Larger cell size reduces varroa?

[stytko]

I was diligently reading through my December 2001 issue of the American Bee Journal, specifically the "Proceedings of the American Bee Research Conference" when an abstract on page 895 caught my attention.

Four researchers in Beijing, China performed an experiment "comparing the reproductive output of mites on two hosts: workers reared in worker-cells or workers reared in drone-cells". Unfortunately, they do not define what exactly is a worker-cell and a drone-cell (i.e. size, etc.).

The results of their experimentation is that workers reared in drone-cells reproduced less mites than workers reared in worker-cells. This seems to me to be the exact opposite of the findings of the Lusby's and many others working with 4.9 mm cell sizing.

The authors also stated that "To our knowledge, this is the first study to show that varroa mite reproduction can be affected by cell size of the host". Maybe Dee Lusby should forward them a couple of reams of her information to bring them up to speed :> )

Happy holidays to all!

Stan Tytko-Enjoying an incredibly mild November in Northern Ohio.

[Dee A. Lusby]

Hi Stan,
You are right, perhaps I should send them a whole downloaded copy of my SAGA from here at beesource.com.

In the mean time, this very paper has just been discussed on Biological Beekeeping found at:
http://groups.yahoo.com/group/BiologicalBeekeeping

If you are not a current member of the daily email discussion group you are hereby invited to join.

In the meantime I am going to post in rapid fire 5 quick postings on this very topic from there to here for both you and others to read.

The first post which started the discussion was Mr Barry Birkey himself, to which he wrote:

For what it's worth:

28. Zhou, T., J. Yao , S. X. Huang , & Z. Y. Huang -LARGER CELL SIZE
REDUCES VARROA MITE REPRODUCTION - In a study trying to determine the
mechanisms of why varroa mites do not reproduce on worker brood of Apis
cerana (the Asian hive bee), we accidentally discovered that both Apis
cerana and Apis mellifera queens lay worker eggs in drone cells in the fall.
We took advantage of this and compared the reproductive output of mites on
two hosts: workers reared in worker-cells (WW) or workers reared in
drone-cells (WD). We selected recently sealed (within 6 hours) brood cells
as transfer hosts. We obtained phoretic mites from adult workers and
transferred them into brood cells with a paint brush after each cell was
opened with a small pin. The opening was immediately sealed with melted
beeswax after mite introduction. The brood frames were incubated at 350C for
9 days after which each cell was opened and mite progeny scored. In 2000,
mites introduced into WD showed differences to WW in both the percentage of
mites that reproduced and the average number of offspring, but the
differences were not statistically significant (mean offspring number: t=
1.6, P = 0.12, % reproduction: X2 = 3.59, P 0.058). This is most likely due
to the small sample sizes (N=7 and 13 for WW and WD, respectively). In 2001,
with larger samples sizes (N = 47 and 29), we found that only 17% (5 out of
29) of mites reproduced on WD, while 100% (47 out of 47) of them reproduced
on WW (X2= 45.7, P <0.0001). Among these mites that reproduced, they also
had less reproductive output: the mean number of female mite off-spring was
0.20 ± 0.2 (mean ± SE) for WD, but 2.38 ± 0.2 for WW (t = 3.87, P <0.001).

To our knowledge, this is the first study to show that varroa mite
reproduction can be affected by cell size of the host. It is not clear why
mites would reproduce less on identical hosts that are housed in larger
cells. One possibility is that workers reared in drone cells are fed a
different diet by nurses. A second, more plausible, mechanism is that
workers spin larger cocoons in drone cells and mites detect this
"geographic" change and somehow change their reproductive behavior
accordingly.

Regards,

Dee

[Dee A. Lusby]

Hi Stan,

Here is my reply back to Barry on Biobee:

Barry wrote:
> 28. Zhou, T., J. Yao , S. X. Huang , & Z. Y. Huang -LARGER CELL SIZE
> REDUCES VARROA MITE REPRODUCTION


Reply:
This is a good experiment and reminds me of another similar one written done
by H. Ramon, and O. Van Laere and M. Ifantidis,from Asian Apiculture,
titled: 'Size of Comb Cell and Reproduction of Varroa jacobsoni' that saw
less reproduction with larger combs. Unfortunately, I think the mites
adapted over time here and would be interesting to see if this adaption
repeats itself in this new testing also.

Regards,

Dee

[Dee A. Lusby]

Hi Stan,

Here is the reply posted on 11-27-01 by Erik for his POV:

Now this test deals with effects on the mite in laboratory environment.

The most interesting thing though is what happens with the bee and the bee
colony in a real environment during a whole season.

What lacks here and everywhere is scientific studies of the immune system
of the bee and the bee colony.

Erik

[Dee A. Lusby]

Hi Stan,
Nancy followed Erik with a great post also on Biobee on 11-27-01:

Barry wrote:
> 28. Zhou, T., J. Yao , S. X. Huang , & Z. Y. Huang -LARGER CELL SIZE
> REDUCES VARROA MITE REPRODUCTION


Dee Replied:
This is a good experiment and reminds me of another similar one written done
by H. Ramon, and O. Van Laere and M. Ifantidis,from Asian Apiculture,
titled: 'Size of Comb Cell and Reproduction of Varroa jacobsoni' that saw
less reproduction with larger combs. Unfortunately, I think the mites
adapted over time here and would be interesting to see if this adaption
repeats itself in this new testing also.

****

Also, the quoted part did not mention if this was tried over more than one
generation in the test hives. A change in cell size may work for one
generation, but as Dee mentions the mites then adapt to the larger size.

However, Dee (& now others) doing regressed hives have shown on generation
upon generation within hives that changing back (smaller) does the same
thing, but that the mites DO NOT re-adapt or adapt or whatever. THe bees are
thus able to handle the mites & other problems without additional chemicals.

I would think that not mentioning that the bees in the study were on 4.9
cell would indicate that these bees are on big foundation and thus they are
talking about 'still bigger' foundation size which Dee (among others) have
now shown is definitively the wrong direction to go.

Nancy

[Dee A. Lusby]

Hi Stan,
Here is the last post made on 11-28-01 by Erik:

Yes Nancy

And too, we don't know how many brood cells were used in the experiment and
from how many different colonies and differen genetic origin. One other
thing, which was mentioned, observations that late in the season the queen
lay worker eggs in bigger cells like drone cells. I have never seen this,
on the contrary actually, they are abandond. Have anyone else seen a thing
like that?

Erik


Well Stan, hope I haven't staggered you with all this quick posting, but wanted to let you know that others read the article also and I am sure that discussion will be hot in many places as to whether or not it has merit or not.

In the mean time, feel free to ask questions here and maybe you might wish to join biobee for daily email discussion with others interested in keeping bees biologically without the usage of various dopes and treatments.

Regards,

Dee

[stytko]

Hi Mrs. Lusby:

Thank you very much for the response to my post. Actually, I've been a member of the bio-bee list for several months, and posted my note on this forum before I logged onto the list and saw Mr. Birkey's and others posts there.

I'm sure you don't remember, but I e-mailed you last year with some questions about installing package bees on 4.9 mm foundation and you were very generous with your time and information on this subject. You introduced me to the bio-bee list at that time, which has provided a wealth of knowledge on small cell and other subjects. So again, thank you for your help.

Have a happy holiday season!

Regards,

Stan Tytko