[Litsinger]

Interesting survey of the known effects of acaricides on bee health - two in particular stood out to me in considering some of the recent challenges with viral issues and colony vitality:

https://www.researchgate.net/publication/328200942_Effects_of_synthetic_and_organic_acaricides_on_honey_bee_health_A_review

Organic acids have been shown to negatively affect the immunity of adult worker bees. For example, formic acid was shown to impact the proteolytic system in the bee cuticle. Adult bees treated with formic acid had a higher H+ protease and H- protease activity. The cuticle of treated bees showed lower antimicrobial activity. This may have critical implications for bee metabolism and body defence. It is widely believed that as a result of impaired metabolism and body defence, bees treated with formic acid are more susceptible to other serious diseases, namely fungal diseases (89). Locke et al. showed that shortly after winter treatment with fluvalinate, the tires of the Deformed Wing Virus (DWV) increased for a certain period of time (121). The authors suggested that this may be because the acaricides application weakens the bees and makes them more susceptible to viral infections.

Another research topic that will require more attention in the future are the wider implications of chemotherapy for bee breeding. The heavy use of chemotherapy in apiculture may have much more pronounced effects on bee colonies then just what may seem as minute sublethal effects. Elzen et al. demonstrated that the European honey bee (A. m. ligustica) was significantly more tolerant to pyrethroids than African honey bees (A. m. scutellata) (135). It was suggested that European bees that are managed much more intensively, face selection pressures because of the routine application of synthetic acaricides. It thus seems that the advent chemotherapy in beekeeping significantly altered A. mellifera phenotype and maybe even its gene pool. This may subsequently bring serious problems in bee breeding.

 

[Litsinger]

But, the issue that resolves many beekeepers to treat remains, regardless of articles like this: Is it better to have clean, naturally kept bees that succumb to Varroa more often than not, or to have treated bees that survive in spite of things like heat shock protein spikes and chemically induced brood breaks?

Good feedback, @NUBE. To be clear, I did not post the paper as an appeal to not treat- only as a point of reference and something to consider as we collectively try to answer the question of why it appears that the threshold for economic damage in the managed colony seems to keep going down. Is it possible this is a side-effect of the treatments themselves impacting viral tolerance and/or altering the genetic trajectory?

 

[Litsinger]

... indicated agenda.

What agenda would you suggest they are trying to push with this survey?

 

[Litsinger]

Did you go back and look at how the common treatments were all lumped together.

I have to say I had a similar issue with that clustering of all treatments into statements that I think have been pretty well verified to be untrue in regard to some of them (I.e. as Frank pointed out, they make no distinction between the synthetics and the organic acids in a statement about persistence in the hive).

I do think I understand where you all are coming from on this. I think part of this is due to the fact that the intent of the paper is not to organize various treatments into varying degrees of 'badness' but rather to underscore their position that, ... every batch of bee medicaments made has its own, unpredictable effects.

So their takeaway is not no treatments but rather, ... that acaricides are only applied as a last resort when the Varroa population reaches damaging levels.

 

[Litsinger]

It just doesn’t help me be unbiased when researchers who are so carefully precise on so many different things make blanket statements in parts of their papers that are anything but exact.

Understood. It should be noted that this is not a research paper per se, but rather a survey of published research literature on the topic of acaricides in honey bees prepared by a student of palaeobiology:

Erik Tihelka | Palaeoentomology

I am a student of palaeobiology at the School of Earth Sciences, University of Bristol, UK. My research focuses on insect evolution. As the most diverse group of macroscopic life, insects represent evolution's greatest 'success story' unparalleled in the known geological history of Earth. Fossil...

www.erik-tihelka.eu

So I expect she is coming at this question more from an insect evolution POV and less of an applied scientist POV and may not have a very nuanced understanding of treatments, protocols, etc.

 

[Litsinger]

We have to attempt to identify and minimize what is fear mongering and what is rose colored glasses predictions.

... an incomplete picture of the issues that we, as beekeepers, are facing.

Indeed. And therein lies the interesting rub. Do we practitioners have a good understanding of the balance point?

 

[Litsinger]

I would say the short answer is NO! We dont know what we dont know Be neither for or against a proposition you are assessing is a good start.

I like it, Frank.

When I speak of balance point, I suppose I am looking a bit past the particular study in question and more to the general question of how do we ascertain the optimal point between applying treatments for the prevention of disease while also allowing innate resistance and tolerance factors to manifest themselves?

It would seem to me the first step in this process is understanding both the benefits and the potential side-effects of the treatment(s) applied.

 

[Litsinger]

One of the issues I see, among many involving varroa, is that the balance point you’re mentioning isn’t something that is static. It changes year to year, month to month, and location to location. Each beekeeper has to use their best judgment given their experience and motivation.

Well-said. My use of the term is admittedly an over-simplification which acknowledges your good point that this balance-point will move based on conditions on the ground.

But I do contend that such a point exists- and I admire folks like you who are making an honest effort at discovering where it is in your locale and management paradigm.

My purpose for posting the study was not to consider whether we should treat or not, but whether there is some merit to the idea that all the current acaricides we currently employ might have side-effects that could be working against the very thing I think we are all trying to secure - resilient bees.

 

[Litsinger]

The vastness of the variables involved with both the bees and its environments, including a non static background of 30 or more viruses and bacterial infections, makes it a shape shifting quarry!

A little Coolidge seems in order here:

“IT is a very old saying that you never can tell what you can do until you try. The more I see of life the more I am convinced of the wisdom of that observation.”

“If you see ten troubles coming down the road, you can be sure that nine will run into the ditch before they reach you.”

“It has been my observation in life that, if one will only exercise the patience to wait, his wants are likely to be filled.”

“Fate bestows its rewards on those who put themselves in the proper attitude to receive them.”

 

[Litsinger]

... a welcome addition to the local anti-meatbee movement.

Let's see how they do up at @Gray Goose's place this winter to see how they fare in more Northerly climates before we send them up for @GregB's experimentation.

 

[Litsinger]

So this thread got me to consider whether studies had been conducted regarding lethal or sublethal effects relative to OA application as a more focused research pursuit. Here are a couple recent ones that appear to be fairly robust in their experimental design and at least begin the conversation about the potential for organic acids having a potentially deleterious effect on colony health:

Effects of Oxalic Acid on Apis mellifera (Hymenoptera: Apidae)

OAD used to treat varroosis of A. mellifera shows a rapid and consistent distribution in the colony for at least up to 14 days, and high efficacy against the mite, but also lethal and sublethal effects. In practical beekeeping, appropriate use of OAD (one topical application, on average 175 µg/bee) is relatively safe for A. mellifera at the colony level, even when some individuals are lost. However, ingestion leads to high mortality. The reported sublethal effects are highly decreased longevity, a reduction in pH-values in the digestive system and the hemolymph, and an increased responsiveness to water. The shift towards stronger acidity after treatment confirms that damage to the epithelial tissue and organs is likely to be caused by hyperacidity. Pathological repercussions e.g., degeneration of rectal epithelium, malpighian tubules and ventriculus may also occur.

These results indicate a general impairment of the bees after treatment. The treatment in autumn or winter affects primarily long-living winter bees which are essential for winter survival and successful colony development in the spring. Treatment during summer with brood can cause substantial brood damage. Even when treating artificial swarms or nucleus colonies it cannot be certain that damages will not occur due to the extensive exposure to OAD in the colony. Long-term effects such as reduced amount of brood in treated colonies have been reported.

OAD is one of the most important organic acids used for the control of V. destructor. It is indispensable but must be dosed precisely and applied as seldom as possible to prevent sublethal damages which eventually lead to the loss of bees. Long disposition in the bee hive can cause accumulation of the acid and therefore induce further damage.

Resistance and Vulnerability of Honeybee (Apis mellifera) Gut Bacteria to Commonly Used Pesticides

In vitro inhibition of core honeybee microbes and in vivo depletion of crop members are potentially concerning for honeybee colony health. Bacteria move within colonies by trophallaxis between bees (Martinson et al., 2012), which includes the exchange of crop contents, via bees picking up bacteria from hive material (Kwong and Moran, 2016), and through consumption of hindgut exudates (Powell et al., 2014). Oxalic acid treatment by trickling depends on the redistribution of the pesticide by the bees themselves (Schneider et al., 2012; Rademacher et al., 2017). While bacteria in most gut compartments may be somewhat protected from oxalic acid, we do observe a significant overall negative effect on microbiome richness, estimated as the number of ASVs bee guts contain. The regeneration of the microbiome after local extinctions in individual bees, or during inoculation of young bees, also depends on bacteria moving from hive to bee and between bees, implying that colony-level impacts from treatment with oxalic acid are likely.

Other studies have found oxalic acid inhibition in vitro of both honeybee microbes (Diaz et al., 2019) and plant pathogens (Kwak et al., 2016), and oxalic acid is present in honey and has been suggested to be responsible for its antimicrobial properties (Bogdanov et al., 2002; Nozal et al., 2003). While most strains appear resistant to oxalic acid in low concentrations, oxalic acid can persist in colonies for multiple weeks (Rademacher et al., 2017). If accumulation occurs after multiple oxalic acid treatments, the pesticide may have a stronger effect on honeybee microbes. Regular oxalic acid application to colonies may also select for resistance in opportunistic bacteria, Varroa, and honeybee mutualists and commensals. This may impair the function constitutive levels of oxalic acid have in honeybee colonies, ultimately requiring treatment with higher concentrations with impacts on colony health and production (Adjlane et al., 2016). As Varroa has a larger impact on honeybee health on the short-term than oxalic acid treatment, we advise exploring genetic resistance to Varroa in honeybees, as it may be a better long-term solution against infection than the application of oxalic acid (Conlon et al., 2019).

 

[Litsinger]

I think even the most strident supporter of treating for varroa and proponents of OA would say the “may” just isn’t necessary there. Genetic resistance is THE long term solution to varroa.

I like the way you think- but I am not certain that everyone agrees there is a genetic solution to varroa. At least not on a short timescale.

 

[Litsinger]

Absolutely! Keep up the genetic exploration but dont knock the crutches needed in the meantime. The enemy of my enemy is my friend!

No argument here, Frank. Just playing devil's advocate, I wonder if what we should be using is not a crutch but rather a walking boot.

As Rothenbuhler famously pointed out, ‘If you are selecting for disease resistance, you must have the disease.’

 

[Litsinger]

So your suggesting TF keepers should encourage there neighbors to raise mite bombs
So as to properly test one's stock

More like the apicultural industry at-large adopt more of a soft bond approach such as Randy Oliver has espoused:

The Varroa Problem: Part 6a - Bee Breeding for Dummies - Scientific Beekeeping

Contents It’s been thirty painful years. 2 Breeding is merely Human-directed evolution. 3 Bees are still pretty wild. 4 Natural and artificial selection. 4 Assessment methods. 5 The Bond method (you get what you wind up with) 5 the bond method, but without the Needless carnage. 8 Getting down to...

scientificbeekeeping.com

 

[Litsinger]

This is the way I have tried to follow for several years.

I'll look forward to reading about your efforts when you have the time and inclination to share about it!

 

[Litsinger]

In regard to the concentration of OA in the drizzle method there appeared to be diminishing returns with higher concentrations, so backing off there would be worth considering. The move to higher volumes for OAV seems to have merit; I was not looking for it, but dont remember reading about any mortality increase of note due to the heavier charge.

I expect that the more we study this, the more we will uncover regarding long-term effects from OA (or any other treatment for that matter), regardless of delivery method. Here's a couple of older studies that deal with OA delivered with water and various sugar solutions:

https://www.apidologie.org/articles/apido/pdf/1999/03/Apidologie_0044-8435_1999_30_4_ART0004.pdf

http://www.fiitea.org/foundation/files/2003/Nanetti.pdf

However, we have the recent scholarship by Dr. Jennifer Barry that came out early this year finding no discernable impact to colony health with repeated applications from OAV:

Assessing Repeated Oxalic Acid Vaporization in Honey Bee (Hymenoptera: Apidae) Colonies for Control of the Ectoparasitic Mite Varroa destructor

The American beekeeping industry continually experiences colony mortality with annual losses as high as 43%. A leading cause of this is the exotic, ectoparasitic mite, Varroa destructor Anderson & Trueman (Mesostigmata: Varroidae). Integrated ...

www.ncbi.nlm.nih.gov

But to me it appears that the most-likely impact from OA is systemic- as noted in the Barry research:

We consider our results here to be among the strongest demonstrations of the relative safety of OA to A. mellifera. Perhaps, future experiments may want to explore the long-term effects and overwintering ability of colonies after being treated with oxalic acid.

Probably the best overarching recent scholarship I have seen on this subject is the following by Bartlett, which while admittedly short on details does present a fairly objective (in my opinion) view of the current state of treatments (or lack thereof) in the fight against parasites and disease:

Frontiers in effective control of problem parasites in beekeeping

Demand for better control of certain parasites in managed western honey bees (Apis mellifera L.) remains apparent amongst beekeepers in both Europe and North America, and is of widespread public, scientific, and agricultural concern. Academically, interest ...

www.ncbi.nlm.nih.gov

While surfing around, I also found the following research put together by an enterprising Master Beekeeper candidate- I would love to see more 'shadetree' research like this:

http://doorcountybeekeepersclub.org...ds/Kevin-ODonnell_Research_Project_Report.pdf

 

[Litsinger]

Randy's recent presentation to New York Bee Wellness has a very detailed break-down of his team's evaluation of OA levels on bees with various application approaches - interesting stuff!

 

[Litsinger]

... how such an apparently simple question can be so difficult to pin down.

Indeed. I suspect given that we are evaluating lifeforms, even the most seemingly straightforward questions come back to Roger Patterson's observation that:

"... we are dealing with biology - as such we are always talking about ranges and overarching principles but rarely absolutes."

Even in Randy's presentation above he summarizes his recent OA findings as follows (i.e. #4):

 

[Litsinger]

Interesting study considering the impact of orally-supplied OA on the survival of larvae. A few take-aways:

On D3 and D4, all live larvae were fed artificial diet with the appropriate concentration of OA for their treatment group. The volume of diet varied by instar stage in order not to suffocate the larvae. Larvae in the second instar stage were fed 20 μl, third instar larvae were fed 50 μl, and fourth instar larvae were fed 100 μl. After 24 h, on D4, larvae were checked for movement as an indicator of survival. All surviving larvae were again fed their corresponding OA concentration diet. The experiment concluded on D5.

Because larvae are protected in brood cells, it is unlikely that they are exposed to the full 3–5% concentration of OA recommended by the EPA for treatment of mites by the solution method of administration. The lower concentration ranges of oxalic acid (0.01–1.0%) used in this study tested may more closely match levels larvae experience due to adsorption of the surrounding colony matrix in response to trickling, spraying, sublimation, or transport of the pesticide through the hive by tracking of adult bees. After a single exposure, the third and fourth instar larvae had higher survival rates in each treatment group compared with the second instar larvae indicating that older larvae have a greater tolerance for the pesticide. A significant decrease in survival in all larvae 48 h post treatment was documented.

While oxalic acid at EPA-recommended treatment levels of 5 ml at 3–5% of OA in sugar water has been found to be safe for adult bees, this study shows that oxalic acid is very toxic to honey bee larvae. The current study provides a reasonable model of larval exposure to OA in treated beehives. Beekeepers should be aware that using OA for mite control while larvae are present could have a negative downstream effect on the colony population size and wintering capability.