IPM 1 Fighting Varroa 1: The Silver Bullet, or Brass Knuckles

IPM 1 Fighting Varroa 1: The Silver Bullet, or Brass Knuckles?

Randy Oliver 2006, 2009

The varroa mite is the toughest challenge ever faced by American beekeepers. Our reaction to it reminds me of the five stages of dealing with trauma (greatly paraphrased from Kubler-Ross 1997):

Stage 1: Denial (this isnt happening to me! There cant be mites on my bees.)

Stage 2: Anger (You little hive-killing buggersIm gonna obliterate you with my Silver Bullet!)

Stage 3: Bargaining (Apistans not working any moreplease give me another Silver Bullet!)

Stage 4: Depression (Its just too danged hard to keep bees anymore!)

Stage 5: Acceptance (I accept the mite as a formidable enemy that Ive got to learn to live with)

After weve passed through these five stages, we have a chance at Recovery, which in this case, is coexistence with the mite, with bees bred for handling the mite on their own.

We went through Denial when we first saw the mite in the 90s (although many beekeepers seem to keep falling back to this stage!). We experienced Anger as we watched colonies collapse by the thousands with PMS (parasitic mite syndrome), and angrily fought back with the fluvalinate silver bullet. The mite even looked to be manageable for a few glorious years while Apistan worked. Unfortunately, the mites resurrected by becoming resistant, and we Bargained with scary-smelling CheckMite, essential oils, and every imaginable desperate home remedy. By the turn of the century, many beekeepers faced Depression, and threw in the towel.

Unfortunately, I still see many beekeepers stuck in Stage 3, placing all their bets on whatever current, or future, Silver Bullets the chemical industry offers up.

The Europeans, however, and a number of successful U.S. beekeepers have taken the more mature view of Acceptance, in which we settle in for a prolonged fight until we achieve Recovery. During this fight we need to make a difficult transition while weaning ourselves from Silver Bullets. This transition involves a multicomponent Brass Knuckles approach to keep the mite in check, while we train the Bee Brigade to take over the task by themselves.

There are a few brave souls who appear to have already reached the Recovery stage by selective breeding and effective management, and are able to keep their colonies alive with no treatments at allI see them as the future of the industry. This article is targeted to those of us who have reached Acceptance of the mite but have not yet achieved Recovery.

The Silver Bullet or Brass Knuckles?Im speaking of choosing between two different paradigms:

Paradigm 1The Silver Bullet approach: stay on the chemical treadmill, beholden to the chemical manufacturers. Always skirting disaster, which will occur when the mite evolves resistance to whatever miticide(s) you are depending upon. In addition, honeycomb absorbs chemicals like a sponge, and our bees wind up living in a toxic stew. The general argument for this strategy is that it is cheap (in the short term) due to low labor costs, and no new equipment or management changes are necessary. One big problem with this paradigm is that many beekeepers dont have a fallback Plan B in place should their current Silver Bullet fail.

Two of the first Silver Bullets. Since these miticides only target specific nerve chemistry, the mites are able to rapidly develop resistance. The other problem is that both chemicals contaminate your combs with harmful residues.

Paradigm 2The Brass Knuckles approach: This mite is one tough bugger, and its here to stay. If my bees and I want to survive, weve got to put on the brass knuckles and learn to fight it hand-on-hand. Im going to learn all about my enemy, and make its life miserable at every turn. Im not aiming for a complete kill, only to keep its population to an acceptable seasonal level. Ill use every weapon at hand, except comb- or honey-contaminating nuclear weapons. Mind you, this is only a transitional approach as we, and the mite, apply selective pressure upon the bees to do the job themselves. Luckily, the Brass Knuckles approach allows the beekeeper to take a fallback position at any time.

To prepare this article, I scoured the research from Europe, Canada, New Zealand, the U.S., and other countries, as well as interviewing successful beekeepers, and trying most of the methods myself. The research is fascinating, and often contradictory. We all are dealing with similar bees, and similar mites, but each country and region tends to take a different tack. Plus, its often difficult to reconcile theoretical conjecture, cherished opinions, laboratory results, proprietary claims, and practical experience. I have tried to distill out only those methods which have proven effective in controlled trials and practice. Since the Brass Knuckles approach is one of engaging in a long war with the mite, Ill add a little levity by using military terms for my headings.

Know Thy Enemy: The Biology of VarroaThe European honey bee has not yet reached a stable relationship with its relatively new parasite, the varroa mite. In a typical, untreated colony, the mite level is at its lowest point about Christmas time. The mite population increases through the spring, reproducing especially in drone brood (a key point to remember). The colony generally tolerates the mites during this time, since the bees are reproducing faster than the mites, and drone brood is more expendable than worker brood. Then in late July or August (depending on your area) three things happen: the bees stop raising drones, they cut back on brood rearing, and the mite population peaks. At this point in time, there are a large number of mites relative to the small amount of worker brood to parasitize, and the developing workers are either killed outright, stressed to the point that they are susceptible to viruses (especially Deformed Wing Virus), or too weakened to become productive workers. Unfortunately, this is the generation of workers that must support the colony through winter. The result is that the Varroa-stressed colony collapses sometime between fall and early spring. Commonly, the beekeeper observes an active colony in the fall, then some weeks later, there are absolutely no bees, and an abandoned hive full of honey. To make matters worse, as the colony collapses, other colonies will rob it out, and in the process carry mites back to the robbing colonythis is the main mode of dispersal of the mite to new colonies (Goodwin 2006).

Ive misplaced the source of this graph. If anyone knows, please email me.

In preparing for our brass-knuckled assault on our enemy, we must know its weak spots (Ive put them in boldface). Unfortunately, during the period that mite populations are building, about two thirds of the mites at any time are safely hidden in sealed brood, protected by the silken bee pupal cocoon. Only a few volatile miticides can penetrate the cocoonnotably formic acid and thymol. In the process, however, these two treatments also kill a percentage of the bee brood.

So, other than using a cocoon-penetrating fumigant, we must hit the mite when it is most vulnerablein the phoretic (hitchhiking) stage. There are two times to do that: when the colony is broodless (during winter, or made broodless by manipulation), or when the mite is feeding on adult bees prior to entering a cell.

Heres the biology: a female foundress mite enters a cell when (or just before) the bee larva is in the propupal stage, but before it spins its cocoon. This occurs about day 8-10 after the bee egg is laid. The foundress mite and any mature daughters emerge with the adult bee on day 21 (if the bee survives until then). Therefore, the mite is hidden for only about 10-12 days. The adult female must then spend from 4 to 15 days sucking the blood of adult bees (usually on nurse bees in the brood nest area) before she is ready to enter a cell and start egg laying. A female mite can live for 3-4 breeding cycles. Reproductive success averages roughly 1-2 viable offspring in worker cells, and 2-3 in drone cells. Because of this low rate, in order for the mite population to increase, female mites must invade a cell and reproduce more than once during their lifetimes. Most all methods of beating up the mite focus on its vulnerability during the phoretic stage.

The varroa life cycle takes about 11-12 days in the cell, then several days in the phoretic stage on adult bees. Credit needed.

Update May 2012: USDA ARS scientist Jeff Harris narrates close-up video of bee and varroa development athttp://video.google.com/videoplay?docid=-7304562435786960616One other aspect of mite biology is of note: the foundress mite is more attracted to, and successfully rears more offspring in, drone brood than in worker brood (on its natural host, Apis cerana, the mite reproduces only on drone pupae), due to the drones larger size and longer developmental period. We can use this fact against our enemy.

Another biological aspect of varroa worth noting is its amazing ability to quickly develop genetic resistance to chemical miticides (at least the synthetic ones that have only one mode of action). Once in a cell, the foundress mite lays a male egg first, then female eggs thereafter. The male mite mates with his sisters, and dies when the cell is opened. This inbreeding locks in successful genetic mutations that might have allowed a particular foundress mite to survive a chemical treatment.

You may have noted that I have not discussed our allies in this battlethe bees (who have a vested interest in surviving). I will cover their contributions further along.

Our Contribution to the ProblemYoure all familiar with selective breeding for better bees. Be aware that we have also been breeding for better mites. That is, mites that can survive our repeated Silver Bullet attacks. Specifically, we have been applying selective pressures to favor mites that:

1. Evolve resistance to miticides

2. Rebuild populations quickly in mite-depopulated colonies (mites with low reproductive success cannot recover from regular treatments)

3. Kill colonies, rather than coexist with them, since colonies that collapse best disperse mites.

In other words, weve been inadvertently selecting for the most virulent, rather than the most benign mites. One could argue that it would be better to change our strategies to reverse the above selective pressures, and promote mites that are less virulent, and that can coexist at a low level in our colonies.

Our Fighting Strategy: Integrated Pest ManagementI already mentioned that the Brass Knuckles approach means that were going to accept the mite as a permanent resident in our hives, but were sure going to make its life miserable. If it starts to build up to a level that hurts our bees, were going hit it from several directions, so that it doesnt have a chance to build a defense (resistance) against any single tactic or weapon. The strategy were going to use is called Integrated Pest Management (IPM). A search of Google definitions for IPM gives us:

The use of different techniques in combination to control pests, with an emphasis on methods that are least injurious to the environment [read that, the honey bee colony, the wax combs, and our honey].

A combination of biological, cultural, and genetic pest control methods with use of pesticides as the last resort. IPM considers a targeted species life cycle and intervenes in reproduction, growth, or development to reduce the population.

An approach to pest control that includes biological, mechanical and chemical means.

Maintaining pest populations below a level at which economic damage results by using the least toxic methods.

An Overview of IPM for VarroaO.K., so what does IPM mean for the beekeeper? In a nutshell, learn about varroas strengths and vulnerabilities. Then develop a strategy to thwart its strong points (especially its ability to evolve resistance to miticides), and exploit its weak points, attacking it from several different directions. Allow me to give you an overview of the rest of this series:

First, you dont have to fight the mite single-handedly. There are bees out there with the genetics to fight the mites themselvestheyll just need your help sometimes. Ill talk about these fightin bees in Choosing your Troops.

VSH (Varroa Sensitive Hygiene) breeder queen. This line was developed by the USDA Agricultural Research Service to fight varroa. Breeder queens are available from Glenn Apiaries. Photo Glenn Apiaries.Second, stop freaking out if you see a mite! Understand your enemy, so youre not irrational with fear. The bees can handle a certain level of mites fairly well. Find out for your area, just what load of mites your colony can safely carry at any time of the year. The level that starts to hurt the colony is called the Economic Injury Level. So monitor your mites to make sure they stay below that level. If the mites are at a lower level, relaxyou can sleep at night. However, if they are starting to approach injury level, start hitting them softly. Only if they are over that level would you consider hitting them hard with some sort of strong chemical (you want to save your strong chemicals like a pistol in your back pocket, just in case things start to get out of hand). Ill cover monitoring under Reconnaissance.

The author inserting a sticky board to monitor mite levels. Other monitoring methods are more accurate in the short term.

A typical sticky board after a day or two. The mites and hive trash fall in lines between the frames, and mites are often mostly in one area. The 1/8 screen keeps the bees from removing the mites.

Third, lets make it generally miserable for the mite to survive, reproduce and disperse; and do all we can to help our bees fight the mite on their own. These tactics fall under Biotechnical Methods.

One biotechnical method is trapping mites in sacrificial drone brood. Im inserting a drone trap frame in February in an almond orchard.Fourth, now that youve done the first three steps, that may be all you have to do to maintain a truce with varroa! Unfortunately, most of us will still have to keep fighting. The next step in IPM is Soft Treatments, i.e., chemicals that kill a moderate proportion of the mites, are gentle on the bees, and unlikely to contaminate the combs.

ApiLife Var was one of the first soft treatments. Its main active ingredient is thymol, along with eucalyptol, menthol, and camphor.

Fifth, if soft treatments still havent done the job, and you need to do something drastic to keep your colony alive, then pull out a Hard Treatment. The temptation may be to just go straight to hard treatments each year, but in the long run that would just put us back on the Silver Bullet treadmill, since the mites will likely develop resistance to any hard treatment used yearly. So we will use hard treatments sparingly.

The Beekeepers IPM StrategyI realize that by using the battle metaphor to describe the situation with varroa, that Im anthropomorphizing the mite. In reality, the mite is a non-thinking automatona very effective little robot with a simple hardwired program. At the individual level, no learning (change) takes place; but at the species level, it can change by small increments in its behavior, morphology (structure), or biochemistry through the process of mutation or gene recombination. The honey bee is much the samea generally nonthinking robot that follows simple behaviors. For example, most bees in the U.S. dont possess the gene for the behavior to bite mites; when that gene becomes more prevalent in the population, we will say that the bees learned to bite mites. The learning didnt occur in any individual beeit occurred in the species by genetic change. The only player in this battle with the ability for cognitive thought is the beekeeper (although, at times, many seem to be devoid of that valuable attribute!).

We should really describe the situation as a battle of robots, led by two very different generals. The mites general is the mathematical hand of natural selection, promoting only those soldiers who are effective at survival. That survival could take the form of the benign coexistence the mite has with Apis cerana, or the form we have driven it torapid population recovery, kill the colony, then spread through robbing. The bees, on the other hand, have a democracy of generalsthe hand of Nature, plus thousands of beekeepers, who, unfortunately, arent about to cooperate in a common battle plan. If we beekeepers could manage to see the Big Picture, and collaborate with the force of natural selection, then we could come to a long-term truce with the mite. That said, let me return to the battle metaphor, and discuss the little mite-robots hardwired tactics program.

The mites success is based upon four main tactics:

1. It hides in the brood (where its hard for us, or the bee, to hit it).

2. It inbreeds, which lets it quickly lock in miticide-resistance mutations.

3. It reproduces relatively slowly, but exponentially, especially in the drone brood. (A weakness: this requires female mites to invade cells multiple times, and thereby expose themselves).

4. It spreads by weakening or killing the colony so that it can hitchhike on robber bees to infest new colonies.

Since we humor ourselves to be smarter than the mite, lets throw a stick into the gears of each of its tactics. What we want to do is to punch the mite from several directions, with each blow coming from a different brass knuckle that only kills, say half of them, so there is less selective pressure for the mite to evolve resistance to any one of our methods. The rationale for this is:

1. There is usually a trade off in overall fitness or vitality involved in the mite changing a behavior, or gaining a biochemical resistance (miticide resistance comes at a cost), and

2. There would be little pressure for the mite to adapt to any one particular threat, since enough mites survive each punch that change is not worthwhile.

3. Remember that varroa peacefully coexists with Apis cerana, and evolved to become less, rather than more, virulent to its original host. So our model is not to exterminate the mite, but rather to just keep it subdued.

So were going to choose a medley of methods and treatments, alternating among them, to keep the mite off balance, and unable to fight back. The key thing to remember is Rule No. 1 of varroa IPM:

DO NOT BECOME COMPLACENT!Many beekeepers have fallen into this trapyou figure out a great seasonal strategy that gives you good mite control for two years in a row. You pat yourself on the back, and lean back in your easy chair, proud of your victory over those dumb mites. Ive got news for youthe mites never relax. The next year (or the next) those mites come back with a vengeance, and bam!, you feel like youre back on Square One. Join the crowdweve all been there!

So what do I mean by Do not become complacent? Beekeeping was easy in the Good Old Days before varroa. You could figure out a seasonal management system, and repeat it successfully year after year. No morenow youve got to spy on the mite regularly, both at home, and elsewhere. Keep abreast of what its doing in the next state, because it will soon be doing it in your apiary! Monitor mite levels regularly. Some years mites will have low populations for no apparent reason; other years theyll roar into battle like a horde of Mongols. Youve got to be ready to adapt. More importantly, be proactive, and keep one step ahead of them (easy to say, huh?).

Now, you may wonder, what strategy am I going to suggest for you to use? The answer is, Im not! There are several reasons for that statement. First, I have no illusions of being The Worlds Greatest Beekeeperin fact, my operation has crashed regularly in my various skirmishes with the mite. Second, Im in the running for the title of being The Worlds Worst Businessman, so Im not about to tell anyone how to run a profitable business. Third, an IPM strategy will be different for every level of beekeeperhobbyist, sideliner, or commercial operator. And fourth, if we all do the same thing, varroa will figure out our strategy, and beat us at our game!

That said, the Europeans, who have had the mite much longer than us, have come to the conclusion that IPM is the only way to go (they also tend to run small, labor-intensive operations). I will list a number of useful papers and manuals available on the Web at the end of this series of articles. For the hobbyist, with isolated small beeyards, and the ability to spend a little time with each colony, organic IPM is clearly the way to go, and he/she can then charge accordingly for their honey. The sideliner (which is the most difficult way to keep bees, since your day job pulls you away from critical beekeeping tasks), is going to need a labor-effective strategy.

The Big Boys, with thousands of colonies, are likely going to resist change until the mite wrests the last Silver Bullet out of their cold, dead hands. Just kidding; I said resist change, not that they wont change. The reality is, there is little incentive for them to change, as long as they can keep their bees alive with inexpensive Silver Bullets. Change involves risk, and extra costs during the learning curve. It generally pays a large operation to act conservatively, and follow someone elses success. A notable exception is B Weaver Apiaries, who bit the bullet and gave up all miticides ten years ago (http://www.beeweaver.com/home.php?cat=1), yet are still running a successful operation. Some queen producers are changing, due to the problem of chemical buildup in their combs hampering queen rearing. Other cutting-edge commercial operators are embracing a new model, and making forward-looking 5-year plans that incorporate IPM. Overall, I see the Industry moving, albeit slowly, in the right direction. Keith Delaplane (2005) recently published an article as to the economic viability of a multi-component IPM approach. If you are successfully practicing IPM, please share what youve learned with the rest of us! Commercial operators: please dont pooh-pooh this as some kind of ivory-tower pie-in-the-sky wouldnt-it-be-nice-if pipedream! IPM is a sharp-pencil bottom-line-driven business decision that can put cold, hard cash in your pocket, and keep warm, healthy bees alive in your boxes. Indeed, IPM has been successfully embraced worldwide by many branches of agriculture.

If youre still dragging your feet, I can understand: Everett Rogers (1962 stated that adopters of any new innovation or idea could be categorized as innovators (2.5%), early adopters (13.5%), early majority (34%), late majority (34%) and laggards (16%), based on a bell curve. Each adopters willingness and ability to adopt an innovation would depend on their awareness, interest, evaluation, trial, and adoption. We owe a great deal to the innovators, who are willing to try something new, often crash and burn, but then get up and use what theyve learned to forge on. Where would you place yourself in the above list?

Rogers also proposed a five-stage model for the diffusion of innovation:

1. Knowledge learning about the existence and function of the innovation

2. Persuasion becoming convinced of the value of the innovation

3. Decision committing to the adoption of the innovation

4. Implementation putting it to use.

5. Confirmation the person evaluates the results of an innovation-decision already made.

OKin this series Im going to give you enough knowledge to get you started. Im obviously trying to persuade you. Its up to you to make the decision, and go through with the implementation! The main impediment to moving our industry towards IPM is the uncertainly felt by beekeepers that it will indeed both work, and be more cost effective than the practices they are currently employing. The tip point will come when enough Early Adopters confirm its success that the majority will embrace the change as a sound business decision. Right now, I call upon you venturesome types to join me in the next stage of recovery from varroa mite trauma. Following is a sample IPM plan for beekeepers in my area. Im not expecting you to copy it exactly, but rather to use it as a starting point from which to develop your own plan. Luckily, you neednt risk allone of the beauties of IPM is that you can start implementing it one small step at a time, without having to take the risk of jumping right in with both feet! Beginning next month, I will cover the various strategies, tools, weapons, and tactics in turn.

IPM 2 Fighting Varroa 2: Choosing your Troops: Breeding Mite-Fighting Bees

Second in a series on Integrated Pest Management of varroaOriginally published in ABJ, Jan. 2007

I got tired of getting my butt kicked by varroa. My first step in getting the upper hand on the mite was to forswear the coddling of wimpy bees with synthetic chemicals. This decision cost me dearly as colonies collapsed right and left. But thanks to the genetics of selected mite-resistant queens, my colonies now look better than they have in many years, and every box is again full of healthy bees.Update June 25, 2012 For a great webpage on the biology of varroa mite reproduction, seehttp://www.ars.usda.gov/services/docs.htm?docid=2744&page=14Update 12/2009 I foreswore synthetic miticides in the year 2000. My bee stocks are not yet completely varroa resistant, but do a good enough job that I now consider varroa to be more of a nuisance than a demon. I ran 700 colonies this summer, and run my bees next to large commercial operations, so my bees are exposed to the full gamut of mites and other parasites.

Authors note: Id like to dedicate this article to Steve Taber, the iconoclastic researcher and bee breeder who continually challenged us to question everything we know about bees and beekeeping.

Introduction to mite toleranceA beekeeper friend asked me the other day, Why havent those danged researchers found us the cure for varroa yet? I replied, They haveMarla Spivaks been on her soapbox for years, telling us what it is: Stop perpetuating bees that can only survive with chemical help. Weve all seen how the mite develops resistance to each new chemical; bees will do exactly the same to develop resistance to the mite, if we just allow selective pressure to exert its effect. Well, duh! Whats it going to take until we all realize this? Heres the skinny from the scientific community: theyre tired of looking for Silver Bullets. There are a few new chemicals coming down the line, but bee scientists in general are telling us that we need to move beyond the numbskull beekeeping practice of throwing a mite bomb into our hives once a year until its ineffective, but rather start practicing smart beekeeping, or IPM, centered around fightin bees that kick mite butt with only occasional help from us.

On its natural host, Apis cerana, varroa is a minor pest. Cerana has evolved a number of defenses against the mitenotably grooming behavior, infested worker brood removal, and trapping the mite in drone brood. These defenses allow the mite to coexist in the colony, but at low levels. This is an expected mature host/parasite relationship. The European honey bee, Apis mellifera, rarely showed any such traits when first infested with varroa, but these days were seeing the behaviors for chewing out infested brood and grooming more commonly.

If there had been no human intervention after varroa made the jump to the European honey bee (EHB), the vast majority of colonies would have died out, but, given a large enough population, and with enough genetic variability, the few survivors would likely have repopulated some or all of the range. The process would have been encouraged by the selective pressure against severely virulent strains of mitethey would have had a hard time dispersing over honeybee-impoverished areas without human assistance (robbing being critical to the dispersal of virulent mites).

This is a colony on the verge of collapse due to the combination of varroa and Deformed Wing virus. Note the circled mite and the bees with deformed wings.

The downside to this process, however, is that agriculture would have suffered; and beekeepers would have gone out of business, what with only a fraction of a percent of colonies initially surviving the varroa onslaught (as in my operation when the mite first hitI lost all but six colonies out of about 250). So we desperately launched into a pitched battle consisting largely of throwing chemicals at the mite. This strategy worked okay at first, but, as weve found, we were simply perpetuating wimpy bees, and inadvertently executing a concurrent breeding program for virulent supermites.

The feral population of bees, left to their own, also largely perished. But we inadvertently hampered their efforts to evolve resistance to the mite by flooding drone congregation areas with mite-susceptible drones from our managed yards, and filling hollow trees with mite-infested swarms, which would then collapse in a year or two. Nonetheless, were seeing feral populations starting to survive. This brings up a good point: If youre not part of the genetic solution of breeding mite-resistant bees, then youre part of the problem. Every time you allow drones or swarms to issue from a colony that owes its survival to a miticide application, youre hindering the natural process of evolution toward mite-resistant bees!Using mite resistant beesSo what is one to do? First, promote mite resistant queens, either by purchasing from a breeder/producer, or taking on the challenge of selecting and raising your own (covered below). (Mite resistance implies active fighting of the mite; mite tolerance includes viral resistance, or other tolerance mechanisms. For the sake of simplicity, I will generally use the term mite resistant.) There are a number of beekeepers throughout the world doing exactly this, either formally or informally, many with considerable success, in both small and large operations. There are several researchers in this country doing the tedious grunt work involved in selection, such as Steve Taber, Marla Spivak, John Harbo (retired) and Jeff Harris, Sue Cobey, Latshaw and McAdams, and Tom Rinderer to name a few, as well as dedicated private parties, such as Dan Purvis, Danny Weaver, Kirk Webster, and Joe Waggle (I know Ive inadvertently left some of you outthese names just came to the top of my head).

Funny thing is, when I talk to the large queen producers, mite tolerance is not the main thing buyers are asking for! (The same thing happened years ago when Steve Taber developed a tracheal mite resistant line). Most breeders are selecting for mite tolerance anyway (even if inadvertently), but Ill tell you, they are going to respond to customer demand. That said, there are few, if any, open-mated stocks that are completely mite proof, so producers are hesitant to promise you the moon (and you may be disappointed by those that do!). Also, many beekeepers unfortunately had poor experiences with the first generations of bees touted to be mite resistant. For example, when John Harbo first released the SMR (suppression of mite reproduction) queens, he was clear that they were not intended to be used for production stock. Despite his caveat, a number of beekeepers (myself included) used them as such, and were disappointed by their performance in the field. Through no fault of the SMR queens, some beekeepers are of the once bitten, twice shy mentality and are hesitant to try resistant stock again.

Another reason for not getting on the bandwagon is, as one of my commercial friends says: Why should I sacrifice five pounds of honey yield by buying mite-resistant stock, when Im controlling the mite just fine with popsicle sticks dipped into the latest agricultural chemical? Their point is: there is no free lunch, i.e., the bees have their hands fulland if you give them a new job to do, they will have to cut elsewhere. A review by Steve Shepard (2006) considers such tradeoffs of mite resistance vs. honey production. However, in the Big Picture colony stress due to mite damage and miticide residues may well cost the colony more in production than behavioral resistance would. After reviewing yields by mite-resistant colonies vs. Starline bees, Spivak and Reuter (2001) conclude: colonies bred for hygienic behavior suffer no apparent fitness costs, and perform as well, if not better, than commercial stocks not bred for hygienic behavior It doesnt appear that lack of production is a necessary fault if one makes a point of breeding only from the strongest and most productive colonies.Breeding for mite toleranceIm not going to explain to you here how to rear queens. But if you already know how, let me make some suggestions for selecting for mite tolerance. Essentially, you want to determine which colonies are handling varroa without help, and breed only from them. John Harbo and Jeff Harris collected survivor queens from apiaries that had collapsed from varroa, and bred from them, selecting for the most mite resistant. Due to an initial misinterpretation of their mode of action in fighting varroa, they labeled them SMR, but now refer to them as VSH (varroa-sensitive hygiene) bees. It appears to me that VSH behavior is one of the traits exhibited by all current mite-resistant stocks of bees. An added advantage of hygienic bees is that they clean up other brood diseases, such as AFB and chalkbrood on their own!

Varroa Sensitive Hygiene (VSH)VSH bees have a simple tactic for fighting varroathey simply chew the buggers out of the capped cell when they try to reproduce (Figure 1). The first time I observed this behavior, I thought I had a new bee disease, until I realized that I was witnessing VSH behavior in action! You can observe it by looking for white-, or purple-eyed pupal faces being uncapped, and the healthy white pupae within often being chewed away. Dee Lusby has been reporting on this behavior for years: www.beesource.com/pov/lusby/lusbyjun.1997.htm. This behavior usually doesnt kill the foundress mite, but sure keeps her from reproducing! You may ask, But doesnt chewing out brood weaken the colony? Answer: it could, but the cost of removing brood is insignificant as long as mite levels remain low. For more information on VSH, see: www.glenn-apiaries.com/vsh.html.

A dark VSH breeder queen (yellow queens are also available) from Glenn Apiaries. Photo Glenn Apiaries.

Figure 1. Illustration of varroa sensitive hygiene (VSH). Workers uncap cells to thwart reproduction by the mite. The beekeeper will observe exposed white- and purple-eyed pupal faces. The pupa may or may not be chewed out in the process.

Strong VSH in action. Note how the bees will remove the cappings over purple-eyed stage pupae, but may not remove the pupae. One bee in the upper right quadrant is chewing out a pupa.

The good news. Tom Glenn has made this map of locations to which he has sent VSH breeders. We are slowly incorporating these genes into the U.S. bee population!

As far as my personal experience, the initial purebred VSH queen mothers I purchased were so inbred, that it was hard to keep their colonies alive, and the workers wanted to supersede them. The F1 crosses were better, but not fully mite resistant, nor great bees. However, two years ago, I ordered an instrumentally inseminated Minnesota Hygienic x VSH queen from Tom Glenn (www.glenn-apiaries.com); she is the best queen Ive seen since before varroa! I call her my Dream Queen. This particular cross of the individual parents was a magical combination. Shes been going two and a half years with absolutely no treatment, in a survival yard with colonies collapsing around her, and has negligible mite levels. Her open-mated daughters were the healthiest, strongest, best honey producers Ive seen, and outperformed all other stocks stuck late in the mud at the end of last years rain-drenched almond pollination season. The Dream Queen colonies came out fat and happy, while everyone else starved. Needless to say, Ive grafted a lot of daughters off her! Bee stock like this is the future of our industry; if all my colonies performed like hers, it would be like beekeeping in The Good Old Days before varroa again!

My Dream Queenperhaps the best queen that Ive ever had. She was a Minnesota hygienic x VSH cross from Tom Glenn, and lasted nearly three full years (finally was superseded after I wrote this article). Mite levels remained negligible without treatment, yet the colony (and her daughter colonies) were by far the most productive in my entire operation. The experience of having a colony like this shows me that breeding is the key to future successful beekeeping!

I can hear the skeptic saying Yeah, but thats how it was when Apistan worked. True, but youre missing the beauty of biological control: a chemical Silver Bullet cant evolve with the mite; mite-resistant bees should be able to continue to handle varroa by evolving in lockstep with it. VSH, for example, is a great trait with which bees can fight the mite, but its not the only one. The bees have some more tricks up their sleeves

Other potential varroa resistance/tolerance mechanismsHere are some more observed or potential varroa-fighting tools likely to be found in the bees genetic toolbox (in rough order of likelihood):

1. Other hygiene-related behaviors (Dr. Marla Spivak is studying these). Apis cerana is so effective at VSH that Varroa jacobsoni generally wont even try to reproduce on worker brood, even if transferred to worker brood of the European honey bee. (Boot, et al. 2004).

2. Grooming behaviorsthere may be several genes involved:

a. Better autogrooming behavior to dislodge mitesespecially useful with screened bottoms,

b. Allogrooming (nestmates grooming each other) behavior, and

c. Signaling or communicating the need to be groomed to nestmates,

d. Crushing of mites in the mandiblesApis cerana and the Africans do this.

3. Resistance to various viruses and better immune system. Its very important for the bees to keep the mite population in check, but its usually not the mites that cause colony collapseits viral infection (notably deformed wing virus) vectored or initiated by mite feeding. Miaoqing, et al. (2005) state: parasitization by varroa suppresses the immunity of honey bees, leading to activation of persistent, latent viral infection. Surprisingly, the Honey Bee Genome Project (Evans 2006) found that compared to flies, honey bees possess only a third as many immunity genes. We should screen for bees naturally resistant to various viruses and other diseases.

4. Post-capping duration: Varroa is not well adapted to EHB worker broodonly 38% of the second female eggs are able to develop to maturity, and only 13% of the third. Theoretically, if the developmental period of the worker were shortened by one day, no third daughters would mature; by two days, very few second daughters (Figure 2). This has not yet been demonstrated by experiment, although it is often cited as a possible mechanism used by the African honey bee. Dee Lusby demonstrated that by selective breeding, one could knock up to 4 days off EHB queen development time (DeGrandi-Hoffman, et al. 1989), implying that worker development time could also be curtailed. Steve Taber suggested a selection method in the November 2006 ABJ.

5. Minimal drone production, since most mite reproductive success takes place in drone brood.

6. Biochemicalmites incorporate some bee proteins unaltered into their eggs without digestion (Tewarson and Engles 1982). Bees might evolve proteins that are deleterious to the mite; or the bee could modify essential proteins that varroa require for reproduction or metabolism.

7. Alteration of bee larval or pupal pheromones/volatiles that initiate mite reproduction or feeding (Denis Anderson in Australia, Yves Leconte, and Peter Teal are all working on this). It is necessary for the mite to read the pheromonal signal of a pupa to tell it to ovulate. Our problem mitethe Korean haplotype of Varroa destructormutated to be able to ovulate in response to worker, as opposed to drone, pheromones. We could breed bees that dont give this signal, and would thus suppress mite reproduction in worker brood.

8. Dr. Spivak suggests that our breeding for bees that use less propolis may have backfired against us, since propolis may be the bees first line of defense against diseases, and possibly mites.

9. Thickened drone brood cappings to trap mites with multiple-infested drones, as in A. cerana.

10. The aforementioned mechanisms are only those that come to my mind. There are likely moremy guess is that weve only scratched the surface. A bibliography of research on varroa resistance can be found at: www.glenn-apiaries.com/bibliog.html11. We must also continue to breed for the usual traits of vigorous broodrearing, honey production, and gentleness, and resistance to tracheal mite and other diseases.

12. Add to the above list that we may wish to screen for virus-free queen lines (as with strawberries and horses). Viruses may lie latent in queens, and be passed on to eggs (Chen, et al. 2006). Furthermore, the manner in which queens are raised may be important. The new science of epigenetics (Watters 2006) has found that nutrition and stress events affect not only the individual, but also the behavior and disease resistance of its offspring, sometimes for several generations. In other words, if a queen is reared under stress or perforated by a mite, she may pass effects on to her offspring.

Wow, breeding for the best mite-tolerant queen is quite an order! Obviously, no breeder is going to investigate, let alone breed, for all these traits. Its hard enough to breed for just a few! Plus, whos to say what the best combination is? Mother Nature uses trial and error and many generations to determine which combinations are most efficient. Just as there are many recipes for the perfect chocolate cake, there may be innumerable recipes for the perfect bee. But we can certainly support researchers who dedicate themselves to the quest, and breeders such as Sue Cobey and Tom Glenn who maintain genetic banks from which breeders can draw stock to experiment with.

Figure 2. Varroa development in drone and worker brood. By breeding for bees with shorter post-capping development time, we may be able to restrain the rate of mite reproduction.

The Russian BeesAnother option is the Russian Bees. Dr. Tom Rinderer of the ARS Baton Rouge lab traveled to the Primorsky region of Russia to where European honey bees have been longest in contact with the varroa mite. He made trips to the region from 1994-2002 to collect promising stock (www.ars.usda.gov/Services/docs.htm?docid=6444), and has now given the resultant lines over to collaborators in the Russian Bee Breeders Association (www.russianbreeder.org).

European bees from the Ukraine were moved to the Primorsky region about 150 years ago, where they came in contact with varroa.

I was able to spend some time with Dr. Rinderer and Russian breeder Carl Webb, in Carls yard in Georgia. The bees were well behaved, productive, and free of diseases. None of the breeders apply any treatments to their colonies.

The Russian bees arent One Trick Ponies. Heres a list that I made of some of the mite resistance tactics that they use. When they shut down broodrearing, they actively scour mites out of the hive. This response to pollen flows may make Russians more suited for stationary, as opposed to migratory, beekeeping.

The Russian bees winter very well, in small clusters, and build up explosively in response to pollen flows in spring (or fall). They are noted for how quickly they will fill the supers, despite having smaller populations than Italian bees.

Ive spoken to a number of beekeepers who swear by purebred Russian stock. Please note that Russian hybrids may not perform nearly as well as the purebreds.

Genetic diversity of bee stocksWe may have a problem: loss of genetic variation in our bees. Genetic variation is the list of ingredients available in a species from which to concoct evolutionary adaptation, or to use in selective breeding by humankind. There may be a paucity of genetic stock due to several factors:

1. The U.S. cut off imports of honeybees in 1922 (due to tracheal mite problems in Europe), leaving us with only 7 subspecies of Apis mellifera (of the 26 known in the world) to breed from. Of these seven, commercial stocks generally are based upon only three!

2. Then we lost about 70% our bees when tracheal mite finally arrived in 1984,

3. and then lost an even higher percentage when varroa arrived in 1987. As if that werent enough,

4. Debby Delany (Washington State Univ) surveyed queen producers and found that in the mid 90s only 603 breeder queens produced one third of all production queens used in the country!

This lack of diversity is called a genetic bottleneck, and means that our bees didnt have many genetic tools to work with to fight varroa. Progressive breeders, such as Sue Cobey and Steve Sheppard,and Tom Rinderer (Russian, www.ars.usda.gov/Services/docs.htm?docid=6444), are bringing in other genetic lines. Others, such as Joe Waggle are selecting from feral colonies http://pets.groups.yahoo.com/group/FeralBeeProject/, in the hope that they possess traits not found in commercial stocks.

Update: further research calls into question whether the U.S. is indeed lacking in bee genetic diversity. I will cover this in a future article.

Diversity within the colonyAn important aspect of bee colony behavior and disease resistance is that a colony of bees is composed of subfamilies of supersisters, all having the same mother (the queen), but each subfamily having a different drone father (due to the queens multiple mating). In a colony, there can exist one group of supersisters really good at honey production, and another group really good at VSH, and another group that excels at comb building. Together, they work as a functional unit superior to any single subfamily of supersisters alone. Tarpy and Seeley (2006) found that colonies headed by multiply-mated queens were more resistant to AFB than those whose queens were inseminated by only one drone. Everything about honeybee mating behavior is geared toward multiple matings to ensure a large number of patrilines present in each colony. We may wish to emulate this natural scheme in our breeding programs.

I got lucky with my Dream Queen, in that I apparently got a perfect mix of supersisters who together, had it all; but it made me realize that our future may lie in returning to programs like the Starline bee. Witherell (1976) describes the maintenance of the famous Starline and Midnight queens developed by Dadant. They were each double (line) hybrids or crosses of four inbred lines specifically chosen for their combining ability to produce exceptional and predictable production queens. Collaborating producers bought Line AxB (Line A queen inseminated by Line B drones) on even years, and Line CxD on odd years. That way, the previous years queens would produce drones with genes derived from, say, A and B lines to mate with virgin queens from this years CxD cross. The next year, the inverse would hold true.

A queen producer (as opposed to a queen breeder) could do something similar today. If he/she produced queens from Minnesota Hygienic x VSH stock this year, their colonies could supply drones next season for a breeder queen of say, Russian x New World Carniolan parentage (I have no idea if any of these particular hybrids would have combining abilityIm just proposing an example). If that double hybrid were successful, the following year the queen producer could purchase another MH x VSH to repeat the cross.

Breeding your own stockYou can shift your operation to varroa tolerance by purchasing selected queenstock, or you can start from your own locally-adapted stock (paying special attention to surviving feral colonies). Erickson, et al. tell you how to do it: Producing Varroa-tolerant Honey Bees from Locally Adapted Stock: A Recipe www.beesource.com/pov/usda/varroatolerantbee.htm. In England, Roger Dewurst selects for bees that bite the beekeeper by tugging at his skin! He finds that the amount of grooming and damage to mites increases in the subsequent generations (see photos at www.kilty.demon.co.uk/beekeeping/improvement.htm).

Many beekeepers are intimidated by the prospect of queenrearing. However, once you try it, you will be amazed at how easy it is! Here Im pulling out a frame of queen cells from a queenright cell finisher colony.

Some breeders, such as Steve Taber and John Kefuss, can be downright brutalusing the so-called Bond method (Live and Let Die) (Kefuss 2004), whereby your best colonies (he suggests starting with freeze-kill tested hygienic bees) are placed into a survival yard, without treatment, to see who survives. As the losers collapse, they infest the survivors with additional mites. You could call it the acid test, but any surviving colonies would be worth breeding from. I personally set up a Bond survival yard, but seeing almond pollination prices pushing $150 last year, I chickened out in late summer, and gave some of the surviving colonies a soft mite treatment (but removed them from the breeding pool). This made me realize that we shouldnt count on western queen producers to perform many survivability trials, since they also depend upon pollination income for their livelihoods! They may have to look for breeding stock from eastern beekeepers who can allow yards to crash, and then make up their winter losses each spring from the survivors. A reasonable compromise is practiced by a number of beekeepers: they just help the bees once or twice a year, say, with a shot of oxalic acid on the broodless winter cluster, so they get a fresh start each season, then breed from their best surviving colonies each spring.

What Im personally doing now is testing all my colonies at the same time each August with sticky boards. Those that have extremely low mite levels (after checking to make sure the colony is populous and productive) are marked as potential breeders, not treated, and watched. If they make it til fall with low levels, they are again checked for condition when I prepare for almonds in late January. The best are put aside for breeders, and the rest get extra drone combs to fill with drones in the almonds, so theyll be good drone mothers when they return home. All other colonies that needed miticide help, have their drone brood removed by trap frames in February and March (so they dont contribute to matings), and are nuked up (killing the queens) to repopulate my operation. I add a few mite-resistant inseminated queens each spring from Tom Glenn and elsewhere, to maintain genetic diversity, by serving (if they prove themselves) as drone or queen mothers next season.

Breed only from healthy, productive colonies that maintain low mite levels.

Update 2009: Survivor stock may handle varroa, but may not be productive enough to be worth keeping. Breeding solely from survivors may lock in certain key alleles for mite resistance, but this avenue may be best left to professional breeders and Mother Nature. In your own operation, I suggest that you only breed from productive colonies, and add resistance alleles via purchased drone mother queens.

If you raise your own queens, it will likely take at least three years to shift the genetics of your operation (since you must also shift the genetics of the feral colonies that send out drones) to the point that you see a major difference.

The genes of the virgin queens in these cells are important, but half the genetics of the resulting colonies will come from the drones that the queen mates with.

Your turnSpring is just around the corner, and with it comes time to requeen colonies. The first step to an IPM program against varroa is to start with mite-resistant queens (www.glenn-apiaries.com/queenproducers.html). If youre adventuresome, and can afford having most of your colonies die, you could start from scratch. However, it would be much easier and quicker to begin with existing mite-tolerant commercial stocks. Demanding mite-tolerant queens from a producer is like buying tomato plants resistant to verticillium wilt. There is no sense in purchasing plants that are likely to die, even with babying and chemical treatments, when there are varieties available that can thrive on their own! Its the same with bees. Ask your queen supplier what treatments he or she uses in their own operation to keep their bees alive. Or better yet, ask how long his/her breeders have gone without any treatments at all for varroa? As purchasers of queens, you have the opportunity to change the market. By demanding mite tolerance in the queens you buy, you can shift the genetic structure of the bee gene pool in North America!

WARNING: it is unlikely that simply requeening with mite-resistant stock will end your mite problems at first! There are other factors involved. Keep in mind that your resistant bees will still have to deal with the onslaught of mites from collapsing colonies in your vicinity until other local beekeeping operations and the feral population shift toward mite resistant genetics. At some point we will reach a tip point where the majority of all colonies are mite resistant, and we wont be picking up the fallout from the chemical-coddled collapsing colonies of our neighbors.

There is also the question as to whether the queens you purchase are well adapted to your area and operationperformance and seasonal behavior of various resistant stocks vary greatly. For example, one of the ways that Russian stocks deal with mites is to overwinter with a small cluster. This may be a problem if you want huge colonies in February for almond pollination. However, there is no reason to think that mite resistant bees cant perform well in migratory commercial operations, as long as one breeds from the best performers each season.

Dont expect a miracle! But remember, we dont necessarily need bees that are 100% resistant to varroaeven bees that can delay the interval between mite treatments are valuable. Varroa opened up a Pandoras Box of problems for our beesstress from being fed upon, weaker wintering, virus and disease issues. Having bees that can keep mite levels lower will help them to overcome all those problems. For some period of time, though, you will likely need to help your bees with the battle. You will want to monitor mite levels, and have backup plans for mite control in place. In coming installments of this series, I will detail your options.

Those of us who were keeping bees prior to varroa remember how much easier it was back then. It is my fervent belief that we can return to that kind of beekeeping once we keep bees that handle varroa on their own!

Update: I will be greatly expanding this section on breeding soon!