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humidity research and varroa


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new research shows interaction between entrance size, insulation, forage and hive humidity.

 

Mitchell, D. (2019). Nectar, Humidity, Honey bees (Apis mellifera) and Varroa in summer: A theoretical thermofluid analysis of the fate of water vapour from honey ripening and its implications on the control of Varroa destructor. Journal of the Royal Society, Interface, 22 May. https://doi.org/10.1098/rsif.2019.0048

Abstract:

This theoretical thermofluid analysis investigates the relationships between honey production rate, nectar concentration and the parameters of entrance size, nest thermal conductance, brood nest humidity and the temperatures needed for nectar to honey conversion. It quantifies and shows that nest humidity is positively related to the amount, and water content of the nectar being desiccated into honey and negatively with respect to nest thermal conductance and entrance size. It is highly likely that honeybees, in temperate climates and in their natural home, with much smaller thermal conductance and entrance, can achieve higher humidities more easily and more frequently than in man-made hives. As a consequence, it is possible that Varroa destructor, a parasite

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@derekm A few initial thoughts; 1. I knew when I got to the word 'tuple' this read was going to take some effort! 2. This might be the nail in the coffin for the 'heating varroa' advocates.

i will wait for @Dave Black to translate it first.

I'm sure lots of things affect varoa and their reproduction but feral hives did not and do not survive varoa .

@derekm

A few initial thoughts;
1. I knew when I got to the word 'tuple' this read was going to take some effort!
2. This might be the nail in the coffin for the 'heating varroa' advocates.
3. Have there been actual measurements (rather than modeling) of humidity a) in natural nests and b) in the putative 'ideal' man-made nest and do they compare with modeling?

4. I need to read it a few more times.

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On 11/07/2019 at 7:30 AM, derekm said:

new research shows interaction between entrance size, insulation, forage and hive humidity.

 

Mitchell, D. (2019). Nectar, Humidity, Honey bees (Apis mellifera) and Varroa in summer: A theoretical thermofluid analysis of the fate of water vapour from honey ripening and its implications on the control of Varroa destructor. Journal of the Royal Society, Interface, 22 May. https://doi.org/10.1098/rsif.2019.0048

Abstract:

This theoretical thermofluid analysis investigates the relationships between honey production rate, nectar concentration and the parameters of entrance size, nest thermal conductance, brood nest humidity and the temperatures needed for nectar to honey conversion. It quantifies and shows that nest humidity is positively related to the amount, and water content of the nectar being desiccated into honey and negatively with respect to nest thermal conductance and entrance size. It is highly likely that honeybees, in temperate climates and in their natural home, with much smaller thermal conductance and entrance, can achieve higher humidities more easily and more frequently than in man-made hives. As a consequence, it is possible that Varroa destructor, a parasite

Is this post complete with regard the last sentence?

 

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Not helpful that the paper sits behind a pay-wall, but I do have a copy.

In brief the proposal is that several studies have shown Varroa breeding tanks in high humidity (@ >80%) so modify beehives to be more like natural nests where the humidity (apparently) is high (@80%). Mitchell has done some interesting work modeling airflow in hives (search the Forum) so it's an idea that should be taken seriously, but should still be discussed critically.

 

Most of you probably have an entirely different idea about the value of humidity in a beehive, so that's probably the place to start.

BTW Derek Mitchell's work is mentioned in Tom Seeley's new book, but it deals with temperature control, not humility control.

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On the plains if we went about reducing hive entrances, while honey is ripening or colonies building up, we would have swarms for Africa. 

 

I am quite happy with my hive temperatures for both honey and queen cell production. 

Certainly good though, to hear other peoples' opinions and research.

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