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  1. #21
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    Default Re: Something you probably didn't know about mite control

    c10250,

    In that same link in post 19 there is this:

    "Right away I contacted Zachary to ask him if anything is known about how this works and whether it is wise for beekeepers to continue lowering hive humidity in the winter. I was really worried about this because hive moisture is my favorite “bad guy.”

    He responded that 1) nothing is known about how high humidity affects Varroa reproduction and 2) it is still good to control hive humidity in winter for other reasons. And since there isn’t much brood being raised at that time, the effect on mite reproduction is probably minimal."

    If this is true, then Zachary appears to not support this concept. I'm confused......

    Oh, and just for the record, the relative AM humidity in Norfolk, VA for May through Nov is:

    78, 79, 82, 84, 84, 83, 79
    Horseshoe Point Honey -- http://localvahoney.com/

  2. #22
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    Default Re: Something you probably didn't know about mite control

    I copied these paragraphs from the end of the Kraus and Velthuis (1997) paper that has been cited several times in this thread:

    RH decreases with increasing temperature. Since ambient tempera- ture in cold and temperate climates is generally clearly below brood nest temperature, RH within the brood nest is comparably low even when ambient RH is high. RH in the brood nest of A. mellifera colonies is usually about 40% [14], and most likely lev- els above 70% hardly occur in tempe- rate and cold climates even under ex- treme conditions [15]. In Mediterra- nean climates during summer tem- peratures close to brood nest tempera- ture are frequent, but RH is usually low. Only in tropical climates are both temperature and RH frequently high. The question is whether and how honey bees can reduce RH under high ambient temperature conditions. Honey bees can increase temperature within the brood nest by generating heat with their wing muscles or de- crease temperature by simultaneously evaporating water and creating cur- rents of air [16] while evaporation without air circulation enables them to increase RH within the brood nest. If, for example, during nectar flow
    RH increases within the colony, the bees raise the temperature within the colony and produce currents of air to transport humid air outside the hive entrance. High ambient temperatures combined with high RH do not allow honey bees to control conditions sig- nificantly and the bees partially evac- uate the nest, clustering at the nest en- trance [17]. Under tropical conditions RH values within the brood nest are therefore most likely frequently equal to ambient RH. The results from our laboratory study provide thus informa- tion concerning conditions for repro- duction of V. jacobsoni in honey bee colonies in tropical climates.
    The present data provide a simple ex- planation for the fact that often in tro- pical climates population growth of V. jacobsoni is unexpectedly low. The significant impact of differences in re- lative humidity of only 9–25% upon reproduction and therewith on popula- tion growth of a parasite demonstrates another probable effect of environ- mental factors upon parasite viru- lance. --Kraus and Velthuis, Naturwissenschaften 1997

  3. #23
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    Default Re: Something you probably didn't know about mite control

    I guess I will play the heavy here--huge problems with this theory:

    1. Mite level is lowest in winter when there is no brood
    2. Condensation is of biggest concern in the winter
    3 Illinois gets cold enough to have big condensation issues
    4 Bee hives are not can not and will not be "like trees" Last time I checked there is not 50 foot or more of open grained pulpy rotten wood above your hive to wick excess moisture away like in a hollow tree
    http://www.peekskillnurseries.com
    Specialists in Ground Cover plants since 1937. Talk to me about ground-covers!

  4. #24
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    Default Re: Something you probably didn't know about mite control

    Quote Originally Posted by xcugat View Post
    I guess I will play the heavy here--huge problems with this theory:

    1. Mite level is lowest in winter when there is no brood
    Definitely, but it's not zero. After January it really picks up . . . ask anyone going to almonds, they want huge, fast buildups. One person I know won't even run with Carni's because they don't build up to the huge populations they need for almonds as fast as Italians. Is this the best case scenario? No. It would be better if you could do this over the summer, but heck, to think that you don't have a lot of brood in early spring/late winter . . . . it's not the case AFIK

    2. Condensation is of biggest concern in the winter

    Why would condensation be a concern? It's only a concern if it drips on the bees. Why would it be a concern if it doesn't. Look at a tree cavity . . .I don't think condensation is a big deal there.

    3 Illinois gets cold enough to have big condensation issues

    It's been below zero this year. My hives seem to be doing quite well based on the orientation flights I had yesterday.

    4 Bee hives are not can not and will not be "like trees" Last time I checked there is not 50 foot or more of open grained pulpy rotten wood above your hive to wick excess moisture away like in a hollow tree

    I'm not saying a bee hive is like a tree. I'm saying that trees don't condense water over the cluster, and neither does my hive setup. The same result without the pulpy rotten wood . . . The only similarity I'm discussing here is their ability to keep condensation off the cluster with higher humidity levels.
    see my comments in the above quote.

  5. #25
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    Default Re: Something you probably didn't know about mite control

    Beekeepers headed to almonds from around here all haul to California or Texas or somewhere in the south in October. They do it so their bees can rear brood during the winter months and go into almonds with large populations. I don't know of anyone moving from the northern tiers of states straight into blooming almonds.

  6. #26
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    Default Re: Something you probably didn't know about mite control

    Data loggers going in this year, we'll see what the RH inside are. Only issue I need to resolve is bees propolizing the probes maybe, but I will screen them off or something.

  7. #27
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    Default Re: Something you probably didn't know about mite control

    Quote Originally Posted by JRG13 View Post
    Data loggers going in this year, we'll see what the RH inside are. Only issue I need to resolve is bees propolizing the probes maybe, but I will screen them off or something.
    That would be great data to have. Keep us posted.

  8. #28
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    Default Re: Something you probably didn't know about mite control

    Quote Originally Posted by Kieck View Post
    Beekeepers headed to almonds from around here all haul to California or Texas or somewhere in the south in October. They do it so their bees can rear brood during the winter months and go into almonds with large populations. I don't know of anyone moving from the northern tiers of states straight into blooming almonds.
    Good point Kieck. I know that last year in March I had 9 frames of bees already. There has to be some brood to go from a small cluster in December to fully covering 9 frames in March. Seriously, look at this picture of my inspection last March!

    https://docs.google.com/file/d/0Bwi-...hMOWt1Nlk/edit

    Look at the background. There is still snow on the ground! Look at that population of bees in March. It was tiny in December. How could there not be a lot of brood in the late winter??? Now, I don't profess to be an expert by any means, but am I missing something here? How do you get a hive this large in March without a lot of brood being reared over the late winter?

  9. #29
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    Default Re: Something you probably didn't know about mite control

    They do raise a lot of brood in late winter, hopefully. The points here are 1) the majority of the time when you could drive up moisture/condensation in the hive coincides with broodless (and therefore no mite reproduction) months, and 2) the RH in the cluster/brood is unknown even when water is running down the walls in the hive.

  10. #30
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    Default Re: Something you probably didn't know about mite control

    Quote Originally Posted by Kieck View Post
    They do raise a lot of brood in late winter, hopefully. The points here are 1) the majority of the time when you could drive up moisture/condensation in the hive coincides with broodless (and therefore no mite reproduction) months, and 2) the RH in the cluster/brood is unknown even when water is running down the walls in the hive.
    Yes and yes. I agree with both.

    This whole theory might be a bunch garbage, however, think of it . . . Mite reproduction/population is exponential. If you could somehow suppress Mites, just a bit, as they are building up in the spring, you might have a much lower population come the summer. Going into Summer with 1/2 the mite population would be huge . .

    Mite populations double every month during brood rearing. Starting spring with 50 mites in the hive in April instead of 100 would be huge at the end of the summer. That's 800 mites compared to 1600 mites by September.

  11. #31
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    Default Re: Something you probably didn't know about mite control

    Here's something interesting. It isn't the humidity of the cluster. It's the relative humidity outside.

    From http://www.extension.org/pages/65450...uctive-biology with emphasis added

    D. Effect of Humidity

    Kraus and Velthuis (1997) wondered why varroa mites were not as big a problem in the tropics (besides that fact that most bees were African), and tested in the laboratory to see if high relative humidity would inhibit mite reproduction. They artificially transferred single mites into newly capped cells, and then kept the brood in an incubator. When relative humidity (RH) was set at 5968%, on average, 53% of the mites produced offspring (N=174 mites); under 7985% 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.

  12. #32
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    Default Re: Something you probably didn't know about mite control

    Here's something interesting. It isn't the humidity of the cluster. It's the relative humidity outside. -c10250
    I'm not sure I follow you on this. In the experiments, to maintain precise humidity levels, the researchers kept capped brood in incubators. No workers were present to maintain temperature (and humidity, maybe?) levels around the capped brood, but temperature control was provided by the incubators.

    I do find it fascinating that humidity levels in the capped brood apparently follow humidity levels in the air immediately around the capped comb. I would have guessed that the wax-capped cells would have insulated their contents against changes in humidity. The cappings must be more permeable than I thought.

    However, in a hive under field conditions, I expect capped brood to still be pretty well covered by the mass of adult bees in the hive. I'm not sure how capped brood would not experience the RH levels found in the brood nest.

  13. #33
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    Default Re: Something you probably didn't know about mite control

    I'm not saying a bee hive is like a tree. I'm saying that trees don't condense water over the cluster, and neither does my hive setup
    Unless I missed something what is your hive setup c102?
    http://www.peekskillnurseries.com
    Specialists in Ground Cover plants since 1937. Talk to me about ground-covers!

  14. #34
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    Default Re: Something you probably didn't know about mite control

    Warre has wood chips at the top to prevent condensation. Similarly, many people used "moister quilt" in Langs. Both of these "devices" imitate the environment in the tree-trunk.

    Regarding main subject. We all need to keep in mind that artificial RH increase is a treatment... if "treatment" used properly, it could help. If it is overused - it creates resistance. If mites managed to create resistance to nasty chemicals, they will develop resistance to the high humidity as soon as it will be widely and unwisely used... Also- "side effects". What about AFB at high humidity or SHB?

    From another hand, approach proposed by c10250 is reasonable,I have no problem with this as long as it works to somebody. Interesting idea - spray bees with water inside the hive and lock them for some period of time (few days?) - see if any mites increase on sticky board...

    Sergey
    Серёжа, Sergey

  15. #35
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    Default Re: Something you probably didn't know about mite control

    Quote Originally Posted by xcugat View Post
    Unless I missed something what is your hive setup c102?
    More insulation over the top of the bees than on the sides of the hive.

  16. #36
    Join Date
    Apr 2010
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    Lititz, PA, USA
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    Default Re: Something you probably didn't know about mite control

    I remember reading the RH thing in BC or ABJ a couple months ago.

    Question for all: For how long can mites survive in the winter anyway? At this point they're basically all phoretic and subject to grooming and beeing bitten by bees. I guess for early spring high humidity might help keep mites in check, but the mite population doesn't go nuts until later in the season anyway. The graph on page 1 here shows a population curve.

    http://scientificbeekeeping.com/ipm-...tion-dynamics/

    This is for a temperate climate I know, but the curves I believe are very similar for a cold winter. To really control the mites you'd need that high RH well into the honey flow at which point there's no way your bees could ever ripen their honey because of the RH unless you could somehow keep the high RH in a brood nest but allow ventilation around the honey.

  17. #37
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    Default Re: Something you probably didn't know about mite control

    Libhart,

    I agree and disagree. If you keep RH high and exit spring with 1/2 the mite population you normally would have had, then in late summer you will have 1/2 the population of mites that you normally would. Even though both populations increase exponentially, starting with less really makes a BIG difference at the end of the summer.

    Start with 50 mites in April and in August you'll have 800
    Start with 100 mites in April and in August you'll have 1600.

    Both populations follow an exponential increase, however, becuase you started with 1/2 the mites, you'll always have 1/2 the mite population.

  18. #38
    Join Date
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    Default Re: Something you probably didn't know about mite control

    >what's the source of this information?

    Most any article on the life cycle of the small hive beetle...

    http://entnemdept.ufl.edu/creatures/...ive_beetle.htm

    Third paragraph down from "Life Cycle"

    http://www.texasdrone.com/Beekeeping...ive_beetle.htm

    Fourth paragraph down.

    http://www.extension.org/pages/60425...l-hive-beetles

    Under "Control" fifth paragraph down.

    One of the best controls for Small Hive Beetle is to keep the humidity down. I think that's why they have less SHB issues when they are in full sun.
    Michael Bush bushfarms.com/bees.htm "Everything works if you let it." ThePracticalBeekeeper.com 40y 200h 37yTF

  19. #39
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    Default Re: Something you probably didn't know about mite control

    Quote Originally Posted by c10250 View Post
    Start with 50 mites in April and in August you'll have 800
    Start with 100 mites in April and in August you'll have 1600.
    And if you were to start with 1 mite in April then by August you would have ....one? (1 to any power is still 1).

    The problem with this math is, what about the mites that the bees pick up (and lose) out in the field? The fact that mites have spread over virtually the entire country since about 1987 shows that they certainly move from hive to hive.
    Graham
    USDA Zone 7A Elevation 1400 ft

  20. #40
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    Default Re: Something you probably didn't know about mite control

    Quote Originally Posted by c10250 View Post
    Both populations follow an exponential increase, however, becuase you started with 1/2 the mites, you'll always have 1/2 the mite population.
    c10250, I agree and disagree.

    An exponential increase means you'll have *way* more than double if you start with double. The 2 also gets the exponential growth. I get your thought, start with as low a number as you can, and that makes total sense. But you need to let that air in at some point so nectar can be dried and I'm not sure that can be late enough to make a big difference...maybe it can.

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