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Dear all,

I was about to ask if anyone had an opinion, but then I thought, asking a beekeeper if they had an opinion is like asking a bee if it likes honey....

Has anyone else seen this thesis of Dr. R. Bahreini regarding restricted ventilation and Varroa mite mortality? And what do you think?

Even what he is saying about queen pheromones and Varroa mite mortality is making me think about the potential advantages of smaller hive designs with restricted air flow to optimize the queen and other pheromones.

[The Costs and Benefits of Resistance and Tolerance Behaviors against Varroa mite (Varroa destructor Anderson and Trueman) in Honey bee (Apis mellifera L.)
By Rassol Bahreini]

???
thanks,
Thomas
 

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I was going to ask you for a link, but found one easily enough:
https://mspace.lib.umanitoba.ca/bitstream/handle/1993/30115/Bahreini-Rassol.pdf?sequence=1

This was his PhD thesis, so it'll take a bit of reading/digesting ... maybe sometime tonight.

In the meanwhile I've sourced a couple of his 2015 papers which are somewhat related:

The Potential of Bee-Generated Carbon Dioxide for Control of Varroa Mite (Mesostigmata: Varroidae) in Indoor Overwintering Honey bee (Hymenoptera: Apidae) Colonies (2015)

Restricting ventilation increased mite mortality, but did not affect worker bee mortality relative to that for colonies under standard ventilation. Restricted ventilation did not affect the overall level of Nosema compared with the control. However, there was an interaction between stock, season, and time of the trial. Unselected stock showed an increase in Nosema over time in the late winter trial that did not occur in the selected stock. In conclusion, these findings suggested that restricted ventilation has potential to suppress varroa mite in overwintering honey bee colonies via a low-cost and environmentally friendly measure.
The effect of queen pheromone status on Varroa mite removal from honey bee colonies with different grooming ability. (2015)

Abstract

The objective of this study was to assess the effects of honey bees (Apis mellifera L.) with different grooming ability and queen pheromone status on mortality rates of Varroa mites (Varroa destructor Anderson and Trueman), mite damage, and mortality rates of honey bees. Twenty-four small queenless colonies containing either stock selected for high rates of mite removal (n = 12) or unselected stock (n = 12) were maintained under constant darkness at 5 °C. Colonies were randomly assigned to be treated with one of three queen pheromone status treatments: (1) caged, mated queen, (2) a synthetic queen mandibular pheromone lure (QMP), or (3) queenless with no queen substitute. The results showed overall mite mortality rate was greater in stock selected for grooming than in unselected stock. There was a short term transitory increase in bee mortality rates in selected stock when compared to unselected stock. The presence of queen pheromone from either caged, mated queens or QMP enhanced mite removal from clusters of bees relative to queenless colonies over short periods of time and increased the variation in mite mortality over time relative to colonies without queen pheromone, but did not affect the proportion of damaged mites. The effects of source of bees on mite damage varied with time but damage to mites was not reliably related to mite mortality. In conclusion, this study showed differential mite removal of different stocks was possible under low temperature. Queen status should be considered when designing experiments using bioassays for grooming response.

https://www.ncbi.nlm.nih.gov/pubmed/25860860
I'm finding it a bit difficult to get excited about the above (at the moment), as he's comparing selected-grooming vs. non-selected stock.

I was rather hoping to see something less 'pre-determined' and thus more widely applicable ... (forever the optimist ... :) )
LJ
 

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Hey, Rod, most of the paper is observation, not theory. The Q pheromones do affect the mite populations, based on his controlled experiments.

Is his theory based on hive temps? I can’t see as how Q pheromones would affect mite populations.
 

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I've noticed the hives with small entrances and less ventilation seem to be healthier. I haven't considered that it could have an effect on Varroa. I haven't seen any evidence of that, but also haven't been looking for it. The general heath issue is one that was purported by Abbe' Warre'.
 
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