OAV questions

[GSF]

Once a hive has been OAV'd when does it go dormant? Undoubtedly less than seven days. Also is it the vapor only that kills them or the residue, i.e. crystals? 

[Barhopper]

My understanding is that the vapor recrystalizes when it cools down. I'm not sure what you mean by dormant.

[Dallasbeek]

When does what go dormant?  The oxalic acid or the hive?  I don't believe the OA goes dormant at all. 

As I understand it, as the vapor cools, it forms crystals, so if you see a puff of white coming from the hive while vaporizing, you're seeing crystals.

Don't know if this in any way answers the questions, but it's just what I can contribute from my meager knowledge of the subject.

[GSF]

What I'm trying to ask is at what time is the OA no longer any good for killing mites. I'm thinking if we have to repeat it every 7 days then there must be a life span on it. Otherwise we'd do it once and that'd be it. Just curious.

[KeyLargoBees]

It only kills mites outside the cells and then the bees clean it up is my understanding so we have to reapply to regenerate new crystals for the next batch of hatch outs.

[Dallasbeek]

It only kills mites outside the cells and then the bees clean it up is my understanding so we have to reapply to regenerate new crystals for the next batch of hatch outs.

That's my understanding, as well -- that it has no effect inside cells and the bees take out the "trash," so we have to repeat the treatment. 

[Dallasbeek]

After the above, I was rereading some of the articles Randy Oliver has written about OA. And found this written in 2007:


"Radetzki found that mite kill takes place in the first week, and tapers off for the next two weeks. One manufacturer claims: ?Without brood one vaporizer treatment is more than 95% effective (note: this is not much better than a good OA dribble) and with a follow up treatment, your bees should be almost mite free.? Some Europeans use it regularly during the summer. Sounds to me like a strategy to develop oxalic-resistant mites?"


i wonder if he still thinks mites could become oxalic resistant.  It does throw the idea some of us have into question, but I don't see how something that's basically mechanical could stimulate resistance.  Back to my earlier analogy (maybe in another thread) of smashing the mites with a brick, some mites might survive getting smashed, but the next time they meet a brick, they aren't tougher as a result of their first encounter.

[texanbelchers]

My understanding is the OA is most effective on days 2 and 3 after a vapor treatment.  The mites are phoretic for 5-11 days, so a 7 day cycle will get most of the just emerged suckers.  Even drone brood that is capped for 14+-1 days is covered by 7+7+(2 or 3).

It is said the bees haul it out like trash, but it is a very fine crystal after vaporization and I'm sure it takes a while.  It is considered safe to put supers back on after 10 minutes, so the crystals aren't floating in the air at that point.

[Hops Brewster]

It is my understanding that with some of the earlier mitecides tried, varroa developed resistance in the first season.  Some others develop resistance in the 2nd season.
So far, I have not read about any evidence that varroa have developed any resistance to OA, whether dribble or vaporized, after being used for about 15 years, first in Europe, then in the U.S.  I have not read of any evidence of varroa developing resistance to formic acid treatments, either.  Perhaps I've missed the evidence.  So what is all the hand wringing about OA resistance?

[Nugget Shooter]

For the mites to build up 'resistance" to OA they would have to develop some sort of acid proof clothing like humans do... Kind of silly way to put it, but it would be similar to you trying to build up a resistance to sulfuric acid without protection from gloves or clothing, every time you pour it onto your skin it will react the same and destroy flesh.

Much different for medication type poison which over time your body can adapt to....

[Acebird]

For the mites to build up 'resistance" to OA they would have to develop some sort of acid proof clothing like humans do...

Does the honeybee have this clothing?  OA is a chemical that appears to give good mite kill results.  It is not known to date how the acid works to achieve this result and it not know what the long term side effects are.  We like the short term results so it's use has grown in popularity.  A lack of knowledge is not a good reason to not be suspicious of the long term side effects.

[Nugget Shooter]

Nope they do not.... And leaves one to ponder doesn't it? Is the damage the bees see minor enough to not cause the hive as a body more problems than the mites? Apparently so from what has been seen over many years use and as with the mites the damage is instant and not something that will lessen or build up over time. It is an acid and acids are very specific as to what they will dissolve, burn, or destroy.

So that said there is no real long term build up in the bees short lives, nor is there a build up of resistance in mites or bees to OA. What again is the damage to bees? Good question and I wonder if anyone has done a study to that affect and perhaps dissected a bee or two exposed. I searched online and see nothing so far, but years of use has shown very little problems with bees properly treated hives and instead the overall health of the hive improves as a result.

We are left with few choices then, no treatment, chemical poisons, or Oxalic acid... For me as a new guy with mites here in Arizona I choose for now to use OAV and once I fully understand managing my bees and understanding the full cycle feeling that not treating would result in disaster. As I learn and grow I may look at treatment free, but there is allot to learn before I will feel comfortable with that.

[GSF]

Interesting point you brought up Nugget shooter, I guess we would have to start with killing a few bees with OAV then look at them through a microscope to see the damage. After we do that then lessen the OAV with a different set of bees and keep going down until we kill mites only. Then we could compare what the first kill looked like compared to the bees who survived when the mites different.

Does any identity have any documentation on what a healthy mite looks like compared to those killed by OAV?

[paus]

someone that has had experience with powdered sugar dusting tell me why this does not work on mites especially with an oil pan under the hive.  I have been killing shb by the hundreds in oil with a double sbb,  screen on top and under the oil pan bee proof,

[iddee]

Here's a tidbit from a post on my forum that may answer that question, acebird.  That's why I belong to a half dozen or more forums. There's good info on all of them.


""The crystals sit on the hairs on the bees body they also sit on the hairs on the varroa
The bees can just groom them off (they do not eat them)
The varroa has sticky pads on its feet these collect the acid crystals
The varroa cannot groom the crystals from their body
If you put the varroa under a microscope after treatment you will see the crystals on the feet and body""

[Nugget Shooter]

Here's a tidbit from a post on my forum that may answer that question, acebird.  That's why I belong to a half dozen or more forums. There's good info on all of them.


""The crystals sit on the hairs on the bees body they also sit on the hairs on the varroa
The bees can just groom them off (they do not eat them)
The varroa has sticky pads on its feet these collect the acid crystals
The varroa cannot groom the crystals from their body
If you put the varroa under a microscope after treatment you will see the crystals on the feet and body""

Thank you and this explains allot.... Man so much to learn.

[GSF]

paus, I can only guess, however I'm thinking that the powder sugar just doesn't kill a high enough percentage of the mites. Therefore their population recovery time isn't that long. With the OAV I've read that as much as 97% of the mites are killed.

All I can say for sure is that I've been doing it for 4 seasons and it's worked every time, not only worked but worked well.

[Psparr]

The powdered sugar doesn't kill them. Only lessens their ability to hang on and they fall off.

[GSF]

well daaaahhh, thanks Psparr. I let that one get by me (lol)

[paus]

Just call me still mixed up.  The powered sugar makes the mites fall off. In a screen bottom board or in an oil pan as I use aren't the mites dead. Isn't the sugar a source of nutrition for the bees?