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Discussion Starter · #1 ·
If I'm reading what Mr. Oliver is stating right that the oxalic acid/glycerin ration is 1:1 by weight. He also states that each sponge should have a total of 50 grams of acid which implies that the total weight per sponge is 100 grams solution.

Doesn't 50 grams of acid, per sponge, seem high?

Or am I reading it wrong?
 

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I have no idea if 50 grams is high or not with that type of delivery system. By comparison, the OAV flash treatment of 1gram per brood box is known to be inadequate (Jack,2021). But OAV is a flash treatment designed to be over in 15 minutes. The sponge is an extended-release treatment designed to release OA onto bees for weeks. The reality is that Randy, at this point, is still only guessing. His guess is much better than most, but it is only a guess. Since the OA is not being vaporized onto the bees or dribbled onto them in a sugar syrup, my armchair-chemist speculation is that the concentration of OA is so high in the sponge because we are relying on the bees to brush up against it and pull only tiny amounts of the solution off onto their bodies over a long period of time. Would stand to reason for me that, given the length of time of the designed treatment and the mode of delivery over that time, you would need to have a significant amount of OA in that solution. This mode of treatment just does not compare with OAV and dribble.
 

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Conceptually this is a slow release process and some of the OA is still in the sponge when removed.

with a dribble or VAP the OA is all applied at that time , here the bees walk over it and drag it thru the hive, over a longer timeline.

per psm1212
Since the OA is not being vaporized onto the bees or dribbled onto them in a sugar syrup, my armchair-chemist speculation is that the concentration of OA is so high in the sponge because we are relying on the bees to brush up against it and pull only tiny amounts of the solution off onto their bodies over a long period of time.

exactally

this would for example work good for an out yard that cannot be visited every 4 days for a brood cycle.
As well if you read Randy's article it seems the presents of the OA in the hive affects the breeding cycle of the Mites.

GG
 

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Discussion Starter · #5 ·
I have no idea if 50 grams is high or not with that type of delivery system. By comparison, the OAV flash treatment of 1gram per brood box is known to be inadequate (Jack,2021). But OAV is a flash treatment designed to be over in 15 minutes. The sponge is an extended-release treatment designed to release OA onto bees for weeks. The reality is that Randy, at this point, is still only guessing. His guess is much better than most, but it is only a guess. Since the OA is not being vaporized onto the bees or dribbled onto them in a sugar syrup, my armchair-chemist speculation is that the concentration of OA is so high in the sponge because we are relying on the bees to brush up against it and pull only tiny amounts of the solution off onto their bodies over a long period of time. Would stand to reason for me that, given the length of time of the designed treatment and the mode of delivery over that time, you would need to have a significant amount of OA in that solution. This mode of treatment just does not compare with OAV and dribble.
I don't know if 50 grams total OA is high or not either...but the LD50 of OA acid in rats is around 7 grams per kilograms (oral) which in my mind is pretty low. It's just that when I read the procedure to making the sponges to his specs each sponge would have to absorb a lot of solution....100 grams to be exact.

Has anyone here tried making the sponges? I know its not legal, but lets be real...a lot of what beekeepers do isn't.

Anyahoo...I'll give it a shot for chitz and giggles
 

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So...they couldn't replicate Mr. Oliver's findings and lost a lot of hives in the process.

Interesting.
Randy Oliver acknowledges this and thinks it's the humidity as mentioned. The glycerin draws moisture, which is what keeps the OA active in dry areas. More studies need to be done.

Monitor, monitor, monitor.
 

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If I'm reading what Mr. Oliver is stating right that the oxalic acid/glycerin ration is 1:1 by weight. He also states that each sponge should have a total of 50 grams of acid which implies that the total weight per sponge is 100 grams solution.

Doesn't 50 grams of acid, per sponge, seem high?

Or am I reading it wrong?
I believe that his tests were done with 50 grams of OA per colony, as well as 18 grams and 25 grams. He usually used two sponges cut to size to absorb the 50 grams. He also notes that all 50 grams do not get on to the bees as much as retained on the sponges. Here is a presentation of his tests:

 

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I have talked to both Jennifer Barry of the University of Georgia and Geoffery Williams of Auburn University who did shop towel studies. I still don't think the study has been published, but I am not sure about that. Both confirmed that Randy's then-current formula with the shop towel serving as the delivery mode simply did not effectively manage varroa. Much was made of the different climates between Randy (arid and dry northern California) and UGA and AU, (hot and humid Southeast), but I don't know if that was ever conclusively proven. I heard Randy Oliver push back on this notion once in a presentation he did.

I think a time-released OA solution is likely our most viable non-synthetic varroa control tool. But I don't think we have quite figured out how to delivery it yet.

I have made up shop towels a couple of years ago based on a formula Randy published back then. I did not sample enough and did not use a control, so I did not come to any real conclusions.
 

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If I'm reading what Mr. Oliver is stating right that the oxalic acid/glycerin ration is 1:1 by weight. He also states that each sponge should have a total of 50 grams of acid which implies that the total weight per sponge is 100 grams solution.

Doesn't 50 grams of acid, per sponge, seem high?

Or am I reading it wrong?
My take on Randy's article is 1:1 ratio, and that is 25 grms (by weight) of Veg. Gly. and 25 grms of OA (by weight). For a total weight of 50 grams per hive.
 

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Discussion Starter · #11 ·
I believe that his tests were done with 50 grams of OA per colony, as well as 18 grams and 25 grams. He usually used two sponges cut to size to absorb the 50 grams. He also notes that all 50 grams do not get on to the bees as much as retained on the sponges. Here is a presentation of his tests:

Thank you for including that video....very helpful.

Make it a great evening Sir.
 

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I don't know if 50 grams total OA is high or not either...but the LD50 of OA acid in rats is around 7 grams per kilograms (oral) which in my mind is pretty low. It's just that when I read the procedure to making the sponges to his specs each sponge would have to absorb a lot of solution....100 grams to be exact.

Has anyone here tried making the sponges? I know its not legal, but lets be real...a lot of what beekeepers do isn't.

Anyahoo...I'll give it a shot for chitz and giggles
The sponge is cut in half, so each half contains 25 grams. Randy's trials used 1 piece (half of a sponge) or 2 pieces (a full sponge). The 2 piece trials had the best efficacy.

It is easy to make them. After they are cut in half (3.5"x8"), stack them together. I heated the glycerin in a glass container in a microwave and then added the OA to dissolve it. I had a shallow porcelain dish (about 6"x9") that I heated to about 160 deg F in the oven so it would not chill the OA/gly solution when poured into the dish. The stack of half sponges are then placed into the dish on edge, not laying flat. I wear a heavy pair of rubber gloves to avoid the heat and turn the stack over after it has sopped up about half of the solution. After all the solution is absorbed, put the stack in a zip lock bag.
 
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