Synopsis : The science of identity … how guard bees recognise nestmates, why drifting bees are accepted into other hives and why robbers are only sometimes rejected.
Honey bees are eusocial insects. The ’eu’ before social is derived from the Greek for ‘good’; these insects – not just honey bees – exhibit the highest level of social organisation, involving the division of labour (nurses, scouts, guards, foragers and in reproductive and non-reproductive sub-groups), cooperative brood rearing and overlapping generations.
Eusociality is a response to evolutionary pressure. Colonies are more successful than individuals.
Sociality involves cooperation. This requires recognition of kin and/or other group members. It also involves defending the shared resources that the group have worked together to collect (stores) or rear (brood).
Without defence, all that hard work would be lost to other competing groups who would try and steal the resources.
Social groups have therefore developed ways to distinguish themselves from other social groups of the same species. Although some social insects use visual clues 1 to distinguish group members (Baracchi et al., 2015), the majority use odours, in particular cuticular hydrocarbons (CHC’s).
Synopsis : The manufacturer’s instructions for miticide use are often poorly worded, confusing or contradictory. Many beekeepers already struggle to control Varroa and this makes things worse.
How many beekeepers read the documentation that accompanies the miticides they use for Varroa control? How many understand what all the terms – including the pharmacological ones – mean?
What about the phrase “Withdrawal period”?
Can all miticides containing the same active ingredient be used in the same way? If not, why not?
What about repeat usage? Can you repeat a treatment (if needed) if the instructions do not explicitly state that repeat treatments are not allowed? 1 Or can you only administer a second application if the instructions explicitly state that it is allowed?
And if a you are allowed to apply a second treatment, can you administer a third? What about treating in November and the following January? Two different calendar years, but well under one year apart.
Don’t expect any answers to these or related questions in this post 😉 .
Out, damn’d mite …
The intention here is to highlight the slightly shambolic nature of the documentation that accompanies (and sometimes does not accompany, but which you are probably expected to read!) the miticides approved for use in the UK. I don’t have time to cover all the miticides in a single post so will restrict this post 2 to two containing formic acid and one that contains oxalic acid.
And … while we’re at it … which are the legally binding instructions? Those in teensy-weensy lettering on the purchased product or the ones listed in the Veterinary Medicines Directorate (VMD) database?
MAQS and FormicPro
MAQS (Mite Away Quick Strips) and FormicPro are very similar products.
Actually, they are so similar that it’s rather difficult to tell them apart.
The packaging is similar – a cardboard box or plastic tub filled with sachets, each containing two strips impregnated with formic acid (and some other stuff – but what isn’t specified). Even the price is similar; two doses (by which they mean sufficient to treat two hives, or one hive twice, cost an eye-watering 3 £16.50. I’ve not checked other suppliers, but Thorne’s list the 2, 10 and 30 dose boxes of MAQS and FormicPro at identical price points 4.
If you bother to read the online documentation (which you should) you will see that both are marketed by NOD Apiary Ireland Limited, and that each strip contains 68.2 g of formic acid. Even the description of the individual gel strips is very similar:
Brown, semi-rigid to soft gel strip covered in a biodegradable laminated paper, which maintains form (FormicPro).
Each strip is an off-white to caramel coloured gel wrapped in white laminated biodegradable paper (MAQS).
So, we have the same active ingredient, formulated in the same way, packaged in a similar manner, with identical diagrams for how to apply two strips to the brood box. The temperature range recommended for use is identical and both have similar warnings about queen damage.
The same but different
But, although MAQS and FormicPro appear to be essentially the same, from a practical beekeeping standpoint they are very different.
MAQS can be used with honey supers on the hive but FormicPro cannot.
Of course, pedantically, that’s not exactly true.
You could use them ’any-damned-way’ you please, but you would probably be breaking the rules.
You are allowed to use MAQS when there are honey supers present, but you are not allowed to use FormicPro – in all other regards an identical product – when there are honey supers on the hive.
Here are the relevant words from the online SPC’s (Summary of Product Characteristics) 5:
Supers with honey must be removed from the hive prior to product application. See Section 4.5. Honey stored in super(s) put on for the treatment period must be removed and not used for human consumption. Spent strips must be removed before supers intended for harvest are placed on the hive (FormicPro – section 4.11 ‘Withdrawal period’).
The strips may be applied during honey flow; put on honey supers if honey flow is anticipated, to allow adequate space for colony expansion (MAQS – section 4.5 ‘Special precautions for use’).
There is one other difference as well … you can buy FormicPro whereas MAQS appears to be out of stock from all the suppliers I’ve checked.
Perhaps it has been withdrawn already by the manufacturer … ?
This is going to confuse a lot of beekeepers who have come to value MAQS as a short-term and effective treatment for Varroa management during the season.
Many will continue to use FormicPro in the same way that they used MAQS … which could be problematic if they are visited by a Seasonal Bee Inspector.
Summary of Product Characteristics (SPC)
Any miticides you purchase should be accompanied by a set of instructions – on the outside of the box, or the foil packet or wherever. These are often like ’ant tracks’ – illegibly small printing, almost impossible to read without the use of a binocular microscope 6.
Api-Bioxal … where’s my microscope?
Importantly, the packet will also carry a lot number and a use by date – you need to keep records of the former for several years 7 after use. I almost always forget to write this into my notes, but I always photograph the packet so have a dated copy on my ‘phone.
Use the VMD search facility to avoid the budgie treatments
A document prefixed SPC (the Summary of Product Characteristics).
A document prefixed QRD (for Quality Review of Documents), which is the Product Literature; essentially the labelling and text that is supplied when you purchase the product.
If you read these you will find a large amount of duplication. These documents are periodically revised – the MAQS and FormicPro paperwork is all dated June 2022, with MAQS being first authorised in 2013 and FormicPro in 2021.
Discrepancies and confusion
Aside from the ‘biggy’ (not being allowed to use FormicPro when there are supers on the hive) there are other discrepancies or confusing text in these documents.
I’ve already listed one example …
The MAQS SPC indicates the ability to use the product when supers are present under section 4.5 ’Special precautions for use’.
In contrast, the FormicPro SPC indicates that the product cannot be used when honey supers are present under section 4.11 ’Withdrawal period’, though they do refer to section 4.5 (where, perplexingly, only empty honey supers are mentioned).
Section 4.5 seems to me to be the logical place to mention the ever-so-slightly-critical matter of not being allowed to use FormicPro when there are honey supers present.
Does anyone proof read or sanity check these documents?
If so, why don’t they ever define the term withdrawal period?
If you do a search online for ’withdrawal period’ there are all sorts of things about hormonal birth control and legal contract cancellations, but you need to scroll down to the penultimate item on the first page to get the relevant meaning:
The time that must elapse between the last administration of a veterinary medicine and the slaughter or production of food from that animal, to ensure that the food does not contain levels of the medicine that exceed the maximum residue limit.
And that’s from the European Medicines Agency; it wasn’t until somewhere on the third page of results I could find anything from the VMD 9.
Helpful? Not 🙁 .
Of course, there’s an argument that if you’re applying the ‘medicine’ then you should understand all the paperwork and seek further advice if needed.
But I suspect many do not.
Whilst very specific in places e.g. duration of treatment, maximum temperature for use 29.5°C (Really? Does that 0.5°C make a difference? How many domestic thermometers are that accurate?), the documentation also carries other contradictory or vague instructions.
Both MAQS and FormicPro contain the following words under Section 4.4 (‘Special warnings for each target species ‘) of the SPC
Use according to local treatment recommendations, if available.
Who makes these local treatment recommendations? Are they legally binding? Can you just invent them? What can they cover or not cover? Could the local treatment recommendations state “Use five strips for a month”?
And what about disposal of the used, unused and waste products? Here you will find instructions in two separate places in the SPC.
When removed, dispose of by composting (FormicPro, Section 4.9 “Administration”).
The strips do not need to be removed from the hive after the application period of 7 days as the honey bees dispose of the spent strips. If they are removed, dispose of by composting (MAQS, Section 4.9 “Administration”).
And, confusingly …
Any unused veterinary medicinal product or waste materials derived from such veterinary medicinal products should be disposed of in accordance with local requirements (MAQS and FormicPro Section 6.6 ‘Special precautions for disposal’)
So can they be composted, or do ‘local requirements’ take precedence?
I can’t even be bothered to comment on section 4.6 ‘Adverse reactions’ which helpfully define very common, common, uncommon, rare etc events, but then only apply them to one adverse reaction, despite listing many others.
I’ve spent a career trying to make sense of badly worded, confusing, verbose, self-contradictory documents (until the arrival of ChatGPT this was the norm for both student essays and University administrative paperwork) but some of these instructions still baffle me.
The active ingredient in Api-Bioxal is oxalic acid (OA). I’ve discussed this extensively in previous posts. There are several other miticides listed on the VMD database that have OA as the active ingredient; Oxuvar, VarroMed (which also contains formic acid), Dany’s BienenWohl powder/solution and Oxybee. Of these, the last two may not be routinely available in the UK.
I’m going to restrict my (brief) discussion to Api-Bioxal as it’s the only one I’m familiar with and because it highlights a different form of internal infernal contradiction in the official instructions and paperwork.
The Api-Bioxal SPC and instructions clearly state (in section 4.5 ’Special precautions for use’ … or ‘the logical place’ as it should be known) that it should be administered when supers are not present on the hive.
In addition, it also clearly states that the withdrawal period is ‘Zero days’ 10.
Sublimox vaporiser … phoretic mites don’t stand a chance
The duration of application for MAQS and FormicPro is seven days and the formic acid permeates the cappings and kills mites in capped cells. In contrast, Api-Bioxal is a single shot treatment … it may (or may not) remain active in the hive for some time after administration, but you essentially apply it and walk away.
Job done 🙂 .
Oxalic acid does not penetrate capped cells and so is only effective if the colony is broodless. The instructions are clear on this point (to their credit).
A single shot used once … or twice?
The instructions describe two approved methods of administering Api-Bioxal. Trickling a 4.2% (w/v) solution made up in 1:1 (‘thin’) syrup onto the visible seams of bees, or vaporising a hive with up to 2.3 g of Api-Bioxal.
Administration by trickling … Up to two treatments per year (winter and/or spring-summer season in brood-free colonies). The treatment should be made in a single administration.
Administration by vaporisation … Maximal dose 2.3g per hive as a single administration. One treatment per year.
I think the ‘single administration’ means that you cannot split a treatment into two e.g. vaporise 1.15 g twice, or trickle 2.5 ml per seam and then repeat it the following day.
What’s odd is that trickling can be conducted twice per year, whereas vaporisation cannot. What about vaporising in December and January? i.e. once in each of two successive years … which could even be on successive days (31/12 and 1/1).
This is odd for two reasons – firstly it seems strange that the same compound can be administered a different number of times depending upon the route of administration.
Well, OK, perhaps it’s really bad for the colony to be vaporised? In that case it would be understandable, though some explanation of the point would help.
The good old days … trickle treating colonies before Api-Bioxal
Trickling and vaporising do cause differential damage to colonies, but it is trickling that does more damage. Trickled OA damages open brood and studies from the LASI group in Sussex showed that colonies trickle-treated when brood was present were subsequently weaker than those that were vaporised (Al Toufailia et al., 2015).
Conversely, several studies of repeated vaporisation have shown that it is well tolerated by the colony.
So, in this instance the instructions are at odds with my understanding 11 of the current science.
If the withdrawal period for Api-Bioxal is zero days (it is), can you add a stack of supers to the colony the day after vaporising or trickle treating a colony?
Which is a little odd as the oxalic acid remains active in the colony for several days after it is added. If you apply Api-Bioxal and then monitor mite drop on a daily basis over about a week it often peaks a day or two after it is administered, but goes on at a reducing rate for ~5-6 days. Whilst it could just be taking its time killing the mites 13, I think it is more likely that residual activity remains for several days.
Perhaps the wording in the instructions on ‘honey flow’ precludes this, but you can certainly add supers before a honey flow and I’d argue that the wording isn’t completely clear cut.
I know almost nothing about the licensing of veterinary medicines. My understanding is that a license is applied for, supported by evidence of efficacy, toxicity etc. and that it is restricted in terms of the range of methods used to apply the miticide.
Therefore, if the manufacturer only applies for a license for trickling or vaporisation, then that’s what they get (if approved). Varromed (an OA solution) can be administered by trickling and spraying. When made up for spraying the OA solution has a long shelf life as there is no sugar present.
But that’s not an option for Api-Bioxal 🙁 .
Beekeepers are restricted in what they can (legally) do by what the manufacturer sought a licence for, even if there are better ways of administering the active compound, or even if the scientific evidence (sometimes preceding licensing, and certainly preceding updates of the documentation) indicates that – for example – repeat administration is both safe and effective.
Trying to make sense of it all
In Scotland a Working Group has been established to try and resolve some of these discrepancies and provide better advice to beekeepers on the use of the currently licensed miticides.
The Working Group involves representatives from a variety of interested parties including an acronym salad comprising SASA, VMD, BFA, FSS, SBA, SRUC, SEPA, APHA, DEFRA, DAERA, NBU and some academics and ex-academics with a particular interest in honey bee health.
I have written a lot about Varroa control on this site. In my view it is relatively straightforward to control mite numbers using the currently licensed miticides appropriately. In my experience it is easier to do this in Scotland, where we have lower winter temperatures and a greater chance of an extended broodless period.
However, Scotland – unlike the Midlands where I have also kept bees – offers some additional complications where Varroa control is concerned. Our most important (by £££) nectar source is heather which yields late in the year, too late in some years to subsequently protect the winter bees from mites and viruses.
Balancing the needs of the bees (low mites and viruses to overwinter successfully) with those of the beekeeper (hundreds of kilograms of heather honey) requires a careful balancing act and a good understanding of the benefits and limitations of the miticides available.
In turn, this needs good documentation and better advice that is both easily accessible and understandable by beekeepers.
And … to my surprise – and I look forward to it being confirmed or refuted – I’m told that the SPC is the legally binding document with regard to the use or misuse of licensed miticides.
I’ve (had to) read them all now … have you?
Al Toufailia, H., Scandian, L., and Ratnieks, F.L.W. (2015) Towards integrated control of varroa: 2) comparing application methods and doses of oxalic acid on the mortality of phoretic Varroa destructor mites and their honey bee hosts. Journal of Apicultural Research 54: 108–120 https://doi.org/10.1080/00218839.2015.1106777.
Synopsis : Join a beekeeping association, get a mentor, get local bees, manage your hopes and expectations, get your bees through the winter. Simples.
Three years ago I wrote a post on ”Start(ing) beekeeping” courses. That was mainly written from the perspective of the tutor. As with many posts on this site, it was read a lot at the time and then rapidly sank down the rankings, being overtaken by posts on swarm control, Varroa management and queen cells … all topics that should have been covered in a course on how to start beekeeping.
Hmmm? … I wonder why that is?
Today’s post is about the same topic, but from the perspective of the beginner.
What should you be doing and what should you not be doing?
What should you expect from your first beekeeping season?
This is different from what you might hope for.
It’s important that you manage your expectations (or someone manages them) as the alternative might well be disillusionment.
Hope for well-tempered bees, balmy summer days filled with the contented buzz of busy foragers 1, and a whopping honey crop to jar for friends and family (and the local shops).
Expect disappointing weather, temperamental bees and possibly even lost swarms, several head-scratching ”WTF? I don’t understand … 🙁 “ moments, worry and – perhaps – some honey.
Nothing like enough to recoup your expenditure, insufficient for your family, let alone your friends, but enough to call yourself a beekeeper.
Except … not so fast.
Hives in the snow
To call yourself a beekeeper I’d argue that you need to get your bees through their first winter.
This last part is so important it should be the primary goal of your first season.
Everything else is a bonus.
Beekeeping involves practical skills
And, unfortunately, you cannot learn these in a draughty church hall on alternate Wednesday evenings, or by reading and re-reading Ted Hooper’s Guide to bees and honey over the Christmas holidays.
At best you can learn the theory from books or from a beginners course.
The theory is useful, don’t get me wrong, but it’s no substitute for doing a few hundred hive inspections and keeping good notes over several seasons.
The books or a Powerpoint presentation cannot convey the weight differences between frames of stores, sealed or open brood, the subtle – and sometimes not so subtle 😉 – difference in behaviour of a queenright and queenless hive, or the physicality of colony inspections in high summer.
They can describe them, but that’s not the same as experiencing them.
One thing they are particularly poor at conveying is the feelings experienced when you open your first really full hive.
Lots of bees
For some ‘beekeepers’ this is the last beekeeping they do.
The ’sheer weight of numbers’ can be a bit overwhelming for some people.
They like the idea of being a beekeeper, but not the weekly interactions with tens of thousands of insects.
Beekeeping ‘taster’ days
Many local beekeeping associations run a ‘beekeeping taster day’ sometime in late spring or early summer. For £30 (or whatever … I’m probably hopelessly out of date) you receive a short introductory talk, before getting dolled up in a profoundly unflattering beesuit and shown the rudiments of using a smoker.
You then both observe and take part in a hive inspection.
A tasty taster day
An experienced beekeeper will open the hive and talk you through the first few frames, but then you’ll be handed the hive tool and helped to ‘have a go’.
If you’re lucky the ‘taster’ day will end, appropriately, with a honey (and mead) tasting session.
I think these are an ideal way to see if you suit beekeeping.
If you recoil at the sight of thousands of flying, crawling, stinging 2 insects then you have the answer. Try watercolour painting, or metal detecting or mixed martial arts instead … and thank me for saving you the additional £970 it would have cost to get you started as a beekeeper.
However, if – as I hope – you find the sight and smell and sound of a hive captivating, if the hive inspection is finished well before you’ve asked all the questions you want to, and if you wonder why you’ve wasted the first forty years of your life as a watercolorist, a detectorist or a cage fighter, then Welcome!3.
These taster days have to be held when the weather is good and the bees are calm 4, perhaps seven months before the winter ‘start beekeeping’ courses. It’s a pity they cannot be juxtaposed.
Join your local beekeeping association
Beekeeping is an essentially local activity. The bees forage within a radius of 2-3 km of the apiary. The available forage influences how the colony develops as the season progresses, the local weather determines which trees and flowers grow and produce nectar, and when that nectar is produced.
Local beekeepers know about these things and are best placed to provide help and advice. Any training they provide will be ‘biased’ (for want of a better word) to local conditions. They’ve dealt with the variably late springs, or the nectar dearth in June, or the ‘boom and bust’ nature of beekeeping in intensively farmed land.
Many beekeepers are very sociable, enjoying a long chat over a cup of tea and biscuits.
You might not be, and you don’t have to be, but access to the wealth of local advice will be invaluable during your formative months and years as a beekeeper.
I fully expect a comment to the affect
”Nonsense … I was given a swarm in a box in 1980 and am entirely self-taught. Never joined the local BKA and never wanted to. I learn from my mistakes and a library book 5”.
All no doubt true, but that does not mean that the learning process wouldn’t have been smoother, or perhaps faster, with a little local assistance.
And it might have been a bit more enjoyable as well.
Remember also that the introduction of Varroa in ’92 made overwintering colonies significantly more difficult, and – three decades on – it remains the biggest problem for beekeepers.
Although I started by saying that, as a practical activity, you cannot learn beekeeping in a lecture theatre, the general principles of beekeeping are important and can be taught in classes, or learned from books. These principles include things like the:
fundamentals of swarm control (not the to and fro shuffling of boxes in a Pagden’s artificial swarm, but the principles that underpin most swarm control methods; separation of old workers and the queen from young workers and brood/queen cells … or preferably queen cell singular)
You can acquire all this knowledge from a good beekeeping book in the company of a wood-burning stove and a large glass of Barolo.
In fact, I’d strongly recommend you do this anyway.
But I’d also recommend you attend a ‘start beekeeping’ course run by your local beekeeping association. You’ll meet local beekeepers, you’ll make friends, you’ll get advice on equipment and apiaries and you’ll eat a lot of chocolate biscuits.
But I don’t think it’s necessary to attend one of these winter course before starting keeping bees. If your association runs evening/weekend apiary sessions and allows you to tag along then do so. Attend the course the following winter, but don’t delay the opportunity to do some practical beekeeping if offered the chance.
Get a mentor
If your local association does not offer some type of mentoring system then move house to an area with an association that does.
Clearly 6 I’m not being serious … but it does reflect how important I think mentoring is.
An association that doesn’t offer some form of active mentoring to all trainees underestimates the difficulties beginners experience and their need, over at least 1-2 seasons, to have some practical help and advice readily available.
Alternatively (or – even worse – as well), the association is offering too many places on the ‘start beekeeping’ course to provide the necessary follow-up support.
These courses can be lucrative; 50 places at £100 per person is a welcome boost to association coffers, but effective training involves more than 8 evenings in the church hall with tea and biscuits 7.
No amount of chocolate biscuits compensate for a lack of mentoring
Are there 25-50 association members available and willing to provide mentoring for those beginners? Remember, the association probably ran the course last year for the same number … who will still need mentoring as they are probably about to get their first experience of swarming.
And, while I’m on the subject, can the association provide nucleus colonies to all the beginners they train? I think mentoring and the provision of nucs are important, and sometimes overlooked, responsibilities. I’ll return to nucs shortly.
Walk before you can run
Beekeeping is a broad church. All sorts of people get involved and there are all sorts of ways to keep bees. These include the type of hive used e.g. removable frame hives – Nationals, Langstroths, Smiths – top bar hives, skeps, tree hives etc and the methods used to manage the bees in those hives.
Perhaps try a National hive first … just sayin’
The majority of beekeepers in the UK use what I would consider ’standard’ management methods – a removable frame hive on which interventions for swarm control are employed and in which Varroa levels are minimised with appropriately used miticides.
But some beekeepers practice and promote others ways of keeping bees; encouraging swarming and avoiding the use of any chemical treatments.
I don’t think these management methods are suitable for beginners. Both are likely to result in the loss of colonies. Most swarms do not survive and it takes exceptional skill to keep bees without chemical miticide control.
I know some associations already promote ‘treatment free’ beekeeping on their winter courses for beginners. I worry about the survival rate of the colonies … and the proportion of beginners that eventually become beekeepers.
My suggestions would always be to learn to keep bees using the ‘mainstream’ methods before trying alternatives.
You might like the idea of keeping bees in skeps, eschewing chemical treatment and allowing them to swarm freely. After all, that’s more natural8. However, you’ll only become a beekeeper if you don’t lose your colonies through swarming or disease.
And if you do repeatedly lose your bees, you’re much more likely to become disillusioned with beekeeping and abandon it for something easier, like quantum physics or ultramarathons.
Become competent in the widely-used mainstream methods of honey bee management and then, by all means, try something different.
Learn one method and learn it well
I’ve discussed this topic recently. Learn the principles that underpin a management method e.g. swarm control, and learn one way of employing those principles to achieve a successful outcome.
Use it, and use it again.
Use it until it becomes second nature, until you can totally depend upon it working, until you understand all the subtleties and nuances, the wrinkles and caveats.
The winter course might feel more comprehensive, but if attendees are just getting bamboozled by all the options then it’s not really helping them.
Personally, although it’s slightly unusual in that it doesn’t exploit the separation of [old bees + queen] from [young bees + brood], I’d teach the nucleus method of swarm control. It’s easy to understand, uses a minimum of additional equipment and – done properly – is 100% effective.
You also get a ‘free’ nuc from it … which conveniently brings me to … 10
Source local bees
Scientific evidence showed that, in a Europe-wide study, local bees did better than bees that were imported. The data indicated that they were better able to tolerate Varroa and that the colonies were larger when they went into winter. Other scientific evidence clearly demonstrates that strong colonies overwinter better than weak ones.
For these reasons alone it makes sense to source local bees when you start beekeeping. Buy a nuc from someone in your association, or offer to help your mentor for the season and get ‘paid’ with a nuc (you helped split) the following spring. An overwintered local nuc is probably the best option …
Alternatively, put your name down for a swarm and be prepared to go on a few trips to capture one.
A bait hive deployed in mid-April in good time for the swarming season ahead
Perhaps also put out a bait hive and one might well come to you.
Over the last decade or so I’ve rarely encountered a really poor quality swarm. They certainly can occur, but the majority would – after a careful check of Varroa levels and other pathogens – be fine for a beginner.
Your mentor will help you with those checks … er, you have got a mentor, haven’t you?
Don’t be in too much of a hurry to get your first bees.
Assuming ‘normal’ spring weather the difference in getting your bees in early April or late May is irrelevant. Neither will get you any honey from the spring nectar. In addition, the weather is often rather changeable in April making your first few, slow, careful hive inspections stressful for the bees as the brood gets chilled. You’ll hold the colony back and not gain much useful experience.
Late April 2016 … OSR and snow
Wait until the weather is better and nucs headed by a current year queen are available.
In Scotland that might be at least late June.
Of course, many beginners will choose to ignore this advice … they’ll order a nuc from one of the large commercial suppliers and collect it as early as possible. The bees may well not have been in the box very long, and the queen is likely to be imported.
By any definition these are not local bees … and they certainly won’t be in 3-4 weeks as all the bees will be then from the introduced queen. Will the seller provide help if things go awry?
The price of early-season nucs 11 reflects the demand, not necessarily the quality or suitability for a new beekeeper.
Your first season
I briefly touched on hopes and expectations earlier. Let’s finish by looking at a messy combination of these masquerading as what I consider priorities for the season:
Successfully overwinter your colony. This has to be the priority as without it you have to start all over again. Successful overwintering requires three basic things:
a healthy colony with low Varroa and virus levels
a strong colony
sufficient stores to maintain the colony through the winter
Pathogen management, which 90% of the time means monitoring and treating (if needed) Varroa. Learn how to spot signs of virus damage and how to count mite levels in the colony. Understand the advantages and limitations of the various treatments that are available. Learn when to apply them for maximum effect, so that you use them as little as possible.
Acquire the skills needed to judge the colony. Is it queenright? Are there the expected ratios of eggs, open brood and sealed brood? Is the colony expanding? Learn how to identify queen cells – even the carefully hidden ones – and to distinguish between play cups and charged cells. Try and understand the link between environmental conditions and colony temperament … which additional means you need to …
Learn how to confidently and competently inspect the colony without overly disturbing or distressing the bees. Only then will you be able to distinguish between a clumsy inspection and a poorly tempered colony, or a usually well-behaved colony that is tetchy because it’s queenless (there are other, more definitive, signs) or because the nectar flow has dried up.
100 kg of honey per hive … if you’re gonna dream, dream BIG! In a normal season you should expect some honey from a spring-bought nuc, but consider it a bonus.
Your second season
Assuming you started the previous year with a late spring or early summer nuc (or a swarm) then this is likely to be the first season your colony will attempt to swarm.
Since it is preferable to have two colonies12 – the comparative performance makes judging problems or environmental changes much easier – the logical thing to do is to use a swarm control method that creates a second colony.
The previously mentioned nucleus method, classic Pagden, or a vertical split will all readily achieve this.
Here’s one I prepared earlier
What’s more, any of these three – conducted at the appropriate time for your local climate and forage – should barely interrupt the spring nectar collection. This means that you should get a spring and summer crop in many areas.
Apart from that it’s more of the same and steady as she goes.
Priorities 1-4 (above) remain equally important in your second season.
And sometime late in that second season, as you pile up the now emptied supers in the shed for year 3 (and consider buying an additional shed as you need the storage space), take a moment to congratulate yourself upon becoming a successful beekeeper 🙂 .
Don’t fool yourself that you know it all, or even that you know enough.
But I don’t either and I did all of the above about 15 years ago and am still learning.
Blah, blah, blah … I don’t think anyone reads this far down and at least two people signed up to Facebook notifications last week. I’m pulling the plug on new post announcements on Facebook very soon 13 so please register instead on one of the social media links in the right margin – Twitter, Instagram or Mastodon.
Synopsis : How promising is the “world’s first vaccine for honey bees”? Separating hype from hope, good news from bad news, and with a bonus discussion of trans-generational immune priming and beemageddon.
Bad news sells newspapers. A survey of two decades of news preferences by the Pew Research Centre showed that the most-read stories were those that could be classified as either war, weather, disaster, money or crime.
’If it bleeds, it leads’ as they say.
And combinations – like crooks making huge profits from pandemics – ensure top billing.
Enough! This isn’t a politics blog … let’s move on.
That survey was ~15 years ago, but it’s equally true today. However, these days additional topics sometimes force their way into the buffet of gloom that make up the headlines. Royalty is one, particularly with the tabloids, though sometimes these could equally well be classified under ‘war, weather, disaster, money or crime’1.
Weather … we’ve been having some
More recently, climate change and environmental apocalypse have started headlining. Unfortunately for journalists, the measurables are often rather esoteric. Kilotons of greenhouse gases or atmospheric CO2 levels of over 400 ppm mean little to the layman, or most journalists.
But cute, furry, hard working bees do … particularly if there’s no mention of stings 😉 .
So, the impact of climate change or the environmental apocalypse on bees often gets top billing … and not just any bees, honey bees.
Everyone knows what a honey bee is, and almost everyone loves honey.
All of which means that some of these stories are couched in terms of the potential for beemageddon. And because honey bees are ‘threatened’ 2 and familiar, related stories about honeybees also tend to get wide coverage.
Royalty, death and bees? BINGO … we have a winner!
One of these – the bee vaccine – looks like it could be good news.
Of course, the need for the vaccine means there’s some bad news to fully justify the story (don’t forget that impending beemageddon).
The world’s first bee vaccine sounds good doesn’t it?
Let’s have a look at some of the claims and the technology behind it.
What is a vaccine?
In the dim and distant past the word vaccine originated from the Latin for ‘cow’ (vacca). The link to vaccines is of course Edward Jenner who made a smallpox vaccine derived from the related cowpox virus.
In 1798, in an experiment that would shred all current ethical regulations, Jenner inoculated James Phipps with cowpox and, six weeks later, challenged him with pustular material from a smallpox case. Not only did Phipps survive, but he developed no smallpox symptoms either.
A vaccine is therefore something derived from an infectious agent that, when administered (inoculated), provides protection (immunity) from subsequent infection (challenge) by the same or a closely related infectious agent.
As an aside, Jenner could perhaps claim to have made the world’s first vaccine … despite the fact that a Dorset farmer, Benjamin Jesty, had done the same thing two decades earlier. In addition, variolation, usually involving administering dried smallpox material from a mild case, had been used prophylactically to prevent smallpox for hundreds of years.
Claiming originality is a tricky business … and something I’ll return to.
In mammals (like James Phipps) vaccines work by primarily stimulating a cell- and protein-based immune response. Cells are ‘primed’ to recognise a pathogen. Should subsequent infection occur, the cells and proteins, which have a molecular memory, are reactivated, amplified and subsequently destroy the invading pathogen.
Similar immune systems have proven so effective that evolution has created lots of them … many of which bear little immediate similarity to the one mammals (and most vertebrates) have. But there are similarities; many also have a ‘memory’ that can be reactivated should subsequent exposure occur.
And, scientists are starting to understand immunity in honey bees, and how to exploit it.
Bees, flies, RNA and, er, dunno
The most detailed studies of insect immunity have been done with fruit flies (Drosophila) as they are, by some distance, the best understood insects. The primary immune system in flies is not protein based, but instead uses nucleic acids. Immunity involves things that are called interfering ribonucleic acids which, understandably, are conveniently abbreviated to RNAi.
‘Experimental’ in this case means ”works, sort of, but not as well as we want … or need”.
But the world’s first bee vaccine that I’m going to discuss this week is not RNAi-based. It uses a completely different immunity system termed trans-generational immune priming, which is also conveniently abbreviated to TgIP (or TGIP in some studies 7 ).
And the thing about TgIP is that we have almost no idea as to how it works.
Just like the press article (“New vaccine to prevent beemageddon”) there’s both good news and bad news resulting from our cluelessness about TgIP.
The good news is that I can focus on the results rather than the mechanism, so making this post precisely 6430 words shorter than it would otherwise be.
The bad news is that by focusing on the results and some of the subsequent claims, the balance between the hope and hype in the title of this post gets shifted a bit 🙁 .
The discovery of TgIP in honey bees
The Tg (trans-generational) in the TgIP reflects the fact that:
‘ … maternal immune experience has been demonstrated to be transmitted to progeny and may therefore have a positive impact on offspring resistance and survival’ (Hernandez Lopez et al., 2014).
Essentially that means that if the mother is inoculated, the ‘children’ inherit some of the immunity.
Although the mechanisms are usually poorly understood – and may well not be the same in all species – TgIP has been demonstrated in vertebrates and invertebrates, including amongst the latter, bumble bees (Sadd et al., 2005), beetles and butterflies (Tidbury et al., 2010; Freitak et al., 2014).
The first study I’m aware of on honey bees was conducted in the University of Graz, Austria (Hernandez Lopez et al., 2014). In this study they demonstrated that queens immunised with the causative agent of American Foulbrood (AFB) subsequently produced larvae that were at least partially resistant to subsequent AFB disease.
American foulbrood is a bacterial disease of honey bees caused by Paenibacillus larvae. The name, foulbrood, reflects the smell of diseased larvae in the hive. It is a brood disease, caused by the ingestion of bacterial spores by very young larvae. The spores are effectively metabolically inert, heat resistant forms of the bacteria, that can survive for decades and germinate when ingested by a larva.
Adult bees are resistant to infection, but are the vectors that transmit the spores between larvae in the hive, and between hives while drifting and robbing.
AFB outbreaks are dealt with by destruction of the colony and in many countries it is a notifiable disease.
Inoculating queens by injection
Hernandez Lopez and colleagues heat-killed (90°C for 10 minutes) a vegetative 8 culture of Paenibacillus larvae and injected mated queens with the resulting ‘soup’ of proteins. They subsequently returned the queens to their nucleus colonies and, at an unspecified time later, removed day old larvae to plastic dishes in an incubator and fed them an artificial diet containing infectious P. larvae spores.
Then it was simply a case of counting the corpses …
Like all proper experiments this one was controlled in a variety of ways. To determine whether any benefit observed was due to inoculation of the queen with the heat-killed bacterial soup they injected a similar number of queens with an inert buffer solution. They repeated the study a year later and used two different strains of P. larvae spores for the challenge.
Finally, they tested the colonies both before and after inoculating the queens. This was an important control. Queens were unrelated and open mated and this control was needed to demonstrate whether there was any inherent differences in susceptibility to AFB, for example reflecting genetic differences between larvae.
For brevity, I’ll only show one set of the results.
Counting the corpses
Results from these type of studies can be presented as dull-as-dishwater numerical tables, or visually-rewarding ‘kill curves’. More properly these are called Kaplan-Meier curves. These plot time (horizontal) against the proportion of test subjects that exhibit – typically – disease or survival (vertical).
The resulting stepped curves therefore start at 100% (sometimes – as here – represented as 1) and drop over time as the corpses pile up. The stepped curves plot the cumulative body count.
Kaplan-Meier plots of larval survival a) before queen vaccination, b) after queen vaccination (11-2 & 11-3)
The black line indicates larval losses due to experimental handling. These control larvae were not challenged with AFB. As you can see, about 5-10% of larvae die off during the experiment and it’s nothing to do with AFB.
The graph on the left (a) shows larval survival after AFB challenge before the queens were inoculated. There’s no statistical difference between the coloured lines indicating that all are equally susceptible to AFB infection.
On the right are the kill curves Kaplan-Meier curves after inoculation of queens with the control buffer (line 11-1) or with the heat-killed P. larvae bacterial soup (lines 11-2 and 11-3). Clearly fewer larvae die over the time course of the experiment from nucs headed by inoculated queens.
Remember, these are cumulative survival curves – each line is derived from 96 to 192 individual challenged larvae.
Overall 65% of challenged larvae from buffer-inoculated (11-1) queens succumbed, whereas only 39% died after challenge if the queen had received the P. larvae ’soup’ inoculation.
Therefore this demonstration of TgIP in honey bees accounts for a reduction in larval mortality of ~26%.
You won’t feel a thing
Whilst broadly encouraging, there are a couple of issues with the Hernandez Lopez study that limit its application or potential usefulness.
The first is the level of protection seen. The dose of spores administered to the larvae was small, and potentially much smaller than one naturally experienced by larvae doing in-hive infection.
How good would the protection be with a dose 10, 100 or 1000 times as large? This can be tested, and presumably white-coated boffins with ample foreheads are busy doing this as I write.
The second is that the queens were inoculated with the P. larvae ‘soup’ by direct injection. This involves chilling the queen on ice for several minutes, injecting her using a sterile syringe, warming her up and then returning her to the colony.
Inevitably a few queens are lost during this process and – at least with workers – there are some issues with longevity for bees that have been cold-anaesthetised (though I can’t remember seeing any data on queen longevity following this procedure).
Injecting queens is practical if you want a few dozen, but it’s a non-starter if you’re producing thousands or need tens of thousands.
For those sorts of numbers you need to feed the queen with the vaccine … which, since mated queens don’t feed themselves, means caging the queen with a few workers and providing a food source laced with the vaccine.
A recent attempt to induce TgIP against European foulbrood (EFB) by feeding the queen with inactivated Melissococcus plutonius (the bacteria that causes EFB) was unsuccessful (Ory et al., 2022).
Perhaps oral induction of TgIP is a non-starter?
A glimmer of hope
However, towards the end of 2022, the University of Graz group published a study demonstrating promising evidence for TgIP using orally administered Paenibacillus larvae (Dickel et al., 2022) and this is the basis for the world’s first bee vaccine.
The paper was published in Frontiers in Veterinary Science and is relatively light on data.
This isn’t unusual for a scientific publication supporting a commercial – or planned commercial – product. The focus is on safety and demonstrating some level of efficacy, rather than understanding the underlying mechanism.
Or for that matter providing too many details that could undermine its potential commercial success, or the attractiveness of the company to future investment.
Bacterin = ’soup’
The vaccine preparation was commercially prepared by the company involved in the study (Dalan Animal Health) and there are no details of how it was prepared or what it contains. It could just be a heat-inactivated bacterial soup, or it might be supplemented with all sorts of weird and wonderful ingredients like unobtanium or virgin unicorn tears.
If you ask them it would probably be a case of ”I could tell you, but then I’d have to kill you”9.
The authors use the term bacterin (you won’t find this word defined in the OED … though unobtainium is in there). If you’re reading the Dickel paper just remember to translate bacterin to soup.
Let them eat cake bacterin
Caged queens, with attendant workers, were fed soup bacterin added to a corn syrup/sugar mix for 8 days and then used to requeen 5 frame nucs 10.
After at least 18 days, day-old larvae were harvested from the nucs, transferred to the incubator and challenged with a stock preparation of AFB spores in larval food. Larvae were subsequently fed AFB-free larval food and monitored for a further 8 days of development.
The experiment was repeated 3 times in two different study sites. In the interests of providing the bare minimum number of results (!) the authors simply plot the proportion of larvae derived from placebo- or bacterin-fed queens that died over the 8 day period.
Larval AFB challenge studies after oral vaccination of queens (see text for details)
Unfortunately, the axis labelling on the graph is almost too small to read in the original let alone the image above.
This figure shows three repeats. Larvae from bacterin- and placebo-fed queens are in light or dark shading respectively. For each repeat, paired bars on the right are the AFB-challenged larvae.
Note that the bacterin-fed larvae are shorter bars i.e. fewer died.
Overall, ~50-60% of larvae from placebo-fed queens succumbed to AFB, a figure that was reduced by 28-30% following prior vaccination of the queens with the bacterin.
The results were statistically significant but perhaps less good than you’d hope for.
An approved vaccine for AFB …
Well, to be pedantic, the approval that has been issued is a conditional licence by the USDA Animal and Plant Health Inspection Service. There’s a PDF with very few details on their woefully slow website . The key quote is:
Conditionally licensed products are required to be pure and safe, and have a reasonable expectation of efficacy.
There may be additional unpublished studies used to support the licensing application … I don’t know.
However, based on the published work what has been approved is:
a proprietary product containing inactivated Paenibacillus larvae11
that reduces a ~50% lethal challenge of AFB spores by ~30%
and that has never been used outside a Petri dish in the laboratory
Clearly that’s some way from an AFB vaccine that’s going to revolutionise bee health and beekeeping (to say nothing of averting the impending beemageddon).
It might, but there’s a long way to go yet … to see just how far let’s briefly return to the villain of the piece, Paenibacillus larvae, and consider its life cycle.
The biology of Paenibacillus larvae
The only known host of Paenibacillus larvae is the honey bee (see Ebeling et al., 2016). Larvae are infected by ingesting spores of P. larvae supplied in brood food from workers in the colony. Exposure and infection during the first 36 hours after hatching is inevitably fatal.
Spores germinate in the midgut lumen, the bacteria proliferate massively, breach the midgut epithelium and reach the haemocoel. By now the larvae are dead. However, the bacteria continue to proliferate, literally ’turning the larval biomass into bacterial biomass’ (a quote from Ebeling et al., 2016).
By this time the bacteria are starting to starve and so sporulate, eventually drying down in the cell to form a scale containing millions of infectious spores.
The dose-mortality relationship depends upon the age of the larvae. The standard way to express infectiousness is the dose required to infect or kill 50% of the test subjects, abbreviated to ID50 or LD50 respectively 12. Studies dating back to the 1960’s reported that the LD50 for 0-6 hour larvae was ~200 spores and for 18-24 hour larvae was ~2000 spores (Hoage and Rothenbuhler, 1966).
However, supplementary information in the Hernandez-Lopez paper reports an LD50 in first instar larvae (<24 hours) of only ~20 spores, and this was the dose used as a challenge in their study.
Whether the LD50 is 20 or 200 spores is probably academic … a single dried scale contains millions of spores.
Hope or hype?
A bit of both.
Hope because a 30% reduction in larval infection is better than none at all.
Hype because there’s no evidence this provides colony-level protection in field-realistic situations.
The LD50 quantification studies show that very small numbers of spores can result in infection. An LD50 of ~20 spores in naive larvae results in 50% of them becoming infected, but perhaps ingesting just 5 spores could result in 5% of larvae becoming infected. 13.
If the larvae originated from a vaccinated queen the level needed to infect should be higher.
But would it be high enough?
I’ve no idea.
I don’t know how many spores are transmitted when an exposed worker feeds a larva and I’m not sure anyone does.
The scale of the problem
However, I do have an idea of the levels of spores in honey and hive debris – both of which are likely to be related to spore counts carried by nurse bees – from a recent paper (Kusar et al., 2021).
Honey from asymptomatic hives (no overt disease) in an apiary where other hives had AFB contained ~100 spores/g. The honey from symptomatic hives in the apiary contained 104 to 106 spores/g … 100 to 10,000 times as much.
Hive debris was much worse.
In hives with disease the debris contained 109 spores/g (that’s 1 billion for those unfamiliar with scientific notation). Asymptomatic hives averaged ~105 spores/g but covered a very wide range (0 to ~1010 spores/g).
That’s a lot of spores.
How many spores might foragers pick up and potentially transfer when drifting or robbing nearby hives?
Perhaps there are some studies of this … the assays are available and it’s information that is needed to determine whether vaccinating queen bees is likely to be beneficial in preventing the transmission of AFB.
I hope it works. I also hope that the hype helped raise some VC or investment money to fund the expensive and extensive field trials that will be needed to show that it works well enough.
In my view, only then will it qualify as the world’s first honey bee vaccine.
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Dickel, F., Bos, N.M.P., Hughes, H., Martín-Hernández, R., Higes, M., Kleiser, A., and Freitak, D. (2022) The oral vaccination with Paenibacillus larvae bacterin can decrease susceptibility to American Foulbrood infection in honey bees—A safety and efficacy study. Frontiers in Veterinary Science 9 https://www.frontiersin.org/articles/10.3389/fvets.2022.946237.
Ebeling, J., Knispel, H., Hertlein, G., Fünfhaus, A., and Genersch, E. (2016) Biology of Paenibacillus larvae, a deadly pathogen of honey bee larvae. Appl Microbiol Biotechnol 100: 7387–7395 https://doi.org/10.1007/s00253-016-7716-0.
Hoage, T.R., and Rothenbuhler, W.C. (1966) Larval Honey Bee Response to Various Doses of Bacillus larvae Spores1. Journal of Economic Entomology 59: 42–45 https://doi.org/10.1093/jee/59.1.42.
Kušar, D., Papić, B., Zajc, U., Zdovc, I., Golob, M., Žvokelj, L., et al. (2021) Novel TaqMan PCR Assay for the Quantification of Paenibacillus larvae Spores in Bee-Related Samples. Insects 12: 1034 https://www.mdpi.com/2075-4450/12/11/1034.
Synopsis : Interpreting waggle dance distances as indicators of seasonal foraging challenges, environmental change and pollinator competition.
The days are getting longer, though not enough to really notice. At almost 57° N we’ve apparently gained ~26 minutes since the winter solstice … but I’ve not seen a bee since early December.
Actually, that’s not entirely true because I checked some colonies this afternoon. As well as hefting the hives to ensure they were still reassuringly heavy I also took a couple of photos from underneath the open mesh floors.
Late December and relatively few corpses on this OMF in the bee shed
Some floors were almost clear, others had a few hundred scattered corpses and there was even the odd bee wandering around.
Why do some floors have more corpses than others?
Remember, the entire worker population of the colony is replaced in the autumn, with the summer foragers gradually dying off and the the long-lived (diutinus) winter bees substituting for them. It’s unlikely that these corpses are summer bee stragglers as they’d be almost three months old by now.
One possibility is that there is a higher attrition rate of winter bees in some colonies (though why is unclear), or the colonies were larger to start with and the same attrition rate yields more corpses. A related explanation would be colonies with the same number of winter bees, though produced at different times. If 1% of bees over, for example, 2 months old died each week 1, a colony that produced the bulk of its winter bees early would have more corpses than one that produced the winter bees later.
The photobombed picture above is of one of my east coast colonies in the bee shed. Here on the west coast my bees are Varroa-free. The ‘corpse count’ is therefore unlikely to be due to different levels of DWV infection resulting from Varroa infestation. My west coast bees have DWV, but only at very low levels.
It’s also not due to differences in undertaker bee activity as temperatures have been too low for any bees to fly for at least a month.
Anyway, enough morbidity …
The ‘corpse count’ is hardly beekeeping, but it’s as close as I’ll get to do any for at least two months. There are always winter tasks … cleaning smokers, frames, wax processing, honey jarring, painting nucs etc. but enthusiasm levels are low and it’s easier to sit in front of the fire and drink coffee 😉 .
My good deed for the day
To take my mind off corpses and all the frames I’ve yet to start building I’ve been doing some reading about foraging distances and how they vary during the season. This is great because it makes me think of summer days, wildflower meadows, fields of clover and acres of flowering oil seed rape.
By coincidence, this morning there were two articles in The Guardian – on deaths attributable to pollinator decline and severe weather events. It struck me that a better understanding of changes in foraging patterns and activity may be informative in investigating both the decline of pollinators and the consequences of severe weather events like drought.
Front page news … The Guardian 9th January 2023
I’ll return briefly to these two articles at the end, but will concentrate upon how we can determine where the bees are foraging and how this changes during the season.
And, even if you would rather not think about potential ecosystem collapse or climate disaster, from a beekeeping perspective it’s just interesting to know how far our bees are going when they zoom out of the hive entrance on a balmy summer afternoon.
It’s good to talk
Although we can communicate with animals to an extent – I can tell our puppy to ‘sit’ (and she might) – it’s not true communication. Similarly, although we can recognise the differences in songbird alarm calls to sparrowhawks vs. cats, the informational content is extremely limited when compared to true communication.
In contrast, and perhaps uniquely, we can eavesdrop on communication by returning foragers with their nest mates and interpret the distance to the nectar or pollen source, the direction the source is from the hive and – to an extent – the quality of the source (I’m going to restrict discussion to distance and direction here).
All of this information is encapsulated in the waggle dance, for which von Frisch was awarded a Nobel Prize in 1973. Without question this is the most complex communication signal known in insects and, arguably, in any animal.
The waggle dance has two phases; the waggle run is essentially movement in one direction while vibrating the abdomen from side to side, the return phase involves the worker looping back to start another waggle run.
The waggle dance
The informational content of the waggle dance is primarily in the waggle run, the:
duration of the waggle run provides distance information
angle of the waggle run provides directional information, relative to the solar azimuth
By keeping bees in a hive with a glass observation panel and videoing waggle dances we can determine the likely location of nectar or pollen (or tree resins or water under certain conditions) sources after analysing the recordings.
However, although it sounds relatively straightforward, dance interpretation is complicated by the inherent noise in the dances of returning foragers.
Foragers returning from a point source of nectar (such as a syrup feeder placed in the field by a scientist) show variation in their waggle dances; both individual foragers in sequential dances, and different foragers reporting the same nectar source.
When decoded this means there is variation in both vector components – distance and direction.
All of which makes accurately monitoring changes in foraging distances over a season or more rather problematic.
However, before describing how scientists have solved this problem think about whether this matters to a bee.
A bit of noise is OK for the bees (right) but just looks like noise to scientists (left)
In nature, although individual locations of nectar 2 might be point sources e.g. a flower in a field, in reality the entire field may be filled with similar nectar-yielding flowers. Typically bees rarely have to return to the reported location of a point source.
As long as the dance followers get to the right field they should be OK.
Noise suppression and increasing probability
Using a syrup source to which a colony had been trained, Couvillon and colleagues (Couvillon et al. 2012 3 ) demonstrated that the first and last waggle runs within any one dance were not very accurate. If these were ignored, but instead four consecutive runs were used from a single dance, this gave much better prediction of the syrup source.
However, this decoded directional and distance information (e.g. 1100 metres at 46°), when plotted onto a map, still just indicates a point source, effectively over-estimating the confidence in the decoded information.
Instead, they reasoned, it would be better to predict a probability distribution.
Roger Schürch did this (Schürch et al., 2013), analysing his own data and published archival data from both von Frisch and Wenner (I introduced you to Adrian Wenner a few months ago when I discussed using Varroa to eradicate honey bees from Santa Cruz Island).
Using some clever 4 statistical analysis Schürch showed that; 1) there was a linear relationship between the duration of the waggle run and distance, 2) that angular variation between dances was independent of distance, and 3) that the combination of the two vectors (from several recorded dances and several thousand dances simulated with appropriate levels of scatter in the distance and angle vectors) could be used to plot a probability distribution of the location the bees were reporting during the dance.
Heat map (b) and 3D representation (c) of combined multiple dances
Effectively this method enables a relatively limited dataset to predict the most likely location of the nectar source – in the image above, blue is less likely than yellow, than red.
As you can see from the 3D projection – where probability increases in the vertical axis – it looks pretty good.
Margaret Couvillon and Roger Schürch worked with Francis Ratnieks at the University of Sussex. Together they applied this methodology to predict the likely foraging areas by conducting waggle dance observations over two full seasons (Couvillon et al., 2014).
They recorded over 5000 dances to track seasonal changes in foraging and so address these questions:
how do foraging areas change over the season?
are foraging distances influenced by temperature?
how might nectar quality influence foraging?
Of course, as soon as you start thinking about questions like these you’ll realise that the observations will inevitably reflect the locally forage available, so the direct results may not be applicable to different areas, but the patterns might be.
And importantly, the methodology may be useful to address other questions in a changing landscape and environment.
4 km circle around the hive location – note urban and rural areas
The hives were located at the University. This was an area surrounded by open farmland 6, but Brighton has encroached from the south west. As a consequence at least ~21% of a 4 km circle centred on the University is classed as urban or suburban i.e. built up, but including gardens and allotments etc.
Seasonal variation in foraging distances
From August ’09 until July ’11 (excluding the months between November and March which are too cold for regular foraging) 5076 dances were videoed and analysed. By plotting the average distance reported7 by returning foragers each month, it was clear that bees traveled much further afield in the summer than they did in either the spring or autumn.
Monthly differences in foraging distances
The average distances for early spring (March), summer (July/August) and autumn (September/October 8 ) were 493 m, 2156 m and 1275 m respectively.
Temperature and foraging
Although summer is the warmest season, there are warm days in spring and cool days in summer. Since the team recorded dances on almost every day good enough for foraging it was possible to look for a correlation between the actual temperature and the distance reported by dancing foragers.
There wasn’t one.
That means that the longer flights in summer were not because the bees needed a higher ambient temperature to fly further. We can therefore assume that the bees were choosing to fly further, not because they could but because they had to.
Nectar and foraging
Honey bees are able to judge the energetic rewards of a nectar source. This involves a calculation of the energy expended collecting it vs. the energetic ‘value’ of the nectar collected. For example, the bees might favour a distant sugar-rich nectar source over a poorer one that is closer.
It was therefore important to determine whether the increased summer foraging distances were because the bees were favouring nectars with a higher sugar content.
How was this determined?
Returning foragers 9 were captured, chilled and gently squeezed to force them to regurgitate the content of their crop. Using a refractometer (of a slightly smaller scale than you might use to measure the water content in a bucket of honey) the sugar content of the crop contents was measured.
About 5% of returning foragers were carrying water, not nectar, and these were excluded when calculating average nectar content.
Whilst there was considerable month to month variation in the sugar content of nectar, there was not a correlation with the foraging distance. Therefore, the bees foraging further afield in the summer weren’t travelling greater distances because the distant nectar sources had a higher sugar content. They were travelling that far because they had to.
The sphere of influence
I used this term previously to describe the area of the landscape potentially impacted by a hive or apiary. Essentially it is defined by the maximum flight distances of the foragers, drones, scouts and queens. Numerically of course, the foragers are the largest group.
Using the methods described above the authors plotted ‘heat maps’ of foraging areas in spring, summer and autumn. The colour scheme is the same as that used above (essentially a probability map of likely foraged areas) – blue is predicted to be the least visited area (though see also the note below), yellow gets more attention and red gets the most.
Heat maps of seasonal differences in foraging – black circles denote 3 and 5 km from hive
There is clearly a big difference in the area visited by foragers in spring (0.8 km2), summer (15.2 km2) and autumn (5.1 km2), and this difference is not because the bees are going further to collect better quality nectars, or because the long hot days of summer encourage them to travel further from the hive.
As an aside … I’d have liked to see this data normalised somehow to forager numbers (which vary over the season) to get a better idea of potential competition for nectar or pollen resources with other pollinators.
It’s worth noting that not all foragers dance, but those that do report the best quality nectar sources. Therefore the maps above, and the distances I discussed even further up the page, represent the best choices the bees have in different parts of the season.
There may be poorer quality nectar sources not mapped by this type of analysis.
Summertime and the livin’ is easy
These studies show that – at least in this particular environment – honey bees have abundant forage close to the hive in early spring. In summer the bees have to forage over an area ~22 times larger 10 than in early spring to collect the resources they need.
Since the nectar sources are no better the livin’ is anything but easy.
Once the ivy starts flowering (mid/late August in this part of the world) then things get appreciably better and the bees don’t need to travel so far.
There’s no discussion in the paper on the areas foraged, or the potential sources of nectar (other than the ivy), or hive weight changes (which would have been really interesting). However, it seems likely that the large tracts of farmland to the north and east of the hives are very poor in forage during much of the season, and especially in the summer.
The heat maps show that the bees appear to spend more time to the south and the west … both areas where there is the greatest amount of urban development.
Readers with good memories will remember a post explaining the differences in foraging distance between urban and rural bees. The former travelled less far.
Urban environments are often better for bees as there is less boom and bust in terms of available nectar sources.
Honey bees are generalists; they can exploit a wide range of nectar and pollen sources. This at least partly accounts for their success and distribution.
Because they are not ‘tied’ to particular flower source(s) they are likely to share many of these sources with other flower-visiting insects, many of which will also be generalists.
It therefore seems likely that the apparent paucity of nectar and pollen sources ‘reported’ by dancing honey bees (who have to travel further to get what they need) will also be experienced by these other pollinators (many of which have smaller home ranges, perhaps 0.25 km2 for Bombus terrestris; see Osborne et al., 2001).
Therefore, rather than conducting time consuming survey work recording which flowers are visited by which pollinators (and when), the overall quality and quantity of nectar and pollen in an environment could be determined by monitoring the distances travelled and areas visited by a few honey bee colonies.
Wildflower meadow (in Andalucia)
Are set-aside and land-management programmes optimised to provide nectar and pollen where and when it needed?
Competition and environmental change
One reason proposed for the huge decline in non-managed pollinators is from competition with managed honey bee colonies. Honey bees may be generalists and are actually rather inefficient at pollination (in terms of fruit set per visit), but they more than make up for this by sheer weight of numbers.
The studies showing competition is responsible are not completely clear cut, and there are almost certainly other factors that have a greater influence e.g. persistent pesticides, removal of hedgerows and wild flower meadows.
However, if honey bees are struggling to find suitable nectar i.e. having to travel long distances, it’s likely they may be having a landscape-scale impact on other pollinators competing for the same resources in their own (smaller) ranges.
It’s a little sobering to think that our apiaries may be influencing survival and reproduction of other pollinators kilometres away.
Finally, as our climate changes, repeated studies of this type every few years would provide a very good insight into the degradation of the environment.
We know that the gradual warming of the environment is changing the flowering times of plants. We also know that weather extremes – particularly drought – can have a significant impact on seed set which, in turn, will influence the abundance of plants flowering in the following seasons.
Honey bees are the only indicators of these types of qualitative environmental changes that we can directly listen to and understand.
These things are not often discussed by beekeepers … perhaps they should be?
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Couvillon, M.J., Riddell Pearce, F.C., Harris-Jones, E.L., Kuepfer, A.M., Mackenzie-Smith, S.J., Rozario, L.A., et al. (2012) Intra-dance variation among waggle runs and the design of efficient protocols for honey bee dance decoding. Biology Open 1: 467–472 https://doi.org/10.1242/bio.20121099. Accessed January 10, 2023.
Schürch, R., Couvillon, M.J., Burns, D.D.R., Tasman, K., Waxman, D., and Ratnieks, F.L.W. (2013) Incorporating variability in honey bee waggle dance decoding improves the mapping of communicated resource locations. J Comp Physiol A 199: 1143–1152 https://doi.org/10.1007/s00359-013-0860-4. Accessed January 9, 2023.