Category Archives: Economics

Apivar & Apitraz = Amitraz

The range of miticides available ‘off the shelf‘ to UK beekeepers has recently been increased by the introduction of Apitraz and Apivar.

‘Off the shelf’ because, until recently, these were only available with a veterinary prescription.

Considering the extensive coverage on this site of oxalic acid-containing miticides and more recent posts about the – regularly ineffective – Apistan, it seemed fair and appropriate to write something on the active ingredient and mode of action of these new products.

Mites on drone pupae ...

Mites on drone pupae …

Conveniently, because the active ingredient is identical, these can be dealt with together in a single post. The similarities don’t end there. The amount of the active ingredient is the same and the way it is administered is very similar. They are different commercial products; Apitraz is distributed by Laboratorios Calier, SA and sold by BS Honeybees, Amitraz is distributed by Veto Pharma and sold by Thorne’s. The strips have a different appearance and a slightly different mechanism by which they are hung in the hive.

They even cost about the same – a single packet of 10 strips (sufficient to treat 5 hives) costs £30.50 and £31 respectively for Apitraz and Apivar.

Amitraz

The active ingredient in both Apitraz and Apivar is Amitraz.

Yes … I find these three names confusing similar as well 😉

Amitraz is a synthetic acaricide – a pesticide that kills mites and ticks. It was discovered and developed almost 50 years ago by the Boots Co. (the drug development predecessor of the Boots the Chemist 1 found in most high streets). Amitraz is the active ingredient in a range of medicines approved by the Veterinary Medicine Directorate, including Aludex and Certifect, both of which are used to treat mange in dogs.

Amitraz

Amitraz …

For completeness I should add that Amitraz used to be used by US beekeepers and was sold as a generic pesticide under the name Taktic, though this was withdrawn in about 2014. I believe that Apivar is now available as a slow-release Amitraz-containing Varroa treatment in the US.

Mechanism of action

Amitraz has to be metabolised (essentially ‘modified’) before it is active. This modification occurs much less well in bees than in mites. In fact, the toxicity of Amitraz for bees has been determined to be about 7000 times less than in mites.

Once converted into an ‘active’ form the most important mechanism of action for Amitraz is through interaction with the alpha-adrenoreceptor and octopamine receptors of Varroa 2.

OK, since you asked … octopamine receptors normally bind a neurotransmitter called – rather unimaginatively – octopamine. Quelle surprise as an apiculteur would say. It’s likely that occupancy of these receptors by Amitraz triggers a series of so-called downstream events that change the behaviour of Varroa. Similarly, amitraz also acts as an agonist 3 when binding to the alpha-adrenoreceptor which normally interacts with catecholamines. This results in neurotoxicity and preconvulsant effects.

That all sounds a bit vague. Essentially, amitraz binds and activates receptors that are critically important in a range of important aspects of the Varroa activity and behaviour. Remember here that the mite is entirely dependent upon proper interaction with the bee to complete the life cycle. For example, if the mite fails to enter a cell at the correct time or doesn’t hitch a ride on a passing nurse bee for a few days, it will likely perish.

Amitraz changes behaviour and so exhibits miticidal activity. It has additional activities as well … these multiple routes of action may explain why resistance to amitraz is slow to develop. More on this later.

Usage of Apitraz and Apivar

Both Apitraz and Apivar are formulated as plastic strips impregnated with amitraz. The bees must come into contact with the strips to transmit the amitraz around the hive. Two strips are therefore placed between frames approximately one-third of the way in from each side of the brood box – typically between frames 4 & 5 and 7 & 8 of an 11 frame box. This assumes the bees occupy the entire box. If they don’t, arrange the strips in the appropriate part of the box with 2 frames separating them. Both types of amitraz-containing strips have a means of securing them hanging between the frames.

The recommended treatment period is 6 (Apitraz, or Apivar with little/brood present) to 10 weeks (Apivar with brood present). As with Apistan, treatment should not be applied during a honey flow or when honey supers are present. Further details are included on the comprehensive instructions provided with both products. There’s also a reasonable amount of information on this New Zealand website for Apivar.

Efficacy

This is the good bit … very, very effective. When used properly, amitraz-containing miticides can kill up to 99% of the Varroa in a colony.

Toxicity and wax residues

The good news first. Amitraz does not accumulate in wax to any significant extent. It is not wax-soluble. This is in contrast to Apistan which is found as a contaminant in most commercially-available beeswax foundation.

And now the bad news. Beekeepers also have alpha-adrenoreceptors and octopamine receptors. So do dogs and fish and bees. Although amitraz has increased specificity for the receptors in mites and ticks, it can also interact with the receptors in other organisms. Consequently, amitraz can be toxic. In fact, if you ingest enough it can be very toxic. Symptoms of amitraz intoxication include CNS depression, respiratory failure, miosis, hypothermia, hyperglycemia, loss of consciousness, vomiting and bradycardia.

And it can kill you.

Admittedly, the doses required to achieve this are large, but it’s worth being aware of what you’re dealing with. Amitraz-containing strips should be used only as described in the instructions for use, handled with gloves and discarded responsibly after use.

Resistance

Multiple modes of action makes it much more difficult for resistance to evolve. But it can and does. Resistance to amitraz is well-documented and is understood at the molecular level. However, this is in cattle ticks, not Varroa.

At least, not yet, though there are numerous anecdotal reports of Varroa resistance.

I’ll deal with resistance in a separate post. It’s an important subject and avoiding it is a priority if amitraz-containing compounds are going to remain effective for Varroa control.

Cost

At about £6 per colony, amitraz-containing treatments are not significantly more expensive than the majority of other approved miticides, perhaps with the exception of Api-Bioxal which is appreciably less expensive (though more restricted in the ways it can effectively be administered 4).

Apivar ...

Apivar …

When you purchase a couple of packets of Apivar – enough for 10 colonies – it might feel expensive 5. However, it’s worth remembering that this is still less than the likely ‘profit’ on a couple of jars of your fabulous local honey per colony per year, which seems pretty reasonable in the overall scheme of things.

And, if you look after your colonies well, you are maximising the potential yield of honey in the future … so you’ll be able to afford it 😉


 

All the gear, no idea

The new Thorne’s catalogue came out a few days ago. I picked up a copy during a visit to the Newburgh store when I bought frames for the upcoming season and some more queen excluders.

Required reading

Required reading

I’ve always enjoyed reading the Thorne’s catalogue. Browsing the 2018 copy brought back memories of my introduction to it a decade or so ago. That was after my very first “Beekeeping for Beginners” evening class with the Warwick and Leamington beekeepers. Everyone left the class clutching a catalogue and an order form for a discounted BBwear suit. 

It was clearly effective and well-targeted marketing. I still spend more than I should (though less than I could, thanks to my catastrophic DIY skills) with Thorne’s and I still use BBwear suits.

Pick a size, any size

Dadant? Smith? Aargh!

Dadant? Smith? Aargh!

The abiding memories of my first experience of the catalogue were the myriad choices … of hives, frames, foundation, tools and – perhaps more than anything else – labels and moulds.

Remember, this was before even the basics of the hive had been introduced in the beginners course. That first evening was probably spent on the distinction between queens, workers and drones, or perhaps ‘the beekeeping year’.

Back to the catalogue … surely there wasn’t the need for all those different frame sizes and styles? DN1, DN2, DN4, DN5, 14″ x 12″ and BS Manley.

Hang on! What happened to DN3’s? 1

And then the hives … National, Commercial, Dadant, Smith, Langstroth … Aargh!

Very confusing. And that’s before some of the hives that didn’t even really look like beehives were considered … Top bar, Dartington, Warré 2 etc.

Of course now, a decade or so later, I know the answer. There’s no logical need for anything other than medium Langstroth boxes and one type of frame 😉

But I and most other beekeepers also know that logic is something in short supply in most beekeeping.

Indeed, logic is almost as rare as adhering to standards.

Which is why I use BS ‘British Standard’ National hives 😉

The essentials and nothing else …

The Thorne’s catalogue3 lists everything an amateur ‘hobbyist’ beekeeper could possibly need and almost everything he or she could possibly want. It also lists several thousand things that are either duplicates of other stuff or, plain and simple, are probably unnecessary.

Eight different types of smoker. Eleven different types of uncapping knives, forks or rollers. Eighteen different types of hive tools. Eighteen! And I daren’t even look at the labels or moulds.

This isn’t a criticism. Choice is great … but is can be really confusing. Particularly when you don’t know the difference between your Bailey, Horsley, Snelgrove, Cloake or Snuggle boards.

Have some sympathy for the hundreds of tyro beekeepers attending winter training courses all over the UK at the moment. In between those two hour lectures in the drafty church hall 4 they’re feasting on the Thorne’s catalogue every evening to provide their necessary daily ‘fix’ of beekeeping enlightenment.

For many, this catalogue is an integral part of their beekeeping education.

Beetradex and the Spring Convention

And then, schooled in basics from their winter training courses and simultaneously confused and enticed by their nightly perusal of the ‘essentials’ in the Thorne’s catalogue, come the two biggies.

Beetradex and the BBKA Spring Convention.

Like lions waiting to ambush an unsuspecting baby wildebeest, the two biggest trade events in the beekeeping year allow all those essential items in the catalogue to be seen, inspected, caressed, agonised over and – finally – bought.

Beetradex ...

Beetradex …

Not necessarily in that order.

In my case sometimes bought, caressed, inspected and then agonised over 🙁

What on earth possessed me to get a Combi-Brush?

All the gear, no idea

Those early beekeeping days were characterised by limitless enthusiasm – in part fueled by the annual Thorne’s catalogue – and precious little practical experience.

"Essentials" ...

“Essentials” …

I’ve still got stuff I bought in those early days. There’s all sorts of bits and bobs stored away which ‘might come in’.

It hasn’t and probably won’t 🙁

One of the characteristics of my beekeeping (and I suspect of many others) is that it has become much simpler and more straightforward as I’ve gained experience 5. The enthusiasm is still there, it’s just tempered with pragmatism and an appreciation that there’s only so much I can fit into the garage.

Enlightened apiculture

I now carry less to the apiary than I did five years ago. The bee bag is slimmed down and much more manageable. My record keeping is more organised – or at least less shambolic. I’ve given away the frame rests, mouseguard magnet … and the Combi-brush.

But, most significantly, I’ve pretty-much standardised on the equipment I use. I buy the boxes ensuring that they’re all compatible with each other. I buy the replacement frames and I buy less and less foundation.

And most of the rest I usually do without or build myself. The latter includes almost all of the ‘horizontal’ components of the hive – the floor, boards, roof, ekes etc.6

And I reckon my beekeeping is better for it. My bank balance certainly is 🙂

What’s new?

Nevertheless, I’ve still enjoyed a quiet hour or two (as the Beast from the East roars outside) with a cup of tea and the 2018 Thorne’s catalogue.

I’ve marvelled at the Adapta hive stand and floor which, by my estimates, would cost an eye-watering £422.92 if you were to buy it with all the accessories.  Actually, I’ve mainly marvelled at their ingenuity in designing all those accessories. This floor has been out a year or two now, but new for 2018 is the Adapta eke.

Or perhaps that should be Eek!

Undoubtedly well made, indubitably multi-functional, but costing £107.50 with all the add-ons.

Eek!

My first hive was a secondhand Thorne’s Bees on a Budget National bought from an association member who had had to give up beekeeping due to allergies. The boxes are still in regular use. It’s still listed in the catalogue and thousands have probably started their beekeeping with one of these hives.

While the basic hive hasn’t changed there are lots of new choices of floor, half-size supers and insulation, polish containers, queen introduction cages and – inevitably – candle moulds.

So … was I tempted by anything?

Of course 😉

Horsley board

Horsley board

A year or two ago Thorne’s started selling Horsley boards (PDF) – an interesting method of swarm control consisting of a split board with an upper entrance, removable slide and queen excluder panel. I built my own a few years ago and have used it successfully. Mine is bodged together from bits of scrap wood and a butchered tin baking tray.

It’s a monstrosity.

They had one in the Newburgh store and it was beautifully made.

I was very tempted.

But I managed to resist … though I’ve looked at it several times in the new catalogue 😉


Colophon

In the interest of literary accuracy I should add that the bit about the Combi-Brush is not entirely true. I’ve never bought one. It was chosen as the most ridiculous piece of beekeeping equipment I could find in the catalogue that readers might appreciate.

However, there are a few things I have bought that, years, months, weeks or just days later, I’ve wondered … “Why?”

What they are will remain a closely guarded secret 😉

The Goldilocks principle

The Goldilocks principle refers to the concept of “just the right amount” of whatever is being considered.

In this case, honey bee colonies.

Beekeeping is a fascinating pastime. During the season – say April to September – there’s lots to keep you occupied and lots to keep your interest.

These are not always the same thing.

Weekly inspections for a start. Swarm prevention as the season properly gears up. Queen rearing. Swarms. Harvesting the early season honey. Possibly more swarms. The summer honey harvest. Autumn Varroa management. Uniting colonies and preparing colonies for winter.

Mid-April in the apiary ...

Mid-April in the apiary …

It’s quieter in the winter, but there’s still lots to do. Preparation for the coming season. Bottling and selling honey. Making equipment. Scouting new out apiaries. Buying more equipment. Midwinter Varroa treatment 1. Fondant top-ups for underweight colonies. Cleansing and sterilising equipment.

And all of the above needs to be done for every colony you have.

One is not enough

I’ve previously written of the importance of managing more than one colony.

The comparison is invaluable. Is the colony you’re worrying about really doing badly, or is it just that there’s a dearth of nectar and all colonies are struggling at the moment?

In addition, if there really are problems with one colony – queenlessness or bad temper for example – you can ‘rescue’ them by taking appropriate action and a frame of eggs from your other colony. Or you can unite the colonies if it’s too late in the season to rear another queen. Frankly, it’s a no brainer …

Two National hives and Himalayan balsam

Two will do …

Logically, the amount of work involved in managing two colonies is double that of one colony.

Except, it isn’t.

Quite a bit of beekeeping is preparation and clearing up afterwards. For example, travelling to and from the apiary, preparing syrup, lighting the smoker, cleaning the extractor and so on. Most of these tasks take little or no more time if you’re dealing with two colonies rather than one.

The actual inspections may take twice the time, but that’s about it.

Even then, you’ll be getting twice the practice when you do inspect, so you’ll probably get more efficient, faster, with two colonies rather than one. At the risk of repeating myself, it’s a no brainer.

From too few to more than enough

Beginners often struggle in their early years of beekeeping 2. Sometimes they have too few bees in the hive. The colonies are weaker than they should be to exploit the forage or to overwinter successfully. Or they lose queens during the season, suffer an extended broodless period, and need to beg or borrow a queen from elsewhere to keep the colony together. It all looked so easy in the books or in that midwinter theory course.

Except, it isn’t.

But, assuming they don’t give up, all this time they’re gaining valuable experience – week by week, month by month and year by year.

And then they pass some sort of invisible inflexion point in their beekeeping ‘career’. This is the point after which they will always have enough bees. Their colony management skills are now good enough to keep large, prolific hives. These crowded colonies necessitate careful swarm prevention and control. Colony numbers can be increased easily.

Six poly nucleus colonies on hive stands

Lots of poly nucs …

From having too few bees they can now rapidly reach the point of having too many. They learn how easy it is to make increase 3 using a well-timed vertical split of a vigorous, healthy colony, or by not reuniting after using the Pagden method for swarm control.

And then they learn to graft, to use mini-nucs, to overwinter 5 frame nucs and – before you know it – they’ve bought a truck 🙂

But is (many) more than two, too many?

And then, at some point, sooner or later, it can become a bit of a chore.

In my experience the swarm season and extremes of weather are the two most testing periods.

During the peak swarming period – mid/late May to mid-June here, but earlier further South – beekeeping can be a ‘full-on’ experience. Timing is critical. Miss a late open queen cell and they’ll swarm on the next available good day. You’ll run out of equipment. You’ll get phone calls in the office asking you to retrieve a swarm from a tree/swing/classroom 4.

And, at the same time you’re coping with all this, it’s also the best time of the year to rear queens.

Your agenda and that of your bees is partially overlapping, but almost certainly not in sync.

And then there’s the weather  … we live in a country where the weather report regularly uses the phrase ‘mainly dry’. Without specifically saying it, this means it will be wet. Almost certainly on the day you need to do your inspections, move the grafted larvae, collect a swarm and feed the mini-nucs. Too many bees and bad weather are a testing combination.

Mainly dry ...

Mainly dry …

But so are too many bees and spectacularly good weather.

Beekeeping is considered a gentle and relaxing pastime. The reality, on a bright sunny day with the temperature reaching 29°C, with full honey supers to remove is rather different. It is physically demanding and exhausting work. In a beesuit and veil you will sweat buckets. Literally. I’ve had to work so hard I could pour out the sweat that had pooled in my boots.

The pain will soon be forgotten, but there will be pain.

The Goldilocks zone

But somewhere between the too few and the too many (colonies) is the sweet spot. Enough that you can experience the wonderful and fascinating variation possible in bees and beekeeping. Sufficient to engage you and allow you to experiment and try new strategies out. Enough to cope with poor seasons and still to produce some lovely honey to give to the family at Christmas and to friends at dinner parties.

The sweet spot ...

The sweet spot …

This is the Goldilocks zone.

Quite where that sweet spot is will depend upon a whole host of different factors. Your interest in bees vs. other competing hobbies and pastimes 5, how full-time the full-time job is, your abilities as a beekeeper and the pressure others 6 put on you to take holidays mid-season 😉

It might be two colonies. Not ‘just’ two, with the sort of dismissive implication that that’s not what being a real beekeeper is. There are some outstanding beekeepers I know who have a couple of colonies in a good area for forage and who consistently produce spectacular honey yields per colony. They are excellent observers, skilled practitioners and really understand what’s happening in their colonies at all times of the season.

Or it might be 200 … in which case you’ve got a stronger back and a bigger truck than me 🙂

For me it’s about a dozen. I can produce enough honey to sell or give away and still have sufficient colonies to dabble or experiment with. Not ‘experiment’ as in my day job (I have more hives for that), but to investigate different ways of improving my stock, alternative approaches to queen rearing and introduction, other types of mite control etc.

Cell bar frame with three day old queen cells, The Apiarist.

3 day old queen cells …

Not all these experiments work. Some are an unmitigated disaster, others are no better than the way I previously did whatever ‘it’ was.

Have you used a Taranov board? Me neither. But I’d like to this season.

Space and spares

The Goldilocks principle can also be applied to having ‘just the right amount’ of equipment and space to manage your chosen number of colonies. This includes, but isn’t restricted to, apiaries, brood boxes, supers, split boards, crownboards, stands, clearers, hive tools, more supers, dummy boards, roofs, frames, more frames, yet more frames etc.

I’ve never met a beekeeper who has managed to achieve this 😉


Colophon

Goldilocks and the three bears fairy tale book cover

Look who is sleeping in my bed!

The Goldilocks principle is named after the well-known 19th Century fairy tale Goldilocks and the Three Bears in which Goldilocks, a little girl, always chooses the ‘just right’ option – of bed, porridge, chair etc. when lost in the forest and finding a house owned by three bears. In each case the ‘just right’ option is the one in the middle e.g. the bowl of porridge that was not too hot, or too cold, but was just right. Goldilocks, the little girl, was introduced in a variant of the original tale “The Story of the Three Bears” in place of a cantankerous, foul-mouthed old woman. Perhaps unsurprisingly, she was preferred by the target audience 😉

The Goldilocks zone has a  specific meaning in astronomy where it indicates the habitable zone around a star. This is defined as the range of orbits within which liquid water could occur if there is sufficient atmospheric pressure.

 

Keeping things ship shape

Thorne’s still list generic oxalic acid, but you have to search for it rather than drilling down through the Health & Feeding … Varroa sub-menus which only now list proprietary products. They also still list the pre-made solution at the recommended 3.2% strength for mid-winter trickling, but remember that this has a limited shelf-life. You’ll be pleased to know that this is my final post on this topic for a bit … 😉

Alternative sources and alternative uses

If you’re wondering where to purchase oxalic acid to keep the wooden decks of your dinghy, motor launch or even your local association yacht looking sparkling clean and ship shape (pun intended) you could do a lot worse than look at Darrant Chemicals. Small, medium and large quantities of 99.6% pure oxalic acid dihydrate are available at very reasonable prices with blisteringly quick delivery.

Here's one I prepared earlier ...

Here’s one I prepared earlier …

25kg of oxalic acid is less than £50 delivered to mainland UK*, enough for even the largest association (yacht). They also sell via eBay (as solvent-shop) but it’s cheaper to deal direct.

You may already know this company as a source of chemicals for your beekeeping, rather than yachting, needs. For example, they also sell acetic acid which is ideal for fumigating brood and super comb in late autumn or winter, killing Nosema spores, chalkbrood and wax moth (as described in this PDF from the National Bee Unit). Both acetic acid for sterilising comb and oxalic acid for scrubbing decks must be used with care.

I’m sure there are other suppliers (perhaps even your local yacht chandlers?) and they might even be cheaper, but I’ve purchased from Darrant and been pleased with the service.


* of course, if you made the mistake of purchasing a similar quantity of Api-Bioxal (a VMD-registered miticide, 88.4% of which is oxalic acid) to clean the decks of your motor launch it would cost more than £5300 😉

Miticide cost effectiveness

There goes a few pence ...

There goes a few pence …

My recent comments on the cost of Api-Bioxal prompted me to look in a little more detail at the cost of miticides routinely available to beekeepers. The figures quoted below are the best prices listed by one of three leading beekeeping suppliers in the UK (E.M. Thorne, Maisemore’s and C. Wynne Jones – there are lots of other suppliers, but I’ve used these three and been satisfied with their service). I made the following assumptions: the beekeeper is purchasing sufficient to treat three single-brooded full colonies for three years (i.e. something with a reasonable shelf-life) with as little left over as possible. Costs per colony treatment were calculated for 9 colonies (3 x 3 years) only … any ‘spare’ can therefore be considered as free. This means that for Apiguard, available in packs of ten trays (5 colony treatments) or a 3kg tub (30 colonies), the cost is calculated per colony from two packs of 10 trays as a full course of treatment for one colony requires two trays. Obviously, buying in bulk – for example through a co-operative purchasing scheme in your beekeeping association – should reduce these costs significantly. No postage costs were included.

Apiguard – two boxes of 10 trays (C. Wynne Jones) = £41 = £4.55/colony

Apistan – two packs of 10 strips (C. Wynne Jones) = £41 = £4.55/colony

MAQS – one 10 dose tub (all suppliers) = £57.60 = £6.40/colony

Api-Bioxal – one 35g sachet (C. Wynne Jones) = £8.20 = £0.91/colony

Oxalic acid (OA) crystals – one 300g tub (Maisemore’s) = £4.32 = £0.48/colony

Note that this simplistic comparison hides a number details.

  1. These various treatments should be broadly similar in their efficacy (see below) in reducing the mite population, but must be used according to the manufacturers instructions for maximum efficiency. Under optimal conditions all quote at least 90% reduction in mite levels. However, Apistan (and Bayvarol, not listed) is pyrethroid-based and resistant mite populations are very widespread. In the presence of totally or partially resistant mites, Apistan will be of little or no benefit. Interestingly, Apistan resistance (which, like resistance to pyrethroids in other species, is due to a single amino acid substitution, so readily selected) appears to be detrimental to the mite in the absence of selection. This means that it may be possible to use Apistan effectively every 3-5 years as part of an integrated pest management as long as other beekeepers in the area follow the same regime. During the years Apistan is not used the pyrethroid-resistant mites should reduce in number, so restoring the efficacy of the treatment. I’m not aware that this idea has been properly tested, but it might be worth investigating.
  2. Only the first four treatments are approved for use in the UK by the VMD.
  3. Both the oxalic acid-containing treatments – Api-Bioxal and OA crystals – require preparation before use, or specialised equipment for delivery. OA vaporisation (sublimation) also necessitates both care and personal protection equipment to prevent exposure to the chemical which is a lung irritant. The costs indicated do not include these additional requirements.
  4. The treatments are not equivalent or necessarily interchangeable. For example, a) only MAQS should be used when honey supers are present, b) Apiguard is moved around the hive by active bees, so treatment is recommended when average daytime temperatures are above 15ºC , and c) there are reports on discussion forums of repeated OA vaporisation treatment – 3 at 5 day intervals – for colonies with brood present. The costs indicated above assume a single treatment (in midwinter or of a swarm/shook swarm in the case of OA) with any of the listed compounds.
  5. Finally, the ‘excess’ amount spare after treating the colonies over three years differs significantly. The first four have sufficient left over for one further treatment. The OA crystals will have enough left over for a further 190 colonies … and buying a 300g tub is probably about the most expensive way to purchase OA per gram 🙂

Bang for your buck

As indicated above, all of the Varroa treatments listed should give 90+% knockdown in mite numbers if used properly. This means following the manufacturers’ instructions – in terms of dose, time and duration of application. A key point to remember is that the mite is only susceptible when outside the capped cell and that 80% or more of the Varroa in a colony at any one time will be inside capped cells if there is brood present. For this reason, it is preferable to treat during natural (or induced e.g. a shook swarm) broodless periods. It has even been suggested that the midwinter OA treatment should be preceded by destruction of any brood present. Although this makes sense, I can understand why some beekeepers might be reluctant to open a colony to destroy brood in the middle of winter. There have been numerous reviews of individual and comparative efficacy of the various Varroa treatments – for example this well-referenced article on mite treatment in New Zealand from 2008. If used properly there’s little to choose between them in terms of efficacy, so the choice should be made on the grounds of suitability, convenience and cost.

‘Suitability’ is a bit of a catch-all, but requires you broadly understand how and when the treatment works – for example, Apistan is a pyrethroid so works well against sensitive mites, but is pretty-much useless against resistant populations, and resistance is widespread in the UK. ‘Convenience’ is generally high in the ready-prepared commercial treatments – it takes seconds to insert a tray of Apiguard – and much lower if the compound has to be prepared or you have to get dolled up in protective gear. In this regard, the absence of a pre-mixed liquid version of Api-Bioxal is a disappointment. Thorne’s still supply (at the time of writing) Trickle 2, a very convenient pre-mixed 3.2% w/v OA treatment for mid-winter trickling, but for how much longer? Similarly, the gloves, mask, goggles and power needed to treat a colony by OA sublimation makes it far from convenient for a single treatment.

Closing thought …

1 lb jar of honey

1 lb jar of honey …

Despite the great differences between the cost/treatment/colony it’s worth noting that even the most expensive is not a lot more than the price of a 1 lb jar of top quality local honey … just like the stuff your bees produce 😉 So, in the overall scheme of things, Varroa treatment is relatively inexpensive and very important to maintain colony health and to reduce overwintering colony losses.

See also Managing Varroa (PDF) published by the Animal and Plant Health Agency