One of the most insightful reads you will find on the subject of OAV intervals is found here on BeeMaster, by coolbees. Though the learnings may go over the heads of folks who have not engaged into OAV treatment yet, it can be easy to miss the key points. Real data and charts go a long way with me and that thread has them.
I have read alot, I have listened to and talked with PhD level experts alot. I have applied and experimented alot. A summary bullet points of knowledge of OAV treatment to share. You can go down the long path of grabbing at everything out there (you should) or for now you can just absorb these bullets below and run with it. These are from my research, my experience, my perspective and how OAV is used in my operation:
- OAV kills mites dead, very dead.
- OAV does not harm the bees. The alternative of OA drizzle does do serious harm to the bee exoskeleton.
- OAV does not harm brood, although I have observed that open youngest brood (teeniest larvae) may be curtailed if the dose applied is too high. Meaning if you are finding spotty or lapse of brood in the youngest patches after treatment, reduce the dose amount, but do not change the frequency schedule.
- How it works: OAV as the hot vapour gets fanned and cools inside the hive, the crystals condense onto combs and bees. Much like water vapor condensing on a cold glass of ice tea. This making a fine microscopic dusting of acid crystals on everything in the hive that a roaming mite will have to touch, be that on or off of a bee. Done well, everything is dusted and the mites cannot escape it. Exactly how (biology-wise) OA kills the mite we do not know nor do we care. The ultimate objective of OAV is to coat all of the internals of the hive where mites would be (brood nest) with the OA dust so they have to touch it. The actual dose (gram per box) really does not matter at all. What matters is that there is enough vapor injected to penetrate the cluster and coat surfaces with condensed OA dust.
- In the high traffic areas of bees cluster and lotsa bees working/walking, that OAV film dissipates (gets worn off or licked off) in the next 24-36 hours. Areas of the hive that have less bee activity will have the OAV film visible and effective much longer.
- because OAV condenses and crystallizes on surfaces such as bee hairs and combs as it cools, it physically cannot penetrate under brood caps. Thus mites under caps are safe until they come out. So OAV can only affect exposed mites.
- an egg laid hatches in 3-4 days. Is open larvae for 4 days. Then is capped. Mites will enter a cell during the larvae stage, which is only a 3-4 day window. This is where the frequency of application comes in. To be truly effective and virtually eradicate the mites in a hive; The treatment must occur on a VERY disciplined schedule to: 1) kill exposed mites on bees and crawling the combs, 2) expose and kill mites that are emerging within the next 24 hours by the crystal film, 3) kill exposed mites before they can crawl into new larvae cells and burrow into the jelly underneath them.
- during normal times, brooding times, the condition/status of brood development is not static. The queen continues to lay new eggs the day of and minutes after OAV has been applied. So the brood cycle and thus effectiveness of OAV at the time of application is sliding, is continually changing. For this reason, multiple applications along that sliding development timeline is necessary.
Although there is much ado about dosage levels in the current mainstream discussions - it is actually the treatment schedule that needs to focus on. A lot of folks just do not make the link between the significance of the brood development timeline with the frequency and number of applications necessary to properly get the job done. At his point in my OAV journey and subsequent results that it is my fairly strong IMHO that the efficacy of OAV has some but very little to do with actual dose level but is absolutely mostly about the schedule. If one looks at a simple egg->larvae->capping chart with continuous egg laying it becomes clear that the most efficient and most effective dose interval needs to be no less than 4 days and never more than 6 days. Original prescriptions for OAV were to apply once a week and only once or twice. Thats all. When you consider the development of the bee (in days), a continuation of egg laying, and the period that a mite has to come out of a cell and go back into another cell - it is painfully clear that the once a week idea is half baked and totally ignorant or simply completely incompetent prescription of this method.
The Frequency MUST be between 4 and 6 days and MUST occur for 6 cycles to extend through to the end of the worker and drone development from egg laid to emerging bee/drone. If even 1 application is missed or extended, the entire regimen must be reset, and retarted back to 1 and go for another 6 cycles.
OAV is VERY very effective. But it can easily be failed by the user because it takes a strict disciplined schedule. If you go about it half baked or loosey goosey and cannot keep yourself on a schedule, then do not bother with it. Miss just one cycle and the mites will -breakaway-. I use OAV exclusively in the Fall and have extraordinary results. But it does take-up alot of cycle time going around and around and around and around every 4-6 days. Moving and consolidating hives into Fall holding yards helps to cut down on alot of windshield time when the regimen is underway.
I suppose you could look at it like if you had an infection. You goto the doctor and are prescribed a bottle of antibiotic pills. You can take the pills on schedule and actually finish the whole bottle as intended, in doing so you eradicate the illness and you become healthy and robust. Or you may instead take the pills sporadically or only half the bottle because you were starting to feel better - then wonder why your illness continues to linger or you become sick again or worse just short time later. Where was the miss? Was it the prescription or was it the application/use. Starting and completing an OAV regimen properly is somewhat like that, and success or failure in the end results of mite control/eradication is exactly like that. Follow the prescription ...
Hope that helps!
Topic: OAV Treatment Schedule with Brood (Read 1472 times)