Oxalic Treatment and Timing

[VEG]

got to watch them pesky counters

 

[user 6228]

....you are treating with warmth and humidity.

To kill varroa mites? Is there evidence to suggest this is effective in controlling infestations?

it affects the mites success at breeding quite dramatically
reference
Kraus, B., & Velthuis, H. (1997). High humidity in the honey bee (Apis mellifera L.) brood nest limits reproduction of the parasitic mite Varroa jacobsoni . Oud.Natur- wissenschaften 84, 217-218.

 

[Stickyfingers]

This has gone a long way to persuade me that monitoring varroa drops is of limited value.

I also believe the count is relative to the current size of your hive. I had various drops from 20 for a small nuc to 200 plus to the biggest hive and numbers in between for the other two.

 

[ianorsven]

it affects the mites success at breeding quite dramatically
reference
Kraus, B., & Velthuis, H. (1997). High humidity in the honey bee (Apis mellifera L.) brood nest limits reproduction of the parasitic mite Varroa jacobsoni . Oud.Natur- wissenschaften 84, 217-218.

Hi Derek
OK read their paper. However, they controlled humidity by placing brood in an incubator where temp and Relative Humidity were under their control. They also note: We found within a range of 31-35 no clear impact of temperature upon the percentage of reproducing mites ; and Temperature within the honey bee brood nest ranges from 31 to 36 C. RH decreases with increasing temperature. Since ambient temperature in cold and temperate climates is generally clearly below brood nest temperature, RH within the brood nest is comparably low even when ambient RH is high. RH in the brood nest of A. mellifera colonies is usually about 40%

So unless I've got this wrong, brood nest temp is determined by the bees and is fairly constant and a relative humidity of well over 79-85% which reduced the rate of mite reproduction was achieved by removing brood to an incubator since this level of humidity does not occur naturally within the brood nest.

 

[user 6228]

it affects the mites success at breeding quite dramatically
reference
Kraus, B., & Velthuis, H. (1997). High humidity in the honey bee (Apis mellifera L.) brood nest limits reproduction of the parasitic mite Varroa jacobsoni . Oud.Natur- wissenschaften 84, 217-218.

Hi Derek
OK read their paper. However, they controlled humidity by placing brood in an incubator where temp and Relative Humidity were under their control. They also note: We found within a range of 31-35 no clear impact of temperature upon the percentage of reproducing mites ; and Temperature within the honey bee brood nest ranges from 31 to 36 C. RH decreases with increasing temperature. Since ambient temperature in cold and temperate climates is generally clearly below brood nest temperature, RH within the brood nest is comparably low even when ambient RH is high. RH in the brood nest of A. mellifera colonies is usually about 40%

So unless I've got this wrong, brood nest temp is determined by the bees and is fairly constant and a relative humidity of well over 79-85% which reduced the rate of mite reproduction was achieved by removing brood to an incubator since this level of humidity does not occur naturally within the brood nest.

The level of humidity depends on how you keep them. if you keep them in a conventional thin walled hive, the relatively cold hive shell acts as a dehumidifier as the hive walls remain below the dew point, or if you have a top vent the warm humid air escapes.

if you keep them in an insulated nest with no top vent the RH rises because the surface temperature of the walls at the top of the nest rises above the dew point

Nearly all research is in either climate controlled or thin walled conventional wooden hives. This researcher has got the achievable RH in temperate climates bit wrong.

pargyle on this forum has observed this elevated RH directly.

in other research Bees preferentially regulate to 75% RH, but cant do this stuck in a strongly dehumidifing box

 

[Hivemaker.]

in other research Bees preferentially regulate to 75% RH, but cant do this stuck in a strongly dehumidifing box

And would tree nests in this country maintain this high humidity.

 

[user 6228]

And would tree nests in this country maintain this high humidity.

one complication is the high heat capacity of the trees, it will take time for the tree cavity to warm up after occupation begins

Another complication is the moisture permiability of the wood/ propolis combination.

so it is possible

given that Northern european bees regulate humidity one can postulate they must have a use for that behaviour in these climates.

I have tried looking for real Tree nest humidity measurements but have yet to find some.

I tried looking for moisture permiabilty for wood/propolis composites but have yet to find any.

 

[Hivemaker.]

one complication is the high heat capacity of the trees, it will take time for the tree cavity to warm up after occupation begins

I was just interested in the varroa control aspect, all the long established bees in tree nests in this area, and many others, collapsed within around 18 months of the arrival of varroa, some of these nests are taken over by escaped swarms, but the same thing happens in most cases. So in our climate....

 

[user 6228]

I was just interested in the varroa control aspect, all the long established bees in tree nests in this area, and many others, collapsed within around 18 months of the arrival of varroa, some of these nests are taken over by escaped swarms, but the same thing happens in most cases. So in our climate....

But in a harsher climate they are surviving well against Varroa(Arnot Forest), but still a high initial failure rate.

Survival of swarms in trees in the face of varroa is obviously not a simple affair and is not just about temperature and humidity. Just the thermal benefits and challenges need quite a bit of unravelling.

but if we dont try we won't get.

 

[Hivemaker.]

Colonies seem to collapse much more quickly now,with fewer varroa, than when varroa first arrived, the biggest problem being the viruses they vector like DWV CBPV ect. Constant splitting and brood breaks does reduce this problem to some extent, without treating, but not much good for productivity.

 

[TryingToLetThemBee]

I was just interested in the varroa control aspect, all the long established bees in tree nests in this area, and many others, collapsed within around 18 months of the arrival of varroa, some of these nests are taken over by escaped swarms, but the same thing happens in most cases. So in our climate....

This is why we MUST have feral bees and why those who lose swarms to the wild are doing beekeeping a huge service. It is where the evolution (of the mites) takes place.

Derek: I know you are a scientist but you've confused me a bit because as you know, given gas exchange (and the bees must breathe), then the moisture content inside the hive equals that outside and if inside is warmer, thenthe RH is lower, so just insulating cannot raise RH, right?

 

[Hivemaker.]

This is why we MUST have feral bees and why those who lose swarms to the wild are doing beekeeping a huge service.

Are you going to be doing beekeeping a huge service by doing no swarm control whatsoever from now on.

Will you stop collecting swarms, thus allowing them to take up residence in trees etc.

I prefer other methods regards breeding resistant bees.

 

[ianorsven]

my apologies! maybe tappers and counters should be segregated under different headings!

I am sure counting is more disturbing than tapping regardless

Hi Pete

How do you come up with this little gem? When I remove and insert trays I make sure to do it gently and without disturbance. The counting itself is a fairly benign activity!

On a more constructive note, if what you are suggesting is: all colonies have varroa and therefore don't need monitoring for mites - just treat them, I would understand and agree in the main.

 

[peteinwilts]

[/B]

Hi Pete

How do you come up with this little gem? When I remove and insert trays I make sure to do it gently and without disturbance. The counting itself is a fairly benign activity!

On a more constructive note, if what you are suggesting is: all colonies have varroa and therefore don't need monitoring for mites - just treat them, I would understand and agree in the main.

My thought is, you gently insert the tray, the temperature and humidity of the hive starts to adjust, the bees compensate, the tray is removed, the bees start to compensate, then the inquisitive beekeeper decides to do it again, and again... yes, the bees have to adjust in a similar manner with the changes of weather, but why force them into doing something that is unnecessary.
Some of my colony's tell me I am not welcome when I am a good distance away, never mind messing with their undercarriage.

If the tray is left in for a good amount of time, the hives internal environment will behave like a closed floor hive without top ventilation, and condensation can form very quickly.
I do not have science papers to back me up, this is just what I believe due to basic logic. I have an open mind, and am happy to be proved wrong.

I am not suggesting all colony's have varroa. I have a mixed bag myself with varroa on a greater or lesser extent on a hive by hive basis, with a small handful dropping no mites at all in Autumn.. all get treated in Winter. 'if' I performed a count before treating and decide not to treat, a small number will multiply and 'drastic' action 'may' be required before the next routine treatment in Autumn.
What I am saying, is how the results are quantified and acted upon. Regardless of the results, what would be done before spring.... If the need arises, why not do a drop count in spring when the bees are more capable to adjust and the colony is in a safer position.

Unless I suspect a hive has a mite issue, I do not count during summer as the signs are so easy to see. I only count in Autumn when the tray is already there.

It is all too easy for an overeager beekeeper to over-manage a hive in Summer or Winter.

 

[TryingToLetThemBee]

Are you going to be doing beekeeping a huge service by doing no swarm control whatsoever from now on.

Not intentionally, but in my first year I am realistic about my prospects during swarm season!

 

[ianorsven]

Thanks peteinwilts for such a thorough reply.
I understand the points you are making. I'm into my fourth year and still working it all out. I agree entirely about over managing and have cut down on the number of times I "check" on hives - guess I'm a bit more confident to leave them to it now. I will keep monitoring for mites at what I think are key times rather than year-round and act accordingly without relying totally on count numbers alone.

 

[TryingToLetThemBee]

My thought is, you gently insert the tray, the temperature and humidity of the hive starts to adjust, the bees compensate, the tray is removed, the bees start to compensate, then the inquisitive beekeeper decides to do it again, and again... yes, the bees have to adjust in a similar manner with the changes of weather, but why force them into doing something that is unnecessary.
Some of my colony's tell me I am not welcome when I am a good distance away, never mind messing with their undercarriage.

If the tray is left in for a good amount of time, the hives internal environment will behave like a closed floor hive without top ventilation, and condensation can form very quickly.
I do not have science papers to back me up, this is just what I believe due to basic logic. I have an open mind, and am happy to be proved wrong.

I am not suggesting all colony's have varroa. I have a mixed bag myself with varroa on a greater or lesser extent on a hive by hive basis, with a small handful dropping no mites at all in Autumn.. all get treated in Winter. 'if' I performed a count before treating and decide not to treat, a small number will multiply and 'drastic' action 'may' be required before the next routine treatment in Autumn.
What I am saying, is how the results are quantified and acted upon. Regardless of the results, what would be done before spring.... If the need arises, why not do a drop count in spring when the bees are more capable to adjust and the colony is in a safer position.

Unless I suspect a hive has a mite issue, I do not count during summer as the signs are so easy to see. I only count in Autumn when the tray is already there.

It is all too easy for an overeager beekeeper to over-manage a hive in Summer or Winter.

I agree with ianorsven (do they ever disagree among themselves. Really useful stuff and whole new perspectives on the board from a newbie's point of view. Thanks.

 

[mbc]

Colonies seem to collapse much more quickly now,with fewer varroa, than when varroa first arrived, the biggest problem being the viruses they vector like DWV CBPV ect.

I am surprised by this, I would say the trend is the opposite of this where I live.

 

[peteinwilts]

I am still new to beekeeping (about to start year 5) and am still learning and improving. A fair number of hives increases the learning curve.

I took part in the European bee health project and had several visits by the regional inspector to survey one of my apiary's.

He stated that my bees were in the best condition of any apiary he has seen and my schedules and techniques were top notch (all learnt from this forum!)

He tried them on his own last winter and when I saw him this year, he asked me if I mind if he teaches them to other beekeepers...

To hear that from a beekeeper of many decades is a really good confidence boost!

 

[user 6228]

This is why we MUST have feral bees and why those who lose swarms to the wild are doing beekeeping a huge service. It is where the evolution (of the mites) takes place.

Derek: I know you are a scientist but you've confused me a bit because as you know, given gas exchange (and the bees must breathe), then the moisture content inside the hive equals that outside and if inside is warmer, thenthe RH is lower, so just insulating cannot raise RH, right?

no... it does.

both water vapour and warm air rise. when cooling and condensation occurs the air falls.

... the full answer is more complicated with stratification and convection circulations

the more insulation the less cooling and so the stratification dominates, and the convection circulation weakens. so the water vapour tend to stay more with surfaces above the dew point until it all reaches equilibrium.

another way to look at it is that condensation needs a heat flow, if you reduce the heat flow with insulation you reduce the rate of condensation.







any top vents and you lose both heat and humidity.