Solar heading of hive to treat varroa

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OursonAnglaise

OursonAnglaise

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Location
Haute Garonne, France
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I have just received my monthly French beekeeping magazine.

One of the first articles is about a new solar panel to increase the hive temp to 40 degrees for 150 minutes, which apparently reduces the varroa by 80%.

Has anyone heard about thus in the UK?
 

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Right, so to summarise, on a sunny day you take of the roof and use a clear crown board to raise the temperature in the brood box to over 40° at which point the mites start to suffer, big time. I could not make out for how long the brood box needs to be at the elevated temperature but our French correspondent uses the figure of 150 minutes (2 1/2 hours).

The only research that comes to mind is that of Zachary Huang of Michigan State University - Varroa mite Reproductive Biology. Almost as an aside he stated "If there are ways to artificially increase the hive RH to about 80%, then the varroa mite population will never increase to a damaging level." Maybe the effect of increased temperature to 40° is to also increase relative humidity - where is Derekm when you need him?

Like all silver bullets, we are bound to ask "if this is so brilliant, why doesn't everybody know about it?" Was there anything in the French article that offered any proof that it actually works as a varroa control system?

CVB
 
Last edited:
http://www.varroa-controller.com/treatment?locale=en



The development of the Varroa Controller is based on the known method of hyperthermia (already investigated in the late 1980s). A successful series of tests with 25 beekeepers using prototypes of the Varroa Controller were completed in 2009 and 2010. Based on the results of these test, the treatment parameters were optimized and a new design of the Varroa controller was developed.
 
It goes back a long way ... this study in 2000 gives you some interesting perspectives:

https://www.ars.usda.gov/SP2UserFil...1-400/384-Harbo--Heating Adult Honey Bees.pdf

The main problem is that 40 degress C is the optimal working temperature to activate the mites dropping off their host bees (it does not kill the mites) and at this tempearture you are very close to also killing your bees. Removing the bees from the hive in order to 'treat' them, IMO, is disruptive.

There is evidence that a slightly lower temperature and high humidity levels (85%+) has an adverse effect on the Varroa's ability to breed and this is one of the key reasons why my bees live in well insulated hives - I've carried out measurememnts of hive temperature and humidity levels in some of my hives over the last few years and the bees seem to thrive best when they are able to maintain a brood nest temperature of about 35 degrees and a relative humidity of above 80% .. this is achievable in my Paynes poly hives with a closed 6mm polycarbonate crownboard and 100mm of Kingspan in a super above it and under the standard roof.
 
pargyle said:
It goes back a long way ... this study in 2000 gives you some interesting perspectives:

https://www.ars.usda.gov/SP2UserFil...1-400/384-Harbo--Heating Adult Honey Bees.pdf

The main problem is that 40 degress C is the optimal working temperature to activate the mites dropping off their host bees (it does not kill the mites) and at this tempearture you are very close to also killing your bees. Removing the bees from the hive in order to 'treat' them, IMO, is disruptive.

There is evidence that a slightly lower temperature and high humidity levels (85%+) has an adverse effect on the Varroa's ability to breed and this is one of the key reasons why my bees live in well insulated hives - I've carried out measurememnts of hive temperature and humidity levels in some of my hives over the last few years and the bees seem to thrive best when they are able to maintain a brood nest temperature of about 35 degrees and a relative humidity of above 80% .. this is achievable in my Paynes poly hives with a closed 6mm polycarbonate crownboard and 100mm of Kingspan in a super above it and under the standard roof.
Click to expand...

Given the extract from Zachary Huang (2013) above, it now seems a pity that Harbo's study in 2000 did not extend its range of RH to see if that made a significant effect - he only used 60% RH.

Use of an Open Mesh Floor but with the monitoring board in place (to maintain humidity) and a well insulated enclosure might just give the combination of temperature and humidity that the Thermosolar Hive and the Varroa-Controller gadgets strive for.

CVB
 
There is evidence that a slightly lower temperature and high humidity levels (85%+) has an adverse effect on the Varroa's ability to breed and this is one of the key reasons why my bees live in well insulated hives - I've carried out measurememnts of hive temperature and humidity levels in some of my hives over the last few years and the bees seem to thrive best when they are able to maintain a brood nest temperature of about 35 degrees and a relative humidity of above 80% .. this is achievable in my Paynes poly hives with a closed 6mm polycarbonate crownboard and 100mm of Kingspan in a super above it and under the standard roof.

Pargyle - is this with the Paynes OMF? And why is the 6mm crown board used as well as the 100m Kingspan? I would have thought that the Kingspan would have been enough by itself.
 
I wonder if different sub species of honeybee maintain colonies at different temps and humidity.
I have noticed over the years that my Native Cornish Amm appear to have low or no varroa.... whereas the Mediterranean subs seem to need constant treatments.
Perhaps the natural varroa tolerance the Amm seem to have is due to the less varroa friendly environment they maintain within the colony??

I have not taken any measurements.
 
charlievictorbravo said:
Right, so to summarise, on a sunny day you take of the roof and use a clear crown board to raise the temperature in the brood box to over 40° at which point the mites start to suffer, big time. I could not make out for how long the brood box needs to be at the elevated temperature but our French correspondent uses the figure of 150 minutes (2 1/2 hours).

The only research that comes to mind is that of Zachary Huang of Michigan State University - Varroa mite Reproductive Biology. Almost as an aside he stated "If there are ways to artificially increase the hive RH to about 80%, then the varroa mite population will never increase to a damaging level." Maybe the effect of increased temperature to 40° is to also increase relative humidity - where is Derekm when you need him?

Like all silver bullets, we are bound to ask "if this is so brilliant, why doesn't everybody know about it?" Was there anything in the French article that offered any proof that it actually works as a varroa control system?

CVB
Click to expand...
For the same air water content raising the temperature lowers the relative humidity. However its complicated by having bees in there. if they evaporate water in the hottest regions (greater than 34C) to cool the hive, In the cooler brood regions the RH may go up.
 
derekm said:
For the same air water content raising the temperature lowers the relative humidity. However its complicated by having bees in there. if they evaporate water in the hottest regions (greater than 34C) to cool the hive, In the cooler brood regions the RH may go up.
Click to expand...

With bees in the box it is not a closed system... how much stability can the bees manage humidity wise and temperature wise...
Sadly I have experience two Pollystyrene hives being dumped on my doorstep full of dead bees because the entrance had been closed off for transport, with the beekeeper thinking an omf was enough... now insist on travel screens!

Thinking about it using one of the solar heating panels frequently could possibly encourage the bees to get up and go look for a more suitable home... yourn neighbors chimney perhaps????


Mytten da
 
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