A question from an earnest beginning beekeeper recently hit home—“If I treat for mites, isn’t that a bad thing, since it slows down the evolution of the bee?” It pains me to see such well-intentioned beekeepers being racked with guilt, due to simple lack of understanding of the biological details involved in both creating and solving The Varroa Problem.

I use the term “scientific beekeeping” because I find it disturbing as to how much “information” given to beekeepers consists of a muddle of misinterpreted anecdotes, indiscriminant repetition of so-called “facts,” and the promotion of theories and practices lacking any supportive evidence. I can’t fault beekeepers for buying into the reasoning of internet beekeeping gurus who push idealistic arguments for why you need to keep bees this way or that, but I suggest that you instead ground your management practices in bee biology, rather than upon catchy names.

Beekeepers can rationalize anything they do, but as an industry, we truly need to address The Varroa Problem, and our part in creating the varroa/DWV Monster. One of my most common suggestions to those touting an idea, is to “think it all the way through”—to follow the logical outcome to the end. My hope is that by providing some graphics that detail the genetic consequences of our actions, we can then visualize the long-term genetic pros and cons of various management strategies on the evolution of The Monster.

Practical application: keep in mind that it is not varroa that kills a colony—it is typically a virulent strain of Deformed Wing Virus, vectored and facilitated by the mite. Once the infestation rate of varroa exceeds about 15% (~50 mites in an alcohol wash of ½ cup of bees), DWV tends to go “epidemic” in the hive, killing the developing brood (Fig. 1).

Figure 1. Brood exhibiting signs of Parasitic Mite Syndrome. This is an indicator that the colony doesn’t have much longer to live, unless varroa is immediately controlled. An important thing to keep in mind is that there may be no external indication that the colony is suffering, and one may not even notice any adult bees with deformed wings.

Once the brood starts to go, pretty soon the adult bees start to disappear (Fig. 2), indications being that some may drift to other hives,[[1]] carrying virus-vectoring mites with them. And when the colony can no longer defend itself, robbing foragers from other hives then unwittingly carry mites back to their own colonies.

Figure 2: Too late—this colony has already collapsed—dispersing bees, mites, and whatever strain of virus that killed the colony to other hives within flight range. It is this dispersal that rewards The Monster for causing the death of a colony late in the season.

We beg people with a cold or the flu to cover their mouths when they sneeze in order to prevent the transmission to others of the virus strain that has infected them. Think of every collapsing hive as being a giant sneeze of virus-transmitting bees and mites.

A Recap: in the previous installment, I illustrated how in nature, without human intervention, natural selection would favor the evolution of varroa-resistant bees and avirulent virus strains. “Standard” beekeeping, involving varroa monitoring and treatment, is relatively neutral—it doesn’t make things worse, but certainly isn’t a part of The Solution, since it propagates non-resistant bee stocks, and depends upon repeated treatments. On the other hand, the lack of varroa control practiced by some “alternative” beekeepers may inadvertently favor The Monster, and be part of The Problem.

There are plenty of vociferous “alternative beekeeping” proponents who have somehow divined how we “should” keep bees. Keep in mind that it’s very difficult to reason a person out of a position that they didn’t legitimately reason their way into,[[2]] so I don’t expect them to change their tune; I’ll leave it up to my readers to decide for themselves whether they are being part of The Problem or part of The Solution, by “thinking it through to the end.”

Let me make clear that I’m in favor of experimentation to improve our beekeeping practices—I spend my life doing exactly that![[3]] But don’t pull the wool over your eyes just because something sounds good, or allows you to dispense with mite monitoring—instead, study the following graphics I’ve created, and pay attention to the genetic consequences of various beekeeping practices.

Defining our Objectives

With regard to solving The Varroa Problem, our objectives are straightforward:

To shift the genetics of the managed honey bee breeding populations towards mite resistance, and
To eliminate the fitness benefit to the varroa/DWV complex resulting from causing the death of their host colony.

So let’s see how various methods stack up in the graphics below—again, red indicates problematic non-resistant bees and virulent DWV; blue indicates mite-resistant bee genetics and less virulent DWV. Follow the genetic consequences from left to right.

LIVE AND LET DIE “Bond Method

One way to solve The Varroa Problem is to step aside and allow natural selection to do so (Fig. 3).

Figure 3. “Live and Let Die” survival selection. One brutal way to eliminate mite-susceptible bee bloodlines is by the “Bond Method.” A good deal of luck may be required and most of your hives may die, plus you may overwhelm your neighbors’ hives with mites.

No need to squint: I realize that these graphics may be difficult to read on the pages of ABJ, so I’ve posted them all in a larger format at https://scientificbeekeeping.com/scibeeimages/The-Monster.pdf.

Given several years, if we all practiced the Bond method, the only bees left alive would likely exhibit some form of mite resistance or tolerance. But nearly all professional beekeepers north of the 30^th latitude would probably be out of business. The reality is that those of us who make our living by pollinating crops and producing honey simply cannot accept those kinds of losses, so IMHO, Bond is dead in the water, other than for researchers or affluent hobbyists.

Practical application: the Bond Method can work, but keep in mind that it is not necessary to punish the colonies in this manner—you can apply equally strong selective pressure by just pinching the queens that don’t make the grade. Then give the colony a second chance with a new queen.

“NATURAL” Beekeeping

Truly “natural” beekeeping would be akin to putting out manmade nest cavities for wild bluebirds to move into (Fig. 4).

Figure 4. Similar to putting out a birdhouse, truly “natural” beekeeping would involve solely offering a cavity for a natural swarm to move into–if you were to stock the hive with bees from somewhere else, you’d then be introducing foreign genetics, as well as unnaturally increasing the density of colonies in the landscape, which would reward The Monster. If you’re lucky, you could be a minor part of The Solution.

But most beekeepers are going to want to keep more than a single hive in an apiary; this is where we become part of The Problem.

The Mutualistic Symbiosis Between the Bee and Humans

Humans were first predators of the honey bee, but then learned to enter into a mutualistic symbiotic relationship (not that the bees would ever notice). By providing the bees with protected nest cavities, and perhaps mechanical migration and/or supplemental feeding and parasite control, both species can benefit. But such benefits may come at a cost to the bee when the unnaturally-maintained density of colonies in the landscape allows for the enhanced transmission of parasites (Fig. 5).

Figure 5. The Varroa Problem is a result of us consistently restocking unnaturally high numbers of honey bee colonies per square mile. Since we will undoubtedly continue to do so, it then confers upon us the responsibility to minimize the transmission of parasites among those hives.

Today’s better professional beekeepers don’t lose many colonies to varroa, mainly by virtue of the application of miticides (whether synthetic or “natural”). Such effective mite management minimizes the reproduction and dispersal of mites and virulent DWV. Unfortunately, it also confers a fitness advantage to any mite that carries an allele that provides resistance to that miticide. Thus, we must consider chemical control of varroa to be a stopgap measure.

But that stopgap measure is still working for the time being. As I showed in Fig. 5 of my last installment, those professional beekeepers who follow best management practices, while not being part of The Solution, are not necessarily part of The Problem, so can be let off the hook for the time being.

Practical application: the beekeepers who are seriously part of The Problem are those, whether large-scale or small, whose poor management unintentionally allows collapsing hives to disperse the most virulent combinations of varroa and DWV to their neighbor’s apiaries in late summer—this is irresponsible and indefensible. But the distressing thing is that there is another group of beekeepers who, while thinking that they are doing good, are actually just as much a part of The Problem.

And this brings us to the subject of the evolution of the fourth player in this game—the population of human bee-keepers.

Recreational Beekeeping

When I was younger, the main reason that people were interested in beekeeping was for honey or pollination, or simply to enjoy the quirky hobby of keeping stinging insects. The local bee club would be populated by aging suburban males. But that population started to change once bees made the papers in the mid 2000’s due to CCD. Recreational beekeeping exploded, and the demographics of the current beekeeper population has now shifted to include a much larger proportion of younger males, females, and urbanites, often motivated by idealism, or the commendable desire to get more in touch with nature. But many of these individuals simply want to “have” bees, rather than commit to the effort involved in being a good bee-keeper.

Such neglectful husbandry, or “bee having,” used to work just fine—before varroa entered the picture. But now it has evolutionary consequences upon the genetics of the honey bee, varroa, and DWV, as well as appreciable biological impacts upon neighboring beekeepers and native pollinators. Unfortunately, many idealistic and well-intentioned beginning beekeepers think that some sort of magic is going to transform the coddled package bees that they just purchased into tough varroa-resistant survivors simply because they call themselves…

“TREATMENT FREE” Beekeepers

Contrary to the old-school beekeepers who managed their bees as livestock, many recreational beekeepers today instead practice some combination of uninformed wishful thinking, hard-core internet dogma, or simple, neglectful husbandry. I live in a rural area, and anyone who does not care properly for the animals that they keep soon makes the local paper with a charge of animal abuse or neglect—unfortunately, this is not the case with beekeepers.

Practical application: I hate having to treat my hives to manage varroa, but have not yet been able to breed bees that can consistently handle the job themselves. So we treat when necessary. I can understand wanting to be “chemical free” and do avoid the comb-contaminating synthetic miticides, so I reach a happy compromise by using organic acids and thymol to control varroa. Most important to us is to take good care of our bees—very few of our colonies ever die from varroa/DWV.

We produce thousands of nucs each season, headed by vigorous and lovely hand-reared young queens. It breaks our hearts to know that some of our buyers will not manage varroa, and that our beautiful young colony is thus doomed to die an untimely and grisly death due to lack of proper care. The saddest part is that those beekeepers truly believe that they are somehow “helping the bees” (Fig. 6).

Figure 6. Treatment-free beekeeping. Although done with the best of intentions, the end genetic result of going “treatment free” with commercial bee stock is exactly the opposite—it actually confers a fitness benefit to the most virulent mites and DWV. However, by taking steps to prevent those untreated colonies from collapsing, the beekeeper could instead perhaps be part of The Solution.

Ways to improve: start with resistant stock (support your local breeders), monitor varroa, treat or euthanize mite-infested colonies before they collapse and spread mites and DWV strains to surrounding colonies. Explain the flaws of this dogma to others—there is no reason to think that commercial stock maintained with miticides will suddenly transform into resistant bees because you wear the “Treatment Free” hat.

Practical application: if you are a recreational beekeeper, and stock your hives with local swarms or cutouts, there is a possibility that you might get lucky and chance upon some bees with a degree of mite resistance. But it would have been natural selection of the wild-type breeding population that favored those genetics, not your beekeeping. To the contrary, you can set that evolutionary progress back when you artificially increase the density of the host (bee) population by adding to the number of colonies per square mile. If your colonies then collapse from the varroa/DWV Monster, you’d be contributing to The Problem in the local wild-type bee population.

I’ve got nothing against the goal of treatment-free beekeeping—we’d all love for that to be a reality. There are a number of relatively-isolated “treatment-free” beekeepers who claim acceptable colony loss rates (treatment-free success is much easier if you’re in an area where there are long brood breaks, and few other beekeepers around). But if you’re not isolated, flooding the environment with mites and DWV from collapsing colonies has indefensible ramifications upon surrounding beekeepers, the wild-type bee population, and perhaps native pollinators. Repeating the same mistake year after year by restocking with package bees and hoping that some miracle not involving varroa treatment will happen is a fool’s errand, and favors The Monster.

The unfortunate fact is, that many of today’s recreational beekeepers are simply too uncomfortable handling bees to perform realistic varroa assessments. So they create an excuse for not doing so by adopting the alluring “treatment free” moniker. My plea is for all beekeepers to question dogma, and instead make the effort to understand the genetic consequences of your beekeeping decisions. The most important thing to do is to stop rewarding The Monster by:

Eliminating the Fitness Benefit to the varroa/dwv complex gained by killing its host hive

You may not be able to control how many hives there are within a 2-mile radius of your apiary, but it is within every beekeeper’s ability to prevent uncontrolled mite buildup and the resulting collapse. Noted bee behaviorist Dr. Tom Seeley makes this point clear in his article on Darwinian beekeeping [[4]].

To help natural selection favor Varroa-resistant bees, you will need to monitor closely the mite levels in all your colonies and kill those whose mite populations are skyrocketing long before these colonies can collapse. By preemptively killing your Varroa-susceptible colonies, you will accomplish two important things: 1) you will eliminate your colonies that lack Varroa resistance and 2) you will prevent the “mite bomb” phenomenon of mites spreading en masse to your other colonies. If you don’t perform these preemptive killings, then even your most resistant colonies could become overrun with mites and die, which means that there will be no natural selection for mite resistance in your apiary. Failure to perform preemptive killings can also spread virulent mites to your neighbors’ colonies and even to the wild colonies in your area that are slowly evolving resistance on their own. If you are not willing to kill your mite-susceptible colonies, then you will need to treat them and requeen them with a queen of mite-resistant stock.

Practical application: It’s Seeley’s last sentence that is most important; unfortunately, many well-intentioned “treatment free” beekeepers overlook the critical need to thwart the dispersal of The Monster.

Darwinian Beekeeping

Below I’ve illustrated a small Darwinian apiary, in which the beekeeper performs a preemptive killing of a mite-infested hive (Fig. 7). Keep in mind that Seeley is clear that the preemptive killing of the entire colony is not necessary—you also have the option of treating the hive and replacing the queen (not shown).

Figure 7. By restricting the cavity size, you minimize the amount of brood and encourage repeated swarming—such colonies may thus be able to tolerate varroa and survive. Given enough time, Darwinian beekeeping may also select for resistance.

As Seeley points out, our large hives and non-resistant bee stock are very favorable to varroa reproduction, so mimicking how colonies survive in the wild is an option for beekeepers. I do question, however, whether most Darwinian beekeepers will actually monitor varroa buildup and preemptively kill their colonies prior to collapse. And others have asked, what’s the point of keeping these tiny colonies if you can’t harvest honey or keep enough hives in an orchard for effective pollination?

The Dream of a “Gentler” Mite

The varroa mite exists in a well-established host-parasite relationship with its native host Apis cerana, in which there is little if any fitness benefit derived from killing its host colony. When we inadvertently introduce varroa to Apis mellifera [[5]], some strains of mites may adapt to a new niche—one with a vast new food resource—closely-located hives full of worker brood [[6]]. Varroa continues to adapt to utilizing worker brood as food,[[7]] so it will be up to A. mellifera in turn to adapt to its new parasite (which it is able to do if humans don’t intervene).

The thought of varroa evolving into a “gentler” mite is a pipe dream—keep in mind that at one time there were two strains of varroa in the Americas—the Korea haplotype and the more benign Japan haplotype. The more “virulent” Korea strain quickly outcompeted and displaced the more benign one.

Due to our movement of queens, packages, and hives, we beekeepers homogenize and disperse varroa bloodlines throughout the country (along with the DWV strains that they carry). I don’t see this situation changing, so it’s likely safe to assume that we beekeepers will inevitably confer a fitness advantage to those strains of mites that are most successful at reproducing in our hives.

Practical application: our established beekeeping practices will always favor the mite bloodlines that are most successful at reproduction and most resistant to miticides, and we will spread those mites everywhere. Just accept this as a given.

Therefore, it’s a no-brainer that we need to step up our efforts to breed for varroa resistant bees.[[8]] Natural selection would do the job for us if we just got out of the way, but our commercial industry would have a hard time taking the hit during the transition. So until truly resistant bees stocks become readily available, we need to focus on management practices that don’t reward The Monster.

Impact Upon other Beekeepers, Wild-type bees, and other Pollinators

And as elucidated by Graystock,[[9]] the pathogens infecting honey bees easily transmit to and from other pollinator species via visited flowers. And collapsing hives very effectively disperse both varroa and virulent strains of DWV to all surrounding colonies—whether managed or wild type. This has major evolutionary implications.

Practical application: as pointed out by Dr. Samuel Ramsey, you are your brother’s beekeeper– even though there may be a thousand beekeepers in an area, the bee population as a whole is like one big apiary due to the proximity of the hives to one another.

Because many recreational beekeepers these days typically have high rates of colony loss due to varroa/DWV and then repeatedly restock with domestic package bees, we are inadvertently perpetuating a strong fitness advantage for the varroa/DWV Monster.

How to be a Part of the Solution

Allow me to reiterate our two objectives:

To shift the genetics of the managed honey bee breeding populations towards mite resistance, and
To eliminate the fitness benefit to the varroa/DWV complex from causing the death of their host colony.

(1) SHIFTING BEE GENETICS TO MITE RESISTANCE

It’s time for some straight talk about shifting the genetics of the honey bee population, as this is where many recreational beekeepers delude themselves. It does no good whatsoever to simply allow non-resistant package bee colonies to die from varroa/DWV (Fig. 6). Neither does it have any appreciable impact upon the honey bee breeding population even if you are lucky enough to identify the rare colony that exhibits mite resistance, unless you then manage to rear hundreds or thousands of daughters from that queen.

Practical application: I hate to pop the that balloon, but no matter how well-intentioned you are, the small-scale beekeeper has virtually zero chance of changing the genetics of any breeding population unless he/she collaborates with a large queen producer.

Such collaboration could consist of letting a queen producer know that you’ve identified a colony that has kept varroa under control for at least a full season. But for most beekeepers, you can exert the most influence by voting with your dollars.

Practical application: with regard to shifting the genetics, this can only happen by changing the market demand for queen bees. So long as beekeepers are willing to pay queen producers for whatever kind of non-mite-resistant queens are available, there is no reason to expect the producers to make the effort to realistically select for mite resistance. Support any breeder who is engaged in a serious program to select, propagate, and sell tested stock that exhibits resistance to varroa. Keep in mind that it is always the consumer that drives any market—when queen buyers finally start to demand mite-resistant stock before they part with their dollars, the queen producers will respond in a heartbeat.

The USDA is currently collaborating with a large-scale queen producer to bring tested mite-resistant VSH queens to the market. There are others who claim to have mite resistant stock, but until we come up with a testing organization, you’ll need to monitor varroa levels in your hives, and let others know if someone is producing stock that exhibits resistance to varroa in your region.

The bottom line is that there is little that the small-scale beekeeper can realistically hope to do with regard to shifting the genetics of any bee population. That is not to say that a local population may not exhibit some degree of mite resistance. If you’re unable to obtain truly mite-resistant bee stock, then you can still be part of The Solution by:

(2) ELIMINATING THE FITNESS BENEFIT TO THE VARROA/DWV COMPLEX FROM CAUSING THE DEATH OF THEIR HOST COLONY.

Without the resulting late-season dispersal/transmission of virulent mites and virus strains, there would be no fitness benefit conferred upon the varroa/DWV Monster from killing its host colony. You can avoid being part of The Problem by not rewarding the varroa/DWV Monster for doing so. Allow me to repeat myself:

Think of every collapsing hive as being a giant sneeze of virus-transmitting bees and mites.

Update 25 May 2019: recent research by myself and others indicates that in some areas, mite and virus drift occurs in conjunction with the robbing out of collapsing hives; in other areas it appears to be more of a function of the drifting of mite-carrying bees from one hive to another. In either case, substantial mite drift can occur in late season.

When you allow a hive to collapse from varroa/DWV, you spread those parasites to all neighboring hives for at least a mile in all directions. Please be a responsible beekeeper! Photo credit Lester V. Bergman.

Along with being part of the beekeeping community comes the responsibility to do everything you can to prevent the transmission of virulent mite and virus strains to others.

I’ll end this article with an illustration of how any beekeeper can help to both shift the genetics of our bees to resist varroa, and at the same time remove the reward to the varroa/DWV Monster from causing colony death (Fig. 8).

Figure 8. Thanks to Dr. John Kefuss for promoting his “Modified Bond” method, of which this is a variation. No colonies need to be sacrificed—all can be productive. The only costs are minimal mite monitoring, application, if necessary, of a non-contaminating strong formic acid “blast,” and the relatively minor cost of rearing replacement queens. Pros: no loss of colonies, honey production, no comb contamination, live colonies for nucs next season. Everyone benefits! Cons: Minor expenses of monitoring, treatment, and queen replacement.

In the above illustration, the beekeeper proactively steps in to prevent any colonies from collapsing and dispersing mites and DWV, and requeens (with potentially resistant queens) any colonies that don’t pass the test. The beekeeper can be every bit as ruthless as nature is in the Bond Method, but no colonies need to die—it is only the genes of nonresistant queens that need to be eliminated. No combs are contaminated with miticides, since formic acid leaves no residues.

Practical application: in our own operation, we’ve found that the cost of checking every hive for its varroa level prior to supering up for honey more than pays for itself in savings in mite treatments, the maintenance of nonproductive hives, and by eliminating most all colony losses (other than from queenlessness). Other than the minimal-mite potential breeders, we treat all the other hives (with thymol and/or oxalic acid) to keep varroa under control, and use a formic blast (Fig. 9) to eliminate the mites (and generally the queen) from any high-mite outliers.

A suggestion: instead of wearing an anti-treatment hat, swap it for a pro-genetic improvement hat.

Figure 9. Here, after removing any honey for extraction, we’ve broken down the high-mite hives into singles. We then apply a formic blast (in hot weather) to kill nearly every mite in the hive (we’re using leftover MiteAway II pads in this photo). We can use a strong dose, since we are not trying to save the queens, and have already pulled the honey.

Practical application: a very effective way to eliminate varroa from an infested hive is to break it into singles, and apply 300 mL of time-release 65% formic acid to each box (home-made pads in Ziploc bags with punched holes, or 3 MAQS). This treatment, even in hot weather, kills only a few workers and young larvae (and generally the demoted queen), but eliminates virtually all the mites within a week. The formic acid then quickly evaporates, leaving no residues, and the hive can then be given a new queen [[10]].

Wrap Up

I appreciate the enthusiasm of today’s new beekeepers, and their desire to help our bees to deal with varroa. And I can’t think of any commercial beekeeper or bee breeder who wouldn’t love to be able to dispense with varroa treatments. I hope that this lengthy article helps us all to make biologically-informed decisions as to how each of us can realistically be part of The Solution, or at least not contribute further to The Problem. To that end, I’ve offered examples of how to evaluate the evolutionary consequences of various varroa/virus management and bee-breeding strategies—please evaluate your own!

My dream is that before I die, I can again enjoy being a successful “treatment free” beekeeper. But it’s not gonna happen as a result of wishful thinking or simple luck—it’s gonna take work, and a realistic commitment to shifting the genetics of entire breeding populations. I encourage all beekeepers to be part of The Solution—first, by monitoring varroa and preventing the collapse of their hives due to DWV, and second by putting the pressure on queen producers to start offering bee bloodlines confirmed by testing to exhibit resistance to varroa. Every beekeeper should be on the lookout for the rare colony that can handle mites on its own, and should they identify one, make sure that someone produces hundreds of daughters from that queen.

And please give your support to the dedicated and hard-working bee breeders worldwide who are engaged in serious programs involving selection for regionally-adapted mite-resistant bees.

Notes and Citations

[1] We clearly need more research in this area—I’ve set up a field experiment to collect supportive data this fall.

[2] I lifted this observation from the excellent book Bad Science, by Ben Goldacre (2008) Faber and Faber. I recommend that every beekeeper read this book before they buy any of the “hive health” products offered for sale without high-quality field data in support of their claims.

[3] My beloved wife Stephanie strongly confirms this point.

[4] Seeley, T (2017) Darwinian beekeeping: an evolutionary approach to apiculture. ABJ 157(3): 277-282. https://www.naturalbeekeepingtrust.org/darwinian-beekeeping

[5] The Korea haplotype of Varroa destructor is currently the most problematic varroa strain worldwide. But other strains of both V. destructor and V. jacobsoni appear to be adapting to parasitize Apis mellifera in different Asian countries. Any of those strains has the potential to become as problematic as the Korea strain.

[6] A resource not available for exploitation in A. cerana due to the intolerance by the A. cerana larva to varroa (apparent self-sacrifice in response to a varroa salivary protein).

[7] I find two recent papers of interest, as researchers study the genetic adaptation of V. jacobsoni to A. mellifera. I’d be very curious to see similar analyses for V. destructor.

Roberts, JMK, et al (2015) Multiple host shifts by the emerging honeybee parasite, Varroa jacobsoni J. Molecular Ecology doi: 10.1111/mec.13185.

Andino, GK, et al (2016) Differential gene expression in Varroa jacobsoni mites following a host shift to European honey bees (Apis mellifera). BMC Genomics17:926.

[8] “Traditionally, the terms “queen rearing” (the propagation of queens) and “bee breeding” (the evaluation and selection of breeding stock) have been used interchangeably in the beekeeping community. These are very different aspects and require different skills, knowledge, and practices….Scientific bee-breeding programs have largely been dependent upon institutional and government support. Frequently subject to short-term funding programs that have been turned over to the industry have historically lacked oversight and soon become unrecognizable. Without a long-term commitment and supporting resources, selection efforts are relaxed and gains are quickly lost.”—Cobey, SW, WS Sheppard, and DR Tarpy (2012) Status of breeding practices and genetic diversity in domestic U.S. honey bees. In Honey Bee Colony Health, CRC Press.

[9] Graystock,P, et al (2015) Parasites in bloom: flowers aid dispersal and transmission of pollinator parasites within and between bee species. http://rspb.royalsocietypublishing.org/content/282/1813/20151371

Graystock,P, et al (2016) Do managed bees drive parasite spread and emergence in wild bees? International Journal for Parasitology: Parasites and Wildlife 5(1): 64-75. Open access.

[10] In our operation, we already have singles with new queens ready, just waiting for the blasted and queenless second brood chambers to be added to them.

Category: Varroa IPM Strategies, Varroa Management