times at 1 week intervals." Schedule
to complete treatment at least 4 weeks before adding honey supers."
Yes, this means that the dosage is about 2.5 times stronger than we
used to use for Nosema apis. Yes, this means many additional visits to
the bee yards. And, if you notice that the bees in the colony just are
not taking up medicated syrup, you may have to pour it on the bees.
That is the procedure used by the Spanish researchers. Spraying the
applications on the bees is being tested, currently, by Medivet.
There are a few other Medivet suggests that bear repeating. Make sure
the fumagillin is well blended into the syrup. This formulation blends
into syrup much more readily than the old Fumidil-B - do not get the
syrup very hot or the fumagillin will be inactivated. Check to see if
the bees are taking the syrup. Nosema ceranae-infected bees often stop
feeding, all together.
You can subscribe to Eric Mussen's electronic Newsletter by visiting the
address below. It is one of the best there is.
http://entomology.ucdavis.edu/faculty/mussen/news.cfm
<http://entomology.ucdavis.edu/faculty/mussen/news.cfm>
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