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  1. #1
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    Arrow What does varroa know?

    The statement "varroa mites tend to invade drone brood more readily than worker brood" can be read in a number of publications.

    Why is this?

    Are the mites attracted to a certain cell size? A certain smell? Or some other trigger mechanism? More food? Larger larvae to feed upon?

    Thank you.

  2. #2
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    Bjorn

    I think it is related to cell size. the larger the cell, the better the reproduction rate, the more offspring they can produce.
    "I reject your reality, and substitute my own." Adam Savage

  3. #3
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    Peggjam,
    How are they recognizing a larger cell size? Are they measuring up the differences in cell size, or is there another trigger mechanism like pheromones, amount of food, larvae size, ect.

    I realize that drones are capped for a longer period than a worker cell and thus more mites can hatch, increasing numbers. But does a mite have this "learned", or is there another trigger mechanism?

  4. #4
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    Just as an off hand guess, I think it is pure instinct on their part. I don't think that the mites intend to kill the coloney, but rather to just feed off it. If you look at the parisite/host relationships in nature, you rarely see the parisite kill the host on purpose. Although there is a fly called a forward fly(not sure that's spelled right) that reproduces and lays it's eggs in fireants, which does result in the larva killing the ant. They are trying this in Texas to help control the fireants.
    "I reject your reality, and substitute my own." Adam Savage

  5. #5
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    It may be as simple as luck. Nick Calderone did a study of nurse bee activities in relation to worker brood and drone brood and discovered that they spend 2.78 more "time" tending drone brood as measured by the number of "tending acts" performed by the bees. Given that mites can reproduce in either worker or drone brood albeit more productively in drone brood, the simple fact is it may just be that varroa just have more opportunity to enter a drone cell. Is that the whole story? Probably not.

    Here's a link to Nick's paper:

    http://www.apidologie.org/index.php?...3/06/M3607.pdf

    There may be more than luck involved. On it's original host, apis cerana, varroa mites enter both worker brood and drone brood but reproduce only in drone brood. Studies have shown that this is a trait of the mites, not the bee species and it's likely that this behavior is crucial in maintaining the successful symbiotic relationship of varroa jacobsoni and apis cerana. When the mites jumped species, more than just their name changed- varroa destructor were successfully breeding in worker brood, though not as successfully as in drone brood.

    Let's not ascribe intelligence and decision making capabilities to varroa destructor when genetic traits and natural selection suffice to explain what is happening.

    Yet another study states:

    "Mites invaded worker cells from 15–20 h preceding cell capping, whereas they invaded drone cells from 40–50 h preceding capping. The larger number of mites generally found in drone cells, when compared to worker cells, may be partly due to the longer period of mite invasion into drone brood."
    But WHY do they invade drone brood over a longer period than worker brood? Is it simply a matter of opportunity or is there something about drone brood that makes it more attractive for a longer period?

    In any case... it's an interesting question.
    Dulcius ex asperis

  6. #6
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    the level of juvenile (sp) growth hormone.

  7. #7
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    Default New beek, so what do I know!

    I think vorra mites prefer drone cells because it takes more time for the drones to emerge, therefore more of the young vorra mite females mature and are mated by their brother. Anyway that is what I think an article I read said?
    Charles

  8. #8
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    The research I've seen says that if you transfer workers to drones and drones to worker cells and leave some as is, the results are preference by the varroa in this order:

    1) drone brood in drone cells
    2) drone brood in worker cells
    3) worker brood in drone cells
    4) worker brood in worker cells.

    To me that would indicate that there are both mechanisms at work, cell size and pheromones, with pheromones having the larger influence.
    Michael Bush bushfarms.com/bees.htm "Everything works if you let it." ThePracticalBeekeeper.com 40y 200h 37yTF

  9. #9
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    I tend to agree with George Fergusson that it is easy to attribute human characteristics to bees. Especially when you spend a lot of time working with them, it is easy to see them as little thinking creatures. But bees respond to differant stimuli with inbred responses. You mix the genes you get differant responses.

    If we can learn what stimuli brings out what response, we can use that to help develope an approach to dealing with differant problems. This is kind of dull and boring to those not interested in the subject so it doesn't make good copy in a newspaper. Sometimes the news media get it right, but it is only by accident.

    Is the varroa destructor or the Nosema ceranae the cause of CCD? I don't know yet. As far as I am concerned the judge is still out. Could either one or both be a factor? Yes, but we don't have enough hard evidence yet to make a conclusive judgement. That doesn't mean we don't continue to work on them, just that they may not be responsible for the newer problem.

  10. #10
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    Quote Originally Posted by tecumseh View Post
    the level of juvenile (sp) growth hormone.
    I read the same thing some place recently . . .I think the article stated Drone Brood has more of it.

    One type of mosiquito control also affects the Juvenile Growth Hormone -- supposedly it doesn't affect honey bees BUT I'm guessing otherwise . . .

    I'll see if I can the locate the article / reference . . .
    "If you're doing all the dos, you ain't got time to do the don'ts"

  11. #11
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    beekeep adds:
    I read the same thing some place recently . . .I think the article stated Drone Brood has more of it.

    tecumseh replies:
    can't recall the source either although I do believe you got the relative levels of juvenile growth hormone correct.

    it is amazing that certain substance in extremely low concentration codes certain species for specific behavior. viewing this type of behavior (especially via invertebrates which really have no brain) as being similar to human thinking is a stretching an analogy a bit much.

  12. #12
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    Default compelled by semiochemicals

    Drone brood has a specific pheromone/ semiochemical "signature" that is very attractive to mites. This makes sense because the longer developmental period of drone brood assures greater reproductive success for the mites. There has been some work done using semiochemicals that simulate the pheromones produced by drone brood to attract Varroa to a trap. A semiochemical is a substance that carries a message. These substances include pheromones, allomones, kairmones, and other compounds that elicit a specific biological response. Much insect and acari behavior can be explained by semiochemicals.
    John B Jacob www.oldsolbees.com

  13. #13
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    A recent study used an “attractant” to lure Varroa, I’ll bet it wasn’t “cell size”.

  14. #14
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    The project I was referring was not based on cell size, just the attractiveness of the semiochemicals and a simple trap.
    John B Jacob www.oldsolbees.com

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