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Use of Chemical and Nonchemical Methods for the Control of Varroa destructor

1819 Views 12 Replies 7 Participants Last post by  BernhardHeuvel
Use of Chemical and Nonchemical Methods for the Control of Varroa destructor (Acari: Varroidae) and Associated Winter Colony Losses in U.S. Beekeeping Operations

Ariela I Haber Nathalie A Steinhauer Dennis vanEngelsdorp
Journal of Economic Entomology, toz088,
Published: 22 April 2019

Free PDF:

The parasitic mite Varroa destructor (Acari: Varroidae) is a major cause of overwintering honey bee (Apis mellifera) colony losses in the United States, suggesting that beekeepers must control Varroa populations to maintain viable colonies. Beekeepers have access to several chemical varroacides and nonchemical practices to control Varroa populations. However, no studies have examined large-scale patterns in Varroa control methods in the United States. Here we used responses from 4 yr of annual surveys of beekeepers representing all regions and operation sizes across the United States to investigate use of Varroa control methods and winter colony losses associated with use of different methods. We focused on seven varroacide products (amitraz, coumaphos, fluvalinate, hop oil, oxalic acid, formic acid, and thymol) and six nonchemical practices (drone brood removal, small-cell comb, screened bottom boards, powdered sugar, mite-resistant bees, and splitting colonies) suggested to aid in Varroa control. We found that nearly all large-scale beekeepers used at least one varroacide, whereas small-scale beekeepers were more likely to use only nonchemical practices or not use any Varroa control. Use of varroacides was consistently associated with the lowest winter losses, with amitraz being associated with lower losses than any other varroacide product. Among nonchemical practices, splitting colonies was associated with the lowest winter losses, although losses associated with sole use of nonchemical practices were high overall. Our results suggest potential control methods that are effective or preferred by beekeepers and should therefore inform experiments that directly test the efficacy of different control methods. This will allow beekeepers to incorporate Varroa control methods into management plans that improve the overwintering success of their colonies.

Boils down to: Amitraz + essential oil + splitting hives do the job.
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"The data used for this study were derived from responses to questions in the annual Bee Informed Partnership Honey Bee Colony Loss and Management Surveys"

"The data reported in the current study come from respondents who answered questions regarding their use of chemical and nonchemical Varroa control treatments and practices."

No further comment.
Yes I gave up on that lot ages ago, you end up with garbage in and garbage out. The latest I hear on Virginia's losses in greater than 40%! funny I lost less than 10% not due to varoa and used only oxalic acid vapor.
I no longer participate in BIP survey either. I'm one of the non-chemical beekeepers that use powdered sugar, diatomaceous earth & screened bottoms to control varroa.
Again, the lack of nuance. New beekeepers doing tf with commercial bees are going to fail in droves. A proper study should group these keepers by years of experience, size of apiary, and source of stock.
Johno you are also a skilled beekeeper and have an over the top mite control program. I am not surprised your loss rates are significantly less than a new BYBK with 2 new packages.

Every one argues when the data doesn't line up with there personal views, but its a big world out there.
I had one yard take 80% losses last year (efb/mite bombs/overgrazed in drought leading to poor fall nutrition and spring was a month late) another yard only lost 2 nucs (great fall rabbit brush flow, no TF nehibors=fat healthy winter bees) My perception on "how the winter went" is very different depending on which location I view it from.
If its "garbage in and garbage out" who's fault is that? Ours as the beekeeping community
sadly, The Bip is about the best we have.

The biggest problem with is they put the raw data up for everyone, and it is often misused/misinterpreted and correlation vs causation gets all mucked up.
a common one is "Is the BIP says it's bad to feed your bees capped honey" Yes those who feed dry sugar lost 28.6% those who fed capped honey lost 44.2%
but is capped honey bad?
look at the likely reasons... Is it just those who lose more bees have more capped frames in the dead outs to feedback?
or maybe the type of keeper who feeds honey frames instead of much cheaper sugar tends to be on the less harsh, and often less effective side of mite control.

A proper study should group these keepers by years of experience, size of apiary, and source of stock.
it does...
shows no to little difference. on years. at a glance. ....and people often use that point as well to attack it, but don't dive in
when you break it down. The BYBK and sideliners seem not to learn from thier mistakes and don't improve with age, But the commercials are a different story. The either figure it out, or perhaps fail , and as a group get much better by the 5+ year mark
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msl;1721561 The biggest problem with is they put the raw data up for everyone said:
Good point. I feed my bees honey in the frame, not from deadouts, but from excess frames from the brood-nests.
I had one colony of 13 come out of Winter with a lot of bees, but no Queen.

It seems to me that data from splitting would be the most easily manipulated, misunderstood or honestly mistakenly reported. I still don't know if there is a consensus *among beekeepers* on how to count losses or gains when splitting is used.

and from the link in the op
"it is also possible that by splitting colonies, beekeepers replaced some or all of their lost colonies, which would have reduced our calculated loss rate for their operations. Thus, the true benefit of splitting colonies, with respect to its effect on Varroa control, may be inflated"

one fun peek is to take a look at losses by "breed"
shows you what is working...
Russian, Minnesota Hygienic, Caucasian, New World Carniolan... the names we here all the time....not so much

Local stock, Buckfast, VSH seem to be much better performers
I went to the site to see if I could break it down a bit more. I couldn't breakdown the data for tf keepers based on years of experience for instance. If someone can illuminate me. I would find the break downs interesting.
The BYBK and sideliners seem not to learn from thier mistakes and don't improve with age, But the commercials are a different story. The either figure it out, or perhaps fail , and as a group get much better by the 5+ year mark

Sadly enough, but least I observe the same.
I think one would have to be careful about your measurables as well. What if the measure for success was how bees would perform untreated. If treated bees performed just as well as untreated bees in this situation, then of course no progress is made with tf. I would suspect my bees would stand up better than other local queens produced because of the level of selection. I would suggest that all apiaries that sold stock be graded by some mite (and others as we get more sophisticated) resistance criteria that could be independently verified. It would provide buyers a heads up whether or not sellers of stock are doing their job and selecting for these traits one way or another.
Selection is nothing a queen producer can do. That must me done by breeders. Breeders usually don't produce many queens for sale, because the work of selecting is so laborious that you can't do any queen producing next to it. :no:

That doesn't mean, queen producers don't produce good queens. But good queens are not breeder queens. Breeder queens often are not that good, they just hold some qualities within their genes that are useful to achieve certain breeding goals.

I reckon it would be good to have more good breeders that are paid to do their job. Plus the breeding systems should be revised and new findings should be included.
Toxicity of oxalic acid and impact on some antioxidant enzymes on in vitro–reared honeybee larvae

Sabová, L., Sobeková, A., Staroň, M. et al. Environ Sci Pollut Res (2019).

Nowadays, Varroa destructor is considered as a serious pest of honeybees (Apis mellifera) and its resistance to acaricides has been reported in Europe since the early 1990s. That is why new methods of treatment for Varroa mites are still in focus of many scientists. In our study, we determined the lethal concentration LC50 (72 h) of 2.425% oxalic acid solution following single spray exposure of honeybee larvae under laboratory conditions (Guideline OECD 237 2013). Potential sublethal effects of oxalic acid were monitored through the determination of the activity of antioxidant enzymes. Activation of primary antioxidant enzymes was observed at 1.75% of oxalic acid; 3.5% of oxalic acid brought on a statistically significant increase of glutathione S-transferase activity. This change was accompanied by an increase in thiobarbituric acid reactive substances, products of lipid peroxidation. Our results indicate that oxalic acid may be harmful to bee brood when present during application.
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