No evidence to support the use of glycerol–oxalic acid mixtures delivered via paper towel

[tristan]

No evidence to support the use of glycerol–oxalic acid mixtures delivered via paper towel for controlling Varroa destructor (Mesostigmata: Varroidae) mites in the Southeast United States

Abstract. A significant amount of researcher and practitioner effort has focused on developing new chemical controls for the parasitic Varroa destructor mi

academic.oup.com

this seams to be a bit of a weird study. maybe you science guys can help me out here.
their graph seams to show the oxalic acid working but claim "no statically evidence". can someone explain the math on that?

however this whole study is weird.
first of all its shop towels not paper towels (blue shop towels are synthetic).
but the big ones is that they are using shop towels which even randy oliver went away from some ~5 years ago (now its swedish sponge, maximizer pads, even cardboard strips). ie they are testing something thats known to work poorly.
also only testing at low acid rates (the highest they tested was 18g), similar to the early testing many years ago now. these days its around 50g.
the whole study is on a method that was only a step in the evolution quite some time ago.

if anything this study reinforces not using out of date methods that have long since replaced with better ones.

 

[Alastair]

Scientists looking for grant money. Come up with an idea for a study that someone is willing to sponsor. The decline of the honeybees is pretty buzzwordy, so someone puts up the money. Waste of time, but they get paid for another year.

 

[Bron]

Strip manufacturers, looking to discredit? Data can be made to jump hoops.

 

[John B]

I have been wanting to do some experiments with oxalic fogging for a while so I deliberately left some lives at home under treated. I may have got a bit carried away with the under treatment as when I finally got around to making my testing gear three of the four was showing signs of PMS. I had intended to monitor the natural drop for a couple of weeks but they would have died if I had left them (they still may). Two hives were weak to start with and are only two frames of bees but had a natural Average drop over three days All of 26 and 7 followed by 170 and 105 the day after the first treatment and the two that were one box of bees were 1 and 50 followed by 27 and 310 . All hives still have brood. Frankly I'm amazed that three of them are still alive. It's my fault I just got busy with other projects. At least I now know for sure that six random fogs over the autumn is not sufficient. The only good thing to come out of it so far is that the hives with the least mites is the one I used for breeding in the autumn.
I intend this to be an ongoing project and I may have to bring home some new hives in the spring. The main thing I'm trying to find out is how many days do the mites keep dying after a fog . There is too much conflicting information out there and like Alistair says it can be very difficult to treat to a regular program. I have seen suggestions for everything from only immediate knockdown to 5 or six days with the highest mortality being on the fourth day.
Please note some of those higher numbers might be out by the odd Mite or two.

 

[tristan]

There is too much conflicting information out there

there is some good information out there.
oxalic only lasts about 4 days in the hive, so you really need to vaporize every 4 days or so until you at least get one whole brood cycle, preferable two.
if the hive is broodless it becomes a whole lot easier, once or twice is enough. i know some who have been trailing caging the queens to force a brood break.

 

[John B]

One month into my fogging experiment and varoa numbers are still high. Hive one was so weak it was barely alive but still regularly supplying varoa.I have given it a frame of sealed brood and some young bees to help. Being run over by a truck (not me) didn't help.Hive two has increased in strength by 50% with even some early drone brood. The mite drop from this hive is very variable with a low of four and a high of 47 in the last week. Hive three is still weak but has increased in strength by about 50% and is looking healthy. A high of 85 this week compared to 252 last week. I have given this hive a frame of sealed brood as well . Hive four has gone from one box of bees down to 4 frames and still looks pretty bad with dead brood and deformed wing virus. Average drop still over 100 and sometimes over 200. Six 2gm treatments mostly five or six days apart. One treatment was delayed by bad weather and so there was seven days between treatments . Even on the last day there was still significant drops . These drops roughly doubled the next day after treatment.
I think I will increase the frequency of treatment to 4 days apart.
Fogging is definitely not a golden bullet but it also doesn't seem to do any harm which quite surprised me . I plan to keep going till either there is no varoa left or I start to see deleterious effects from the oxalic. I am becoming more and more convinced that it actually makes the hives healthier probably by controlling nosema .

 

[tristan]

Six 2gm treatments mostly five or six days apart.

is that enough? 2gm sounds low but i don't know what size hives you have.

again you want it to be 3-4 days apart. that extra day or two is enough for them to breed up some more. there is a write up somewhere of someone who went through all this and kept good records. they found they needed to do it every 3-4 days.
you highlight one of the problems with this method, being able to keep on time. like almost all treatments when there is brood, it needs to be be constant otherwise you allow the mites to continue to breed and be hidden away from the treatment.

 

[NatureAlley]

In addition to the factors Tristan mentioned as being weird in the referenced study I find the time of the year they put the treatment in (equivalent to mid December to mid January in Aotearoa) quite weird as well. As far as my experience goes that is a time when mites are still slowly building up. Is it reasonable to expect much effect while Varroa numbers are low? It would have made more sense to test the treatment during those periods of the year (end of summer and autumn or end of winter into spring) when OA/GLY strips are more commonly being put in. I have used OA/GLY strips that way and been happy with Varroa counts. In my early days one of my hives managed to survive my inexperience, i.e. late treatment as a result of which it produced about 20,000 mites over ~3 months in autumn dropping on a sticky board during treatment. It gives me enough confidence to carry on, but in a more timely fashion.