Small, but perfectly formed

We’re in the hiatus between the end of the beekeeping season and the start of the beginning of the planning for the preparation for the next. Or, I am.

Of course, if you’re reading this from Australia (G’day … the 5th largest readership globally) or Chile (Hola … 62nd in the list) then things are probably just getting really busy.

Inevitably things here are going to be a bit quiet for a few months. Have patience.

Getting ready for winter

Here in the Northern hemisphere, at a latitude of about 56°N, the nights are rapidly getting longer and the temperature is tumbling. We’ve had several sharp frosts already. I checked my bees yesterday through the perspex crownboards – where present – and most were pretty tightly huddled together. In the very warmest part of the day there were a few flying in the weak sunshine, but the majority of colonies were quiet.

Since many of the most recent posts have been rather long (and I’m pressed for time with work commitments) I’m going to restrict myself to a few brief comments about this tidy – and tiny – little hive tool from Thorne’s.

Pocket hive tool

Pocket hive tool

One of the final tasks of the year is to slice off the brace comb built in places along the tops of the frames while feeding colonies. I only use fondant, usually adding 12.5 kg to start with and then a further few kilograms if I think the hive is a bit light. All this fits nicely under one of my inverted, insulated perspex crownboards. However, as the fondant it taken down and stored, the bees tend to build little pinnacles of comb under or around the plastic bag.

Before closing the colony up for the season all these bits of brace comb need to be tidied away. I simply run a sharp hive tool along the top bars of the frames, remove the wax and – eventually – melt it down in my steam wax extractor. If you leave the wax in place you can’t put the crownboard back the right way up … or, when you do, you risk crushing bees.

Bargains in the sales

In the Thorne’s summer sales this year I bought the usual range of stuff I have almost no use for, together with half a dozen of the cheapo copies of their claw hive tool to replace those I’ve lost or lent during the year.

In addition I bought a couple of their ‘pocket hive tools’ (shown above) for a quid each.

These are small and neat, have a simple frame lifter at one end and a very good, sharp, chisel tip at the other. They are made of stainless steel. They fit neatly into the palm of the hand, don’t project too far and yet are enough to provide the leverage to separate all but the most stubbornly propolised frames.

For tidying up the top bars of my hives before closing them up for year this little hive tool was just the job.

‘Pocket hive tool’ is a bit of a misnomer though. It’s certainly small enough to fit into your beesuit pocket, but just about sharp enough it won’t be staying there long. Any serious pressure, for example as you get back into the car/van/truck risks either a nasty injury ( 😯 ) or it will eventually escape through a neatly sliced-through seam.

It might be better to keep it in your bee bag, or – as I do with other hive tools – store it in a bucket of soda in the apiary.


Colophon

The phrase small, but perfectly formed is at least 200 years old. Google Books first lists it in the Gentleman’s Magazine and Historical Chronicle of 1779 (though in those days they used a medial or long ‘s’ so the title was the Gentleman’s Magazine and Hiſtorical Chronicle) where it appears in an article by Mr Rack describing (or deſcribing) a new found aquatic animal. Whether ‘small, but perfectly formed‘ is now an idiom or a cliche is unclear. The usually excellent Brewers Dictionary of Phrase and Fable (2014) defines the idiom as meaning “something noticeably small but compensating for this by a perfection of quality”. Their first reference to the phrase occurs in a letter written in October 1914 by Duff Cooper to Lady Diana Manners, later his wife, and quoted in Artemis Cooper’s Durable Fire (1983): ‘Your two stout lovers frowning at one another across the hearth rug, while your small, but perfectly formed one kept the party in a roar’. The expression was probably not original to Cooper but drawn from the fashionable talk of the period. The usage is often tongue-in-cheek or journalistically formulaic for anything small … which is exactly how I’ve used the term in the title of this post.

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Talk the talk

With the practical season now over we’re entering the period of regular winter beekeeping talks and weekend conventions. For five or six months the closest many of us will get to bees is a draughty church hall with a cup of tea at the end.

And a chocolate digestive biscuit if the Association Secretary has managed to get everyone to pay their subs.

What? No chocolate?

What? No chocolate?

Listening

I enjoy these events. There’s a healthy, competitive camaraderie to the conversations before and after the talk …

How was your season?

80lb? Per colony? Or in total?

Didn’t lose a swarm all season!

… and so on. The old-timers smile knowingly and keep quiet about the best sites, the ‘newbees’ enthusiastically recount the ups and downs of their first season and those on the beginners course this winter simply try and work out what the heck a ‘Demaree’ is.

During the talk the lights are dimmed. We all peer through the gloom at a slightly skewwiff image projected onto the cream-painted wall which has a picture hook irritatingly visible just left of centre.

The old boy in the fifth row falls asleep and starts snoring gently.

Forty-five to fifty minutes flies by, the lights come up and there’s an opportunity for questions. By this time everyone is gasping for a cuppa or the loo, or both, so appreciation is shown “in the usual manner” and the formal part of the evening draws to a close.

Drinking

Tea is brewed, biscuits are scoffed. Now is the time to ask the question you wish you’d asked at the end of the talk – either of the speaker or of the more experienced ‘beek’ (and in my experience there are always more experienced beekeepers at these things) sitting next to you.

Friendships are re-established, new contacts are made, recipes are exchanged and tips and tricks are offered.

The audience breaks up into little groups discussing honey or queen rearing or the upcoming sale at Maisies. People drift away. The Secretary scurries round trying to get the usual suspects to pay the subs that have been due since last January (which is why there weren’t any chocolate digestives). Cups are washed, the library is packed away and the hall locked up.

But it’s not over yet … twos and threes loiter in the car park where the real gossiping occurs. Unless it’s snowing. Who’s been buying in imported colonies or queens for selling on as “local”? How many times has ‘Fred’ recycled that winning jar of clover honey in the show? Which farmers will be growing borage next year?

Ah! That's better

Ah! That’s better

Talking

I enjoy these as well. I usually end up getting invites to present at just about the same number of talks I manage to attend at my own associations each winter. Some are round the corner or pretty local, others are at the other end of the country. I was recently excellently hosted by the Devon BKA (~500 miles away) and presented at a meeting in Chillán (~7500 miles away) of Chilean beekeepers in March.

With the exception of these long-distance trips the process is pretty similar. The satnav is programmed with the venue details. The bag is checked for the laptop and every possible connector that might be needed. A spare copy of the presentation is carried on a memory stick ‘just in case’. The car is loaded with any additional stuff used in the presentation (nothing for a science talk, but lots for talks on practical beekeeping).

I set off later than intended but earlier than needed. There’s almost nothing worse than turning up late. I find the venue, park nearby in the dark, locate the draughty church hall and the Secretary lurking in wait for early arrivers (who haven’t paid their subs yet).

The laptop is set up, the projector checked and the screen/image is levelled as the audience dribbles in. Old friends say hello. The lights are dimmed and we’re off!

The reflection from the screen casts an eerie light across the audience. Faces in the front couple of rows are clear and bright. Those further back are more like a grainy black and white image. Expressions are more difficult to see. Are they still following this? Am I going too fast? Too slow?

Laughing

Oops

Oops …

I chuck in a joke or anecdote to liven things up. That’s better. Or not. My jokes aren’t good.

A particularly pale slide casts a brighter reflection deeper into the crepuscular gloom at the back of the hall.

The old boy in the fifth row who has been gently snoring for the last 15 minutes can now be heard and seen.

I gallop towards the end, thanking the organisers, my research team, those who gave us the money to do the work and the beekeeping associations we’re privileged to be working with.

Mild applause … someone nips out to turn the urn on.

Questions

These are by far and away the best bit. As a speaker it’s how I judge how successful I was at getting the message across.

Questions range from simple and straightforward to long, rambling and exquisitely complicated.

All are welcome.

Not all can be answered.

Simple questions about things I’ve covered, albeit quickly or as a peripheral point, are easy to answer and I make a mental note to deal with the subject better in the future (or avoid it for clarity).

Difficult questions about things I’ve covered may require a longer answer, more thought or a cup of tea. Inevitably, some topics are outside the experience or interest of most of the audience. A detailed explanation of molecular biology (science) or long-winded discussion of grafting tools (queen rearing) needs to be postponed …

Gasping

Gasping …

Let’s discuss that over a cup of tea and a chocolate digestive” … the latter said hopefully.

Questions about things unrelated to my talk are not unusual. Long, rambling and exquisitely convoluted questions about a totally different topic are sometimes asked. There’s a direct relationship between the number of people wanting to ask questions and the length, ramblingness, and distance off-topic of these types of questions.

I usually hope the Association Secretary or Chair steps in at this stage and announces that tea is ready.

Experience

As a scientist I’m used to talking at conferences where the audience ranges from undergraduate students to internationally-renowned Emeritus Professors. As a beekeeper I’m well aware that the audience at Association events may include the full spectrum of experience and abilities … from those on the winter “Introduction to Beekeeping Course” to some who earn a living beekeeping.

I’m also well aware that the old boy in the fifth row who gently snored through my entire talk is probably just knackered having spent whole the day extracting 500 lb of heather honey.

Which is almost, to the ounce, 500 lb more than I got 😉

All he came for was a cup of tea and a chocolate digestive biscuit.

The end

I pack up the cables and the laptop, say my goodbyes, weave my way through the little groups in the car park gossiping about the price of Api-Bioxal or where to buy cheap fondant. I finally locate my car, plug in the satnav, turn up the radio (it’s late and I’ve got a three hour journey ahead) and wend my way home.

By midnight I’m wishing I’d had one less cup of tea and one more chocolate digestive.

Homeward bound ...

Homeward bound …


† I’ll deal with Conventions some other time. These are increasingly popular, often draw big, knowledgeable, audiences and usually have the added distraction of the trade stands.

‡ I’m well aware not all of these talks are held in draughty church halls. I’ve spoken in draughty village halls, draughty sports halls and draughty community centres. I’ve also spoken in some great venues, with excellent AV facilities, comfortable chairs (particularly in the fifth row), really good tea and coffee and some spectacularly tasty home-made cakes (thank you Arran Bee Group!). Whatever the venue, as long as we manage to get the laptop to talk to the projector – and even if we don’t – it’s great to meet enthusiastic beekeepers wanting to ‘talk bees’ on a cold winter night.

Colophon

Someone who can ‘talk the talk‘ speaks convincingly on a specific subject, showing apparent mastery of its jargon and nuances. You often hear it used in conjunction with the phrase ‘walk the walk‘ e.g. He can talk the walk but can he walk the walk?

Walk the walk essentially means to back up the talk with actions. It’s related to expressions like ‘action speaks louder than words’, ‘talk is cheap’ and ‘practice what you preach’. If you can’t ‘walk the walk’ then it’s simply empty bragging … in the UK the phrase ‘all mouth and no trousers’ is another way to say this, though it perhaps has rather sexist overtones.

 

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Being Certan

It’s November and the end of the ‘bee season’ is well and truly here. Inspections finished some time ago (or should have) and the winter Varroa treatments are completed (or should be).

My precious …

Preparation for the coming season should now be the priority. One of the first things that needs to be done is protecting any valuable drawn comb not covered with bees.

Drawn comb is a really precious resource and is well worth looking after carefully. All beekeepers are likely to have super frames of drawn comb after honey extraction. Some will additionally have drawn brood frames. Finally, beekeepers who do a lot of queen rearing may have drawn frames of drone comb. All can be re-used, in the case of super frames many, many times, so saving the bees the effort (and the nectar used) to draw fresh comb.

Super frames

I allow the bees to clean out super frames from which the honey has been extracted. I place them back on the hive in the evening and the bees clean out the traces of honey. After clearing them again I stack them outdoors carefully on a plastic or Correx ‘floor’ and a wasp-proof roof. Sometimes – though not every year due to forgetfulness – I treat them with acetic acid to kill Nosema spores. I’ll discuss this in a future post as I’ll be doing it this season. If I remember.

I’ve got super frames dating back to my first year of beekeeping that are still perfectly usable. Any with odd-shaped comb just get sliced back square to the sidebars with a breadknife.

Any which has had brood reared in it (for example, when the queen sneaks above the excluder, or I’ve run a colony as ‘brood and half’, both increasingly rare events) goes into the steam wax extractor.

Brood frames

Spare brood frames are a great thing to have at hand when making up nucleus colonies, during queen rearing or at a variety of other times. They deserve to be protected and stored properly.

Unless, of course, they’ve had more than about three years of use, in which case they are also usually rendered down in the steam wax extractor. Even these old ones sometimes get a reprieve. I give them one more season as the single frame of old brood comb in my bait hives. These manky old frames should also be treated with acetic acid to kill Nosema spores and protected and stored carefully.

Galleria mellonella and Achroia grisella

Lesser wax moth (12mm)

Lesser wax moth (12mm)

These are respectively the greater and lesser wax moth. They infest stored comb and favour brood comb with old cocoons, traces of pollen and larval faeces. If unchecked they can destroy your valuable comb, converting the lovely wax to a mass of silk-lined tunnels and dust. They much prefer brood comb to super comb and seem to avoid supers stored ‘wet’ i.e. extracted but not subsequently cleaned by the bees.

It’s difficult, but not impossible, to provide moth-proof storage for your comb. They can sneak through a surprisingly narrow gap in the joint of a brood box.

In early copies of Hooper’s Guide to Bees and Honey it was recommended to use paradichloro-benzene (or, more correctly, 1,4-dichlorobenzene) to protect your brood frames from the ravages of wax moths. This is the stuff that makes moth balls stink. It’s pretty unpleasant, potentially neurotoxic (for humans) and not something I want anywhere near my ‘honey for human consumption’ bees.

I’ve not got a current copy of Hooper, so don’t know what is recommended now, but there are much better alternatives.

Biological control

Wax moths lay their eggs in stored frames, the eggs hatch and the larvae (caterpillars) burrow through the wax, eating their way through the old cocoons and other rubbish, creating a huge network of silken tunnels which eventually trash the comb. They then pupate and subsequently emerge as moths to fly off and decimate more stored comb. Little blighters!

It’s the ‘eating’ in the paragraph above that makes them susceptible to biological control with Bacillus thuringiensis.

Bacillus what?

B401 Certan

B401 Certan

Bacillus thuringiensis is a bacterium. During its replication it generates spores and a so-called crystal protein that is lethal to the moth larvae in which it is replicating. I’ll return to the spores later … these are a thermally and environmentally stable form of the bacterium, protected by a thick cell wall. 

The crystal protein (or, more correctly, δ-endotoxin) dissolves in the alkaline environment of the insect gut, thereby making it susceptible to digestion by proteases present in the gut. This protease cleavage releases the active form of the toxin which inserts into the cells of the gut, paralysing the cells and finally resulting in the formation of a pore.

This isn’t good for the moth larva. Not good at all. Actually, it’s probably a rather grisly end for the moth but, having seen the damage they can do to stored comb, my sympathy is rather limited.

However, it’s very good news for the beekeeper. It’s particularly good because of the specificity of the toxin (which is often referred to as Bt-toxin). The vast majority of Bt-toxins used for biological control are specific for the larvae of the lepidoptera – the butterflies and moths. These have no activity against bees or other pollinators.

Since the only moth or butterfly larvae that occur in hives, or on stored comb, are the unwanted wax moths, this is an effective and safe way of preventing infestations.

Preventing, not curing. Once infestation is present the damage is largely done.

Biological control is compatible with organic farming methods, if that’s what floats your boat.

Certan

B401 Certan is the most commonly available and regularly used Bt-toxin for beekeepers. You can buy Certan from the majority of beekeeping suppliers. Certan is supplied in bottles containing the spores or protein toxin of Bacillus thuringiensis subspecies aizawai. You make it up in water and spray it onto both faces of the drawn comb you want to protect from wax moths.

Certan costs about £16 a bottle which is sufficient to treat 120 brood frames (~13p/frame). Certan is used at a 1:20 dilution in water i.e. a 5% solution. Full details are available from Vita Bee Health who are distributors for Certan. There’s a nice video on the Vita site which shows how easy it is to administer.

DiPel DF

DiPel DF

DiPel DF

As an alternative to Certan, some beekeepers use DiPel DF. This contains the kurstaki subspecies of Bacillus thuringiensis. Although a different subspecies, the toxin is equally effective and equally specific. DiPel DF is widely available from agricultural suppliers and costs about £55 for 500g. DiPel DF sourced from Italy is routinely listed on eBay at a much lower price.

Because DiPel DF isn’t specifically sold for beekeepers the recommended dilution to be used isn’t published. However, if you grow tomatoes under cover the recommended dose is 100g per 100 litres of water i.e. a 0.1% solution.

I’ve used DiPel DF at a 1% concentration. I mixed the powder thoroughly 1 part in 20 and then used this stock solution 1:5 to make the working-strength solution to be sprayed onto the frames. About 10 ml per side per frame is used, sprayed with a fine nozzle. At this dilution, DiPel DF costs about 2p per frame … a very considerable saving. It may be equally effective at 0.1% – I’ve not tried – in which case it would obviously be even more economical.

DiPel is listed as non-toxic for bees and it’s certainly effective against wax moth.

A pressurised hand sprayer works well to administer DiPel or Certan. You can usually get these sprayers from big supermarkets for a couple of pounds.

Spores store

The beauty of spores is that they’re very stable. This means you can store them for long periods without them ‘going off’. Neither Certan or DiPel DF make absolutely clear what the bottle contains – sometimes they refer to ‘active protein’, sometimes to ‘toxin’ and sometimes to Bacillus thuringiensis. Some even suggest a mix … Valent BioSciences, the manufacturer of DiPel DF claim that it contains an optimized blend of four potent Bt protein toxins and a spore. They should know. The DF suffix means ‘dry flowable’ by the way.

Whatever is actually in the bottle, it’s pretty stable. If you store the powder in a cool, dry, frost-free location it should be OK for several years. The safety data sheet for Certan states that it remains active for at least 5 years if stored unopened at 5°C or less.

Store frames

The Certan or DiPel-treated frames should be stored, dry, in empty brood or nucleus boxes. These are best stacked outside, protected from rain or being blown over, until they’re needed next season.

Which is a long way off, but slowly getting closer …


Hic!

Hic!

† Certan is also a well known and respected Bordeaux wine from the appellation Pomerol. The full name is Château Certan de May de Certan, which is both a bit of a mouthful and internally redundant. The middle ‘de May’ part of the name is derived from the Demay family, the original owners, who were of Scottish origin and lived in France from the Middle Ages.

Make sure you buy the right Certan … whilst the stuff from Thorne’s is not inexpensive, a 2005 Vieux Château Certan will cost about £360  🙁  However, this is a bargain when compared with a similar aged Petrus (which shares the same clay soil on the right bank of the Gironde) at ten times the price.

Oh yes … these prices are per bottle  😯

The day job

It’s no secret that I have both amateur and professional interests in bees, bee health and beekeeping.

During the weekend I sweat profusely in my beesuit, rushing between my apiaries in Central and Eastern Fife, checking my colonies – about 15 at the autumn census this year – averting swarms, setting up bait hives, queen rearing and carrying bulging supers back for extraction.

Actually, not so much of the latter in 2017  🙁  I did get very wet though, much like all the other beekeepers in Fife.

The BSRC labs

The BSRC labs …

During the week I sit in front of a large computer screen running (or sometimes running to keep up with) a team of researchers studying the biology of viruses in the Biomedical Sciences Research Complex (BSRC) at the University of St. Andrews. Some of these researchers work on the biology and control of honey bee viruses.

During the winter the beekeeping stops, but the research continues unabated. The apiary visits are replaced with trips in the evenings and weekends to beekeeping associations and conventions to talk about our research … or sometimes to talk about beekeeping.

Or both.

This weekend I’m delighted to be speaking at the South Devon Beekeepers Convention in Totnes on the science that underpins rational and practical Varroa control.

Which came first?

I’ve been a virologist my entire academic career, but I’ve only worked on honey bee viruses for about 6 years. I’ve been a beekeeper for about a decade, so the beekeeping preceded working on the viruses of bees.

However, the two are inextricably entwined. Having a reasonable amount of beekeeping experience provides a unique insight into the problems and practicalities of controlling the virus diseases that bees get.

Being able to “talk beekeeping” with beekeepers has been very useful – both for the communication of our results to a wider audience and in influencing the way we approach our research.

Increasingly, the latter is important. Researchers need to address relevant questions, using their detailed understanding of the science to deliver practical solutions to problems1. There’s no point in coming up with a solution if there’s no way it’s implementation is compatible with beekeeping.

Deformed wing virus

DWV symptoms

DWV symptoms

The most important virus for most beekeepers in most years is deformed wing virus (DWV). This virus “does what it says on the tin” because, at high levels, it causes developmental defects in pupae that emerge with shrivelled, stunted wings. There are additional developmental defects which are slightly less obvious, but there are additional (largely invisible) changes which are of greater importance.

DWV reduces the lifespan of worker bees. This is probably not hugely significant in workers destined to live only a few weeks in midsummer. However, the winter bees that get the colony through from September through to March must live for months, not weeks. If these bees are heavily infected with DWV they die at a faster rate. Consequently, the colony dwindles and dies out in midwinter or early Spring. At best, it staggers through to March and then never builds up properly. It’s still effectively a winter loss.

Our research focuses on how Varroa influences the virus population. There’s very good evidence now that DWV transmission by Varroa leads to a significant increase in the amount of virus, and a considerable decrease in the diversity of the virus population.

So what?

Well, this is important because if we want to control the virus (i.e. to reduce DWV-associated disease and colony losses) it must help to know the proper identity of the virus we are trying to control. It will also help us measure how well our control works. We know we’re measuring the right thing.

We’re working with researchers around the world to define the important characteristics of DWV strains that cause disease and, closer to home, with entire beekeeping associations to investigate practical strategies to improve colony health.

Chronic bee paralysis virus

CBPV symptoms

CBPV symptoms

We’re about to start a large collaborative project on the biology and control of chronic bee paralysis virus (CBPV). This virus is becoming a significant problem for many beekeepers and is increasing globally. It’s a particular problem for some bee farmers.

CBPV causes characteristic symptoms of dark, hairless, oily-looking bees that sometimes shiver, dying in large smelly piles at the hive entrance. It typically affects very strong colonies in the middle of the season. It can be devastating. Hives that should be the most productive ones in the apiary fail catastrophically.

Why is a virus we’ve known about for decades apparently increasing in the amount of disease it causes? Are there new virulent strains of the virus circulating? Are there particular beekeeping practices that facilitate it’s spread? We’re working with collaborators in the University of Newcastle to try and address these and related questions.

I’ll write more about CBPV over the next year or so. It won’t be a running dialogue on the research (which would be crushingly dull for most readers), but will provide some background information on what is a really fascinating virus.

At least to a virologist 😉

And perhaps to beekeepers.

Grow your own

As virologists, we approach the disease by studying the virus. Although we maintain an excellent research apiary, we don’t do many experiments in ‘the field’. Almost all the work is done in test tubes in incubators in the laboratory … or in bees we rear in those incubators.

Grow your own

Grow your own …

We can harvest day-old larvae (or even eggs) from a colony and rear them to emergence as adult bees in small plastic dishes in the laboratory. We use an artificial diet of sugar and pollen to do this. It’s time consuming – they need very regular feeding – but it provides a tightly controllable environment in which to do experiments.

Since we can rear the bees, we can therefore easily test the ability of viruses to replicate in the bees. Do all strains of the virus replicate equally well? Do some strains outcompete others? Does the route by which the virus is acquired influence the location(s) in the bee in which the virus replicates? Or the strains it is susceptible to? Or the level of virus that accumulates?

And if our competitors are reading this, the answer to most of those questions is ‘yes’ 😉

We can even ask questions about why and how DWV causes deformed wings.

Again, so what? We suspect that DWV causes deformed wings because it stops the expression of a gene in the bee that’s needed to make ‘good’ wings. If we can identify that gene we might be able to investigate different strains of honey bee for variation in the gene that would render them less susceptible to being ‘turned off’ by DWV. That might be the basis for a selective breeding project.

It’s a simplistic explanation, but it’s this type of molecular interaction that explains susceptibility to a wide range of human, animal and plant diseases.

Bee observant

Bee health is important, and not fundamentally difficult to achieve. There are some basics to attend to … strong hives, good forage, good apiary hygiene etc. However, it primarily requires good powers of observation – does something look odd? Are there lots of mites present? How does the brood look?

If things aren’t right – and often deducing this means comparisons must be made between hives – then many interventions are relatively straightforward.

Not long for this world ...

Not long for this world …

The most widespread problems (though, interestingly, this doesn’t apply to CBPV) are due to high levels of Varroa infestation. There are effective and relatively inexpensive ways to treat these … if they’re used properly.

More correctly, they’re relatively inexpensive whether they’re used properly or not. However, they’re pretty ineffective if not used properly 😉

Regular checks, good record keeping, comparisons between hives and informed observation are what is needed. Don’t just look, instead look for specific things. Can you see bees with overt symptoms of DWV? Are there bees with Varroa riding around on their backs? The photo above has both of these in plain view. Are some hairless bees staggering around the top bars with glossy abdomens, or clinging to the side bars shaking and twitching?

Don’t wait, act

I’ve no doubt that scientists will be able to develop novel treatments to control or prevent virus infections of bees. I would say that … I’m a scientist 😉  However, I’m not sure beekeepers will be able to afford them, or perhaps even want to use them, or that they’d be compatible with honey production or of any use in Warré hives etc.

I’m also not sure how soon these sorts of treatments might become available … so don’t wait.

If there are signs of obvious DWV infection you need to do something. ‘Obvious’ because DWV is always present, but it’s usually harmless or at least tolerated by the bees. My lab have looked at thousands of bees and have yet to find one without detectable levels of DWV. However, healthy bees have only about 1/10,000 the level of DWV present in sick bees … and these are the ones that have obvious symptoms.

I’ve discussed Varroa control elsewhere, and will again.

Unfortunately, if your colony has signs of CBPV disease then Varroa control is not really relevant. The virus is transmitted from bee to bee by direct contact. This probably accounts for the appearance of the disease primarily in very strong colonies.

At the moment there’s little you can do to ‘cure’ a CBPV-afflicted colony. I hope, in 2-3 years we will have a better idea on what interventions might work. We have lots of ideas, but there are a lot of basic questions to be addressed before we can test them.

Field work

Field work

Business and pleasure

The half of my lab that don’t work on bee viruses study fundamental mechanisms of virus replication and evolution. They do this using human viruses, some of which are distant relatives of DWV. They work on human viruses as it’s only these that have excellent model systems to facilitate the types of elegant experiments we try to do. They’re also relatively easy to justify in funding applications, and it allows us to tap into a much bigger pot for funding opportunities (human health R&D costs probably total £2 billion/annum, bees might be £2 million/annum).

And no, my lab don’t get anything like that much per year for our research!

Importantly, the two activities on human and honey bee viruses are related. Our experience with the human viruses related to DWV made us well-qualified to tackle the bee virus. They replicate and evolve in very similar ways, we quantify them in the same way and there may be similarities in some ways we could approach to control them.

And with the bee viruses I can mix business with pleasure. If I’m going to the apiary I’ll get to see and handle bees, despite it being officially “work”. It doesn’t happen as much as I’d like as I’m usually sat behind the computer and all of the ‘bee team’ have been trained to work with bees by the ESBA.

However, at least when I talk to collaborators or to the beekeeping groups we’re fortunate to be working with we – inevitably – talk about bees.

And that’s fun  😀


Several years ago I delivered an enthusiastic and rather science-heavy talk at a Bee Farmers Association meeting. I thought it had gone reasonably well and they were kind enough to say some nice things to me … and then I got the question from the back of the room which went something like “That’s all very well young man … but what have you made NOW that I can put into my hives to make them healthy?”.

I’m sure my answer was a bit woolly. These days the presentation would have had a bit less science and bit more justification. We’ve also made some progress and it’s possible to now discuss practical strategies to rationally control viruses in the hive. It’s not rocket science … though some of the science it’s based on is reasonably fancy.

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Trick(le) and treat

Tools of the trade

Tools of the trade

This is the third and final post on why, with what, when and how to minimise mite levels in colonies in midwinter.

In the first post I explained why midwinter mite treatment makes sense. In the second I described how oxalic acid-containing solutions should be prepared and stored.

Oxalic acid-containing” solutions includes both Api-Bioxal, the VMD approved treatment, and the unadulterated chemical. All three posts focus on trickling or dribbling – I’ve covered sublimation previously and both are essentially equally effective. Sublimation or vaporisation is currently very fashionable … but trickling is simplicity-itself and requires almost no special equipment.

In this post I’ll discuss how to administer the oxalic acid-containing solution.

For readability I’ll use the term OA solution to mean any oxalic acid-containing solution. About 50% of the readers of this site are from outside the UK; local rules may determine what you are or are not allowed to administer to your bees.

Trickling or dribbling

You’ll hear both terms used interchangeably1. The general principle is that you directly administer 5ml of a 3.2% w/v solution of oxalic acid in thin (1:1) syrup per seam of bees in the colony.

Directly‘ because you administer the OA solution to the seam of bees. You don’t count the seams and then simply pour it into the hive. You don’t spread it across the top bars. The idea is that the bees at the top of the seam get coated in the solution and that it dribbles down through the colony, being passed from bee to bee as they feed and groom and move about.

Two seams of bees

Two seams of bees …

During this process any phoretic mites will also get exposed to the oxalic acid. Since mites are readily damaged by the OA solution they fall off and gradually drop out of the bottom of the cluster. Gradually, as it takes a few days for gravity to deliver all the corpses.

You can therefore determine whether mites were present and killed by placing a Varroa tray underneath the open mesh floor of the hive. Note that this doesn’t tell you how effective the treatment has been … for that you’d need to know the mite infestation level before treatment as well.

When to treat

In many ways this is the critical decision. As described previously, maximal benefit occurs when the colony is broodless. Ideally you want an extended cold period late in the calendar year. The colony will cluster tightly and brood rearing will slow down or stop completely.

If the cold period has lasted 2-3 weeks, even better. This will mean that some or all of the brood present will have emerged. The more sealed brood present, the less effective trickling OA solution is as a means of controlling mites.

Choose a calm, cool or cold day. I usually wait for a day with temperatures between 0 and 5°C. Much warmer than that and the cluster starts to break up or the bees are more likely to fly about as the crownboard is lifted. Windy or wet days disturb the bees (at least when you prise the crownboard off), so it’s best to avoid those.

I prefer to treat before the year end, rather than after, if I can. From a few irregular midwinter peeks into the cluster I think queens start laying earlier than most beekeepers think.

It pays to be prepared …

Trickle 2 - £1

Trickle 2 – £1

… Aesop (~620-560BC) was right, though he wasn’t talking about beekeeping. Before treating your colonies there is some preparation needed. Do this properly and it’s a doddle.

Purchase a Trickle 2 container from Thorne’s. These are a measly quid each. You’ll only need one.

Practice with the Trickle 2 container (see below).

Gently warm your pre-prepared OA solution to about 25°C. If you made it up in advance and stored it at 4°C in the fridge this will take an hour or two. The easiest way is to stand the container (preferably thin-walled … I use a well-rinsed milk carton) in a basin of warm water.

Pour the pre-warmed OA solution into a well-labelled vacuum flask. You can buy these from Tesco for £2.50 with a capacity of 1 litre. The aim here is to take everything you need ready-prepared to the apiary so the treatments take the minimum time possible.

Remember that OA is toxic. Label everything carefully, make sure children can’t get near it and don’t use it again for food/drink purposes.

That’s it … you’re ready. You’ll need a hive tool, a bee suit, thin gloves (to protect you from the OA, not the bees), your vacuum flask of OA solution and the Trickle 2 bottle. By all means take your smoker, but you shouldn’t need it.

I’ve got a 5 ml (or 25 ml) syringe … won’t that do?

Yes … but no.

A Trickle 2 bottle holds 100ml of prepared OA solution. It takes two hands to fill the bottle, but only one hand to use it. That 100ml is sufficient for 20 seams of bees i.e. two completely full colonies (assuming an 11 frame National box). In midwinter the colony is unlikely to occupy 10 seams. A Trickle 2 bottle is also pretty accurate, reproducibly dispensing about 4.6-4.8ml of liquid. That’s close enough to 5ml.

In contrast, a syringe also takes two hands to fill (and refill). However, unless it’s a 5ml syringe, it’s difficult to accurately and reproducibly dispense liquid without using two hands. A 5ml syringe gives you the necessary accuracy, but needs refilling for every seam of bees. This takes time … during which the crownboard is off and the colony is getting chilled.

I’ve done both and can assure you that the Trickle 2 bottle is much better. Just buy one. It’s only £1 and it’ll last ages if one of your association members doesn’t borrow it … or doesn’t return it.

How to use a Trickle 2 bottle

  • Remove the cap and fill to the top of the lower chamber with liquid (practice with water).
  • Replace the cap.
  • Hold the bottle with your thumb and fingers on opposite sides of the lower chamber, with the external ‘pipe’ to the upper chamber next to your palm.
  • Undo the spout about a turn.
  • Gently squeeze the lower chamber. Liquid is forced up the pipe into the upper chamber. Hold it against the light to observe this.
  • Once the upper chamber is full, stop squeezing. Excess liquid drains back into the lower chamber.
  • If you are right handed turn the Trickle 2 bottle anti-clockwise2 using your wrist and gently squeeze the bottle to dispense the liquid in the upper chamber from the spout. If you’re left handed you need to turn the bottle clockwise.

And in practice

The single-handed operation for the Trickle 2 container really pays dividends when treating a colony. You can gently prize up one side of the crownboard, hold it in one hand, administer the OA solution to each seam with the other hand and gently lower the crownboard back down … all in less time than it took me to write that.

Like this:

This is a reasonably sized colony being treated in the second week of January 3 years ago. The video is 1’45” long, but the crownboard is only open for about 50 seconds. And I was chatting with Mick Smith off camera, so could have perhaps gone a bit faster if I’d concentrated … 😉

Here’s a more detailed view of treating a small colony:

33 seconds of warmed, acidic goodness to slaughter the mites and give the colony the best possible start to the upcoming season.

Cautions and considerations

Discard any OA solution that’s not been used. Warming it will have raised the HMF levels and this may be toxic for your bees. However, read footnote 3 for another way to avoid HMF buildup3.

Wash everything carefully – the Trickle 2 bottle, the vacuum flask, gloves etc. Since the OA solution was in syrup everything gets sticky and gummed up. Clean stuff up, make sure it’s labelled and not going to be used in the kitchen and put it away until next year.

Oxalic acid kills mites, but it’s also toxic for unsealed brood. This is perhaps unsurprising considering it has a pH of 1 (i.e. very acidic) and ‘naked’ larvae aren’t protected by the tough exoskeleton that adult bees have. This is another reason to treat during a broodless period in midwinter.

In summer, swarms can also be treated with trickled oxalic acid-containing solutions before they have sealed brood. If a swarm arrives in bait hive, let it settle and start drawing comb on the foundationless frames. A day or so later treat it with oxalic acid by trickling. When I’ve done this I usually wait until late afternoon or early evening, so most of the bees are in the box. The colony obviously won’t be clustered, but the principle is the same – 5ml of syrup down each seam. Easy peasy. Effective.

Swarms have a significant mite load, so it’s well worth treating them before they rear brood and give the phoretic mites somewhere to breed.

Finally, it’s often recommended that a colony is only treated once per year with oxalic acid by trickling or dribbling. I’m not sure where this advice originates, but it’s probably wise.

‘Vaping’ vs. trickling

The discussion forums are awash with recommendations to ‘vape’ the colony, rather than trickle. Vaporisation, or more correctly sublimation, is a widely used method and has been in use for two decades. It’s currently very fashionable. I’ll write a more substantial comparison sometime in the future, but the following brief notes might be of interest.

Sublimation can be done repeatedly with brood present (though there’s no peer-reviewed evidence of efficacy) and is both well-tolerated by the colony and is not toxic to unsealed brood. It requires specialised and potentially expensive equipment, both for delivery and personal protection. You can build your own vaporiser, but shouldn’t skimp on protection for the operator. With a well designed vaporiser and hive there’s no need to open the colony to administer treatment.

In contrast, trickling requires only the Trickle 2 bottle and vacuum flask described here. Personal protection is a pair of latex gloves. It should only be conducted when the colony is broodless, should probably only be conducted once and does require the hive to be opened (albeit briefly).

You’ll be told that vaporisation is faster. It isn’t. Watch the videos above. Even my Sublimox – probably the fastest ‘active’ vaporiser on the market – takes well over a minute per colony if you take into account sealing the box, moving the generator about, unsealing the hive etc.

There are reports that sublimation is more effective, but the difference is marginal, and possibly not statistically significant. There is also a report that colonies are stronger in the Spring after sublimation, though this may be due to toxicity to open brood by trickled OA solution. If the colony is broodless this shouldn’t be an issue.

I’ve used both many, many times without a problem. Across the UK I suspect more beekeepers trickle OA, rather than ‘vape’ (a word I dislike), though the vocal ones on the discussion forums currently favour vaporisation.

What’s more important than how you deliver the oxalic acid, is that you do treat. Trickling OA solution is so easy and inexpensive that there’s no reason not to … and your colonies will be much healthier for it.

Get dribbling 😉


If the beekeeper is of a certain age you’ll hear these terms used in a different context. We’re restricting discussions here to delivering OA 😉

If you are left handed you need to turn the Trickle 2 bottle clockwise. Actually, to be pedantic, if you are left handed and holding the bottle in your left hand, turn it clockwise. It’ll make sense once you try.

3 In the previous article on preparing oxalic acid solutions Calum posted a comment on preparing the OA in water and only adding and dissolving the required amount of sugar just before use. This has the advantage that there will be no HMF buildup. OA solution in water should be perfectly stable. I’ve not done it this way, but it makes sense and might be worth trying.

Colophon

The title of this article is a twist on the term Trick or treat. This is not entirely inappropriate as Trick or treating is a Halloween (31st October … just a few days away) custom dating back – in various forms – centuries.

The modern usage, essentially North American, dates back to the 1920’s and refers to children in costumes going house to house threatening to play a trick unless the homeowner provides a treat, usually sweets or toys. In Britain these traditions date back to the 16th Century, both of children going house-to-house asking for food and of dressing up in costumes at Halloween.

Closer to home, ‘guising‘ – children in Scotland going from door to door in disguise asking for food, coins or chocolate  – dates back at least a century.

The term Trick or treat only entered common usage in the UK in the 1980’s.

 

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Oxalic acid preparation

This is the second of three articles on midwinter treatment of colonies with oxalic acid to minimise Varroa levels. In a recent post I explained why a midwinter treatment was necessary, even if you’d treated three months earlier. Essentially this is because:

  • there will still be some residual Varroa, particularly if you treated in late summer rather than early autumn (and this post explains why early treatment is preferable)
  • midwinter is the time when brood levels are at a minimum, so most mites will be phoretic and readily accessible to the miticide treatment

Midwinter is the time to use oxalic acid-containing treatments. It can be delivered in a variety of ways; by sublimation (vaporisation), spraying or trickling (dribbling).

Trickling or dribbling

This post is about the preparation and storage of oxalic acid-containing solutions for trickling. Sublimation is covered elsewhere and spraying is not approved or widely used in the UK.

The process for trickling is very straightforward. You simply trickle a specific strength oxalic acid solution in thin syrup over the bees in the hive. The oxalic acid kills the mites. How isn’t entirely clear – it’s thought to corrode the mouthparts and soft tissue. It’s more than 90% effective in killing phoretic mites when used like this.

Beekeepers have used oxalic acid for years as a ‘hive cleaner’, as recommended by the BBKA and a range of other official and semi-official organisations. All that changed when Api-Bioxal was licensed for use by the Veterinary Medicines Directorate (VMD).

Oxalic acid and Api-Bioxal, the same but different

Spot the difference ...

Spot the difference …

Api-Bioxal is the VMD-approved oxalic acid-containing miticide. It is widely available, relatively inexpensive (when compared to other VMD-approved miticides) and very easy to use.

It’s very expensive when compared to oxalic acid purchased in bulk.

Both work equally well as both contain exactly the same active ingredient. Oxalic acid.

Api-Bioxal has other stuff in it (meaning the oxalic acid content is a fraction below 90% by weight) which actually makes it much less suitable for sublimation.

How much and how strong?

To trickle or dribble oxalic acid-containing solutions you’ll need to prepare it at home, store it appropriately and administer it correctly.

I’ll deal with how it is administered next time. This is all about preparation.

The how much is easy. You’ll need 5ml of oxalic acid-containing solution per seam of bees. In midwinter the colony will be reasonably well clustered and its likely there will be a maximum of only 8 or 9 seams of bees, even in a very strong colony.

Hold on … what’s a seam of bees?

Two seams of bees

Two seams of bees …

Looking down on the colony from above, a seam of bees is the row visible between the top bars of the frames.

Remember to prepare ~10% more than you think you need. You’ll inevitably spill some when using the Trickle 2 bottle to administer it to the colony. It’s not that expensive, so don’t risk running out.

And the how strong? The recommended concentration to use oxalic acid at in the UK has – for many years – been 3.2% w/v (weight per volume) in 1:1 syrup. This is less concentrated than is recommended in continental Europe (see comments below on Api-Bioxal).

My advice – as it’s the only concentration I’ve used – is to stick to 3.2%.

Listen very carefully, I shall say zis only once

A bit of basic chemistry coming up. Skip to the warning in red below and then the recipes if you want, but this explains some important things about working out how much to use.

The molecular formula of oxalic acid is C2H2O4. The molecular weight of oxalic acid is 90.03 g/mol. However, the oxalic acid you purchase – including Api-Bioxal – is the dihydrated form of oxalic acid.

Di as in two, hydrated as in water.

The molecular formula of oxalic acid dihydrate is C2H2O4.2H2O and oxalic acid dihydrate has a molecular weight of 126.07 g/mol.

Therefore the weight of oxalic acid in 1 g of oxalic acid dihydrate is 90.03/126.07 = 0.714 g.

Caution

Oxalic acid is toxic

  • The lethal dose for humans is reported to be between 15 and 30 g. It causes kidney failure due to precipitation of solid calcium oxalate.
  • Clean up spills of powder or solution immediately.
  • Take care not to inhale the powder.
  • Store in a clearly labelled container out of reach of children.
  • Wear gloves.
  • Do not use containers or utensils you use for food preparation. A carefully rinsed plastic milk bottle, very clearly labelled, is a good way to store the solution prior to use.

Recipes : oxalic acid

The standard recipe is 100 g water plus 100 g white granulated sugar. Mix well and then add 7.5 g of oxalic acid. The final volume will be 167ml i.e. sufficient to treat over 30 seams of bees, or between 3 and 4 strong colonies (including the 10% ‘just in case’).

This final concentration is 3.2% w/v oxalic acid … (7.5 * 0.714)/167 * 100 = 3.2. Check my maths.

0.01 g to 500 g

0.01 g to 500 g

If you have more colonies to treat, or have trouble weighing 7.5g, scale everything up ten-fold. Or buy a small, accurate set of digital scales – like these for £9 which work very well. 1 kg of sugar plus 1 kg (1 litre) of water requires 75 g of oxalic acid and makes 1.67 litres … enough to treat all the colonies in the association apiary.

Which is not such a bad idea. Make it up carefully once and share it with your fellow beekeepers. Storage details are provided below.

Recipes : Api-Bioxal

Warning – the recipe on the side of a packet of Api-Bioxal makes up a much stronger solution (4.4% w/v) of oxalic acid than has historically been used in the UK. Stronger isn’t necessarily better. The recipe provided is 35 g Api-Bioxal to 500 ml of 1:1 syrup. By my calculations this recipe makes sufficient solution at a concentration of 4.4% w/v to treat 11 hives. 

To make a 3.2% Api-Bioxal-based oxalic acid-containing solution using the 35 g pack of Api-Bioxal you need to mix the entire contents of the pack with 691 ml of 1:1 syrup.

Here’s the maths:

  • 35 g of Api-Bioxal contains only 22.14 g of oxalic acid. 88.6% of the 35 g is oxalic acid dihydrate (the remainder is cutting agents like glucose and powdered silica) and so the oxalic acid content is ((35 * 0.886) * 0.714) = 22.14 g.
  • To calculate the volume of syrup you need to divide it by the final percentage required i.e. (22.14 / (3.2/100)) = 691 ml. I don’t know the exact amount of sugar and water needed to make this amount … it’ll be about 430 g of each (I think).

A 35 g packet of Api-Bioxal is therefore sufficient to treat about 15 colonies (assuming 5 ml per seam, 8 seams per hive and 10% ‘just in case’) at the recommended concentration of 3.2% w/v.

Api-Bioxal is sold in three pack sizes (35 g, 175 g and 350 g). If you are wealthy enough to be able to purchase the larger pack sizes you’ve probably got your own beekeeper (or mathematician). Relax on your yacht while they do the calculations for you 😉

On the other hand … if you have a smaller number of colonies either make a full 35 g packet up and share it, or use accurate scales and the following table:

Api-Bioxal recipes for 3.2% OA trickling

Api-Bioxal recipes for 3.2% OA trickling

Storage

Storage of oxalic acid syrup at ambient temperatures rapidly results in the acid-mediated breakdown of sugars (particularly fructose) to generate hydroxymethylfurfural (HMF). As this happens the colour of the oxalic acid-containing solution darkens significantly.

This breakdown happens whether you use oxalic acid or Api-Bioxal.

Stored OA solution and colour change

Stored OA solution and colour change …

HMF is toxic to honey bees at high concentrations. Studies from ~40 years ago showed that HMF concentrations below 30 mg/l were safe, but above 150 mg/l were toxic1. HMF buildup is one way overheated honey is detected.

At 15°C HMF levels in OA solution can reach 150 mg/l in a little over a week. At room temperature this happens much faster, with HMF levels exceeding 150 mg/l in only 2-3 days. In the dark HMF levels build up slightly less quickly … but only slightly 2,3.

Only make up OA solutions when you need them.

If you must store your oxalic acid-containing syrup for any length of time it should be in the fridge (4°C). Under these conditions HMF levels remain well below toxic levels for at least one year. However, don’t store it for this long … use it and discard the excess. Don’t use discoloured oxalic acid solutions as they’ve been stored incorrectly and may well harm your bees.

Please re-read the comments above about the toxicity of oxalic acid. If you are going to store it in the fridge it must be very clearly labelled and there must be no chance that children can reach or open the container.

Conclusions

Api-Bioxal is the least expensive VMD-approved miticide and powdered oxalic acid is much, much cheaper. Both contain the same active ingredient, oxalic acid, which is highly effective against phoretic mites.

In midwinter, with very low levels (or no) of brood, a single oxalic acid-containing treatment minimises mite levels for the coming season.

Oxalic acid-containing solutions are easy to prepare. I recommend you make sufficient for your own colonies and those of your beekeeping friends and association members. My previous BKA used to distribute litres of the stuff for use in midwinter. Use this solution in midwinter and then discard any that is unused.

Oxalic acid-containing solutions are inexpensive and easy to administer by trickling. As I shall demonstrate next time.

Please re-read the safety instructions highlighted in red above.


Michelle Dubois

Michelle Dubois

† Listen very carefully, I shall say zis only once was a catchphrase used by “Michelle of the Resistance” in the 1980’s comedy ‘Allo ‘Allo! Michelle (Dubois) was rarely seen without a trench coat and beret, had a corny French accent and was played by Kirsten Cooke.

‘Allo ‘Allo! ran for 85 episodes in the decade from 1982 on BBC one. It was about a café in Nazi-occupied France and the French Resistance, just about. It mixed bawdy humour with gross stereotypes (posh British twits, sex-obsessed French) and was a parody of ITV’s series Secret Army (’77-’79).

Early episodes had obvious and rather dull titles. In the later series the individual episodes had some quite good puns like Awful Wedded Wife.

Michelle – Listen very carefully, I shall say zis only once

René – Well, in that case, could you please speak slowly?

You had to be there … 😉

‡ Oh alright then, since you insist. The 175 g pack of Api-Bioxal (~£39) needs to be made up in 3.459 litres of 1:1 syrup and the 350 g pack (~£65) 6.919 litres of 1:1 syrup. Determining how much water and sugar to mix to make these amount is, as they say, an exercise for the reader. Assuming a 3.2% solution and 8 seams of bees per colony Api-Bioxal costs between 63p and 41p per hive (see note below), depending upon the pack size you purchase. I know that beekeepers moan on and on about the outrageous cost of Api-Bioxal (as do I), but is 63p per colony really an unreasonable amount to spend on VMD-approved medicines to keep your colony as clear of Varroa as possible? I don’t think so.

Note – the costs in the paragraph were calculated using the lowest prices I could currently find for Api-Bioxal. C Wynne Jones has the 35g packets for £9.50 and Maisemores have the 350g packets for £64.79. Prices correct on 9/10/17.

1 Jachimowich T., El Sherbiny G., Zur Problematik der verwendung von Invertzucker für die Bienenfüttering, Apidologie 6 (1975) 121-143.

2 Bogdanov S., Kilchenman V., Chamere J.D.. Imdorf A. (2001) available online.

3 Prandin, L., Dainese, N. , Girardi, B., Damolin, O., Piro, R., Mutinelli, F. A scientific note on long- term stability of a home-made oxalic acid water sugar solution for controlling varroosis Apidologie, 32:) 451-452

 

Kick ’em when they’re down

Out, damn'd mite ...

Out, damn’d mite …

Why bother treating colonies in midwinter to reduce Varroa infestation? After all, you probably treated them with Apiguard or Apivar (or possibly even Apistan) in late summer or early autumn.

Is there any need to treat again in midwinter?

Yes. To cut a long story short, there are basically two reasons why a midwinter mite treatment almost always makes sense:

  1. Mites will be present. In addition, they’ll be present at a level higher than the minimum level achievable, particularly if you last treated your colonies in late summer, rather than early autumn.
  2. The majority of mites will be phoretic, rather than hiding away in sealed brood. They’re therefore easy to target.

I’ll deal with these in reverse order …

Know your enemy

DWV symptoms

DWV symptoms

The ectoparasite Varroa feeds on honey bee pupae and, while doing so, transmits viruses (in particular DWV) that can completely mess up the development of the adult bee. Varroa cannot replicate anywhere other than on developing pupae. It’s replication cycle, and the resulting mite levels in the colony, are therefore tightly linked to the numbers and availability of hosts … honey bee pupae.

If developing brood is available the mite can replicate. Under these conditions, newly emerged adult, mated, female Varroa spend a few days as phoretic mites, riding around the colony on young bees. They then select a cell with a late-stage larvae in, enter the cell and wait until pupation occurs. If developing worker brood is available each infested cell produces 1 – 2 new mites (drone cells produce 3+) and mite numbers increase very rapidly in the colony.

In contrast, if there’s no developing brood available, the mites have to hang around waiting for brood to become available. They do this as phoretic mites and can remain like this for weeks or months if necessary.

Therefore, when brood is in abundance and the queen in laying freely mites can replicate to very high levels. In contrast, when brood is limiting and the queen has reduced her egg laying to a   v  e  r  y     s  l  o  w     r  a  t  e     the mite cannot replicate and must be predominantly phoretic.

When does this happen?

Lay Lady Lay … or don’t

Ambient temperature, day length and the availability of nectar and pollen likely influence whether the queen lays eggs. When it’s cold, dark and there’s little or no pollen or nectar coming into the hive the queen slows down, or even stops, laying eggs.

About 8 days after she stops laying there will be no more unsealed brood in the colony. About 13 days after that all the sealed brood will have emerged (along with any Varroa). Therefore, after an extended cold period in midwinter, the colony will have the lowest level of sealed brood … and the highest proportion of the mite population will be phoretic.

Under normal (midsummer) circumstances about 10% of the mite population is phoretic. It’s probably unnecessary to state that, if there’s no brood available, 100% of the mites must be phoretic.

All licensed miticides work extremely well against phoretic mites.

Caveats, guesstimates, global warming and the Gulf Stream

Global warming

Global warming …

Whatever the cause, the globe is warming (irrespective of what Donald Trump tweets). Long, hard winters are getting less common (or perhaps even rarer, as they were never particularly common in the UK). In Central, Southern or Eastern Britain it’s possible that the colony will have some brood present all year. In parts of the West, warmed by the Gulf Stream, I’d be surprised if a colony was ever broodless. Only in the North is it likely that there will be a brood break in midwinter.

Most of the paragraph above is semi-informed guesswork. I don’t think anyone has systematically analysed colonies in the winter for the presence of sealed brood. Sure, many (including me) have opened colonies for a quick peek. Others will have peered intently at the Varroa board to search for shredded wax cappings that indicate emerging brood. The presence of brood will vary according to environmental conditions and the genetics of the bees, so it’s not possible to be dogmatic about these things.

However, it’s safe to say that in midwinter, sealed brood – within which the mites can escape decimation by miticides – is at a minimal level.

Reducing mite levels and minimal mite levels

Within reason, the earlier you apply late summer miticides, the better you protect the all-important overwintering bees from the ravages of viruses, particularly deformed wing virus. This is explained in excruciating detail in a previous post, so I won’t repeat the text here.

However, I will re-present the graph that illustrates the modelled (using BEEHAVE) mite levels.

Time of treatment and mite numbers

Time of treatment and mite numbers

The gold arrow (days 240-300 i.e. September and October) indicates when the winter bees are being reared. These are the bees that need to be protected from mites (and their viruses). Mite numbers (starting with just 20 in the hive on day zero) are indicated by the solid coloured lines. The blue, black, red, cyan and green lines indicate modelled mite numbers when the colony is treated with a miticide (95% effective) in mid-July, August, September, October or November respectively.

The earlier you treat, the lower the mite levels are when the winter bees are being reared. Study the blue and black lines.

This is a good thing.

In contrast, by treating very late (the cyan and green lines) the highest mite numbers of the season occur at the same time as the winter bees are being reared. A bad thing.

But … look also at mite numbers after treatment

Look carefully at the mite numbers predicted to remain at the end of the year. Early treatment leaves higher mite levels at the start of the following year.

This is simply because mites escaping the treatment at the end of summer have had an opportunity to reproduce during the late autumn.

This is why the additional midwinter treatment is beneficial … it kills residual mites and gives the colony the best start to the new calendar year§.

Kick ’em when they’re down

Early treatment protects winter bees but risks exposing bees the following season to unnecessarily high mite numbers. However, in midwinter, these residual mites are much more likely to be phoretic due to a lack of brood in the colony. As I stated earlier, phoretic mites are relatively easy to target with miticides.

So, give the mites a hammering in late summer with an appropriate and effective miticide and then give those that remain another dose of the medicine in midwinter.

But not another dose of the same medicine

Since the majority of mites in a colony with little or no brood will be phoretic, you can easily reduce their numbers using a single treatment containing oxalic acid. This can be administered by sublimation (vaporisation) or by trickling (dribbling).

There’s no need to use any treatment that needs to applied for a month. Indeed, many (Apiguard etc.) are not recommended for use in winter because they work far less well on a largely inactive colony.

Trickle 2 - £1

Trickle 2 – £1

I’ve discussed sublimation previously. However, since this requires relatively expensive (£30 – £300) specialised delivery and personal protection equipment it may be inappropriate for the two hive owner. In contrast, trickling requires almost no expensive or special equipment and – reassuringly – has been successfully practised by UK beekeepers for many years. I did it for years before I bought my Sublimox vaporiser.

Therefore, in two further articles this autumn (well before you’ll need to treat your own colonies) I’ll describe the preparation and storage of oxalic acid solutions and its use.

Be prepared

If you want to be prepared you’ll need to beg, borrow or steal the following – sufficient oxalic acid (or Api-Bioxal), a Trickle 2 bottle sold by Thorne’s, a cheap vacuum flask (Tesco £2.50), granulated sugar and a pair of thin disposable gloves.

Do this soon. Don’t leave it until midwinter. You need to be ready to treat as soon as there’s a protracted cold spell (when brood will be at a minimum). Over the last few years my records show that this has been anywhere between the third week in November and the third week in January.

More soon …


† Only MAQS is effective against mites sealed in cells. This is why most miticides are used for extended periods in the late summer or early autumn … the miticide must be present as Varroa emerge from sealed cells.

‡ I’ll repeat the caveat that this is an in silico simulation of what happens in a beehive. Undoubtedly it’s not perfect, but it serves to illustrate the point well. It’s freely available, runs on PC and Mac computers, and is reasonably well-documented. In the simulations shown here the virtual colony was ‘primed’ with 20 mites at the beginning of the year. BEEHAVE was run using all the default settings – climate, forage etc. – with the additional application of a miticide (95% effective) in the middle of the months indicated. Full details of the modelling have already been posted.

§ The National Bee Unit recommend Varroa levels are maintained below 1000 throughout the season. Without treatment, 20 mites at the start of the season can easily replicate to ~750 in the autumn. If you start the season with 200 mites then levels are predicted to reach ~5000 in the following summer. The colony will almost certainly die that season or the next. There’s a more detailed account of the consequence of winter brood rearing and the level of mite infestation written by Eric McArthur and reproduced on the Montgomeryshire BKA website that’s worth reading.

¶ The cumulative (year upon year) effect of late summer treatment with no midwinter treatment has been discussed previously. I’ll simply re-post the relevant figure here – 5 years of bee (in blue, left axis) and mite (in red, right axis) numbers with only one treatment per season applied in late September. Within two years the higher mite numbers that are present at the start of the year reproduce to dangerously high levels.

Mid September

Mid September

Landing boards

I’ve bought and used a number of Abelo poly hives this season. I’m going to review these once I see how the colonies perform overwinter. However, one of their ‘features’ is an integral landing board that forms part of the removable floor (colonies 1 and 3, facing, below).

Abelo poly National hives ...

Abelo poly National hives …

Landing boards are great. They provide a large flattish or gently sloping ramp that leads to the hive entrance. There’s something mesmerising about watching heavily-laden foragers performing an inelegant ‘tail-down’ crash-landing several inches short of the entrance, righting themselves, and marching purposefully forwards into the gloom of the hive.

During a heavy nectar flow this happens dozens of times a minute, with a strong colony making about 35,000 foraging trips per day. It’s great to rest your elbows on the hive roof, peer over the top and watch hundreds of foragers bringing the nectar back, 40 milligrams at a time.

Integral landing boards and DIY

Mine's bigger than yours

Mine’s bigger than yours

Landing boards must be popular with other beekeepers as well as they regularly feature in commercially available hives. The Abelo implementation is relatively neat, projecting perhaps 5cm from the front face of the hive.

Other variants are rather more in-your-face. The version in the image on the right is on an early variant of a Maisemore’s poly National hive (I think – please correct me if I’m wrong – Matt Harris helpfully corrected me here … they’re Paynes hives). Frankly, I think it looks pretty ghastly, but at least returning foragers could crash-land some distance away and still walk the last few hundred yards unimpeded 😉

If your hives are cedar you can easily add a flat or sloping landing board to the front of the floor. If you’re going to do this use reasonable quality wood – the exposed edge of a strip of plywood tends to delaminate pretty quickly. Alternatively, build something cheap, functional and easily replaceable from Correx.

Thorne's budget hive ...

Thorne’s budget hive …

The bee shed houses up to 6 colonies, each with a simple short ‘tunnel’ ending in a 1-2″ aperture in the vertical shed wall. I’ve built simple Correx landing boards on these and they’ve performed extremely well over the last two years. Each piece of folded Correx is a distinctive colour to aid the bees returning to the correct hive.

Landing boards ...

Landing boards …

If you take advantage of abandoned ‘For Sale’ signs you can get Correx in a wide range of contrasting colours which saves having to spray paint them before use.

Take a stand

Landing boards don’t need to be attached to the hive front or floor. Some of our early research colonies were housed in lovely cedar hives built by Pete Little of Exmoor Bees & Hives. He provided stands with integral sloping landing (‘alighting’) boards. These are great, though they extend the need for compatibility from the hive itself to the stand as well.

Stand and integral landing board

Stand and integral landing board …

Nice, but not needed

Despite the pleasure to be gained from watching bees return to the hive entrance, landing boards aren’t really necessary and they can get in the way.

Feral colonies generally don’t have the benefit (or need) of a nicely sloping landing board. They cope admirably with a simple unadorned hole through the soffit, with nothing more than the painted boards to cling to … upside down. Crevices or holes in trees, or the church tower, probably have ‘grippy’ surfaces that aid arrival, but there’s no evidence they’re selected on any criteria other than the volume and overall location of the potential new ‘home’.

I used to build my preferred floor – the kewl floor with a mouse-proof and wasp-resistant ‘L’ shaped underfloor entrance – with a shallow integral Correx or plywood landing boards.

Original design

However, over time these all got damaged in transit, or I got sick of bees wandering underneath the floor if they landed on the stand, not the landing board. I’ve recently described a modified entrance to these kewl floors, again made from Correx, that is a marked improvement.

Correx landing board ...

Correx landing board …

There’s a very short video on the page describing these modified entrances showing bees landing and entering the hive perfectly well.

Damaged in transit … or in a pile (up)

The main problem with any sort of protruding landing board is that, by definition, it protrudes.

It therefore gets in the way.

It makes strapping hives up during transport more difficult and means the hives don’t stack together quite as neatly. I only move small number of colonies about, so it’s the inconvenience, not the space, that is the issue.

Abelo hives in transit ...

Abelo hives in transit …

Similarly, during the winter or after uniting colonies in the season, spare floors and other pieces of kit need to be neatly stacked out of the way. Protruding landing boards prevents them being placed on the top of the stack (because the roof fouls the landing board) and – in certain orientations – stops stacks being pushed close together.

Stacked boxes

Stacked boxes …

As an aside, you probably don’t want these floors at the bottom of the stack. Firstly, you’ll inevitably need one when putting together a new hive and it’s easiest not to have to remove the entire stack to access the floor. Secondly, unless blocked off with a sheet of polythene or Correx, they’ll allow wasps and bees access to the stack … or even encourage a swarm to move in.

So … over the years landing boards on my hives have evolved or, more accurately, atrophied. They’re now only present on the outside of the bee shed, on purchased poly hives and, in a rather truncated version, at the cavernous mouth of the Thorne’s Everynucs that I favour.

No landing boards here ...

No landing boards here …

Asian hornet 2017

Last month I wrote about the discovery and predicted spread of the Asian hornet (Vespa velutina) once (if) it gets established in the UK.

New Asian hornet isolation in North Devon

The National Bee Unit (NBU) and DEFRA have today (26th September 2017) reported the identification of an Asian hornet in the Woolacombe area of North Devon. This is about 100 miles from the Tetbury site (near Stroud) where the Asian hornet was isolated in September last year. There was an additional isolation in North Somerset in autumn 2016, though the precise location was not publicised.

Asian hornet

Asian hornet …

Genetic analysis by the NBU will determine whether the new isolate is related to previous isolates. This would imply, though not prove, that the hornet may be established and breeding on mainland UK.

I’m speaking at the Devon Beekeepers Convention in Totnes next month and expect to hear more about efforts to track down and destroy the (or nests) at the meeting.

The Asian hornet appears to now be established on Jersey in the Channel Islands.

Light my fire

If something is described as a “A triumph of form over function it looks better than it works. Here’s the diametric opposite – something that works really well, but looks a bit rubbish.

Re-using dark wax

Wax extracted from old brood frames is often too dark to use for candle making. You can exchange it for cash or new foundation at Thorne’s – either at one of their regional stores or at the big beekeeping conventions. However, if you use a lot of foundationless frames you’re unlikely to need much foundation (by definition 😉 ). If you have the patience of a saint you could consider making your own starter strips. As an alternatively you use can this old, dark wax to prepare perfectly good firelighters for a wood burning stove. With British summer time ending in a couple of days sooner than you think§, now is as good a time as any to prepare a stock for the winter.

Guess which are handmade ...

Guess which are handmade …

There are lots of suggested ‘recipes’ for these on the web. Many of these combine wax with pine cones, sometimes with the addition of a wick. By adding a few drops of essential oils to the melted wax you can create both an attractive and fragrant item to decorate your home.

Note I said “decorate your home”, not “light your wood burning stove”. Take it from me … they’re pretty hopeless as firelighters. Been there, sent a postcard. I’ve collected pine cones, dried them for weeks in the boiler room, wrapped a wick around them, dipped them in scented wax and been wholly unimpressed at how poor they are as firelighters.

Flamers

Flamers …

Don’t bother.

Commercial firelighters for wood burning stoves are usually composed of a wax-dipped, twisted wood shavings. Flamers work very well. However, at £24 for 200 they’re not inexpensive – particularly for something that’s going to just sit next to the stove in a bowl and then, in the space of a few minutes, literally disappear in a ball of flame.

Roll your own

Elm bowl ...

Elm bowl …

You’ll need some wood shavings, egg boxes and molten beeswax. You can buy the coarsest animal bedding material or – better still – find a friendly wood-turner and ask them to save some of their discarded shavings (which will also work well in your smoker). Melt the beeswax in a slow cooker or Bain Marie. Stuff the wood shavings reasonably tightly into the wells of the egg box and dribble liberally with melted wax.

Job done.

If you want to make them slightly fragrant then add a few drops of juniper or patchouli essential oils to the melted wax before pouring it over the wood shavings. They’ll smell nice but they’ll still look rubbish.

Come on baby ...

Come on baby …

Tear and share

These are not the sort of things you’ll see featured in Homes and Gardens or Country Living. They are a triumph of function over form. Hide them away somewhere close to the stove. When needed, simply tear a ‘cell’ off the egg box, stack it onto the pile of kindling and logs (I’m an advocate of the ‘top down’ or Swiss style method of firelighting), light the blue touchpaper and retire to an armchair to enjoy the fire.

I claim no originality for this idea. There are loads of websites with similar suggestions, using everything from sawdust to the lint from a spin-dryer as the flammable material. Some of them look even worse than mine 😉

Ugly but fully functional ...

Ugly but fully functional …


This phrase is a bastardisation of the term form follows function originally used by the architect Louis Sullivan in an 1896 paper The Tall Office Building Artistically Considered. It became widely associated with modernist and industrial architectural design in the early 20th Century, essentially meaning that the shape of a building should reflect its primary purpose.

§ This post was written in the chilly early Spring with the intention of publishing it sometime in October (when BST ends). However, an extended period of travelling in late August and much of September meant I had to bring the date forward to post something vaguely useful (I hope) and  topical when I’d been doing no practical beekeeping for 3+ weeks. Coincidentally the date this appeared (22nd September 2017) is the autumn equinox … the date at which day and night are of approximate equal duration everywhere. About the time I’ll get the wood-burning stove going regularly.

 This phrase used to be the safety instructions on fireworks (and may still be for all I know) and became widely used as doing something incendiary. ‘Touchpaper’ was the paper fuse soaked in potassium or sodium nitrate.

Colophon

Light my Fire was a 1967 song by The Doors that first appeared on their self-titled debut album.

But you knew that.