Derek Mitchell article discussing effect of higher humidity on varroa
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  1. #1
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    Default Derek Mitchell article discussing effect of higher humidity on varroa

    Derek Mitchell has another research article that addresses hive configuration and its impacts on humidity. Apparently, it also covers the implications of higher humidity on varroa reproduction.

    https://royalsocietypublishing.org/d...rsif.2019.0048

    From the abstract:

    "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 implicated in the spread of pathogenic viruses and colony collapse, which loses fecundity at absolute humidities of 4.3 kPa (approx. 30 gm−3) and above, is impacted by the more frequent occurrence of higher humidities in these low conductance, small entrance nests."

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  3. #2
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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    Quote Originally Posted by clong View Post
    Derek Mitchell has another research article that addresses hive configuration and its impacts on humidity. Apparently, it also covers the implications of higher humidity on varroa reproduction.

    https://royalsocietypublishing.org/d...rsif.2019.0048

    From the abstract:

    "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 implicated in the spread of pathogenic viruses and colony collapse, which loses fecundity at absolute humidities of 4.3 kPa (approx. 30 gm−3) and above, is impacted by the more frequent occurrence of higher humidities in these low conductance, small entrance nests."
    Possibility of CO2 and/or humidity being a factor is often mentioned.
    For sure, bees in the trees have much better control of both as well as higher presence of both (vs. the commercial hives, since we are so crazy about "ventilation").
    One reason I really want to trial a Warre-formatted hive, but built similar to this:
    https://www.youtube.com/watch?v=tV90sHPOd70
    Former "smoker boy". Classic, square 12 frame Dadants >> Long hive/Short frame/chemical-free experimentations.

  4. #3
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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    Quote Originally Posted by GregV View Post
    One reason I really want to trial a Warre-formatted hive, but built similar to this:
    https://www.youtube.com/watch?v=tV90sHPOd70
    Interesting video, GregV. Initially I thought we were looking at thin-walled hive bodies but then I realized that the top super had a rabbet along the whole perimeter of the box to receive the plastic? inner sheeting. Also it may be based on the width of the top bars, but it looks like his frame spacing is wider? Maybe 1-1/2" center-to-center?

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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    Quote Originally Posted by Litsinger View Post
    Interesting video, GregV. Initially I thought we were looking at thin-walled hive bodies but then I realized that the top super had a rabbet along the whole perimeter of the box to receive the plastic? inner sheeting. Also it may be based on the width of the top bars, but it looks like his frame spacing is wider? Maybe 1-1/2" center-to-center?
    Unsure of his center to center.
    Pretty sure standard 35mm (1-3/8).
    The top bars, however, are metal pipe about 1/2 inch - this allows for pass-thru up and down.
    These thin top bar create an illusion of wider frame (the are not really).

    He has two hive formats:
    * 12 frame (the original format)
    * 8 frame (this one the author favors now as he is an older dude).

    The box walls are compatible to our 2x wood.

    The clear heavy plastic completely seals the top.
    Lately he switched to using clear silicon film, actually - a great idea.
    I think this material is like silicon rubber and thinking get some and test it.
    Check it out - great specs, about ideal:
    https://www.amazon.com/Silicone-Rubb...01201172&psc=1
    Former "smoker boy". Classic, square 12 frame Dadants >> Long hive/Short frame/chemical-free experimentations.

  6. #5
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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    More vids of the same - just observe the heavy film/silicon.
    The hives come out of winter:
    https://www.youtube.com/watch?v=QrkSnEjYBng
    https://www.youtube.com/watch?v=OV0gcwb7HKo
    Former "smoker boy". Classic, square 12 frame Dadants >> Long hive/Short frame/chemical-free experimentations.

  7. #6
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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    8-frame square;
    silicon completely seals the top;
    metal plate - helps to condense the water by cooling off the seal - this is early summer and condensation is very good help for brood rearing;
    notice how bees do NOT propolise the film between the combs - NOT needed - the non-permeable seal is already in place
    https://www.youtube.com/watch?v=WLduRE96S_U

    PS: the propolise pushing researchers should watch this video and think - WHY is it bees not propolising the film over the brood nest???
    because it is NOT needed and they will not spend the time/effort doing it if the surface is already satisfactory in sealing the nest
    Yes - very unhealthy - no propolise ..... - I am being sarcastic now.

    For this exact reason they will propolise my burlap completely - to seal it closed.
    Former "smoker boy". Classic, square 12 frame Dadants >> Long hive/Short frame/chemical-free experimentations.

  8. #7
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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    Quote Originally Posted by GregV View Post
    I think this material is like silicon rubber and thinking get some and test it.
    GregV:

    Thank you for your reply. I do hope you give this a try and let us know how it works out for you. I for my part am still hesitant to incorporate anything that is vapor impervious in my hives, but watching CLong's success with his highly insulated assemblies makes me want to dip my toes in the water and give it a try- at least on the top.

    Thanks again for the response- I do appreciate it.

    Russ

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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    Quote Originally Posted by Litsinger View Post
    GregV:

    I for my part am still hesitant to incorporate anything that is vapor impervious in my hives, but watching CLong's success with his highly insulated assemblies makes me want to dip my toes in the water and give it a try- at least on the top.
    Russ,

    I can understand your hesitance to create a vapor barrier in you hives. It goes against conventional wisdom. But it is done the world over, including in feral colonies. In fact, in Tom Seeley's latest book, he suggests that having a sealed hive with only a lower entrance is beneficial to the colony especially when water is needed in the winter.

    I wouldn't call my efforts "success". When I see 80% survival rates, and 100 lbs of honey/hive, then I will start to celebrate.

  10. #9
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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    Quote Originally Posted by clong View Post
    I wouldn't call my efforts "success". When I see 80% survival rates, and 100 lbs of honey/hive, then I will start to celebrate.
    CLong:

    I for one applaud your efforts and it seems to me that you are moving in a direction which has been more successful year-over-year. That is progress!

    Your efforts and results have convinced me to at least increase the resistance of the roof assembly as a start, so I am listening.

    Keep up the good work, and thanks for sharing your experiences here for the rest of us to learn from.

    Russ

  11. #10
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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    Quote Originally Posted by clong View Post
    Derek Mitchell has another research article that addresses hive configuration and its impacts on humidity. Apparently, it also covers the implications of higher humidity on varroa reproduction.

    https://royalsocietypublishing.org/d...rsif.2019.0048

    From the abstract:

    "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 implicated in the spread of pathogenic viruses and colony collapse, which loses fecundity at absolute humidities of 4.3 kPa (approx. 30 gm−3) and above, is impacted by the more frequent occurrence of higher humidities in these low conductance, small entrance nests."
    The full article:

    https://eprints.whiterose.ac.uk/1464...se22052019.pdf

  12. #11
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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    There is an article in the Feb.-ABJ by Bill Hesbach on ventilation of the Condensing Colony that ties in nicely with these articles about high humidity and varroa control. It definetly has changed my view of top and bottom ventilation- especially for Winter. Makes you think about the old rules of top and bottom ventilation.
    I'd like to hear others views.
    Jerry

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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    Quote Originally Posted by Swarmhunter View Post
    I'd like to hear others views.
    Jerry:

    Good post- I saw their is an accessible online article from Mr. Hesbach here:

    https://www.beeculture.com/winter-management/

    For my part I have a mix of standard Langstroth hives that I run with a top entrance consisting of a single 1" diameter hole and Warre hives with a single 7/8" diameter hole in each and every box.

    I have found that in preparation for Winter all colonies will work to partially occlude the openings but rarely close them off completely.

    Further they seem to be constantly working on the openings, adding and removing the propolis plug as overwintering progresses.

    Based on this completely anecdotal feedback I've concluded that they know what they want and I let them open or close the openings as they see fit.

    It also does appear that they tend to utilize the upper entrance preferentially for cleansing flights in the Winter, so there might be some marginal benefit there.

    What do you observe in your locale?
    Ecclesiastes 11:4

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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    I'm in the process of converting my timetable to be OTS freindly. I'm also reconfiguring my hives to be closer to natural beehives. More insulation summer and winter and entrances on the sides , half way up. no upper or lower entrances. I really think the bees will thank me.
    Way to much cold wet dripping on bees the way we've been ventilating. Going to change some things
    Jerry

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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    I have not had a duel vent hive in three years; choosing to have a bottom vent only. I have been trying for several years to define the design requirements for an enclosure for honey bees. "Homeostasis", year round, sums all the issues in a neat definition. Defining the variables is not easy but I think I am approaching a new level - seeing homeostasis within a hive - but still have a lot to learn. I need more sensors in more hives. Existing data out there helps a lot, leap-frogging doubts, when I know how to ask a question of Google Scholar; Seeley, Mitchell, Ellis,Tautz, Mobus all have a lot to offer. Hesbach offers some good explanations.

    My trend is simply emulation of typical tree hive characteristics but larger volumes, different materials. Do not underestimate the effect of wind on heat transfer, both convective heat transfer coefficients and tidal / mass flow effects. I am becoming a believer in conservation of water within a hive and buffering characteristics. I don't like plastic only nor more vents, propolis is amazing. Observation: It is amazing how fast moisture leaves a hive when it is cold and dry outside - my bees forage for water anytime it is above 40F and sunny, sometimes grey skies (dehydration issues?). I live in a wet area near the ocean and have a lot more to learn, so it seems. Best of luck to all who experiment ( and everyone else) this coming Spring.

  16. #15
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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    Robert-
    Sounds like your asking a lot of the same questions a lot of us are pondering. I've got almost all 8 frame equipment and I'm really glad I went that way because of the way I'm thinking of wintering my bees starting next year. Taller , narrower, better insulated, a3-4 inch deep area between the bottom board and brood area and only one entrance - 1x3 inches-- half the way up the hive into the brood area. Radical? Not according to mother nature.Top- heavy insulation with a short spacer for natural air circulation and patty feeding. Natural warm air of the hive will circulate across the top and down the sides for condensation on the sides instead of dripping from top.
    Just my ideas for next winter. Sick of losing bees (7 this winter). Going to do a lot of things different the next 6 months
    Jerry

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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    Jerry: I cannot comment on 8 frame versus 10 except form a concept point of view. Horizontally there is less insulation but that is easily accounted for by sizing insulation. I put a 2 inch spacer on top of my propolized 12 oz. duck cloth - inner cover . I put my remote sensor here on the canvass. I also loosely pack in some old cotton tee-shirts. ( Shades of a quilt box approach but no direct venting) I soon realized I have created some sort of" tree like" topping. I have watched water collect on the top canvass, eliminated that issue and then the I have watched the RH change slowly with ambient weather. RH is always high in this top zone but temperatures just below the dew point - a controlled water vapor buffer zone? It is also very curious that the colonies have raised the canvas on short, top bar columns of waxy propolis providing circulation like passage ways, I think.

    I feed heavily in the Fall to "weight" ( see M. Palmer). I am going to modify by canvass inner cover by adding a central hole to allow emergency or early Spring syrup feeding if necessary. It will also be useful for installing sensors and probing quickly. I currently stick a simple dial thermometer ($5.00) in each hive top canvass as a simple data point and verification the colony is alive.

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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    Delete; off topic
    Last edited by crofter; 02-09-2020 at 09:01 AM.
    Frank

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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    I have been feeding water back to my hives since December either through a wet sponge on the landing board or from spritzing their sugar bricks. So while they now have a dry cavity I’m reevaluating the top entrance again if I already have vent holes and vivaldi quilt box.

    Just read the ABJ article. Wondering again how much colony death has more to do with dehydration then starvation aided by hive design. The well known “they were surrounded by honey but couldn’t move” problem. Maybe they couldn’t metabolize their food from lack of water and humidity.
    I'm smart but at the end of the day I'm still the help.

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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    Quote Originally Posted by Swarmhunter View Post
    Way to much cold wet dripping on bees the way we've been ventilating. Going to change some things
    Good thread, Jerry. It is interesting and helpful to read about how others are approaching this issue. I imagine that the 'right' answer may at least in part have something to do with one's specific climate and weather patterns.

    For my part (as previously noted) I run top and bottom entrances on all hives and the bees respond by laying down propolis in varying degrees to the upper entrance in preparation for colder weather (example photos attached) and seem to be continually monkeying with the opening size (with no discernible pattern) throughout the winter.

    This winter (and based on the success of others on this forum), I decided to add 1" closed-cell foam insulation to the colonies for added benefit, with some worry that this might lead to the accumulation of condensation above the cluster.

    On one of our recent mild days, I popped the tops and to my joy only found two colonies with condensation on the inner cover- in both cases it was in the corners and not over the cluster, which squares with what I believe CLong has observed with his highly-insulated assemblies.

    I do sincerely hope you are able to find a hive set-up that provides reliable condensation control in your locale, and I look forward to reading about your experiments.

    Russ

    20200208_115235.jpg 20200208_115258.jpg 20200208_115437.jpg 20200208_115925.jpg 20200208_115947.jpg
    Ecclesiastes 11:4

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    Default Re: Derek Mitchell article discussing effect of higher humidity on varroa

    What are you using (how big?) - for an entrance hole and where is it placed. Also what are you using for insulation on the sides and are you leaving it on in the summer?

    Jerry

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