Anti-Varroa (Closed) Screened Bottom Board

[TooBee...]

Came across this article, after visiting a website promoting Warre Hives, in which it started that under some circumstances a Anti-Varroa Screened Bottom Board could increase Varroa! However upon speed reading the pdf it is in Canada where their swings to low temperatures are much greater than in the UK.

I have pasted the "Recommendations" below and emphasized the part that got my attention.

"Based on the results obtained during the two years of trials, we are convinced that the anti-varroa bottom board is a good means of slowing the progression of the varroa mite population in the colonies ... The anti-varroa bottom board should however be used with a closed bottom in order to not, contrary to the desired result, encourage an accelerated increase in the varroa mite population which would follow a lowering of the hive temperature. This word of caution is very important. The bottom must be closed by means of a movable drawer that permits, at regular intervals, a cleaning of accumulated hive debris. This drawer is also useful for sampling purposes. We also recommend that the distance between the bottom of the sampling drawer and the screen be at least 4 cm (1 5/8”) to prevent the re-entry of the varroa mites into the hive..."

http://www.calgarybeekeepers.com/Bee-Club-Library-2/AV-BOTTOM_BOARD1.pdf

I don't want to start and argument, but I do know that most of us use this system of Varroa control and there is some debate as to whether or not the floor should be closed or not during the Winter; I was not aware Varroa could not climb back into the brood area if it fell 4cm+ below the comb? Just food for thought.

 

[Erichalfbee]

My varroa trays are a good 2/3 inches below the OMF so I leave them in.
I look at mites and cappings every day, but then I'm mad!
In the summer they are away completely.
That's having the bottom open as far as I'm concerned.

I was not aware Varroa could not climb back into the brood area if it fell 4cm+ below the comb? Just food for thought.

Doesn't matter; the number of live ones that fall through are insignificant

 

[For want of a better word]

Have seen a system where a bottom tray was filled with rotting debris containing a mix of compost ( bog moss ( Peat) free of course) rotting wood and bullshit ( probably)....

Erica... do this.. it saves you having to inspect the bees.. or tray for varroa!!

Yeghes da

 

[oliver90owner]

They are ‘open mesh floors’, not ‘varroa floors’.

The advantages would be there whether there wrre varroa or not. Simple as that.

Bees do not need a floor at all in winter - provided there is sufficient distance between the cluster and any moving air. Floors are only really there to keep out unwanted intruders.

 

[Finman]

.
Varroa kills hives, no mater what kind of floor is. Does varroa kill the hive this year or next year, floor has no meaning in this.

.

 

[Finman]

Have seen a system where a bottom tray was filled with rotting debris da

I use to clean them off. And same do the bees.

May be the case you saw was a mouse nest.

 

[TooBee...]

Doesn't matter; the number of live ones that fall through are insignificant

Ahh, I see! My Organic / Natural Beekeeping type books had sold me the idea that an Open Mesh Floor would allow Varroa to fall through it and not be able to climb back up, as it was too far for them, maybe a bit of wishful thinking!

But surely those advocates of breeding hygienic bees claim that their hygienic bees pick off the Varroa from the backs of their sisters and the Varroa drops through the mesh and onto the ground; you don't think that this type of behavior with a mesh floor would make much of a difference? Just asking as I don't know the answer.

 

[Erichalfbee]

Have seen a system where a bottom tray was filled with rotting debris containing a mix of compost ( bog moss ( Peat) free of course) rotting wood and bullshit ( probably)....

Erica... do this.. it saves you having to inspect the bees.. or tray for varroa!!

Yeghes da

Then what would I do in the morning when I walk the dog over the fields to the bees?

 

[Fritillary]

Then what would I do in the morning when I walk the dog over the fields to the bees?

Check for wax moth in the tray. - They loved it when I installed a deep floor filled with leaves etc.

 

[wessexmario]

Came across this article, after visiting a website promoting Warre Hives, in which it started that under some circumstances a Anti-Varroa Screened Bottom Board could increase Varroa! However upon speed reading the pdf it is in Canada where their swings to low temperatures are much greater than in the UK.

I have pasted the "Recommendations" below and emphasized the part that got my attention.

"Based on the results obtained during the two years of trials, we are convinced that the anti-varroa bottom board is a good means of slowing the progression of the varroa mite population in the colonies ... The anti-varroa bottom board should however be used with a closed bottom in order to not, contrary to the desired result, encourage an accelerated increase in the varroa mite population which would follow a lowering of the hive temperature. This word of caution is very important. The bottom must be closed by means of a movable drawer that permits, at regular intervals, a cleaning of accumulated hive debris. This drawer is also useful for sampling purposes. We also recommend that the distance between the bottom of the sampling drawer and the screen be at least 4 cm (1 5/8”) to prevent the re-entry of the varroa mites into the hive..."

http://www.calgarybeekeepers.com/Bee-Club-Library-2/AV-BOTTOM_BOARD1.pdf

I don't want to start and argument, but I do know that most of us use this system of Varroa control and there is some debate as to whether or not the floor should be closed or not during the Winter; I was not aware Varroa could not climb back into the brood area if it fell 4cm+ below the comb? Just food for thought.

I've just had a quick read, and done some searches through the document, but I cannot find in the paper any reference to the configuration of the top of the hive, whether cover boards, top entrances, or roof.

My level of surprise or not at their findings will be directly related to whether the hive had a solid cover board and top insulation, or had top ventilation or entrances and no roof insulation. The paper is inconclusive without that information.

 

[TooBee...]

I've just had a quick read, and done some searches through the document, but I cannot find in the paper any reference to the configuration of the top of the hive, whether cover boards, top entrances, or roof.

My level of surprise or not at their findings will be directly related to whether the hive had a solid cover board and top insulation, or had top ventilation or entrances and no roof insulation. The paper is inconclusive without that information.

Excellent points, which I completely missed, thank you for that.

 

[charlievictorbravo]

I use an Under Floor Entrance (UFE) and the vertical gap between the mesh floor and the monitoring board is about 3.5" (85mm). The monitoring board is slightly smaller than the gap in the floor and is supported on 4 nails, set as low as possible in the UFE. My thinking was to leave a small gap between the board and the UFE so that any live mites have a gap to cross to climb back up, through the mesh, into the brood box. If they were lucky enough to find a nail "bridge", good luck to them. Impossible to know whether my design works as intended but that was the thinking behind it.

CVB

 

[Finman]

.
It has been known 20 years that varroa cannot rise to the cluster if it drops through the mesh floor. It has been counted that mesh floor kills 25% out mites.

Well, is it true of not, very few any more writes about mesh floors mite killing properties.

It is too "happy beekeepers floor", which does the same thing. But research showed that it does not work.

Once Canadians started to research the mesh floor and varroa with 20 hives. All hives got so bad chalk brood that research was stopped to save the colonies.

 

[Finman]

.
AbstractThe study was carried out between 18 August and 30 December 2004 in the Experimental Apiary and in the Health Laboratory of the Catholic University of Temuco, located in Campus Norte, Rudecindo Ortega 02950 in the city of Temuco. The aim of the study was to evaluate the use of anti-varroa (AV) floor traps as a method for the physical control of the mite Varroa destructor. The study was carried out on ten colonies of Apis mellifera bees in Langstroth hives, with two models of AV floor traps: five tube model anti-varroa floor traps (AVT) (T1) and five mesh model anti-varroa floor traps (AVM) (T2), which were placed in the bottoms of the hives. The evaluation consisted of the observation and daily count of varroa mites which fell onto the base sheets of the AV floor traps with each treatment, identifying live and dead mites in order to make a comparison and determine the effectiveness of each type of trap. The efficiencies determined for the mesh and tube AV traps were 19.76% and 15.87%, respectively. Both types are options for the physical control of the varroa mite and may form part of an integrated mite control strategy.

Evaluation of two models of floor traps for the control of the mite Varroa... | Request PDF. Available from: https://www.researchgate.net/public...arroa_destructor_Oud_on_bees_Apis_mellifera_L [accessed Jan 27 2018].