Will mites become resistant to oxalic acid?

[user 20297]

Rusty Burlew, on the Honey Bee Suite blog has this to say,
"Lots of folks insist that mites cannot possibly become resistant to oxalic acid. Well, maybe. But just because it hasn’t happened yet, doesn’t mean it won’t. I put odds on the mites"
I've previously gained the impression that in US beekeeping, the general attitude to the use of oxalic acid is more relaxed than in the UK. I am wrong; the official approach is appropriately cautious in respect of human health and safety, and in avoiding the potential for mite resistance.
Something that I hadn't thought of before is that Rusty suggests that we should vary the application method regularly.
Until there is a definitive understanding of exactly what the acid is doing to the mites, I think her cautious attitude is well founded.

https://www.honeybeesuite.com/oxali...dz6jGMqJRyE2gfDerErAnvEaJVwu1ZO5vxZQjquf4lOfA

 

[Anduril]

The US dosage is 1g for sublimation, which is rather pointless and ineffective. In Europe we are using around 2.3g for sublimation and it has always been the case in the UK to vary the miticides.

 

[Wilco]

Varying treatments doesn't necessarily stop resistance developing if it's something to which resistance can develop. It just means it develops more slowly but when it does occur it's more likely to be multi-resistant.

 

[blackcloud]

I was under the impression it caused physical harm to them- if so then we have some time to go yet.

 

[user 20297]

The US dosage is 1g for sublimation, which is rather pointless and ineffective. In Europe we are using around 2.3g for sublimation and it has always been the case in the UK to vary the miticides.

In the blog, the suggestion is that the application method of the oxalic acid should be varied.

 

[user 20297]

I was under the impression it caused physical harm to them- if so then we have some time to go yet.

Yes, difficult to imagine a creature becoming resistant to having its legs burned off.

 

[user 20297]

Varying treatments doesn't necessarily stop resistance developing if it's something to which resistance can develop. It just means it develops more slowly but when it does occur it's more likely to be multi-resistant.

Interesting, but why is that more likely?

 

[Skinfaxi]

With plants you target pests in different ways. different chemicals hormones to biological to physical control. Oils like neem oil smother the target or make it difficult to moves. Predatory wasps etc. I used to manage a high health site for strawberries and raspberries. Chemicals where rotated constantly also weekly leaf samples to check for pest levels.
But what else to use? Api life var is ok but still not as effective broodless vape.

 

[Anduril]

In the blog, the suggestion is that the application method of the oxalic acid should be varied.

The EPA recommends rotating the use of mite treatments rather than using the same one time after time. Specifically, the label reads, “When possible, rotate the use of miticides to reduce selection pressure as compared to repeatedly using the same product, mode of action, or chemical class. If multiple applications are required, use a different mode of action each time before returning to a previously used one.”

This section says to rotate the miticides, nothing about varying the oxalic treatment. At one time the NBU only recommended the trickle method, this way you are not poisoning passers-by and not endangering your health if the safety equipment was to fail.
https://nationalbeeunit.com/downloadDocument.cfm?id=1102

 

[user 20297]

The EPA recommends rotating the use of mite treatments rather than using the same one time after time. Specifically, the label reads, “When possible, rotate the use of miticides to reduce selection pressure as compared to repeatedly using the same product, mode of action, or chemical class. If multiple applications are required, use a different mode of action each time before returning to a previously used one.”

This section says to rotate the miticides, nothing about varying the oxalic treatment. At one time the NBU only recommended the trickle method, this way you are not poisoning passers-by and not endangering your health if the safety equipment was to fail.
https://nationalbeeunit.com/downloadDocument.cfm?id=1102

I'm not trying to pick fault with any official advice, whether from the US or the UK, I'm echoing a notable beekeeper's thoughts on resistance. But "a different mode of action", isn't that referring to subsequent use of the same chamical treatment rather than a different type of chemical?

 

[Skinfaxi]

With the brood break method discussed by i think Prof Ralph Buchler you have two interventions. The first is 25 days brood break that must in my opinion disrupt the mites livecycle and then oxalic acid..

 

[Skinfaxi]

Yes i would say needs to be different chemical not a differennt mode of application

 

[user 20297]

Yes i would say needs to be different chemical not a differennt mode of application

But if that were the case, it would be invalid to apply multiple applications of ox-vap, only a few days apart.

 

[Ian123]

I don’t think it’s totally completely understood how oxalic works, but most quote physical affects on mites. It would be the same as humans developing resistance to bullets or hitting a brick wall at 60mph…..in all probability not going to happen. Guess it gives people something to blog about though or a new pet theory

 

[Anduril]

Rusty mentions that some US beekeepers are not following the approved government method of application, but instead they are using methods that go outside the law.

 

[Wilco]

Interesting, but why is that more likely?

Where resistance is able to develop it's usually that there is an existing genetic basis for it (most bacterial antibiotic resistance occurs through selection of existing genes (plasmid or main genome) so they occur more frequently and/or are expressed more).

Obviously slightly different with mites but essentially if there are resistance genes present at a low level then every treatment acts as a selection pressure. Whilst it is less likely that any given organism or local population will have multiple resistance genes from the outset, it's likely that somewhere there is one or due to the way we humans spread things around, populations with one resistance gene come in contact with other populations with other resistance genes. Thus with rotation of treatments there is a selection towards resistance to multiple treatments. It may take longer but if (and the emphasis is on if) it is genetically possible for resistance to a treatment then over time it will be selected for. This is obviously not an issue where there cannot be resistance such as the brick wall analogy above.

 

[Ian123]

Rusty mentions that some US beekeepers are not following the approved government method of application, but instead they are using methods that go outside the law.

So like the UK then!

 

[blackcloud]

That's shocking.
They should all be rounded up ,put in a field and bombed.

 

[Sutty]

For any organism exposed to a new toxin there is pressure to develop resistance as only resistant ones get to reproduce (if the toxin is fully effective). Resistance is usually created by mutations eg varying an enzyme that a toxin inactivates so that it is no longer inactivated. However there is usually a "cost" to the mutation - maybe the enzyme works less well even when no toxin present, or it takes more energy to produce. As a result in the absence of the toxin the non-resistant organism will usually out-compete the resistant one.
This is the basis for rotating several agents, using one for a while will start to see resistance appear, switching to another with a different mode of action then usually sees a reduction in resistance to the 1st agent. Depending on speed of resistance occurring it may require several different agents to maintain overall effectiveness.
Problems include (for us) several beekeepers in an area using different agents at the same time with crossover infestation occuring all the time. Ideally we would all synchronise.
The speed of resistance building up varies a lot depending on length of life cycle and number of offspring - bacteria develop resistance as a population faster than elephants!
Of course some agents may work in a way in which resistance cannot occur because the changes required in the target organism would have to be too massive - to go to extremes eg EFB bacteria haven't managed to evolve to survive being burnt!
We can only hope that oxalic acid is in the latter group, until the mechanisms of action are properly understood we won't know for sure.

 

[Hachi]

Rusty Burlew, on the Honey Bee Suite blog has this to say,
"Lots of folks insist that mites cannot possibly become resistant to oxalic acid. Well, maybe. But just because it hasn’t happened yet, doesn’t mean it won’t. I put odds on the mites"
I've previously gained the impression that in US beekeeping, the general attitude to the use of oxalic acid is more relaxed than in the UK. I am wrong; the official approach is appropriately cautious in respect of human health and safety, and in avoiding the potential for mite resistance.
Something that I hadn't thought of before is that Rusty suggests that we should vary the application method regularly.
Until there is a definitive understanding of exactly what the acid is doing to the mites, I think her cautious attitude is well founded.

https://www.honeybeesuite.com/oxali...dz6jGMqJRyE2gfDerErAnvEaJVwu1ZO5vxZQjquf4lOfA

Haven't read the above in detail but Randy Oliver is perhaps an SME on Varroa having scientifically tested and continues to test I think varroa control methods, plus running scientific studies for the development of resistant bees.

Has Rusty shared her thoughts &/or work with him do you know or is it just an opinion?

Also, the University of Georgia with support from Bob Binnie has completed a number of scientific studies looking at the effects of OA on bees. For example, a single dose of OA trickling is recommended and the amount of OA in the solution needs careful mngt or it would have a detrimental effect on your colony. They have also looked at the vaping doses and found up to 8 grams used on a hive has no detrimental effect on the bees. Vaping is obviously a different delivery mechanism.