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Varroa and the Honey Bee Understanding the Dynamics

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  • Gary
    How does an infestation of Varroa affect honeybees throughout a season and what can be done about it? You will have to refer to this chart to understand the
    Message 1 of 1 , Sep 9, 2008
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      How does an infestation of Varroa affect honeybees throughout a
      season and what can be done about it?

      You will have to refer to this chart to understand the following
      article: http://www.biobees.com/forum/viewtopic.php?t=443

      I originally wrote this for the biobees web site, This article was
      reviewed and edited by Phil Chandler and Norm Weston

      The following is based on various research and years of observing
      mites decimate untreated colonies. The Biobees team does not claim to
      have all the answers nor do we wish to give the impression that our
      recommended methods are absolute doctrine. We only wish to share
      experience with the bee keeping community in order to show that there
      are ways to combat this parasite without the use of poisons within
      the hive.

      Understanding the Basics

      Making simple assumptions for this scenario, assume the colony went
      into the winter healthy OR we have a new package, first season
      colony. At this point, the colony is assumed to be healthy! This
      colony is not treated with anything.

      The colony population is a cycle of rises and declines in both Bee
      and mite. Starting in spring; the time of year when the colony is
      building up its work force, the queen begins to lay eggs in the core
      brood nest as cells are emptied of honey and become available. At
      this time worker bees are preparing these cells for the queen to lay
      in which includes cleansing debris and any lingering pests! The mite
      population for a healthy colony is in check at this point. Looking at
      the graph you can see the bees maintain a relatively higher
      population than the mites. This is the host parasite ratio the colony
      CAN exist with, provided there are no additional stressors placed on
      it. A stressor can be anything from pesticide problems to bee keepers
      that need to play with their bees every chance they get!

      In this scenario after mid April the converging lines show what can
      happen if an additional stressor is placed on the colony. This can
      happen anywhere along the time line! Proceeding along the time line
      the two populations are beginning to close in on each other, this is
      where the danger begins.

      A probable cause is the bees change in focus to preparing for the
      winter. Part of their preparation is a reduction in colony population
      to optimize their use of winter stores. The mite population is still
      increasing No longer are they picky about drone cells now, it's a
      matter of survival, so any cell will do for mite reproduction. Where
      the two lines cross marks the economic threshold (the point at which
      the host can no longer support itself and the parasite.) After this
      point has been reached, you will see bees emerge from the colony with
      deformed wings (DWV) deformed wing virus and a host of other nasty
      viruses known as PMS (parasitic mite syndrome) as the mites
      parasitize what little brood is left. As long as there is brood this
      will continue and eventually result in the failure of the colony.

      Identifying the Change of Focus

      A decrease in bee population in a colony occurs naturally on two
      occasions, the first being reproductive swarming and the latter being
      preparation for winter. This change in focus is marked by a decrease
      in laying by the queen and the back filling of the brood nest with
      nectar/honey. When we treat a hive we knock down the mite population
      and keep the two lines from crossing thus maintaining the host
      parasite ratio the colony can sustain!

      Treatment Free?

      Our aim is to create conditions in which our bees can attain a state
      of sustainable, dynamic balance with the mites and other invaders
      that will always be present in and around a colony. One way in which
      we can help them is to reduce the mite load at critical points using
      a treatment that has significant impact on the mites and minimal
      impact on the bees.

      There are several treatment options that do not require the use of
      synthetic miticides, such as organic acids, sugar dusting and 'shook
      swarm'. While organic acids (such as formic, lactic, acetic and
      oxalic) are widely regarded as effective and 'natural' compared with
      synthetics (such as pyrethroids and organo-phosphates) they
      nevertheless pose a health risk for the beekeeper and are not
      entirely benign towards the bees. Sugar dusting is, we believe,
      entirely harmless for the bees and has a significant knock-down
      effect on mites, caused by interference with their ability to cling
      to their hosts. The bees clean the powdered sugar from each other and
      thus may physically assist in the mite drop.

      Shook swarm has been practiced for many years by beekeepers as a
      control for European Foul Brood. Done at the right time - in spring,
      as the colony is building up strongly and may be making swarm
      preparations - it can be an effective way to both radically reduce
      the mite load and to propel the bees into 'new swarm' mode, when they
      will work with renewed vigor as if they had, in fact, swarmed.
      Nevertheless, there are risks with this procedure and if the timing
      is wrong, the bees may abscond or fail to thrive.

      Overall, it is important to remember that we, as beekeepers, can be
      the primary cause of stress to the bees in our care and that it is an
      important part of good husbandry to strike the right balance between
      correct monitoring and too much interference. The bees know what they
      are doing: our job is mostly to keep out of the way.

      What to Look For

      The signal that it is time to do something is an increase in natural
      mite fall. This signals a stressor that the colony encountered and
      cannot handle at this point. A smart chemical free beekeeper should
      break out the powdered sugar and dust each frame, repeating two weeks
      later to ensure you get as much of the mite cycle you can! Should you
      have a bar of capped drone brood you can pull it out, freeze it, and
      return it to the colony to be cleaned.

      Why is the TBH Hive conducive to Sustainability?

      A proven contributor to the survival of the colony is natural comb.
      Natural comb allows the free building of comb by bees at the bees
      will. This in turn allows the construction of “the core brood
      nest” this is the part of the nest constructed with smaller cells.
      It is the part of the nest that is reserved and cleaned for periods
      of reduced brood rearing. This is why small cell worked so well. The
      theory of small cell (first mentioned by the Lusbys) was just never
      thought through to the end until Dennis Murrell came along and
      finished it. We have Dennis to thank for all the references to the
      core brood nest contained here in. The cleaning of this part of the
      brood nest keeps the mite load in check at crucial times of colony
      development.

      Anything extraneous added by the beekeeper i.e. foundation, frames
      and artificial feed can be grouped into the category of stressors. So
      use a Varroa screen w/sticky board to monitor mites and remember it
      was never intended to be a ventilation device!

      Conclusion

      Anything you do that decreases the mite population keeps the two
      lines on the graph from crossing which translates to maintaining a
      higher bee population. Using sugar dusting and drone comb trapping
      methods are the softest non chemical approaches available today. The
      most efficient times to treat are the periods just before the mite
      population reaches the bee population or the economic threshold A
      colony just beyond this point can be saved, however, the chances for
      survival decrease every day left untreated there after.

      The colonies that need least treatment should be the ones to select
      for breeding.

      A few of many references for this research are:-

      http://www.masterbeekeeper.org/pdf/varroa_drone_removal.pdf

      http://apis.ifas.ufl.edu/papers/austin.htm

      https://secure.csl.gov.uk/beebase/public/BeeDiseases/ModellingVarroaTr
      apping.pdf

      http://www.saudibiosoc.com/SJBS/11-1/files/3.pdf

      Also see:

      http://www.scientificbeekeeping.com//index.php?
      option=com_content&task=view&id=23&Itemid=40

      http://www.sharebooks.ca/free_ebook_downloads.php?
      filename=ReturnToResistance.pdf
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