Oxalic sublimation efficacy and effect on open brood

[dickbowyer]

I have previously treated hives after removal of honey supers by 3 applications of sublimated Oxalic Acid in its licensed version at 5 day intervals in late summer as described on this forum on a previous sticky link I can no longer find. Is this still thought to be effective? Recent paper this month Evaluating the Efficacy of Oxalic Acid Vaporization and Brood Interruption in Controlling the Honey Bee Pest Varroa destructor (Acari: Varroidae) seems to suggest it is not effective but researchers may have used a suboptimal dose, using only 1g rather 2.3g. I was also surprisingly informed that the sublimated Oxalic acid damaged/killed open brood, information apparently pick up by this beekeeper from a lecture by David Evans. Is this really a recognised effect?

 

[pargyle]

No ....and No it does not kill open brood.

 

[jenkinsbrynmair]

So what does Evans base his theory on? LASI used the optimal 2.3g dose and reported no brood damage

 

[mdotb]

I have previously treated hives after removal of honey supers by 3 applications of sublimated Oxalic Acid in its licensed version at 5 day intervals in late summer as described on this forum on a previous sticky link I can no longer find. Is this still thought to be effective? Recent paper this month Evaluating the Efficacy of Oxalic Acid Vaporization and Brood Interruption in Controlling the Honey Bee Pest Varroa destructor (Acari: Varroidae) seems to suggest it is not effective but researchers may have used a suboptimal dose, using only 1g rather 2.3g. I was also surprisingly informed that the sublimated Oxalic acid damaged/killed open brood, information apparently pick up by this beekeeper from a lecture by David Evans. Is this really a recognised effect?

In addition to using a lower dose, they treated at 8 day intervals, which potentially provides sufficient time that many of the mites emerging from the brood which was sealed during peak effectiveness of the first treatment may have been able to return to open brood and be resealed before the subsequent treatment. Too long an interval essentially reduces the effectiveness to that of the first treatment only as the mites which "escaped" the first time can continue to escape subsequent treatments simply by going about their normal breeding cycle.

However fundamentally my criticism of the experimental technique is that the efficacy of killing varroa was measured by "dead mites in 72 hr board collections". Taking their +ve control (Amitraz) it presented more "dead mites" than any other experiment. It is a potent chemical. There is however no measure of how many mites remained alive (e.g. alcohol wash at end of month, or even the non-destructive and almost as accurate sugar roll "wash"). As a beekeeper that's what I want to know about. I accept that they took other measures for "health" of the colony over a longer period, but their measure of mite control - the main point of the study - appears poor. Add that to the small sample (60 colonies used, but with 6 treatment regimes and 2 controls that makes 7.5 colonies per regime on average) and the usual variation in colony size, honey yield etc., they could easily have conducted much improvement measurement of efficacy, and did not.

Regarding oxalic acid on open brood, trickling/dribbling oxalic acid in sugar solution has been reported to have detrimental effect on open brood - though whether that is proper studies or anecdotal I don't know; I am not aware of any [peer reviewed studies] evidence of sublimation of oxalic acid having any effect on brood.

 

[madasafish]

IF OA sublimation kills brood, why don't I see lots of dead brood on the entrance or the ground underneath the entrance after the bees have cleaned the cells?
Why don't I find dead larvae in the combs?
Why do the thousand of UK beekeepers who vape report the same?

Answer : because it is bull excrement..

And if it is ineffectual, why do my hives not have high varroa counts?
Why do the thousand of UK beekeepers who vape not report the same?

Answer : because it is bull excrement..

I would expect Researchers who find their researches prove the world is flat - when everyone else knows from experience it is round - should stop and reconsider BEFORE they publish.

 

[jenkinsbrynmair]

Regarding oxalic acid on open brood, trickling/dribbling oxalic acid in sugar solution has been reported to have detrimental effect on open brood - though whether that is proper studies or anecdotal I don't know;

Proper studies, numerous

I am not aware of any [peer reviewed studies] evidence of sublimation of oxalic acid having any effect on brood.

#
Read the Sussex Plan - 'Integrated control of Varroa mites'

 

[dickbowyer]

So what does Evans base his theory on? LASI used the optimal 2.3g dose and reported no brood damage

This is reportedly what he said so may not be what he actually said.

 

[mdotb]

Proper studies, numerous
#
Read the Sussex Plan - 'Integrated control of Varroa mites'

Francis reports " Applying oxalic acid in solution via spraying or dribbling can be effective at killing varroa, but also harms the colonies. " in his article for the BBJ, but since the experiments in his cited papers are exclusively limited to "broodless periods" to the extent that he consistently removes any (capped) brood before implementing the test regimes, and has been known to advocate that beekeepers do so in the winter when treating I refer back to not personally having seen scientific measurements taken on mortality of open brood with trickling. I note that the citations says "harms the colonies" not "harms open brood". I haven't read every paper published. Following your direction above - I have read the cited papers from LASI, and although they have quoted the result as a sideline, I cannot see their data source for it.

I guess my point is that there is consistently reported "no negative effect when sublimating", however I am still as sceptical of the source of the less widespread "trickling harms open brood" data as of many other results that crop up without clear view of the experimental approach and measurement. It's a 'result' that I've seen mentioned "numerous times". But the same is true of many - now debunked - former beekeeping practices.

I'm certainly not saying open brood damage doesn't happen, merely trying to distinguish between those "facts" that I am convinced of through direct experimentation or evidence that I have critiqued, and those others that I have heard quoted but never seen the source of.

 

[Apiarisnt]

Al Toufailia, H.M., Scandian, L, Ratnieks, F. L .W. (2015) Towards integrated control of varroa: comparing application methods and doses of oxalic acid on the mortality of phoretic Varroa destructor mites and their honey bee hosts. Journal of Apicultural Research, 54(2), 109-121

 

[madasafish]

Al Toufailia, H.M., Scandian, L, Ratnieks, F. L .W. (2015) Towards integrated control of varroa: comparing application methods and doses of oxalic acid on the mortality of phoretic Varroa destructor mites and their honey bee hosts. Journal of Apicultural Research, 54(2), 109-121

Thanks
I quote " This confirms that applying OA via sublimation in broodless honey bee colonies in winter is a highly effective way of controlling V. destructor and causes no harm to the colonies. "

 

[mdotb]

Al Toufailia, H.M., Scandian, L, Ratnieks, F. L .W. (2015) Towards integrated control of varroa: comparing application methods and doses of oxalic acid on the mortality of phoretic Varroa destructor mites and their honey bee hosts. Journal of Apicultural Research, 54(2), 109-121

Which does not mention any effect on open brood present at the time of trickling or spraying. The relevant result is:

"The amount of brood after four months is also of interest. In particular, sublimation resulted in significantly more brood than controls, at 4.8 (average of the four treatment means) vs. 4.1 frames. The numbers of frames of brood was not different among control, trickling, and spraying colonies. However, there was a trend towards lower amounts of brood with higher doses for both trickling and spraying. Previous research also reported a negative effect on brood rearing following the application of OA via spraying and trickling (Higes et al., 1999; Rademacher & Harz, 2006)."

So the amount of brood present 4 months after treatment.

Higes et al (cited) took a similar measurement, that being that there were 8 weeks of "kill and count the surviving mites" using Fluvalinate and then (because they had resistant mites) coumaphos. They they looked at how much brood was in the colonies 8 weeks after the final OA application. They found a statistically significant reduction in brood levels compared to control (which in their case was water spraying).

Rademacher & Harz (cited) didn't actually conduct any experiments for that paper, they reviewed previous work. Within that review they tabulated "brood cells present" where original authors had provided that data - there is no detail given by Rademacher and Harz as to whether previous author's techniques were comparable which is not really surprising given that they don't make any conclusions relating to the effect of treatments on brood, only the effectiveness against mites. It appears to be a bit of a false reference.

So Toufaila, Scandian and Ratneiks found that 4 months after treatment (brood lasts 21 days) there was the same amount of brood in untreated controls, trickling, and spraying, but statistically significant more in vaporised. That sounds good, healthy colonies rear more brood, I think most people accept that vaporising OA does not negatively impact the bees etc., but once again, this doesn't suggest any negative impact on the open brood.

I suspect it may be this result - misunderstood or misquoted - and perhaps others like it that are becoming the "story" about trickling killing open brood. If it is not, I hope we stumble across whatever result which does show harm to brood, but in the meantime I will remain sceptical on the basis that I've not seen data and that the cited sources show something different to "harm to brood".

In practical terms all of these results still support both delivery mechanisms, and seem to slightly favour vaporisation.

 

[polymath]

I have previously treated hives after removal of honey supers by 3 applications of sublimated Oxalic Acid in its licensed version at 5 day intervals in late summer as described on this forum on a previous sticky link I can no longer find. Is this still thought to be effective? Recent paper this month Evaluating the Efficacy of Oxalic Acid Vaporization and Brood Interruption in Controlling the Honey Bee Pest Varroa destructor (Acari: Varroidae) seems to suggest it is not effective but researchers may have used a suboptimal dose, using only 1g rather 2.3g. I was also surprisingly informed that the sublimated Oxalic acid damaged/killed open brood, information apparently pick up by this beekeeper from a lecture by David Evans. Is this really a recognised effect?

You may want to look at the research by Professor Ratnieks, at Lasi, 97% effective, two treaments, 7 -10 days apart, they also show the effect of varying the doses. I have attached it for ease. Think this is what you need.

 

[polymath]

Which does not mention any effect on open brood present at the time of trickling or spraying. The relevant result is:

"The amount of brood after four months is also of interest. In particular, sublimation resulted in significantly more brood than controls, at 4.8 (average of the four treatment means) vs. 4.1 frames. The numbers of frames of brood was not different among control, trickling, and spraying colonies. However, there was a trend towards lower amounts of brood with higher doses for both trickling and spraying. Previous research also reported a negative effect on brood rearing following the application of OA via spraying and trickling (Higes et al., 1999; Rademacher & Harz, 2006)."

So the amount of brood present 4 months after treatment.

Higes et al (cited) took a similar measurement, that being that there were 8 weeks of "kill and count the surviving mites" using Fluvalinate and then (because they had resistant mites) coumaphos. They they looked at how much brood was in the colonies 8 weeks after the final OA application. They found a statistically significant reduction in brood levels compared to control (which in their case was water spraying).

Rademacher & Harz (cited) didn't actually conduct any experiments for that paper, they reviewed previous work. Within that review they tabulated "brood cells present" where original authors had provided that data - there is no detail given by Rademacher and Harz as to whether previous author's techniques were comparable which is not really surprising given that they don't make any conclusions relating to the effect of treatments on brood, only the effectiveness against mites. It appears to be a bit of a false reference.

So Toufaila, Scandian and Ratneiks found that 4 months after treatment (brood lasts 21 days) there was the same amount of brood in untreated controls, trickling, and spraying, but statistically significant more in vaporised. That sounds good, healthy colonies rear more brood, I think most people accept that vaporising OA does not negatively impact the bees etc., but once again, this doesn't suggest any negative impact on the open brood.

I suspect it may be this result - misunderstood or misquoted - and perhaps others like it that are becoming the "story" about trickling killing open brood. If it is not, I hope we stumble across whatever result which does show harm to brood, but in the meantime I will remain sceptical on the basis that I've not seen data and that the cited sources show something different to "harm to brood".

In practical terms all of these results still support both delivery mechanisms, and seem to slightly favour vaporisation.

The article does not quote the frequency but i have that in an email from Ratnieks

 

[Erichalfbee]

You may want to look at the research by Professor Ratnieks, at Lasi, 97% effective, two treaments, 7 -10 days apart

Isn’t that without brood though?

 

[jenkinsbrynmair]

Isn’t that without brood though?

probably
The man is obsessed with going in and digging out brood - blankly refused to even contemplate a three stage dose at five day intervals when asked

 

[Erichalfbee]

probably
The man is obsessed with going in and digging out brood - blankly refused to even contemplate a three stage dose at five day intervals when asked

Yes he wouldn’t even acknowledge questions about that at one talk of his I was at. He just skipped to the next person until he liked a question. Strange

 

[Arfermo]

Yes he wouldn’t even acknowledge questions about that at one talk of his I was at. He just skipped to the next person until he liked a question. Strange

Perhaps not so strange if you don't have an answer!!

 

[jenkinsbrynmair]

Yes he wouldn’t even acknowledge questions about that at one talk of his I was at. He just skipped to the next person until he liked a question. Strange

And let's not talk about live streaming a football match (sound on) during one of Tom Seeley's lectures at Aberystwyth summer school

 

[Ian123]

And let's not talk about live streaming a football match (sound on) during one of Tom Seeley's lectures at Aberystwyth summer school

I was never sure about the work they did down there. Not sure there was anything new they worked on that had not been covered elsewhere. Suppose they could have taken the opportunity to study the control of EFB though

 

[Finman]

When European Union Workgroup developed 20 years ago varroa treatments, they suggestet that do not trickle the hive, which has brood.
- First it violates larvae,
- And second, it does not kill mites, because 80% out of mites are under brood caps.

Group tested carefully the conventration of syrup and percentage of oxalic acid

Some countries use different values, but they do not have much difference.

- 2,8% Switzerland, canada
- 3,5% most countries
- 4,0% Italy

Ratsniek made a miserable studies about trickling. He calculated too early the dead mites after 2 weeks, when mites die about during 4 weeks.

Very carefull studies have been made 20 years ago. EU tested 3 years efficacy in 6 countries and they counted tens of hives.

Ratsniek was really in a hurry to get out his results. EU group made 6 years work.

He said that he was the first on globe to compare trickling and gasifying to each other.
That was strange, because in every treatment methods the final efficacy percent has bee reported.

A Japanese professor published gasifying method 1964.