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Interesting Mite Reproduction Success

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Crofter:
http://bees.msu.edu/2012/varroa-repro/

This is one of the most thorough yet understandable articles on mite reproduction variables. AHB vs EHB  vs Apis Ceranae. Also goes into significance of different mite species.

LazyBkpr:
Wow, Good read!
   This sheds a LOT of light on why certain methods and bees can produce "resistant" bees in one location that fail completely in another location.  The humidity factor being one of those things. If you have high humidity, resistant bees, and use some IPM you have a better chance of getting bees to survive than if you have low humidity;

 They artificially transferred single mites into newly capped cells, and then kept the brood in an incubator. When relative humidity (RH) was set at 59–68%, on average, 53% of the mites produced offspring (N=174 mites); under 79–85% RH, only 2% (N = 127) of the mites reproduced. The difference in mite fertility was highly significant. My postdoctor recently incorrectly set the incubator at a RH of 75% (instead of 50%), and very few mites reproduced as a result. If there are ways to artificially increase the hive RH to about 80%, then the varroa mite population will never increase to a damaging level.

   I also did not realize that the bees only targeted and removed Pupae that had female mites;

 the bees do not open cells containing non-reproducing mites, but rather target those having mite daughters.

   And of course the ever popular small cell debate. I had read this before;

 An earlier study (Message and Goncalves, 1995) showed in Africanized bees, larger cells had a higher invasion rate, and also had higher effective fecundity in mites.

   And in this statement he seems to contradict himself, saying that Mites Increase in smaller cells, yet closer to the bottom he seems to indicate otherwise..   so not sure how to interpret it?

we accidentally discovered that in both A. cerana and A. mellifera queens laid 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).   In 2001, both the fertility and fecundity of the two groups were significantly different (Fig. 4). It is not clear why mites would reproduce less on identical hosts that were housed in larger cells. One possibility is that workers reared in drone cells are fed a different diet by nurses (One study showed workers reared in drone cells were heavier and had more ovaries, suggesting a different diet or more nutrition).  A second possibility is that workers spin larger cocoons in drone cells, and mites detect the extra space, and this affects their reproduction.

  LOL, so which is it? Less or more?

   Good read. Thanks for posting the Link!

Crofter:
On the divergent answers to cell size I think it might point to there often being other, stronger forces at play that were unaccounted for by the various experiments. If cell size were a cut and dried controlling factor in mite suppression the matter would have been settled long ago.

LazyBkpr:

--- Quote from: Crofter on February 17, 2014, 10:38:47 am ---On the divergent answers to cell size I think it might point to there often being other, stronger forces at play that were unaccounted for by the various experiments. If cell size were a cut and dried controlling factor in mite suppression the matter would have been settled long ago.

--- End quote ---

   Very true..
   Another thought;

 (One study showed workers reared in drone cells were heavier and had more ovaries, suggesting a different diet or more nutrition)

   Would that also translate to a greater ease of developing a laying worker?

Crofter:
That would seem a natural consequence. Make them more dastardly if they were to lay anyways!

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