# Fine scale Varroa study shows importance of horizontal spread



## JWChesnut (Jul 31, 2013)

Full text free: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5089174/

Apidologie. 2016; 2016: 1–9.
Published online 2016 Jun 13. doi: 10.1007/s13592-016-0453-7
PMCID: PMC5089174
NIHMSID: NIHMS790181
Fine scale population genetic structure of Varroa destructor, an ectoparasitic mite of the honey bee (Apis mellifera)
Travis L. Dynes,1 Jacobus C. De Roode,1,2 Justine I. Lyons,1,2,3 Jennifer A. Berry,4 Keith S. Delaplane,4 and Berry J. Brosi1,5

Our results surprisingly indicate that detectable hierarchical genetic variation exists between apiaries, between colonies within an apiary, and even within colonies. This finding of within-colony parasite diversity provides empirical evidence that the spread of V. destructor is not accomplished solely by vertical transmission but that horizontal transmission (natural or human-mediated) must occur regularly.


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## Himmel-Hund (Aug 1, 2015)

Genetic variation of mites between colonies?!

I doubt that this publication is worth the paper it's printed on!


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## JWChesnut (Jul 31, 2013)

Sort of negative are not you. The key finding is variation within a colony, as this indicates non-clonal expansion, and that means horizontal flow between hives.


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## heaflaw (Feb 26, 2007)

Does this mean that there are different "strains" of varroa which could vary in their effect on bees? I thought I had read that since the males mate with their sisters, there is very little genetic variation.


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## Himmel-Hund (Aug 1, 2015)

JWChesnut said:


> The key finding is variation within a colony, as this indicates non-clonal expansion ...


... which is virtually impossible due to the way Varroa is reproducing.

I know some guys will soon pop up here, stating, that it is possible, provided a cell is infested with 2 or more adult females.
But those females are clones themselves, thus it is very - very - very- ... - very unlikely that a genetical change can happen this way.

I'm not kind of negative. It's just that I don't appreciate the way some "scientists" blowing sand into the eyes of the beekeepers.


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## BadBeeKeeper (Jan 24, 2015)

Himmel-Hund said:


> Genetic variation of mites between colonies?!
> 
> I doubt that this publication is worth the paper it's printed on!


Did you read the paper? Do you know how to read the paper? They just used a whole crapload of words to say "Mites are transferred between colonies by bees and beekeepers more often than we thought."

My primary issue with their method is that they examined 589 mites from 200 colonies, this is just a hair less than three mites per colony. In my mind, this is far too small of a sample size.



heaflaw said:


> Does this mean that there are different "strains" of varroa which could vary in their effect on bees? I thought I had read that since the males mate with their sisters, there is very little genetic variation.


There is little variation on a large scale. They were examining very, very tiny differences. What they noted, was that there is a large amount of mite transfer between colonies, and that under highly infested conditions more than one foundress may lay eggs in a cell which can result in unrelated offspring mating and a concomitant genetic variation.



Himmel-Hund said:


> Re: Fine scale Varroa study shows importance of horizontal spread
> 
> 
> > Originally Posted by JWChesnut View Post
> ...


No, they are NOT necessarily clones, and it is -very- possible for two unrelated females to lay eggs in the same cell, which is exactly what the report says. Nobody is "blowing sand" into the eyes of beekeepers. The problem lies with having the scientific background that enables one to read, comprehend, digest and summarize the findings of a scientific report.

Judging by the title of the thread I'm reasonably sure that Mr. Chestnut understands the significance of the study, which is really rather simple...it's just that the paper is filled with a whole bunch of 'science-speak' that lets other scientists evaluate the methodology and accuracy of the study, in order to enable peer-review and replication.


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## Michael Bush (Aug 2, 2002)

>I thought I had read that since the males mate with their sisters, there is very little genetic variation.

But what happens when two Varroa foundresses enter a cell... then you get some genetic variation out of meiosis...


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## Himmel-Hund (Aug 1, 2015)

I'm not a geneticist - so correct me, if I'm wrong:

To my understanding this can not be the case if the female is homozygoteus.

Inbreeding tends to create homocygoteus individuals, doesn't it?


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## Saltybee (Feb 9, 2012)

Wonder what the seasonal drone drift has to do with it. Spacing is not going to stop drone drift. Does mite genetics vary with it?
Mites would not be the only species to have a stranger preference for breeding, so simple chance numbers in a colony may not govern horizontal breeding.


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## BadBeeKeeper (Jan 24, 2015)

Himmel-Hund said:


> I'm not a geneticist - so correct me, if I'm wrong:
> 
> To my understanding this can not be the case if the female is homozygoteus.
> 
> *Inbreeding tends to create homocygoteus individuals, doesn't it?*


That is completely irrelevant. I think I summed it about just about as simply as possible for you, and I don't think it can be made any simpler. What part of this are you not understanding? The whole point of the paper was that there appears to be a greater amount of 'mite swapping' between colonies than had previously been assumed, leading to greater genetic variance.


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## Himmel-Hund (Aug 1, 2015)

It is relevant, though you don't seem to understand it ...

I don't see any reason to continue your personal attacks, except you were involved in this lousy paper or any similar ones.


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## lharder (Mar 21, 2015)

Might be interesting to do this kind of study looking at hive spacing and bee keeping practice. Within my own little apiary there is lots of opportunity for site to site transmission of mites and viruses when moving bees.


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