OAV overdose?
Page 1 of 2 12 LastLast
Results 1 to 20 of 37

Thread: OAV overdose?

  1. #1
    Join Date
    Nov 2012
    Location
    Plymouth, MA USA
    Posts
    29

    Default OAV overdose?

    Does anyone have any ideas on limits of OAV exposure for a hive? I have just given my hives a 9th treatment, with treatments applied every 4-5 days. I feel that this is kind of extreme, but each treatment has dropped 1000-2000 mites until this last treatment, when the 48 hour drops were 555, 136, and 378 for my three hives. I have never seen anything like this; yet those numbers would suggest to me that the hives with the two largest drops at least need to continue treatment, but I am really hesitant to go further.

  2. Remove Advertisements
    BeeSource.com
    Advertisements
     

  3. #2
    Join Date
    Aug 2002
    Location
    Nehawka, Nebraska USA
    Posts
    53,922

    Default Re: OAV overdose?

    When I was experimenting with OAV I was doing a treatment every week for three weeks and saw no noticeable difference in the health of the bees between one treatments and three treatments. There did not seem to be any cumulative ill effects. If there is still brood in the hive then they will keep emerging.

    http://www.bushfarms.com/beesvarroatreatments.htm

    The best, of course, is a treatment with no brood in the hive.
    Michael Bush bushfarms.com/bees.htm "Everything works if you let it." ThePracticalBeekeeper.com 42y 40h 39yTF

  4. #3
    Join Date
    Nov 2012
    Location
    Plymouth, MA USA
    Posts
    29

    Default Re: OAV overdose?

    Thanks, Michael - I have never done more than 5 previously, which is one thing, but going on 10 seems a different order of exposure, no? Plus, I would think that by this time, here in New England, that the hives should be broodless.

  5. #4
    Join Date
    May 2019
    Location
    Lake County, Illinois
    Posts
    152

    Default Re: OAV overdose?

    I would be more concerned about protecting you health from OAV.

  6. #5
    Join Date
    Aug 2002
    Location
    Nehawka, Nebraska USA
    Posts
    53,922

    Default Re: OAV overdose?

    > but going on 10 seems a different order of exposure, no? Plus, I would think that by this time, here in New England, that the hives should be broodless.

    If you did 10 treatments a week apart the ones from the first four treatments have died of old age by the time you are doing the tenth treatment. I would have to do more math to figure it at five days apart, but off the top of my head I guess that the ones from the first two treatments have died of old age by the tenth treatment.
    Michael Bush bushfarms.com/bees.htm "Everything works if you let it." ThePracticalBeekeeper.com 42y 40h 39yTF

  7. #6
    Join Date
    May 2011
    Location
    Algoma District Northern Ontario, Canada
    Posts
    5,074

    Default Re: OAV overdose?

    I have heard people relate that in conditions where the colony is brooding heavily that they have had to go to continual applications at 3 day intervals to start to see the mite drop numbers to show reasonable progress. If you have untreated colonies surrounding you it compounds the problem.

    OAV is not the best option under such conditions but it will work if you shorten intervals so there is no opportunity for lapses in coverage. I haven't seen reports of mortality even with some extreme examples.
    Frank

  8. #7
    Join Date
    Mar 2013
    Location
    fairfield, sc
    Posts
    217

    Default Re: OAV overdose?

    I have been using OAV for a couple of years now and this year bought the $500 tool to try and make things easier for me.
    Things I've found out, or realized -

    It's not a 'sure' kill - even with treatments every 5-7 days for 3 or 4 treatments. the best and only method of assuring a good treatment - provided you can travel to out yards that frequently.
    It's a pain in the butt to drag out all the equipment every time I visit the yards (15-20 per yard x 5 yards) for 'anything'.
    Although I can quickly go thru a hive ( <~10 minutes) it's still a pain doing treatments.
    moving from screened to solid bottoms have helped (i think) in better application of the OA treatments - at least more consistent 'coverage' of the hives.
    purchasing multiple 'disks' to put the measured treatments while i gas them speeds up the treatment time.
    once the hive i started on initially for the first visit has calmed down, i 'tweak them' again whenever i gas them.
    it seems like in heavy brood periods, like spring or summer nectar flows - treating with OA isn't worth it - just causes me more time 'out'.
    if you start in a yard - you have to do all of them. don't just treat 1 or 2 hives in your yard that are 'high' in numbers.

    all that said - i still use a 'heavy' treatment either in the spring - or fall that has a prolonged treatment (pro or maqs) to get the 'best' treatments.

    just my 2 cents...

  9. #8
    Join Date
    Mar 2014
    Location
    Milford, Michigan USA
    Posts
    304

    Default Re: OAV overdose?

    For a few years now after removing my honey supers in mid August I begin oav about every five days or so depending on weather and my other responsibilities and continue until the end of October and have seen no ill effects.

  10. #9
    Join Date
    May 2009
    Location
    Grand Rapids MI USA
    Posts
    1,599

    Default Re: OAV overdose?

    I tried 7 treatments every 3 days this year and saw no ill effects at all.

  11. #10
    Join Date
    Nov 2012
    Location
    Plymouth, MA USA
    Posts
    29

    Default Re: OAV overdose?

    Thanks, everyone - your responses are really helpful. It's so good to be able to get information on what others have done/experienced in a case like this.

  12. #11
    Join Date
    Mar 2015
    Location
    Triadelphia, West Virginia
    Posts
    581

    Default

    Wait for forum member snl to post. I may be mistaken but I seem to remember him saying he had a test hive that he treated daily with OAV as an experiment. He reported no ill effects. I know from personal experience that you can treat them with way more OA than recommended and it doesn't hurt them but no experience with frequency beyond five treatments every five days.

  13. #12
    Join Date
    May 2017
    Location
    Spokane, Washington, USA
    Posts
    265

    Default Re: OAV overdose?

    I did 12 treatments on most of my hives this fall. Some were ok after 9. No ill effect noted.
    So then, as we have opportunity, let us do good to everyone, and especially to those who are of the household of faith.

  14. #13
    Join Date
    Nov 2009
    Location
    Manning, SC
    Posts
    5,219

    Default Re: OAV overdose?

    As a seller of vaporizers, I wanted to do some testing...
    So, last year I kept 2 “OAV” test hives. One was Italian the other a Carni?? I isolated the marked queens on 3 frames. I watched frames of brood from laid egg to emerging bees. During the period late March through mid August I vaporized those 2 hives every time I went to the Apiary which was at least every week, sometimes more. I found no harm to eggs, larvae or the queens (which we’re still the same queens in August.)
    So can you vaporize to the degree that you cause harm? Probably, but I haven’t tested to that point.
    http://OxaVap.com Your source for the ProVap 110
    OA Vaporizer. The fastest vaporizer on the market!

  15. #14
    Join Date
    Oct 2019
    Location
    Wakefield, Rhode Island, USA
    Posts
    216

    Default Re: OAV overdose?

    Hi TJC1 , Interesting as I am nerby in RI and experiencing the same thing - a prolonged, repeated treatment this year. I also think the colonies, in this mild weather, have continued to raise winter brood in quantity which may be part of the issue. I tried to post my first thread related to this subject but failed for unknown reasons so I will post it here. After reading my comments and you want to discuss raw Varroa Dead Drop Count data, 13,340 dead varroa and still counting, let me know. BTW, I have not used my mask for OAV, just wood cutting in two years but I do protect my eyes when handling OA crystals. I simply forgot to use it.

    2019 Varroa Dead Drop Count:

    Three years in a row I have experienced what I think are serious horizontal spreading issues of Varroa or Varroa Bombs in my neighborhood. I have been trying to understand the source of the Varroa, home-grown or invaders. I think the answer is both but horizontal migration dominates in the Fall. Fall invasions result in re-infestation of brood - winter brood!

    This year I was a little more methodical in my evaluation of the treatment steps I take. I have 9 colonies undergoing OAV treatments post "super" removal. I use a Dead Drop Count (DDC) via a sticky board as an evaluation method. One colony was put through a brood break, one was a July nuc which built-up to hive level, one was Spring "save" which grew and grew to be a sizable colony and six were strong Spring survivors. All, except the nuc, were OAV treated, once last Christmas to start the new season. Monitoring all summer was by sticky board observations + drone removal (near nil) and a July inspection of 800 capped drones plus random samplings of worker brood and drones in other hives ( 6 Varroa found in 800 capped drones - it is not easy searching in the soup). Six colonies have VSH type queens, one hive has a possible 4 year old Hawaiian queen, two others have mutt queens raised from swarm cells the prior year.

    My hives are located on 5 platforms separated by approximately 100 feet or more with one or two hives to a platform. In one case two hives and a grown-up nuc share a platform (nuc hive to be moved soon).

    These comments are not based on a large data pool of numbers but more on several years of Contrarian experiences using OAV. My observations so far are:

    1. Winter OAV treatment has a dramatic impact on Varroa infestation and growth all Spring and Summer - low numbers until Fall.

    2. My strong colonies find and rob other colonies but seldom within the apiary.

    3. Less than a 100% efficacy, generally 85 to 95%, typical of all treatment methods, allows Varroa infestation of winter brood while treating. I need to try other treatment methods to truly compare results but that is a big, well- planned effort. It is possible using APIVAR for a comparison would be interesting. Simple logic /math supports this conclusion. No vendor claims 100% efficacy and OAV does not kill capped Varroa. Phoretic Varroa can have a 4.5 day turn-around in re-infestation of larva. Even less, a day perhaps, if a phoretic Varroa mite migrates to a new colony.

    4. Brood break treatment method (sample of one) appears to verify low summer numbers but is affected by horizontal migration. This is suported by a sharp, 2-3 week Fall Varroa DDC rise and fall versus longer, 6-7 week elapsed time curves for other hives being treated.

    5. Varroa Resistance is possible. After 5 years, I have a colony with a NWC queen that has amazingly low Fall numbers. The colony seems to defend against immediate neighbors causing horizontal spreading. They may also have a non-robbing trait. At the opposite end of the spectrum I have a mutt queened, strong hive which I predict will not survive the winter based on Dead Drop Mite Counts and infestation length of time while raising winter brood .

    6. Multiple OAV treatments appear to have no significant effect on colonies or queens ( observation, no data). I had the unique accidental experience of OAV treating a hive which superceded ( or emergency cell), queen open mated and produced brood and survived winter.

    I have spent two full months, 8 treatments in total, this 2019 Fall period of repeated OAV treatments to kill off Varroa so that my Dead Drop Count falls below 50 in each hive and hopefully into single digits (5 colonies). One colony remains above 50 @ 91 as of 11-18-2019, 1st treatment 9/18/2019. All colonies are still active and raising winter brood ( I think, by observation, as I do not disturb them now). I plan on OAV treating and counting once more before Thanksgiving to complete this testing sequence. I will also OAV treat twice, 14 days apart, around Christmas or New Years ( hopefully a 99.7% efficacy result).

    This effort begs the question - how do we stop Varroa at the entrance? Ankle biting? Elimination / reduction of weak, failing colonies? Modify robbing behavior? I think hygienic behavior is a latent, defensive response and not a preventative solution for Fall Varroa Bombs.

  16. #15
    Join Date
    Oct 2019
    Location
    Wakefield, Rhode Island, USA
    Posts
    216

    Default Re: OAV overdose?

    There is a retired Maine State bee inspector who has claimed that most Maine hives almost always have some brood - all winter. A bit north of me.

  17. #16
    Join Date
    May 2019
    Location
    Lake County, Illinois
    Posts
    152

    Default Re: OAV overdose?

    This thread raises a question that I have. At what point does multiple treatments of OAV contaminate the wax and ultimately the honey. Is there a residue from the treatments especially since various products and intensities of OAV are used. Does anyone use laboratory analysis to determine what residue if any goes into the wax or honey?

  18. #17
    Join Date
    Oct 2019
    Location
    Wakefield, Rhode Island, USA
    Posts
    216

    Default Re: OAV overdose?

    Laboratory analysis has already been done in the EU. From memory: 1) It is difficult to find OA in honey due to masking ny formic acid and the very short half life of OA in honey but it is a natural constituent of honey. 2) no accumulation of OA in beeswax as the compounds are basically insoluble in each other. 3) This is the basis as to why the EU has no restrictions on the use of oxalic acid. EU controls total acidity of the honey as a test method for "contamination". In the USA I have been unable to find out why OA has such a bad reputation as compared to formic acid in MAQS other than it has no real corporate sponsor. OA applications thus lack real trial data on how best to use it. University of Sussex, England has been doing some significant testing, especially for winter applications and comparing oxalic acid spraying versus dribble versus sublimation (vaporization). It seems trial and error of the general public will determine the best method. I have used OAV for 4 years and give my bee's honey to my grandchildren.

    If someone has contrarian oxalic acid research data, test report references would be appreciated. Side Pro - Con note about oxalic acid; oxalic acid is very important for human peristaltic action, excessive consumption of spinach and the like can contribute to kidney stones in susceptible people.

  19. #18
    Join Date
    Jun 2016
    Location
    Geauga, Ohio
    Posts
    455

    Default Re: OAV overdose?

    Thanks Robert Holcombe for sharing your mite management experiences with recording mite drops post treatment, and tracking through the years.

    This is my second winter using the _prior_ fall/winter treatment (so in 2018) as the only _current_ summer treatment (for summer 2019).

    Last fall, I had 8 hives, all started in June (so had brood break), and treated in the fall/winter of 2018 3-4 times. The previous fall/winter (2017) was their most recent treatment save the brood breaks. Mite fall post OAV was 200-300. That's accumulation in about 9 months, including summer.

    But this year... whew! I have 16 hives where I was checking the post OAV mite drop at the beginning of october. One hive has had a cumulutive mite drop of 250, one has had a cumulitive drop of nearly 4000. They are in fact sister queens.

    So.... was my mite management plan faulty? did the bees raise those mites in the nearly 4000 hive? I have 2 reasons to say no. 1) the sister and neighbor queen mite drops of 200-400 are all of similar strength, similar length of time with brood- did not produce the same number of mites; and 2) a buddy less than a mile from me treated with MAQS in Aug and in Sept. Then we did OAV in Oct. Mite drops of 1500+ in each of his 4 hives.

    Oh and we stop having brood production here once the pollen stops - usually once frost hits, so 10/15 would be the last egg laid, and not even full capacity then. This ain't SC! And I have checked a hive in early April - no capped brood. I don't think there is much (at least for my bees) until pollen starts coming in, early-late March. Again, this ain't the south!

    So it's encouraging to hear that others have had good control with the fall/winter treatments only, and that many OAV treatments have not resulted in supercedures or brood being acidified and then dragged out, or anything like that. Thanks for sharing the boots-on-the-ground experiences everyone!

  20. #19
    Join Date
    May 2015
    Location
    Vauxhall, Alberta, Canada
    Posts
    350

    Default Re: OAV overdose?

    I have used OAV for 4 years and give my bee's honey to my grandchildren.
    Well, Robert, I don't know if that will go through as scientific proof.

    I am certain it has been established well enough that 3 gram for a double deep brood box setup is the standard, 1.5 - 2 gram for a single deep & nuc. Now, this is for one treatment!

    I have, in 2018, (wash count 1.5% avg.) used the 3 gram on all (four) hives every three days 8 times= 24 days and all hives survived. This year I had less then 1% mites and used one hive 6x4 days apart and two hives 3x8 days apart.

    The trick is do do this before the bees are in a cluster, or all is for the dogs.

    My personal opinion: I would be more concerned with miticide (APIVAR etc.) overdose and carryover in hives then OA.

    BTW, if one treats a miticide in the brood boxes, who guarantees that the bees don't move this stored honey in June or July up to the supers?

    My conclusion: lowest risk possible is OA, no question.
    Summ Summ Bienchen summ herum

  21. #20
    Join Date
    Aug 2002
    Location
    Nehawka, Nebraska USA
    Posts
    53,922

    Default Re: OAV overdose?

    >This thread raises a question that I have. At what point does multiple treatments of OAV contaminate the wax and ultimately the honey.

    Oxalic acid is water soluble and not fat soluble so it will not build up in the wax. Of course since it is water soluble it will end up in the honey. But honey already contains oxalic acid (along with several other organic acids, including formic and malic) so as long as the amounts remain low, and evidence is that they do with normal treatments, then the added amount is undetectable because it's already there and the amounts are so low. My bigger concern is the effect on the 8,000 microorganisms that live in a healthy colony...
    Michael Bush bushfarms.com/bees.htm "Everything works if you let it." ThePracticalBeekeeper.com 42y 40h 39yTF

Page 1 of 2 12 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •