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  1. #1
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    Default Resistance to varroa : what mechanisms?

    Does the mechanism that bees resistant to varroa use is only one?
    No!

    Does the mechanisms that bees resistant to varroa use is universal?
    No!

    Does the method used to create bees resistant to varroa ( bond selection vs. genetic laboratory selection) condition the varroa resistance mechanism?
    The best answer I know is yes!

    For those who want to deepen these aspects I recommend reading this article: https://hal.archives-ouvertes.fr/fil...l-01003560.pdf

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    Default Re: Resistance to varroa : what mechanisms?

    What I'd like to know is the influence of hive continuity over pure genetics on VSH. In other words, how important is the influence of older bees passing on VSH traits to younger bees as opposed to those traits being inherited.

    For example, has anyone tried requeening existing VSH hives and non-VSH hives with II VSH sister queens? If it's a purely inherited trait then the non-VSH hives should become VSH once the adult bee population is replaced with the VSH queen's offspring and within a couple of months both sets of hives should be exhibiting similar levels of VSH behaviour.

    I'd be grateful if someone could point me to research on this aspect.

  3. #3
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    Default Re: Resistance to varroa : what mechanisms?

    Quote Originally Posted by Snowhitsky View Post
    What I'd like to know is the influence of hive continuity over pure genetics on VSH. In other words, how important is the influence of older bees passing on VSH traits to younger bees as opposed to those traits being inherited.

    For example, has anyone tried requeening existing VSH hives and non-VSH hives with II VSH sister queens? If it's a purely inherited trait then the non-VSH hives should become VSH once the adult bee population is replaced with the VSH queen's offspring and within a couple of months both sets of hives should be exhibiting similar levels of VSH behaviour.

    I'd be grateful if someone could point me to research on this aspect.
    I think its broadly understood that traits are inherited, not taught.

    Thanks Eduardo. For those short on time, the conclusion is:

    "In conclusion, this study presents colony level
    characteristics in a population of surviving
    honey bee colonies that limit the mite
    population growth by either suppressing mite
    reproductive success or limiting mite reproductive
    opportunities by reduced brood production.
    Although the exact mechanisms
    behind these traits are not yet identified, the
    information collected from this investigation
    is a step forward towards understanding the
    adaptive processes of mite tolerance in honey
    bee colonies. The only documented sustainable
    tolerance to V. destructor mite in European honey
    bees are of colonies that have not been selected
    by humans but that have been exposed to natural
    selection pressures."

    I'm not sure if that 'only documented' still stands up, or if the reason for it is lack of documentation of private beekeepers - who can't be documented.

    Mike (UK)
    The race isn't always to the swift, nor the fight to the strong, but that's the way to bet

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    Default Re: Resistance to varroa : what mechanisms?

    Quote Originally Posted by Snowhitsky View Post
    I'd be grateful if someone could point me to research on this aspect.
    Snow, if I understand well your question in principle two sisters artificially inseminated with identical semen theirs offspring should present a very similar behavior with regard to VSH behavior. But it is a speculation, I don' t know no experimental design to test directly the issue. Already in VSH sisters mated outdoors the differences can be huge. View Erik Osterlund (POV in Beesource).

    However Randy Oliver talking about the effectiveness of this behavior (varroa tolerance) he said that this behavior can be seriously compromised by the very conditions/ context of the apiary. Listen here http://kiwimana.co.nz/randy-oliver-f...keeping-km061/ from 38:55. As he says the answers to these and other questions about bees are anything but simple.

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    Default Re: Resistance to varroa : what mechanisms?

    You understood me perfectly. I wonder if everybody is going down the genetics line simply because most competent beekeepers can attempt to select for genes and other potential solutions are much harder to investigate.

    In everyday life we often approach problems by well-trodden routes because they work but also out of convenience/laziness. I've worked in quite varied sectors and as the complete beginner I've sometimes changed working practices by asking apparently "stupid" questions.

    I suspect I'm barking up the wrong tree on this one but hey you never know!
    Last edited by Snowhitsky; 12-18-2014 at 05:28 AM.

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    Default Re: Resistance to varroa : what mechanisms?

    Quote Originally Posted by mike bispham View Post
    Thanks Eduardo. For those short on time, the conclusion is:
    Mike (UK)
    I read that (interesting study, thanks Eduardo) and thought the conclusion would be right up your street Mike, broad spectrum colony traits providing the resistance rather than specific vhs(or other) mechanisms. Seems more achievable by your low tech husbandry approach.

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    Default Re: Resistance to varroa : what mechanisms?

    Quote Originally Posted by Snowhitsky View Post
    You understood me perfectly. I wonder if everybody is going down the genetics line simply because most competent beekeepers can attempt to select for genes and other potential solutions are much harder to investigate.
    I think mostly people go down the genetic line because both thousands of years of empirical evidence and the entire body of modern husbandry understanding both indicate clearly that... the more genetics are neglected, the more problems tend to increase; and vice versa.

    Husbandry is about controlling genetics. Period.

    Mike (UK)
    The race isn't always to the swift, nor the fight to the strong, but that's the way to bet

  9. #9
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    Default Re: Resistance to varroa : what mechanisms?

    I thought this interesting since many of their conclusions come from the % of fertile to infertile etc...

    "In the surviving population, a total of 614 cells were examined in 23 colonies, and a total of 592
    cells were examined in the 21 control colonies with observations between ten and 35 cells per colony"

    That doesn't sound like a very large sample group to me within each colony.. I think even the pin prick, triangle sample is at least 100 cells.

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    Default Re: Resistance to varroa : what mechanisms?

    Quote Originally Posted by Brandy View Post
    I think even the pin prick, triangle sample is at least 100 cells.
    I'm not a statistician , but I think there are statistical procedures robust enough to deal with small samples. I hope that was the case. Peer review is usually attentive these failures. But I am no expert I repeat.

    "A highly significant difference was observed in the average proportions of successfully reproducing Varroa mites between the surviving colonies 0.480.02 (x SE, n=23) and the control colonies 0.780.02 (x SE, n=21, F1, 41.4 =75.78, P<0.0001)." p. 537

  11. #11
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    Default Re: Resistance to varroa : what mechanisms?

    This was another study done here where they used 200 cells etc...

    http://www.ars.usda.gov/SP2UserFiles...evaluating.pdf

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    Default Re: Resistance to varroa : what mechanisms?

    Brandy I'm confused about the rationale that you are following. In the study of colonies in Gotland , Sweden were analysed a little over 1200 cells to reach conclusions. The study you shows have been analysed, if I not misinterpreted, in a first trial 100 cells, 200 cells in the second trial and, in a third trial, 100 cells. Conclusions are reached from a total of 400 cells. What you draw from these figures about the credibility of both studies? If you can help me better understand your reasoning...

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    Default Re: Resistance to varroa : what mechanisms?

    Quote Originally Posted by Michael Bush View Post
    Producing Varroa-Tolerant Honey Bees from Locally Adapted Stock: A Recipe
    http://www.beesource.com/resources/u...tock-a-recipe/
    Thank you Michael Bush. A very practical recipe that illuminates me the way to get ahead in my project bees resistant/tolerant to varroa.
    The latest data are from 2000. Are there more recent data and a follow-up?

  14. #14
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    Default Re: Resistance to varroa : what mechanisms?

    In the section on "Suppression of mite reproductive success" they talk about how they measured mite reproduction and it's success or failure. They mentioned "In the surviving population, a total of 614 cells were examined in 23 colonies, and a total of 592
    cells were examined in the 21 control colonies with observations between ten and 35 cells per colony."

    I merely mentioned and thought that most of the studies I've seen use a greater number of cells as a sample group. I'm not a statistician either but 35 cells out of a frame with potentially 3500 cells on one side seemed small.

    The other study I mentioned used a few more. I think we're all just trying to understand/verify what will give us an accurate reading when we apply some of these tests to our own colonies..

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    Default Re: Resistance to varroa : what mechanisms?

    Quote Originally Posted by Brandy View Post
    I think we're all just trying to understand/verify what will give us an accurate reading when we apply some of these tests to our own colonies..
    Yes I get it the pragmatic goal you seek.

    The collection procedure in the Swedish colonies is described below:
    "Complete mite families from single-mother mite-infested cells were removed using a fine brush and examined under a stereo microscope. Within each pupal cell, the following information was collected:
    1. Whether the mother mite reproduced; 2. The total number of offspring per mother mite, 3. Whether an alive male was present or absent, 4. The number of dead mite progeny, and 5. The developmental stage of each individual mite offspring.
    " pg. 536.

    This procedure is not practical for the beekeeper .
    In my opinion we should look to a level above this , the colony level and the visible manifestations of varroa and / or counting of mites by convencional methods.
    As for the total sample of cells analysed in both studies, the Swedish study is 3 times higher. In this respect we have different opinions.

  16. #16
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    Default Re: Resistance to varroa : what mechanisms?

    I am seeing evidence of accumulation of multiple small genetic effects that result in gradually increasing mite tolerance. This is accompanied by ongoing attrition as susceptible stocks are wiped out year after year. The way to keep this going is to produce large numbers of colonies, let mites destroy the susceptible as fast as possible, and breed from the resistant colonies. Guess what treating for mites prevents?

    IMO, it would be counterproductive to focus entirely on one trait such as VSH when other traits such as mite entombment are available and effective. We should be working on bees that combine as many resistance traits as possible, caveat that some may be mutually exclusive.
    DarJones - 45 years, 10 colonies (max 40), sideliner, treatment free since 2005, 11 frame broodnest, small cell

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    Default Re: Resistance to varroa : what mechanisms?

    Quote Originally Posted by Fusion_power View Post
    IMO, it would be counterproductive to focus entirely on one trait such as VSH when other traits such as mite entombment are available and effective. We should be working on bees that combine as many resistance traits as possible, caveat that some may be mutually exclusive.
    Do you know what is the mechanism(s) that your resistance/tolerance to varroa feral swarms use in USA? Do you know if some research has been done on this aspect?

  18. #18
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    Default Re: Resistance to varroa : what mechanisms?

    Quote Originally Posted by Fusion_power View Post
    IMO, it would be counterproductive to focus entirely on one trait such as VSH when other traits such as mite entombment are available and effective. We should be working on bees that combine as many resistance traits as possible, caveat that some may be mutually exclusive.
    Yes Fusion the data from this research show that the mechanisms of resistance / tolerance to varroa are other than the grooming or hygienic behaviour. The conclusion I draw is that the response of bees to the challenge of the plague of mites can be and is very plastic . Here too the maximum that " beekeeping is local " seems to apply.

    "Based on the results of this study, neither hygienic behaviour nor grooming behaviour can be considered characteristics responsible for the mite tolerance observed in this surviving honey bee population in Sweden. Therefore, selection for these traits was probably not as important as traits related to mite reproduction for their survival with Varroa mites. This is an important observation considering the attention mite-resistant breeding programmes put towards these behavioural traits (Büchler et al. 2010; Rinderer et al. 2010)." pg. 539

    "Our results clearly demonstrate a significant reduction in the reproductive success of Varroa mites (measured as the ability to produce at least one viable offspring) in a European population of A. mellifera colonies where no mite control was practiced for more than 10 years. The surviving colonies had on average almost twice the proportion of infertile mites, more than twice the proportion of dead progeny, significantly reduced fecundity and an overall reproductive success rate of less than 50% compared with over 75% in control colonies. Delayed egg- laying by the mother mites was proportionally the most frequent cause of reproductive failure with dead progeny as the second most common cause. Reduced fecundity, along with the reduced ability to produce viable female offspring clearly, is important to explain the lower mite infestation rates in the surviving population."pg.538

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    Default Re: Resistance to varroa : what mechanisms?

    This other research carried out in feral swarms of Avignon, France, to 2000 Km of Gotland, Sweden, hereby presents data also very interesting, in my opinion. For those who want to deepen the analysis and reflection on this subject I leave the site where they can consult the paper. The discussion of researchers around the phenomenon of coevolution deserved a lot of attention from me.

    "Honey bee societies (Apis mellifera), the ectoparasitic mite Varroa destructor, and honey bee viruses that are vectored by the mite, form a complex system of host–parasite interactions. Coevolution by natural selection in this system has been hindered for European honey bee hosts since apicultural practices remove the mite and consequently the selective pressures required for such a process. An increasing mite population means increasing transmission opportunities for viruses that can quickly develop into severe infections, killing a bee colony. Remarkably, a few subpopulations in Europe have survived mite infestation for extended periods of over 10 years without management by beekeepers and offer the possibility to study their natural host–parasite coevolution. Our study shows that two of these “natural” honey bee populations, in Avignon, France and Gotland, Sweden, have in fact evolved resistant traits that reduce the fitness of the mite (measured as the reproductive success), thereby reducing the parasitic load within the colony to evade the development of overt viral infections. Mite reproductive success was reduced by about 30% in both populations. Detailed examinations of mite reproductive parameters suggest these geographically and genetically distinct populations favor different mechanisms of resistance, even though they have experienced similar selection pressures of mite infestation. Compared to unrelated control colonies in the same location, mites in the Avignon population had high levels of infertility while in Gotland there was a higher proportions of mites that delayed initiation of egg-laying. Possible explanations for the observed rapid coevolution are discussed." in http://onlinelibrary.wiley.com/doi/1.../ece3.248/full

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    Default Re: Resistance to varroa : what mechanisms?

    Quote Originally Posted by mike bispham View Post
    I think its broadly understood that traits are inherited, not taught.


    Mike (UK)
    Mike,

    Yes that would seem to be the case according to this study: http://www.gmb.org.br/Revistas/V18/v18a028.pdf

    However, I note on p178 that the II queens were introduced into mating nuclei containing brood, honey and pollen. Although they don't mention it, I suspect they must have added adult bees too and this seems to be implied a couple of paragraphs further on when they explain how they waited three months to be sure all adult bees were the II queen's offspring. I assume the added bees were from the same hive as the II queen and shared her traits.

    I'd love to find out if the results would have been the same if the added bees had been from another hive with different but measurable VSH characteristics. That would clearly prove without a shadow of a doubt that VSH is a wholly inheritable trait and not a one transmissible between adult bees.

    I know I'm grasping at straws but...

    Thanks to Michael Bush for the list of articles, much appreciated.
    Last edited by Snowhitsky; 12-19-2014 at 09:05 AM.

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