Darwinian beekeeping

A fortnight ago I reviewed the first ten chapters of Thomas Seeley’s recent book The Lives of Bees. This is an excellent account of how honey bees survive in ‘the wild’ i.e. without help or intervention from beekeepers.

Seeley demonstrates an all-too-rare rare combination of good experimental science with exemplary communication skills.

It’s a book non-beekeepers could appreciate and in which beekeepers will find a wealth of entertaining and informative observations about their bees.

The final chapter, ‘Darwinian beekeeping’, includes an outline of practical beekeeping advice based around what Seeley (and others) understand about how colonies survive in the wild.

Differences

The chapter starts with a very brief review of about twenty differences between wild-living and managed colonies. These differences have already been introduced in the preceding chapters and so are just reiterated here to set the scene for what follows.

The differences defined by Seeley as distinguishing ‘wild’ and ‘beekeepers’ colonies cover everything from placement in the wider landscape (forage, insecticides), the immediate environment of the nest (volume, insulation), the management of the colony (none, invasive) and the parasites and pathogens to which the bees are exposed.

Some of the differences identified are somewhat contrived. For example, ‘wild’ colonies are defined fixed in a single location, whereas managed colonies may be moved to exploit alternative forage.

In reality I suspect the majority of beekeepers do not move their colonies. Whether this is right or not, Seeley presents moving colonies as a negative. He qualifies this with studies which showed reduced nectar gathering by colonies that are moved, presumably due to the bees having to learn about their new location.

However, the main reason beekeepers move colonies is to exploit abundant sources of nectar. Likewise, a static ‘wild’ colony may have to find alternative forage when a particularly good local source dries up.

If moving colonies to exploit a rich nectar source did not usually lead to increased nectar gathering it would be a pretty futile exercise.

Real differences

Of course, some of the differences are very real.

Beekeepers site colonies close together to facilitate their management. In contrast, wild colonies are naturally hundreds of metres apart 1. I’ve previously discussed the influence of colony separation and pathogen transmission 2; it’s clear that widely spaced colonies are less susceptible to drifting and robbing from adjacent hives, both processes being associated with mite and virus acquisition 3.

Abelo poly hives

50 metres? … I thought you said 50 centimetres. Can we use the next field as well?

The other very obvious difference is that wild colonies are not treated with miticides but managed colonies (generally) are. As a consequence – Seeley contends – beekeepers have interfered with the ‘arms race’ between the host and its parasites and pathogens. Effectively beekeepers have ‘weaken[ed] the natural selection for disease resistance’.

Whilst I don’t necessarily disagree with this general statement, I am not convinced that simply letting natural selection run its (usually rather brutal) course is a rational strategy.

But I’m getting ahead of myself … what is Darwinian beekeeping?

Darwinian beekeeping

Evolution is probably the most powerful force in nature. It has created all of the fantastic wealth of life forms on earth – from the tiniest viroid to to the largest living thing, Armillaria ostoyae 4. The general principles of Darwinian evolution are exquisitely simple – individuals of a species are not identical; traits are passed from generation to generation; more offspring are born than can survive; and only the survivors of the competition for resources will reproduce.

I emphasised ‘survivors of the competition’ as it’s particularly relevant to what is to follow. In terms of hosts and pathogens, you could extend this competition to include whether the host survives the pathogen (and so reproduces) or whether the pathogen replicates and spreads, but in doing so kills the host.

Remember that evolution is unpredictable and essentially directionless … we don’t know what it is likely to produce next.

Seeley doesn’t provide a precise definition of Darwinian beekeeping (which he also terms natural, apicentric or beefriendly beekeeping). However, it’s basically the management of colonies in a manner that more closely resembles how colonies live in the wild.

This is presumably unnnatural beekeeping

In doing so, he claims that colonies will have ‘less stressful and therefore more healthful’ lives.

I’ll come back to this point at the end. It’s an important one. But first, what does Darwinian mean in terms of practical beekeeping?

Practical Darwinian beekeeping

Having highlighted the differences between wild and managed colonies you won’t be surprised to learn that Darwinian beekeeping means some 5 or all of the following: 6

  • Keep locally adapted bees – eminently sensible and for which there is increasing evidence of the benefits.
  • Space colonies widely (30-50+ metres) – which presumably causes urban beekeepers significant problems.
  • Site colonies in an area with good natural forage that is not chemically treated – see above.
  • Use small hives with just one brood box and one super – although not explained, this will encourage swarming.
  • Consider locating hives high off the ground – in fairness Seeley doesn’t push this one strongly, but I could imagine beekeepers being considered for a Darwin Award if sufficient care wasn’t taken.
  • Allow lots of drone brood – this occurs naturally when using foundationless frames.
  • Use splits and the emergency queen response for queen rearing i.e. allow the colony to choose larvae for the preparation of new queens – I’ve discussed splits several times and have recently posted on the interesting observation that colonies choose very rare patrilines for queens.
  • Refrain from treating with miticides – this is the biggy. Do not treat colonies. Instead kill any colonies with very high mite levels to prevent them infesting other nearby colonies as they collapse and are robbed out.

Good and not so good advice

A lot of what Seeley recommends is very sound advice. Again, I’m not going to paraphrase his hard work – you should buy the book and make your own mind up.

Sourcing local bees, using splits to make increase, housing bees in well insulated hives etc. all works very well.

High altitude bait hive …

Some of the advice is probably impractical, like the siting of hives 50 metres apart. A full round of inspections in my research apiary already takes a long time without having to walk a kilometre to the furthest hive.

The prospect of inspecting hives situated at altitude is also not appealing. Negotiating stairs with heavy supers is bad enough. In my travels I’ve met beekeepers keeping hives on shed roofs, accessed by a wobbly step ladder. An accident waiting to happen?

And finally, I think the advice to use small hives and to cull mite-infested colonies is poor. I understand the logic behind both suggestions but, for different reasons, think they are likely to be to the significant detriment of bees, bee health and beekeeping.

Let’s deal with them individually.

Small hives – one brood and one super

When colonies run out of space for the queen to lay they are likely to swarm. The Darwinian beekeeping proposed by Seeley appears to exclude any form of swarm prevention strategy. Hive manipulation is minimal and queens are not clipped.

They’ll run out of space and swarm.

Even my darkest, least prolific colonies need more space than the ~60 litres offered by a brood and super.

Seeley doesn’t actually say ‘allow them to swarm’, but it’s an inevitability of the management and space available. Of course, the reason he encourages it is (partly – there are other reasons) to shed the 35% of mites and to give an enforced brood break to the original colony as it requeens.

These are untreated colonies. At least when starting the selection strategy implicit in Darwinian beekeeping these are likely to have a very significant level of mite infestation.

These mites, when the colony swarms, disappear over the fence with the swarm. If the swarm survives long enough to establish a new nest it will potentially act as a source of mites far and wide (through drifting and robbing, and possibly – though it’s unlikely as it will probably die – when it subsequently swarms).

A small swarm

A small swarm … possibly riddled with mites

Thanks a lot!

Lost swarms – and the assumption is that many are ‘lost’ – choose all sorts of awkward locations to establish a new nest site. Sure, some may end up in hollow trees, but many cause a nuisance to non-beekeepers and additional work for the beekeepers asked to recover them.

In my view allowing uncontrolled swarming of untreated colonies is irresponsible. It is to the detriment of the health of bees locally and to beekeepers and beekeeping.

Kill heavily mite infested colonies

How many beekeepers reading this have deliberately killed an entire colony? Probably not many. It’s a distressing thing to have to do for anyone who cares about bees.

The logic behind the suggestion goes like this. The colony is heavily mite infested because it has not developed resistance (or tolerance). If it is allowed to collapse it will be robbed out by neighbouring colonies, spreading the mites far and wide. Therefore, tough love is needed. Time for the petrol, soapy water, insecticide or whatever your choice of colony culling treatment.

In fairness to Seeley he also suggests that you could requeen with known mite-resistant/tolerant stock.

But most beekeepers tempted by Darwinian ‘treatment free’ natural beekeeping will not have a queen bank stuffed with known mite-resistant mated queens ‘ready to go’.

But they also won’t have the ‘courage’ to kill the colony.

They’ll procrastinate, they’ll prevaricate.

Eventually they’ll either decide that shaking the colony out is OK and a ‘kinder thing to do’ … or the colony will get robbed out before they act and carpet bomb every strong colony for a mile around.

Killing the colony, shaking it out or letting it get robbed out have the same overall impact on the mite-infested colony, but only slaying them prevents the mites from being spread far and wide.

And, believe me, killing a colony is a distressing thing to do if you care about bees.

In my view beefriendly beekeeping should not involve slaughtering the colony.

Less stress and better health

This is the goal of Darwinian beekeeping. It is a direct quote from final chapter of the book (pp286).

The suggestion is that unnatural beekeeping – swarm prevention and control, mite management, harvesting honey (or beekeeping as some people call it 😉 ) – stresses the bees.

And that this stress is detrimental for the health of the bees.

I’m not sure there’s any evidence that this is the case.

How do we measure stress in bees? Actually, there are suggested ways to measure stress in bees, but I’m not sure anyone has systematically developed these experimentally and compared the stress levels of wild-living and managed colonies.

I’ll explore this topic a bit more in the future.

I do know how to measure bee health … at least in terms of the parasites and pathogens they carry. I also know that there have been comparative studies of managed and feral colonies.

Unsurprisingly for an unapologetic unnatural beekeeper like me ( 😉 ), the feral colonies had higher levels of parasites and pathogens (Catherine Thompson’s PhD thesis [PDF] and Thompson et al., 2014 Parasite Pressures on Feral Honey Bees). By any measurable definition these feral colonies were less healthy.

Less stress and better health sounds good, but I’m not actually sure it’s particularly meaningful.

I’ll wrap up with two closing thoughts.

One of the characteristics of a healthy and unstressed population is that it is numerous, productive and reproduces well. These are all characteristics of strong and well-managed colonies.

Finally, persistently elevated levels of pathogens are detrimental to the individual and the population. It’s one of the reasons we vaccinate … which will be a big part of the post next week.


 

Which is the best … ?

It’s (slowly) approaching the start of the beekeeping season.

From draughty church halls across the land newly trained beekeepers are emerging (or eclosing, to use the correct term), blurry-eyed from studying their Thorne’s catalogues, desperate to get their hands on some bees and start their weekly inspections.

Their enthusiasm is palpable 1.

The start of the beekeeping season, any season, after the long winter is always a good time. Longer days, better weather, more light 🙂 . For current beekeepers we can stop fretting over stores or winter losses. The long days with plentiful forage are getting nearer. We’ll soon be doing inspections in our shirtsleeves and thinking about swarm prevention.

New beekeepers, those who haven’t had to worry about Storm Ciara wrecking their apiaries or subsequent flooding washing hives away, simply want to get started as soon as possible.

Moving to higher ground ...

Moving to higher ground …

But, of course, they want to do things properly.

They don’t want to cut corners, they don’t want to skimp or make false economies. They want the best for their (as yet, non-existent) bees.

They’re committed and serious and determined to make a success of beekeeping … and get a great honey crop.

It needs to be great as they’ve already ‘promised away’ half of it to friends and family 🙂

Which is the best …?

If you look on the online beekeeping discussion fora, or questions to the BBKA Q&A monthly column or listen to discussions at local association meetings, many start with the words “Which is the best …”.

Which is the best hive, the best strain of bees, the best fuel for your smoker etc.

These questions reflect a couple of things:

  1. A lack of experience coupled with an enthusiasm to properly care for their charges.
  2. The generally misguided belief that these things make any substantive difference to the welfare or productivity of the bees.

Neither of these are criticisms.

All beekeepers should want the best for their bees.

Inexperienced beekeepers don’t know what works and what does not work, but they want to ensure that – whatever they do – the bees do not suffer (or fail to thrive).

They want the best bees, presumably defined as those that are calm, frugal, populous and productive and they want the best hive so these bees are warm enough in winter and cool enough in summer, or have enough space, or are easiest to manipulate, or best resembles a tree trunk.

And the smoker fuel should be the best so that it’s easy to light, never goes out and calms the bees quickly.

The best smoker fuel

Logic dictates that if there was a ‘best’ smoker fuel then almost everyone would be using it.

The septuagenarian ‘expert’ with 50 years experience would have said “Stuff your smoker with XYZ” when describing hive inspections on the beginners course. Other experienced beekeepers around the room would nod sagely and that would be the end of the matter.

If a beginner were to ask “Why don’t you use hessian rather than XYZ?” over a cuppa and a digestive afterwards there would be an awkward silence and a simple “Because XYZ is the best smoker fuel you can use” response.

The group would then move on to talk about something else.

Fuel bucket

XYZ …

And that happens … precisely never.

What actually happens is that eight beekeepers (with varying levels of expertise) contribute eleven different opinions of their personal view of the ‘best’ smoker fuel.

The only thing vaguely in common in these opinions is that some of the recommended fuels burn.

Note that I said ‘some’ 😉

The point I’m trying to make is that the ‘best’ smoker fuel does not exist. It’s what works for you when you need it … dried horse manure (yes, really), grass, wood chips, Thorne’s cardboard packaging, rotten dried wood etc.

It’s what’s in your bag, it’s what you carefully collected last month, it’s what you find in the car glove compartment when you can’t find anything else.

If it burns – ideally slowly and gently – producing good amounts of smoke, if it’s easy to light, light to carry, stays lit and is available when you need it, it’ll do.

The best hive

I’ve previously discussed the ridiculously wide range of hives and frames available to UK beekeepers.

Knowing that, or spending just half an hour perusing the Thorne’s catalogue, shows that there is clearly no ‘best’ hive. Any, and probably all, of the hives work perfectly satisfactorily. In the right conditions and with sympathetic and careful beekeeping all are capable of housing a colony securely and productively.

It’s the hive type that is compatible with those used by your mentor 2, it’s the type you have a stack of in the corner of the shed, it’s what you can borrow at short notice when you’ve run out of broods or supers.

It’s what’s available in the end of season sales or it’s what you started with (or your mother started with) and it ‘just works’.

If there was a best hive type, or hive tool or smoker fuel the Thorne’s catalogue would be about 3 pages long.

It’s not, it’s approaching 100 pages in length, with 12 pages of hive types alone (including a nice looking Layens hive). The 2020 catalogue has even more hive tools than the seventeen I counted in 2019 🙁

If there’s no ‘best’, will anything do?

Just because there might not be the perfect hive, smoker fuel or hive tool does not mean that it doesn’t matter what you use.

There are some that are unsuitable.

Smoker fuel that doesn’t stay lit, or that burns too fiercely. Hive tools with blunt edges, or that rust badly and are difficult to sterilise, or that bend 3. Hives with incorrect dimensions, ill-fitting floors, overly fussy designs or a host of other undesirable ‘features’.

Just because there’s no single best whatever definitely does not mean that anything will do.

Anthropocentrism

But, before we move on, note that all the things I used to define a smoker fuel or hive as ‘the best’ were anthropocentric 4 criteria.

It’s what suits us as beekeepers.

And, since there are a wide range of beekeepers (by education, age, height, intellect, shoe size, strength, wealth, petty likes and dislikes etc.) there is inevitably a very wide choice of stuff for beekeeping.

Which also emphasises the irrelevance of the ‘best type of ‘ question.

The full version of the question is “Which is the best type of hive tool for beekeepers” 5.

But what’s best for the bees?

None, or any, of the above.

Clearly no single hive tool is better than any other as far as the bees are concerned.

Take your pick ...

The bees do not care …

Likewise, as long as the smoker fuel generates cool, not-too-acrid, smoke, as far as the bees are concerned it’s just smoke. It masks the smell of the alarm pheromones and encourages the bees to gorge on honey, so they remain calm. Used judiciously, which is nothing to do with the fuel and everything to do with the beekeeper, one type of smoker fuel should be as good as any other.

And the same thing applies to hives. Assuming they’re secure, wind and watertight, large enough to fill with stores, have a defendable entrance and proper bee space around the frames, they’ll suit the bees perfectly well.

Think about the trees that wild-living bees naturally choose … do they prefer oak or lime, tall chimney-like cavities or largely spherical hollows?

Oak … preferred by bees. Or not.

Do they do better in one species of tree over another, one shape of space over another?

No.

Doing better …

How do we tell if the bees are ‘doing better’ anyway?

We can’t ask them.

We cannot, despite the assurances of the so-called bee-centric or bee-friendly beekeepers, tell whether they’re happy or not.

I’m a very bee-friendly beekeeper, but I don’t anthropomorphize and attribute feelings like happy or sad to my bees 6.

I determine whether a colony is doing well (or better) by very similar criteria to those you would use to judge whether a colony in a tree was flourishing.

Are they building up well, are they storing sufficient pollen and honey stores, is there overt disease, are they going to swarm?

The hive tool, smoker fuel or any one of a dozen or more hive types, have little or no influence on these measurable definitions of ‘doing well’.

What is it that determines the success or otherwise of a colony?

Essentially it comes down to two things – forage and colony health.

Bees ‘do well’ when they have ample and varied forage and when they are (largely) free of disease 7.

A healthy colony with ample forage will do better irrespective of the hive tool, hive type or smoker fuel used. You could house them in a plastic dustbin, prize the lid off with a screwdriver and waft a smouldering egg box across the entrance and they’ll still ‘do well’.

Egg box smoker

Smouldering egg box …

Conversely, put a disease-weakened colony in an area of poor forage and they’ll do badly (probably very badly) … again irrespective of the hive type, tool or smoker fuel.

Good forage does not just mean lots of it (though that helps). It means early-season pollen for colony build-up, it means late-season nectar and pollen to help develop a strong population of winter bees, it means a varied diet and it means season-long availability.

A healthy colony is one that has no overt disease. It has low levels of parasites and pathogens 8 and is able to survive periods of nectar shortages without succumbing to disease. In addition, it is resilient and genetically diverse.

And so back to those eclosing trainee beekeepers … the real ‘best’ questions they should be asking are:

  • Where is the best place to site my colonies to ensure good, season-long forage availability?
  • How to I best keep my colonies as disease-free as possible so that they can exploit that forage?

Focusing on these questions will help ensure the honey crop really is great so you can provide all those friends and family with the jars they have been promised 😉

Exceptions to the above

Inevitably there are exceptions.

It wouldn’t be beekeeping without qualifications and caveats.

The best bees are almost certainly local bees. There are several studies that demonstrate locally-adapted bees do better than imported bees. This does not mean that imported (and not necessarily from abroad) bees cannot do well. I’ve discussed some of these studies recently.

Finally, whilst the smoker fuel is irrelevant, the smoker is not.

The best smoker is the large Dadant smoker. The small Dadant is pretty good, but the large one is the bee’s knees 9.

Large Dadant smoker

I know, because my happy bees told me so 🙂


 

 

The Lives of Bees

The Lives of Bees

The untold story of the honey bee in the wild by Thomas D. Seeley, Professor of Biology at Cornell University.

Well, not quite untold, but this is a highly informative and entertaining book about the biology of honey bees living wild, primarily in the Arnot Forest, near Ithaca in the Finger Lakes region of New York.

Thomas Seeley conducts simple, elegant experiments to address interesting or important questions about bees. He then presents the studies and the conclusions in an easily understandable form, unencumbered by statistical mumbo-jumbo or extensive caveats and qualifications. 

This makes the work very accessible, even for those with no scientific training. You don’t even need extensive knowledge of honey bees; he explains the background to the experiments in sufficient detail that they are comprehensible without lots of prior knowledge.

For this reason, this is an ideal book to introduce a new beekeeper to the biology of bees.

However, for reasons to be covered separately, I think the suggestions it makes on practical beekeeping is very poor advice for the new beekeeper 🙁

A three part story

Essentially the book is in three parts, divided into eleven chapters.

After a general introduction there are three chapters that provide a historical perspective to the bees in the Arnot Forest and, more generally, to beekeeping. Not the practical aspects of beekeeping, but the interaction of humans and bees over tens of thousands of years.

The Beekeepers and the Birdnester by Pieter Bruegel (c. 1568)

Chapters 5 to 10 cover key aspects of the biology of the colony. These are:

  • the features that influence selection of a nest site
  • an overview of the annual cycle; spring build up, overwintering etc.
  • colony reproduction i.e. swarming
  • thermoregulation of the colony
  • collection of pollen, nectar and water – the food and stores needed for survival
  • defence of the colony – from microscopic viruses to (distinctly) macroscopic black bears

The final chapter – Darwinian beekeeping – contains Seeley’s suggestions for changes to beekeeping practice, informed by the observations presented in the six preceding chapters.

I’ll discuss Darwinian beekeeping another time as it deserves a post of its own.

Something for everyone

Each chapter is accompanied by a couple of pages of explanatory notes and there is a 19 page bibliography should the reader want to consult the primary sources.

An interested lay person could spend hours enjoyably reading about the biology of wild-living honey bees without ever consulting the notes or references. These don’t litter the text, making the book very much more accessible to those unused to the sort of cite-every-statement-to-avoid-offending-the-peer-reviewers style of writing that plagues most reviews (Bloggs et al., 1929b).

Alternatively, if you really do want to find out the original source you usually can, by consulting the notes and the references. Inevitably some things are missed, but that’s the nature of an eminently readable tome covering about a million years of Apis mellifera biology, 4500 years of beekeeping and at least 300 years of scientific observations about bees.

One of the great aspects of Seeley’s writing is that things are often presented with reference to some long-lost study which would otherwise have been forgotten.

A couple of weeks ago I discussed the importance of checking hive weights at this time of the year. The rate of stores usage increases significantly as more brood is reared. How do we know this increased rate of stores usage is due to increased brood rearing, rather than just correlating with it?

Seeley presents his data on colony weight changes but does so with reference to Clayton Farrar’s study of brood rearing by colonies lacking pollen in the 1930’s. These used only half as much of their stores because brood rearing needs pollen. Farrar’s study was published in the American Bee Journal in 1936.

There are several examples in the book where modern molecular studies are juxtaposed with some of the great observational science of the first part of the 20th Century. As someone involved daily at the gene-jockey end of science, this historical perspective alone makes the book worth purchasing.

Wild vs. domesticated bees

Throughout the book Seeley focuses on bees living in the wild i.e. without help intervention from beekeepers. His contention is that it is only by studying bees in their natural habitat that we’ll be able to properly understand what they need to survive and thrive when managed.

Seeley has studied bees in the Arnot forest for at least 40 years. He can therefore provide a ‘before and after’ view of the impact of the introduction of Varroa which probably occurred in the early 1990’s. Surprisingly, the overall number and density of colonies living in the forest in the 1970’s is about the same as it is now. This is discussed in several places in the book.

How can wild bees cope with the mites that, uncontrolled, generally destroy a hived colony within a year or two? His explanations of this is the underlying thread running through much of the book and the primary topic of the final chapter.

Are bees domesticated? This topic gets an entire chapter of its own. The genetic changes that species undergo during domestication 1 are not seen in honey bees.

Although perhaps not ‘domesticated’, through environmental manipulation we have significantly changed our relationship with bees. We now determine the size of the colony (or at least the space it has). By moving or manipulating the hive we influence what it produces (e.g. propolis, Royal Jelly, heather honey). We also control whether or not it reproduces. Indeed, most beekeepers try to stop their colonies reproducing (swarming) as it results in the loss of bees, and honey.

Throughout the book comparisons are made between the choices ‘wild’ bees make and the choices made for them by beekeepers. For example, the thermal conductivity of the hives used by beekeepers compared with a nest in a tree trunk.

Untold?

Not really.

The strapline on the front of the book indicates that this is the untold story of the honey bee in the wild.

In reality it’s not.

More accurately it’s a very readable compendium of studies published by Seeley and others over the last century or so.

But that’s hardly going to make copies of this £25 book fly off the shelves, so ‘untold’ it is.

In fact, several aspects of the biology of the wild-living honey bee will be familiar to readers of this site. I’ve covered studies by Seeley in discussion of bait hives, drifting, robbing, polyandry and mites in swarms. A quick search turns up ~25 posts in which he gets a mention.

In addition, anyone who is fortunate enough to have already read Honeybee Democracy will be familiar with many bits in the chapter that cover nest site selection. Similarly, the bee lining methods used to locate nests in the Arnot forest have been described in exhaustive detail in his previous book Following the Wild Bees.

Don’t let this put you off.

Honeybee Democracy takes ~250 pages to describe in exhaustive (but still entertaining) detail how swarms choose new nest sites. This topic, together with all sorts of fascinating stuff on comb building and propolis, takes just part of the 40 page ‘Nest’ chapter of The Lives of Bees.

Bee·lining box, in cutaway view to show construction detail.

Similarly, the mechanics of bee lining don’t really get described in the new book, but the wild-living nests discovered using this method feature throughout.

Recommended?

Absolutely. It’s an excellent book.

But be aware that, in addition to a comprehensive account of how bees live in the wild, there’s an agenda here as well.

The sleeve notes (does anyone really read these?) include the words ” … and how wild honey bees may hold the key to reversing the alarming die-off of the planet’s managed honey bee population”.

Global beehive numbers 1968 – 2018

What alarming die off?

The graph above is of the global total of beehive numbers over the last 50 years or so. During this period the number has increased by ~1.7 times.

Of course, there are more beekeepers over the last 50 years (and the global population has more than doubled). This increased number of beekeepers are having to work harder to maintain (and increase) the stocks they manage.

But increasing they are … 2

It is therefore both inaccurate and an oversimplification to claim that there’s an alarming die-off in honey bee colonies.

Perhaps the sleeve notes are just to help boost sales?

Something a bit spicy to entice the browser to think that the book they are holding contains the ‘untold’ secrets to ‘saving the bees’?

Save the bees … save humanity

It’s not the first time ‘Save the bees … save humanity’ has been used as a marketing ploy 3. Here’s a graphic I regularly use to introduce my talks on rational Varroa control.

Save the bees ...

Save the bees …

Pity the image is of a wasp 🙂

Again, don’t let these minor errors in the sleeve blurb put you off.

Whatever the relevance to practical beekeeping (or reversing the “alarming die-off”), the first ten chapters provide the best overview of the lives of wild-living honey bees written by an acknowledged master of science communication.

I read a lot of stuff about honey bees, for work and pleasure.

The Lives of Bees had a wealth of information I was unaware of.

Buy it, or borrow it from your library … you won’t be disappointed.


 

Vaccinating bees

Brace yourselves. There’s some heavyweight science this week.

I’m going to discuss a very recent publication 1 on vaccinating bees against parasites and pathogens.

The paper involves a whole swathe of general concepts many readers will have some familiarity with – vaccines, immunity, infections, parasites, the gut microbiota 2 – which, because the paper is about bees, bear little recognisable relationship in the details.

And the devil is in the detail.

The paper appears to offer considerable promise … but I’ll return to that later.

To start with, let’s begin with measles.

Measles

Measles is a virus. It is highly contagious – typically being transmitted by coughing or sneezing – and causes a characteristic rash. Complications associated with measles infections – pneumonias, encephalitis and other respiratory and neurological conditions – are responsible for a case fatality rate of ~0.3% in the USA, or up to 30% in populations that are malnourished or have high levels of immune dysfunction.

Sixteenth century Aztec drawing of a measles victim

In 1980, 2.6 million people globally died of measles. That’s about five people (mainly kids) a minute 3.

By 2014 this figure had dropped to 73,000 due to a global vaccination campaign.

The measles vaccine is excellent. It is an attenuated (weakened) strain of the virus that is injected. When it replicates it produces all of the measles virus proteins. These are not naturally found in the human body, so the vaccinee 4 recognises them as foreign and produces an immune response that eventually stops the vaccine growing.

The really important thing about the immune response is that it lasts i.e. it has a memory. If the vaccinated individual is exposed to a virulent strain of measles in the future the immune response ‘wakes up’ and stops the virus replicating.

This immune response is effectively lifelong.

One important component of the immune response are antibodies. These are proteins that specifically recognise the measles virus, bind to it and lead to its destruction.

If you’ve been vaccinated (or have survived a previous infection) and subsequently get infected your body produces lots of antibodies which destroy the incoming strain of the measles virus, so protecting you (but this immune response is very specific … the response to measles does not protect you from poliomyelitis or coronavirus or mumps.).

OK, enough about measles 5.

Bees don’t have antibodies

The point about the stuff on measles was to introduce the principles of a protective immune response.

It has several characteristic features, including:

  • highly specific
  • destruction of the incoming pathogen
  • longevity (memory)

In humans, all of the above are provided by antibodies 6.

Bees don’t have antibodies, but they do have an immune response which has all of the characteristic features listed above.

The immune response of bees uses nucleic acids 7 which are common chemical molecules found in the bodies of all living things. Specifically bees use ribonucleic acid (RNA) that interferes with the nucleic acids of invading pathogens.

RNAi

To make ribonucleic acid (RNA) that interferes easier to say it is abbreviated to RNAi 8.

RNA is made up of individual building blocks called nucleotides. There are four nucleotides, with names abbreviated to A, C, G and U. These join together in long strands e.g. ACGUUGUGCAG … the order (or sequence) of which has all sorts of important biological functions we don’t need to worry about for the purposes of vaccinating bees.

Pairs of nucleotides in different strands have the ability to bind together – A binds to U, G binds to C or U. Individually, these bonds are weak. When lots occur close together they are much stronger and therefore very specific.

For example, the sequence ACGUUGUGCAG binds very well to UGCGACGCGUU. In contrast, it binds very much less well to CGUUAGCAUUG (just count the vertical bars which indicate each of the weak bonds between the nucleotides in the two strands. The left hand pair bind tightly, those on the right do not).

                         ACGUUGUGCAG          ACGUUGUGCAG
                         |||||||||||           || | | 
                         UGCGACGCGUU          CGUUAGCAUUG

Finally, these short RNAs interfere when they bind very well to their target sequence.

What does that mean?

In the cartoon above, imagine the text in red represents the RNAi and the text in blue represents part of the RNA genome of deformed wing virus (DWV), the most significant viral pathogen of honey bees 9.

The specific binding of RNAi to its target sequence recruits enzymes that result in either the destruction of the target, or the impairment of its functionality.

RNAi binding to DWV results in the inactivation and eventual destruction of the virus genome.

Virus replication is therefore stopped.

This is a ‘good thing’.

“Foreign”

Before we get on to vaccinating bees I have one final thing to explain.

How does the bee ‘know’ it is infected with DWV (or a similar viral pathogen) and how is the RNAi actually made?

OK, that’s two things, but they’re actually closely related to each other.

I said earlier that our bodies recognise the proteins that the measles virus (or vaccine) produces as ‘foreign’ i.e. something not normally present in the body. It turns out that many organisms – including bees – have evolved specific ways of detecting double stranded RNA as a ‘foreign’ entity.

Double stranded RNA (dsRNA) is made when RNA viruses replicate, but it is never normally present in the cells of a healthy bee. Therefore if the bee detects dsRNA it ‘knows’ it is infected and it induces an immune response … specifically an RNAi-mediated immune response.

The dsRNA is recognised by a protein called Dicer which cuts up the double stranded RNA into smaller duplex RNAi molecules, one of the pair of these then associates with additional proteins (including Argonaute; Ago 10) to form the RNA induced silencing complex (RISC).

RISC, which includes the RNAi, binds to the specific target e.g. the genome of other DWV viruses, and chops it up and destroys it.

The mechanism of RNAi-mediated silencing

Finally, because RNAi is a small molecule it can easily move from cell to cell. So RNAi made in one cell can move to regions of the bee some distance away.

Phew … OK, that’s the end of the whistle-stop introduction to RNAi and insect immunity 11.

Vaccinating bees

It’s been known for some time that you can directly introduce RNAi into bees and reduce the levels of some of the viruses present.

Frankly the data on DWV has not been great, but there are reasonably compelling studies of reductions in Israeli Acute Paralysis Virus (IAPV) levels and even field trails showing benefits at the colony level.

In these studies you either inject individual bees with RNAi, or you feed them large amounts of sugar syrup containing huge amounts (in value) of RNAi.

Neither of these routes is practically or financially viable.

Injecting individual bees takes a very long time 12. You need to anaesthetise the bee with CO2 or by chilling it on ice. It’s pretty tough on the bee and not all survive the anaesthetic or the injection. You need good lighting, good eyesight and a very small needle. It’s obviously a non-starter.

What about feeding? Syrup feeding is incompatible with honey production. It’s also a rather inefficient way to deliver RNAi. RNA is a very sensitive molecule. It is easily damaged. If it has to sit around in syrup for a few days, get collected by the bee, stored in the honey stomach, regurgitated and passed to another bee etc. there’s a risk it will be inactivated.

And it’s very expensive to produce …

The gut microbiota

Which in a really roundabout way brings us to this recent study by Leonard et al., published at the end of January in the prestigious journal Science

Leonard et al., (2020) Science 367, 573-576

In this study, the authors have modified a harmless bacterium normally present in the honey bee gut so that it produces double stranded RNA specific for DWV. This bacterium, specifically called Snodgrassella alvi, is a present in the gut of all bees. It is a core member of the gut microbiota, the bacterial population present in the honey bee gut.

The concept is relatively simple, but the science is pretty cool.

The bacterium sits around in the honey bee gut producing DWV-specific RNAi. If the bee gets infected – through feeding or injection, for example by Varroa – the RNAi (which has diffused around the body of the bee) is ready and waiting to ‘silence’, through RNA interference, the replicating DWV genome.

The bee remains healthy and happy 13.

But there’s more … Snodgrassella alvi is presumably passed from bee to bee during feeding (of larvae or adult workers). Therefore the RNAi-expressing version should naturally spread through a colony, protecting all the bees. In addition, because it is present throughout the life of the bee, a genetically engineered form of the bacterium should provide the longevity that is characteristic of a protective immune response.

So, does it work?

The paper includes lots of introductory studies. These include:

  • demonstrating that engineered Snodgrassella alvi – which for pretty obvious reasons I’ll abbreviate to S. alvi for the rest of this post – colonises the bee gut and could be spread from bee to bee.
  • the introduced bacterium produces double strand RNA (dsRNA) precursors of the RNAi response.
  • that dsRNA produced in the bee gut spreads to other areas of the bee body.
  • and that the presence of dsRNA upregulates components of the immune response.
  • the demonstration that it was possible to control host gene expression using this dsRNA 14.

I’m going to return to some of these points in a future post (this one is already too long) as there are both promising and disturbing features buried within the data.

Let’s cut to the chase …

Symbiont-produced RNAi can improve honey bee survival after viral injection.

Seven day old adult worker bees were fed with S. alvi expressing RNAi to DWV or to an irrelevant target (GFP). Seven days later some were injected with DWV (solid lines in the graph above), others were injected with buffer alone (dashed lines).

In the 10 days after injection about 25% of the bees injected with buffer died. This reflects the ageing of the bees and the attrition rate due to handling in the laboratory.

About 75% of the bees ‘vaccinated’ with S. alvi expressing GFP RNAi or no RNAi died after DWV challenge over the 10 day period.

In contrast, only ~60% of the S. alvi bees expressing DWV-specific RNAi died. This is a relatively small difference, but – because the experiment was conducted with lots of bees – is statistically significant.

Killing mites

The results presented above are promising but the authors also explored the logical extension of this work.

If the RNAi produced by the engineered S. alvi becomes widely distributed in the honey bee, perhaps it also could also taken up when Varroa feeds on the bee?

In which case, if you engineered S. alvi to produce Varroa-specific RNAi’s, perhaps this would help kill mites.

Symbiont-produced RNAi kills Varroa mites feeding on honey bees

It does.

Using a similar ‘vaccination’ schedule as above, only ~25% mites exposed to bees carrying S. alvi expressing Varroa-specific RNAs’s survived 10 days, whereas 50% of mites survived when feeding on bees carrying non-specific engineered strains of S. alvi.

Again, this is encouraging.

Only encouraging?

Yes, at the moment, only encouraging.

Don’t get me wrong, this is pretty fancy technology and the results represent a lot of very laborious and elegant experiments.

At 2100 words this post is already too long … so here are a few things to think about which help justify my qualified enthusiasm for the paper.

  1. Although I didn’t show the data, transmission of engineered S. alvi between bees was rather inefficient. Over 5 days, only 33% of naive co-housed bees demonstrated infection with the modified symbiont. Why might this be an issue? Alternatively, is transmission between adult bees important? When might it be important to not transmit between adult bees?
  2. None of the experiments included any virus quantification. Did the bees that didn’t die after DWV injection challenge have lower DWV levels? If not, why not? What is the mechanism of protection?
  3. Actually, there were some virus quantification studies buried in the Supplementary data. In these the authors showed that virus levels were lower in all bees carrying engineered S. alvi, even those expressing the GFP negative control RNAi. This suggests a non-specific up-regulation of the immune response.
  4. All the challenge experiments were done with 7 day old worker bees. Are these the bees we really need to protect from DWV? Why didn’t they do any studies with larvae and pupae? These are much easier to handle and very much easier to inoculate. And very much more relevant in terms of virus-mediated colony losses.
  5. What other species sharing the environment with honey bees carries S. alvi? Why should this matter? Snodgrassella is a gut symbiont of honey bees and lives in the ileum. Is it present in honey bee faeces?

I’ll post a follow-up in the next few weeks to discuss some of these in further detail.

Congratulations to those of you who have got this far … don’t get rid of your Apivar and oxalic acid stocks just yet 😉


 

Weight for spring

I’m currently reading The Lives of Bees by Thomas Seeley. It’s a very good account of honey bee colonies in the wild.

In the book Seeley describes studies he conducted in the early-80’s on the changes in weight of unmanaged colonies during the season 1.

One particular figure caught my attention as I was off to the apiary to heft 2 some hives and check on the levels of stores.

Colony weight (top) and weekly weight change (lower). Black arrows midwinter, red arrows early spring.

The upper panel shows the overall hive weight over a period of ~30 months, including three successive winters. I’ve butchered annotated the figure with black arrows to mark the approximate position of the winter solstice and added red arrows to indicate early spring (approximately mid-February i.e. about now) 3.

Look carefully at the slope of the line. In each year it steepens in early spring.

Shedding pounds

During the winter the colony survives on its reserves. There’s no forage available and/or it’s too cold to fly anyway, so the colony has to use honey stores to keep the worker bees alive.

In late autumn and early winter they can get by using minimal amounts of stores, just sufficient to keep metabolic activity of the bees high enough to maintain a cluster temperature of ~10°C.

All of this uses stores and so the colony gradually loses weight.

Frosty apiary

Frosty apiary

The weekly weight gained and lost is shown in the lower panel. In 1981/82, with the exception of a tiny weight gain in late August, the colony lost weight every week from mid-July until mid-April (9 months!).

But from mid-April to early-July the colony literally piles on the pounds 4.

To achieve this they need a strong population of worker bees. It’s not possible to collect that much nectar with just a few thousand bees. The colony must undergo a large population expansion from the 5,000-10,000 bees that overwintered the colony to a summer workforce of 30,000+.

This expansion is not simply the addition of a further 20,000 bees. At the same time as the new workers are emerging the winter bees are dying off. The colony therefore needs to rear significantly more than 20,000 bees to be ready to exploit the summer nectar flow.

And, since it takes bees to make bees this means that the colony must rear repeated cycles of new workers starting in very early spring.

But you can’t rear brood at 10°C

Brood rearing requires a cluster temperature of ~35°C. This is achieved by the bees raising their metabolic activity, repeatedly flexing their flight muscles and generating heat.

All of which uses lots of energy … which, in turn, is derived from the honey stores.

Which explains why, in early spring, the rate at which stores are consumed suddenly increases. And the rate at which the colony uses the stores is the weight lost per unit time i.e. the slope of the graph shown above, or below for emphasis.

Colony weight in early spring

Of course, some of the honey stores are also consumed by the developing larvae. How much presumably depends upon the amount of brood being reared and the external temperature.

Less brood requires less honey stores. Lower temperatures mean more energy must be expended to keep the brood at 35°C, so more stores are used.

Rearing brood also requires protein (pollen). Nearly 90 years ago Clayton Farrar studied the spring weight loss of colonies in Wisconsin maintained with or without pollen stores. Colonies unable to rear brood because they lacked pollen used ~50% less stores over the same period.

Thermoregulation is energetically costly and colonies must raise the temperature of the cluster to ~35°C in very early spring to rear sufficient brood to exploit the late spring nectar sources 5. They need to maintain these elevated temperatures – using yet more stores up – until the spring nectar flows start.

The danger zone

All of which means that we’re currently approaching the danger zone when colonies are much more likely to starve to death if they have insufficient stores.

The next six to eight weeks or so are critical.

If they have ample stores they will rear plenty of brood.

Clear evidence for brood rearing on trays under colonies in the bee shed

If they have borderline levels of stores they might be able to maintain viability of the colony, but they’ll only achieve this by not rearing brood 6.

If they start brood rearing and then run out of stores they will likely starve to death.

Winter chores

Every couple of weeks I check all of my colonies.

I confirm two things:

  • the entrance is clear i.e. not blocked with the corpses of dead bees.
  • the colony has sufficient stores for another few weeks.

This takes no more than one minute per colony and can be done whatever the weather, or even at night if you cannot get to the apiary in the short daylight hours.

Bent bicycle spoke to keep entrances clear

The floors I favour have an L-shaped entrance tunnel which during extreme periods of confinement can get blocked with dead bees. A quick scrape with a bent piece of stiff wire clears them away.

Even ‘normal’ entrances should be checked as it’s surprising the number of corpses that can accumulate, particularly after a long period of very adverse weather when no undertaker bees are flying.

As an aside, assuming no brood rearing, a colony entering the winter with 25,000 bees will likely lose an average of ~150 bees a day before brood rearing starts again in earnest. They will not be lost at the same rate throughout the winter. Do not worry about the corpses (though it’s worth also noting that a strong, healthy colony should clear these).

Hefting the hive

The weight of the hive can be determined in at least three different ways:

  1. wealthy beekeepers will use an electronic hive monitoring system with integral scales. No need even to visit the apiary to check these 😉 Where’s the fun in that?
  2. thorough beekeepers will use set of digital luggage scales to weigh each side of the hive, summing the two figures and noting the total carefully in their meticulous hive records.
  3. experienced beekeepers will briefly lift the back of the hive off the stand and decide “Hmmm … OK” or “Hmmm … too light”. This is termed hefting the hive.

If this is your first winter I strongly recommend doing the second and the third method every time you visit your apiary.

The second method will provide confidence and real numbers. These are what really count.

Hefting the hive for comparison will, over time, provide the ‘feel’ needed to judge things without a set of scales.

Over time you’ll find you can judge things pretty well simply by hefting. I do this 7, but only after removing the hive roof. I’ve got a variety of roofs in use – deep cedar monstrosities, dayglo polystyrene and lots of almost-weightless folded Correx – which, coupled with the variation in the number of boxes and the material they’re made from, complicates things too much.

Without the roof I find it a lot easier to judge.

Hmmm … too light

Anything that feels too light needs a fondant topup as soon as possible.

If you even think it feels too light it’s probably wise to add a block of fondant.

You need to use fondant as it’s probably too cold for bees to take down syrup. Fondant works, whatever the weather.

How much fondant should you add?

Look again at the hive weight loss per week in the early months of the year in the lower panel of the first graph. These colonies lost at least 1-1½ lb per week.

When will you next check them?

Do the maths as they say …

If you check them fortnightly you really need to add 1-2 kilograms which should be sufficient to get them through to the next check. Do not mess around with pathetic little 250g blocks of clingfilm-wrapped fondant. They might use that in three days …

You also don’t want to be opening the hive unnecessarily. Add a good-sized block and let them get on with things.

Recycle

Loads of supermarket foods are supplied in a variety of clear or semi-translucent plastic trays – chicken, mushrooms, tortellini, curry ready meals etc 8. Throughout the season I wash these out and save them for use with the bees.

I stressed clear and semi-translucent as it helps to be able to tell how much of the fondant the bees have used up when you’re trying to judge whether they need any more.

Waste not, want not

Many of these trays are about 6″ x 4″ x 2″ which when packed with fondant conveniently weighs about a kilogram. I fill a range of these with fondant, cover them with a single sheet of clingfilm and write the weight on the clingfilm with a black marker pen.

Location, location, location

In the winter the goal should be to locate the fondant block as close as possible to the cluster.

This means directly over the cluster.

Not way off to one side because there are fewer bees on the top bars that are in the way.

There’s no point in adding fondant if you also force the bees to move to reach it.

You’ll need an eke (or a nice reversible, insulated crownboard) to provide the ‘headspace’ to accommodate the fondant block 9.

Fondant block directly over the top of the cluster (in this case on a queen excluder)

Don’t delay.

Don’t wait for a ‘nice’ day.

You’ve decided the colony is worryingly light so deal with it there and then.

Remove the roof and the crownboard. If it’s cold, windy or wet the bees are going to be reluctant to fly. Don’t worry, you’re helping them. You’ll do more harm by not feeding them than by exposing them to the elements for 30 seconds 10.

Remove the clingfilm entirely 11 and invert the plastic tub directly over the top of the cluster.

Add the eke. Replace the crownboard, the top insulation and the roof.

Job done.

Crownboards with holes and queen excluders

Some crownboards have holes in them. Often these in the centre of the board.

It’s often recommended to add the fondant block above the hole in the crownboard. I think it’s better to place the fondant directly onto the top bars for the following reasons:

  • the central hole in the crownboard is probably not above the cluster 12. Why give them more work to do to collect the stores you’re providing?
  • it’s cold above the crownboard. The bees are less likely to venture up there if it’s chilly and uninviting.
  • fondant deliquesces (absorbs moisture) and can get distinctly sloppy when located in the humid headspace above the crownboard. In contrast, if the fondant is on the top bars of the frames any moisture absorbed softens the fondant surface at exactly the point where the bees are going to eat it anyway.

Finally, if there’s any reason you need to go through the brood box (before the fondant is finished) place the fondant on top of a queen excluder directly over the frames. Fondant has a tendency to stick down firmly to the top bars and it’s a nightmare to remove it to get to the frames. In contrast, if it is on a queen excluder you can easily lift it off.

You might not need to do this, but I learnt the hard way 🙁


 

Who’s the daddy?

I’ve recently discussed the importance and influence of polyandry for honey bee colonies. Briefly, polyandry – the mating of the queen with multiple (~12-18) drones – is critical for colony fitness e.g. ability to resist disease, forage efficiently or overwinter successfully.

Hyperpolyandry, for example resulting from instrumental insemination of the queen with sperm from 30+ drones, further increases colony fitness and disease resistance.

How do you measure polyandry?

Essentially, you genetically analyse the worker bees in the colony to determine the range of patrilines present. Patrilines are genetically distinct offspring fathered by different drones. Essentially they are subfamilies within the colony.

With a finite number of patrilines – which there must be, because the queen does not mate with an infinite number of drones – there will be a point at which the more workers you screen the fewer new patrilines will be detected.

Search and ye shall find – detecting rare patrilines

The more you screen, the more you are likely to have detected all the patrilines present.

However, the queen uses sperm randomly when fertilising worker eggs. This compounds the difficulty in determining the full range of different patrilines present in a population. In particular, it makes detecting very rare patrilines difficult.

For example, if 20% of workers belong to one patriline you don’t need to sample many bees to detect it. In contrast, if another patriline is represented by 0.0001% of randomly selected workers you would probably have to screen thousands to be sure of detecting it.

Consequently, rare patrilines in the honey bee worker population are very difficult to detect. Inevitably this means that the number of drones the queen mates (~12-18) with is probably an underestimate of the actual number 1.

Half-sisters and super-sisters

Worker bees are often described as ‘half sisters’ to each other. They share the same mother (the queen), but different fathers.

Actually, as you should now realise, that’s an oversimplification because – with only ~12-18 different fathers contributing to the genetics of the colony – some workers are going to be more related to each other because they share the same father and mother.

Half-sisters share the same mother but have different fathers and share about 25% of their genes.

Super-sisters share the same mother and father and so share about 75% of their genes (25% from the queen and 50% from the drone).

Super-sisters are more likely to help each other in the colony 2.

Emergency queens and nepotism

What’s the most important decision a colony makes?

If the queen is killed (or removed) the workers rear new queens under the so-called ’emergency response’. They feed selected young larvae copious amounts of Royal Jelly to rear a replacement queen.

Arguably, the most important decision the workers make is the selection of the day-old larvae to rear as new queens.

If they get it wrong the colony is doomed. If they get it right the colony will flourish 3.

But as described above, workers are more or less related to each other genetically.

To ensure the continued propagation of at least some of their genes it might be expected that the nurse bees making this selection 4 would choose larvae more closely related to themselves.

Do worker bees exhibit nepotism when rearing emergency queens?

If workers were nepotistic you’d expect the most common patrilines in the nurse/worker bee population would also predominate in the queens reared.

However, for at least 20 years evidence has been accumulating that indicates bees are not nepotistic. On the contrary, emergency queens appear to be reared from some of the rare patrilines in the colony.

A recent paper from James Withrow and David Tarpy has provided some of the best evidence for the existence of these so-called royal patrilines in honey bee colonies 5.

Royal patrilines

Evidence for these goes back to at least 1997 6, with about half a dozen publications in the intervening period. Essentially all used broadly the same approach; they genetically screened worker bees and the emergency queens they reared to determine which patrilines were present in the two groups. 

With certain caveats (size of study, number of microsatellites screened, colony numbers etc.) all concluded that colonies rear emergency queens from some of the rarest patrilines in the colony.

The recent study by Withrow and Tarpy is well explained and probably the most comprehensive, so I’ll use that to flesh out the details.

Experimental details

Six double-brood colonies were each split into a three separate colonies; a queenright single-brood colony and two five-frame nucs. The latter contained eggs and young larvae and so reared emergency queens.

Seven days later the developing emergency queens were all harvested for future analysis. One or two frames from the nucs were then exchanged with frames containing eggs and day-old larvae from the matched queenright colony.

The nucs then started rearing new queens … again.

And again … and again.

This process was repeated until the nucs failed.

In total over 500 queens were reared (to 7 days old) from these six original colonies. These queens were analysed genetically by microsatellite analysis, as were over 500 workers from colonies.

Within the 6 experimental colonies the authors identified a total of 327 patrilines (or subfamilies as Withrow and Tarpy describe them), ranging from 34-77 per colony. 108 patrilines (4-40 per colony) were exclusively detected in worker bees and 130 patrilines (5-55/colony) were exclusively detected in queens.

Cryptic “royal” subfamilies

Over 40% of queens raised per colony were produced from the patrilines exclusively detected in the queen population.

Subfamily distribution per colony.

As shown in the figure above, many queens (black bars) were reared from subfamilies (patrilines) not represented in the worker bee population (grey bars, sorted left to right by abundance).

Since there were different numbers of patrilines per colony (34-77), the bias towards the rarer patrilines is more apparent if you instead split them into tertiles (thirds) based upon worker abundance.

Are the queens predominantly reared from the most common tertile, the intermediate tertile or the rarest tertile?

Frequency distribution of subfamilies.

It’s very clear from this graph that workers select queens from the rarest patrilines within the colony.

It is therefore very clear that worker bees do not exhibit nepotism when choosing which larvae to rear emergency queen from.

Implications for our understanding of honey bee reproduction

Two points are immediately apparent:

  • there is a cryptic population of queen-biased patrilines that have largely been overlooked in genetic studies of honey bee polyandry
  • honey bee queens mate with more drones than conventional studies of worker bee patrilines indicate

Colony 5 had at least 77 distinct subfamilies (there might have been more detected had they screened more than the 94 workers and 135 queens from this colony). By extrapolation it is possible to determine that the effective queen mating frequency (me; the number of drones the queen had mated with) was ~32 if all the samples (worker and queen) were taken into account. If only the worker or queen samples were used for this calculation the effective queen mating frequency would be ~12 or ~65 respectively.

The average effective queen mating frequency over the six colonies was ~33 (total), significantly higher than the oft-quoted (including at the top of this page) me of ~12-18.

So perhaps honey bees really are hyperpolyandrous … or even extremely hyperpolyandrous as the authors suggest.

It’s worth noting in passing that routine mating frequencies over 30 are almost never quoted for honey bees 7, but that the ‘normal’ me ~12-18 is rather low when compared with other species within the genus Apis. The giant honey bee, Apis dorsata, exhibits mating frequencies of greater than 60.

Who’s the daddy?

So, when it comes to emergency queens , although we might not know precisely who the daddy is, we can be pretty certain the particular patriline selected by the workers is most likely to be one of the rare ones in the colony.

Mechanistically, what accounts for this?

Are these larvae selected solely because they are rare?

That seems unlikely, not least because it would require some sort of surveying or screening by nurse bees. Not impossible perhaps, though I’m not sure how this would be achieved.

Perhaps it is not even worker selection?

An alternative way to view it is larval competition. A better competing larvae would be fed Royal Jelly and would be much more likely to pass on her genes to the next generation.

We don’t know the answers to these questions … yet.

Or whether they’re the wrong questions entirely.

Swarming and supercedure

The colony rears a new queen under three conditions; enforced queenlessness (as described above) which induces emergency queen rearing, prior to swarming and during supersedure.

These are fundamentally different processes in terms of the larvae used for queen rearing.

During swarming and supersedure 8 the queen lays the egg in a ‘play cup’ which is subsequently engineered into a queen cell in which the new queen develops.

Play cups

However, it is known that the patrilines of queens reared during the swarming response are similar to those of workers in the same colony 9, implying that there is no overt selection by the workers (or the parental queen).

Queen rearing

Does this insight into how bees rear new queens have any implications for how beekeepers rear new queens?

There are about as many queen rearing methods as there are adult workers in a double-brood colony in late June. Many  exploit the emergency queen rearing response by a colony rendered temporarily or permanently queenless.

Beekeepers often comment on the differential ‘take’ of grafted larvae presented to queenless cell raising colonies.

Sometimes you get very good acceptance of the grafted larvae, other times less so.

Of course, we only show the ones that worked well!

3 day old QCs ...

3 day old QCs …

Differential ‘take’ is often put down to the state of the cell raising colony or the nectar flow (or the cackhandedness of the grafter, or the phase of the moon, or about 100 other things).

I have never heard of beekeepers comparing the ‘take’ of larvae originating from the cell raising colony with those from another colony. The latter are always going to be ‘rare’ if you consider the patrilines present in the cell raising colony. However, grafts taken from the same colony as used for cell raising 10 are likely to reflect the predominant patrilines.

Are these accepted less well by the nurse bees?

I suspect not … but it is testable should anyone want to try.

My expectation would be that the presentation of larvae in a vertically oriented cell bar frame would likely override any genetic selectivity by the colony. They’re desperate to raise a new queen and – thank goodness – here’s a few that might do.

Alternatively, differential acceptance is more likely to reflect use of larvae of an unsuitable age, or that have been damaged during grafting.

As I listen to the wind howling outside it seems like a very long time until I can test any of these ideas … 🙁


Colophon

Ray Winstone (as Carlin) 1979

Who’s the daddy? is British slang for who, or what, is the best. It originated in a line by Ray Winstone’s character Carlin from the 1979 film Scum. This was not a romantic comedy and I’m certainly not recommending viewing it. Nevertheless, the phrase became widely used over the subsequent couple of decades and seemed appropriate here because the colony is dependent on selecting high-quality larvae for colony survival.

Apivar (amitraz) resistance

Apivar is a widely used acaricide (a pesticide that kills mites and ticks) used to control Varroa.

The active ingredient of Apivar 1 is amitraz, a synthetic chemical discovered and developed almost 50 years ago.

Amitraz

Amitraz …

Amitraz has multiple molecular targets. I previously discussed the mechanism of action and summed it up with the words:

Essentially, amitraz binds and activates receptors that are critically important in a range of important aspects of the Varroa activity and behaviour … amitraz changes [this] behaviour and so exhibits miticidal activity. It has additional activities as well … these multiple routes of action may explain why resistance to amitraz is slow to develop.

I made the point in a subsequent post that amitraz resistance was very well documented … in cattle ticks 2 but that there was only anecdotal or incompletely documented evidence of resistance in Varroa in the USA, Argentina and Europe.

Apivar strip – fit and (don’t) forget

Amitraz has been used for mite control in honey bees for over twenty years. Considering its widespread use, the concentrations it is used at, and the relatively high replication rate of Varroa it is surprising that there has not been better evidence of resistance.

But that is no longer the case 🙁

Do you want the good news or the bad news first?

The bad news

A very recent paper 3 has clearly documented amitraz resistant Varroa in several commercial beekeeping operations in the USA.

I’ll discuss the key results of this paper first and then make some general comments on the implications for beekeepers and beekeeping.

The study had three components:

  1. Determine the sensitivity of Varroa never treated with amitraz to the chemical. This forms the baseline sensitivity against which field samples from commercial beekeepers could be tested.
  2. Screen Varroa from hives maintained by commercial beekeepers (with a multi-year history of Apivar usage) for amitraz resistance.
  3. Validate that the reduced efficacy of Apivar correlates with the observed amitraz resistance.

Essentially it involved harvesting live Varroa from colonies by a large-scale dusting with icing sugar 4. The Varroa were then tested to determine whether they showed resistance to amitraz, and the sensitivity was compared with the baseline sample of mites from colonies never treated.

Finally, an Apivar sensitivity test was conducted to determine the proportion of mites killed in a standardised assay in a set time period, again compared with the control (baseline sample).

The results of the study

You should refer to the paper for the primary data if needed.

Not all the apiaries tested yielded sufficient mites to screen for Apivar resistance. This is part of ‘the good news’ which I’ll get to shortly … but first the science.

Of those apiaries that did, Apivar resistance (determined by LC50 – the Lethal Concentration required to kill 50% of the mites) ranged from similar to that seen in the baseline samples to ~20-fold greater than the controls.

Two apiaries had an over 10-fold increase of the resistance ratio (the observed LC50 divided by the baseline LC50), with some individual colonies having high levels of Varroa infestation despite an active application of amitraz.

Apivar kills mites very quickly. Using a known number of mites trapped in a cage with a single small square of Apivar it is possible to ‘count the corpses’ and plot a kill curve over time. Sensitive mites from the control colonies were all killed within 3 hours.

Time course of Apivar efficacy in amitraz-susceptible Varroa

Using this as the baseline control it was then possible to determine the efficacy of Apivar in killing the mites (in the same 3 hour timeframe) from apiaries exhibiting resistance.

Apivar efficacy in commercial beekeeping apiaries.

Two apiaries (B and C, above) contained mites that exhibited high levels of resistance to Apivar, reflected in a low level of Apivar efficacy (above). In these apiaries, an average of less than 80% of mites were killed within the 3 hour assay.

Finally, the author demonstrated a correlation between Apivar efficacy and amitraz resistance. Unsurprising, but a necessary concluding point for the experimental data.

Within apiary variation

It was interesting that the author notes that the range of Apivar efficacy was much greater in colonies from apiaries with clear evidence of amitraz resistance.

For example, apiary B exhibited a range of Apivar efficacy in colonies from 28% to 97%, with an average (plotted above) of 68%. Whilst this is clearly an unacceptably low level, it is interesting that some of the colonies within the same apiary had mites killed at an efficacy similar or better (>90%) to apiaries A2 and A4 in the graph above.

I’ve re-plotted the primary data of Apivar efficacy vs. mite counts from individual colonies to emphasise this point.

Variation of Apivar efficacy vs mite infestation levels in individual colonies from commercial apiaries

Apiaries B and C (red markers) could be considered as ‘failing apiaries’ as the average Apivar efficacy of each was below 80% (see bar chart). Together the average mite load and Apivar efficacy for these two apiaries was 6.75 mites/100 bees and 72% respectively.

However, of the 16 colonies screened from these two apiaries (8 from each):

  • One colony had insufficient detectable mites to be included in the the full analysis.
  • Eight dropped less than 3 mites/100 bees during the sugar dusting analysis (the average over the 63 colonies screened was 5.33 mites/100 bees).
  • Four colonies exhibited ≥90% Apivar efficacy.
  • One colony from apiary B was a clear outlier, with >50 mites/100 bees ( 😯 ) and only ~28% Apivar efficacy. Inevitably this sample skews the averages …

Clearly the average figures presented in the bar chart above hides a very significant level of within-apiary variation.

Weird

I commented recently on the variation in mite levels during midwinter treatment of colonies with OA/Api-Bioxal. I attributed this – with little supporting evidence (!) – to different rates of late-season brood production. Colonies brooding late into the autumn were expected to have higher midwinter mite levels.

However, the variation seen here is different.

With the exception of that one heavily infested colony from apiary B, the mite levels in the ‘failing apiaries’ (B and C) are actually less than the average of the remainder of the study group (3.88 vs. 4.85).

What differs is the efficacy of Apivar treatment, not the resulting mite levels.

Frankly, this is a bit weird … on two counts:

  1. If Apivar treatment had been failing for a long time in apiaries B and C I would have expected much higher than average mite levels.
  2. Considering the amount of drifting and robbing that goes on between juxtaposed colonies I would have also expected Apivar-resistant mites to be very widely distributed within the ‘failing apiaries’.

Caveat on the mite counts – Apiaries in Louisiana, New York and South Dakota were analysed in this study. Louisiana apiaries were sampled in April, the others in July and August. I don’t know enough about the climate or mite-replication kinetics in these states to know how much this would have influenced the mite infestation levels (or prior or ongoing treatment regimes, which would also influence mite numbers). Unfortunately, the locations of the apiaries (A, B, C etc.) are not provided, other than the control apiary which is in Baton Rouge, LA. If the study had been done in the UK mite drops in April and August would have been wildly different depending upon the location.

Idle speculation

Apivar resistance does appear to have arisen in some of these colonies, but it does not appear to have become widely distributed within the apiary.

Why not?

I don’t actually think we have enough information to work with. The paper contains almost no additional background details – Apivar treatment history, use of other treatments, colony loss data etc.

But that won’t stop me speculating a little bit 😉

Do Apivar-resistant mites stop bees from drifting? Probably not, but it would explain why resistance was not widespread in the apiary 5.

More sensibly, perhaps Apivar resistance is detrimental in the absence of selection.

In the colonies in which resistance evolves it gives the mites a significant advantage. The ongoing infestation could encourage prolonged or repeated treatment, so selecting for yet more resistant mites. Eventually the colony succumbs to the resulting high viral load.

In other colonies, treatment is withdrawn (or forgotten … remember, we have zero information here!) and the Apivar-resistant mites are then at a disadvantage to their sisters.

This isn’t unheard of.

Apistan resistance appears to be detrimental in the absence of selection. There are some relatively straightforward molecular explanations for this type of phenotype.

You would have to assume differential colony treatments within apiaries B and C for this to be part of the explanation (and to account for drifting). Let’s hope the colony records are less shambolic than mine many beekeepers keep 😉

Until a clearer picture emerges of the management history of these colonies all we’re left with is the slightly (or very) confusing observation that Apivar resistance is a hive-specific phenomenon.

As the author states:

This colony level resolution suggests that each colony may act an island of resistance with its own distinct Varroa population. Beekeepers have reported inconsistency in amitraz treatment efficacy among colonies within an apiary and this variation seems to support those anecdotal observations.

And the good news?

I think there are two ‘encouraging’ observations in this paper (though of course I’d be happier if there was no resistance).

  1. About half of the commercial apiaries surveyed (5 of 11 that had a long history of Apivar usage) had too few mites detectable to screen for amitraz resistance. Clearly Apivar works, and often works very well indeed.
  2. Apivar resistance is not widespread in the apiaries within which it had arisen. For whatever reason, resistant mite populations appear restricted to individual colonies.

And these, in turn, have implications for practical beekeeping.

Implications for practical beekeeping

How does Apivar resistance evolve? Classically, misuse or overuse of treatments results in their eventual failure. Antibiotics are a good example of this.

I’ve been told by commercial beekeepers that some use a half dose of Apivar midseason to knock mite levels back sufficiently for the late season nectar flows. This is a typical example of misuse. It may not result in the development of resistance and it may not be a strategy used by the beefarmers managing apiaries B and C, but it is not the correct way to use Apivar.

What about overuse? Mites still dropping after 6 weeks of Apivar? Go on, slip another couple of strips in for another month or two. An (expensive) example of overuse.

Used Apivar strips

Or what about the Apivar strip found lying on the bottom of the hive at the first spring inspection? Again, overuse as there are likely to be lingering traces of Apivar present in the colony all winter 6.

So the first implication for practical beekeeping is to use Apivar correctly to help avoid the development of resistance. Don’t overdose or underdose, remove after 6-10 weeks, do not leave in over the winter.

Secondly, use alternate treatments to knock back the mite population. This is again a classic strategy to avoid selecting for resistance.

For example, use Apivar in late summer and Api-Bioxal in midwinter.

The mechanism of action of these two treatments is fundamentally different, so resistance to one will not confer resistance to the other (and there are no documented cases of oxalic acid resistance I’m aware of).

If you don’t treat midwinter (and you probably should 7) then use Apiguard one year and Apivar the next. Again, totally different mechanisms of action.

Finally, do not rely on individual colonies within an apiary being indicative of all colonies. I know some beekeepers who only conduct mite drop counts in one colony as a ‘sentinel’ 8.

If the drop is high then treatment is needed.

Or vice versa … no mites, so no treatment needed.

There’s a lot of colony to colony variation so it’s worth monitoring them all 9. And this is probably even more important with the colony level Apivar resistance reported in this paper.

Just something else to worry about … 🙁


 

“Start beekeeping” courses

It’s mid-January. If you are an experienced beekeeper in the UK you’re being battered by the remnants of Storm Brendan and wondering whether the roofs are still on your hives.

If my experience is anything to go by, they’re not 🙁

But if you’re a trainee beekeeper you may well be attending a course on Starting Beekeeping, run by your local beekeeping association. Typically these run through the first 1- 3 months of the year, culminating in an apiary visit in April.

Trainee beekeepers

Trainee beekeepers

Sometimes a not-really-warm-enough-to-be doing-this apiary visit in April 🙁

Beekeeping, just like driving a car

Many years ago I attended the Warwick and Leamington Beekeepers Introduction to Beekeeping course. It was a lot of fun and I met some very helpful beekeepers.

But I learnt my beekeeping in their training apiary over the following years; initially as a new beekeeper, and subsequently helping instruct the cohort of trainees attending the course and apiary sessions the following year(s).

Teaching someone else is the best way to learn.

The distinction between the theoretical and practical aspects of the subject are important. You can learn the theory in a classroom, refreshed with tea and digestive biscuits, with the wind howling around outside.

Plain chocolate are preferable

However, it is practical experience that makes you a beekeeper, and you can only acquire these skills by opening hives up – lots of them – and understanding what’s going on.

Some choose never to go this far 1, others try but never achieve it. Only a proportion are successful – this is evident from the large number who take winter courses compared to the relatively modest growth in beekeeper numbers (or association memberships).

Beekeeping is like driving a car. You can learn the theory from a book, but that doesn’t mean you are able to drive. Indeed, the practical skills you lack may mean you are a liability to yourself and others.

Fortunately, the consequences of insufficient experience in beekeeping are trivial in comparison to inexperienced drivers and road safety.

Theoretical beekeeping

What should an ‘introduction to beekeeping’ course contain?

Which bits are necessary? What is superfluous?

Should it attempt to be all encompassing (queen rearing methods, Taranov swarm control, Israeli Acute Paralysis Virus) or pared back to the bare minimum?

Who should deliver it?

I don’t necessarily know, but for a variety of reasons I’ve been giving it some thought(s) … and here they are.

The audience and the intended outcome

You have to assume that those attending the course know little or nothing about bees or beekeeping. If you don’t there’s a good chance some of the audience will be alienated before you start 2.

When I started I had never seen inside a beehive. I don’t think I even knew what a removable frame was. Others on the course had read half a dozen books already. Some had already purchased a hive.

Some even had bees (or ‘hoped they were still alive’ as it was their first winter) 😯

I felt ignorant when others on the course were asking Wouldn’t brood and a half be better? or I’ve read that wire framed queen excluders are preferable.

Framed wire QE ...

Preferable to what?

What’s a queen excluder?

By working from first principles you know what has been covered, you ensure what is covered is important and you keep everyone together.

Some on the course like the idea of keeping bees, but will soon get put off by the practicalities of the discipline. That doesn’t mean they can’t still be catered for on the course. It can still be interesting without being exclusive 3.

But, of course, the primary audience are the people who want to learn how to keep bees successfully.

For that reason I think the intended outcome is to teach sufficient theory so that a new beekeeper, with suitable mentoring, can:

  • acquire and house a colony
  • inspect it properly
  • prevent it swarming, or know what to do if it does
  • manage disease in the colony
  • prepare the colony for winter and overwinter it successfully

The only thing I’d add to that list is an indication of how to collect honey … but don’t get their hopes up by discussing which 18 frame extractor to purchase or how to use the Apimelter 😉

Course contents

I’m not going to give an in-depth breakdown of my views of what an introduction to beekeeping course should contain, but I will expand on a few areas that I think are important.

The beekeeping year and the principles of beekeeping

I’d start with an overview of a typical beekeeping year. This shouldn’t be hugely detailed, it simply sets out what happens and when.

It provides the temporal context to which the rest of the course can refer. It emphasises the seasonality of beekeeping. The long periods of inactivity and the manic days in May and early June. It can be quite ‘light touch’ and might even end with a honey tasting session.

Or mead … 😉

‘Typical’ means you don’t need to qualify everything – if the spring is particularly warm or unless there’s no oil seed rape near you – just focus on an idealised year with normal weather, the expected forage and the usual beekeeping challenges.

The normal beekeeping challenges

But this part of the course should also aim to clearly emphasise the principles and practice of beekeeping.

Success, whether measured by jars of honey or overwintered colonies, requires effort. It doesn’t just happen.

Hive inspections are not optional. They cannot be postponed because of family holidays 4, weekend breaks in Bruges, or going to the beach because the weather is great.

Great weather … good for swarming and swimming

Quite the opposite. From late April until sometime in July you have to inspect colonies at weekly intervals.

Whatever the weather (within reason).

Not every 9-12 days.

Not just before and when you return from a fortnight in Madeira 🙁

Andalucian apiary

While you’re looking at these Andalusian hives your colony might be swarming.

And hive inspections involve heavy lifting (if you’re lucky), and inadvertently squidging a few bees when putting the hive back together, and possibly getting stung 5.

The discussion of the typical year must mention Varroa management. This is a reality for 99% of beekeepers and it is our responsibility to take appropriate action in a timely manner (though the details of how and when can be saved for a later discussion of disease).

Finally, this part of the course should emphasise the importance of preparing colonies properly for the winter. This again necessitates mentioning disease control.

By covering the principles and practice of a typical year in beekeeping the trainee beekeepers should be prepared from the outset for the workload involved, and have an appreciation for the importance of timing.

We have to keep up with the bees … and the pace they go (or grow) at may not be the same every year, or may not quite fit our diaries.

Bees and beekeeping

There is a long an interesting history of beekeeping and an almost limitless number of fascinating things about bees. Some things I’d argue are essential, others are really not needed and can be safely ignored.

Bee boles in Kellie Castle, Fife, Scotland … skep beekeeping probably isn’t an essential course component.

Of the essential historical details I’d consider the development of the removable frame hive is probably the most important. Inevitably this also involves a discussion of bee space – a gap that the bees do not fill with propolis or wax. Of course, bee space was known about long before Langstroth found a way to exploit it with the removable frame hive.

The other historical area often covered is the waggle dance, but I’d argue that this is of peripheral relevance to beekeeping per se. However, it could be used to introduce the concept of communication in bees.

And once the topic turns to bees there’s almost no limit what could be included. Clearly an appreciation of the composition of the colony and how it changes during the season is important. This leads to division of labour and the caste system.

It also develops the idea of the colony as a superorganism, which has a bearing on swarm preparation, management and control.

Queen development

Queen development …

Probably most important is the development cycle of the queen, workers and drones. A proper understanding of this allows an appreciation of colony build-up, the timing of swarming and queen replacement, and is very important for the correct management of Varroa.

As with the beekeeping year, sticking to what is ‘typical’ avoids confusion. No need to mention laying workers, two-queen hives, or thelytokous parthenogenesis.

Keep on message!

Equipment

What a minefield?!

As long as the importance of compatibility is repeatedly stressed you should be OK.

An Abelo/cedar hybrid hive ...

An Abelo/cedar hybrid hive …

A little forethought is needed here. Are you (or the association) going to provide your beginners with bees?

I’d argue, and have before, that you really should.

Will the bees be on National frames? 14 x 12’s? One of several different Langstroth frames? Smiths?

Or packages?

I said it was a minefield.

Beginners want to be ready for the season ahead. They want to buy some of that lovely cedar and start building boxes. They need advice on what to buy.

What they buy must be influenced by how they’re going to start with bees. One of the easiest ways around this is to allocate them a mentor and let them lead on the specifics (assuming they’ll be getting bees from their mentor).

One thing that should be stressed is the importance of having sufficient compatible equipment to deal with swarming (which we’ll be coming to shortly).

Dummy board needed ...

5 frame poly nucleus hive needing a dummy board …

My recommendation would be to buy a full hive with three supers and a compatible polystyrene nucleus hive. In due course beginners will probably need a second hive, but (if you teach the simplest form of swarm control – see below) not in the first year. A nuc box will be sufficient.

Swarming and swarm control

Swarming is often considered to be confusing 6.

It doesn’t need to be.

The life cycle of the bee and the colony have been covered already. Swarming and queen cells is just honey bee reproduction … or it’s not swarming at all but an attempt to rescue the otherwise catastrophic loss of a queen 🙁

Deciding which is important and should influence the action(s) taken.

The determinants that drive swarming are reasonably well understood – space, age of the queen etc. The timing of the events, and the importance of the timing of the events leading to swarming is very well understood.

Preventative measures are therefore easy to discuss. Ample space. Super early. Super often.

It’s swarm control that often causes the problem.

And I think one of the major issues here is the attempts to explain the classic Pagden artificial swarm. Inevitably this involves some sort of re-enactment, or an animated Powerpoint slide, or a Tommy Cooper-esque “Glass, bottle … bottle, glass” demonstration 7.

Often this is confounded by the presenters’ left and right being the audiences right and left.

Confused? You will be.

Far better to simply teach a nucleus hive-based swarm control method. Remove the old queen, a frame of emerging brood, a frame of stores and a few shakes of bees. Take it to a distant apiary (or block the entrance with grass etc. but this adds confusion) and leave a single open charged queen cell in the original hive.

This method uses less equipment, involves fewer apiary visits, but still emphasises the need for a thorough understanding of the queen development cycle.

And, to avoid confusion, I wouldn’t teach any other forms of swarm control.

Yes, there are loads that work, but beginners need to understand one that will always work for them. Hopefully they’ve got dozens of summers of beekeeping ahead of them to try alternatives.

I think swarm control is one area where the KISS principle should be rigorously applied.

Disease prevention and management

Colony disease is a reality but you need to achieve a balance between inducing paranoia and encouraging complacency.

This means knowing how to deal with the inevitable, how to identify the possible and largely ignoring the rest.

The inevitable is Varroa and the viruses it transmits. And, of at least half a dozen viruses it does transmit, only deformed wing virus needs to be discussed. The symptoms are readily identifiable and if you have symptomatic bees – and there can be no other diagnosis – you have a Varroa problem and need to take action promptly.

Worker bee with DWV symptoms

Worker bee with DWV symptoms

In an introductory course for new beekeepers I think it is inexcusable to promote alternate methods of Varroa control other than VMD-approved treatments.

And, even then, I’d stick to just two.

Apivar in late summer and a trickle of Api-Bioxal solution in midwinter.

Used properly, at the right time and according to the manufacturer’s instructions, these provide excellent mite management.

Don’t promote icing sugar shaking, drone brood removal, small cell foundation, Old Ron’s snake oil or anything else that isn’t documented properly 8.

Almost always there will be questions about treatment-free beekeeping.

My view is that this has no place in a beginners course for beekeepers.

The goal is to get a colony successfully through the full season. An inexperienced beekeeper attempting to keep bees without treatment in their first year is a guaranteed way to lose both the colony and, probably, a disillusioned trainee beekeeper from the hobby.

To lose one may be regarded as a misfortune, to lose both looks like carelessness. 9

Once they know how to keep bees alive they can explore ways to keep them alive without treatment … and they will have the experience necessary to make up for the colony losses.

In terms of other diseases worth discussing then Chronic Bee Paralysis Virus (CBPV) is rapidly increasing in prevalence. Again the symptoms are pretty characteristic. Unlike DWV and Varroa it’s not yet clear what to do about it. Expect to see more of it in the next few years.

Nosema should probably be mentioned as should the foulbroods. The latter are sufficiently uncommon to be a minor concern, but sufficiently devastating to justify caution.

By focusing on the things that might kill the colony – or result in it being destroyed 🙁 – you’re obviously only scratching the surface of honey bee pests and pathogens. But it’s a start and it covers the most important things.

Most beginners have colonies that never get strong enough for CBPV to be a problem. Conversely, their weakness means that wasps might threaten them towards the end of the season, so should probably be discussed.

And, of course, the Asian hornet if you’re in an area ‘at risk’.

My beekeeping year

By this time the beginners have an overview of an idealised beekeeping year, an appreciation of the major events in the year – swarming, disease management, the honey harvest and preparation for winter.

Sounds easy, doesn’t it?

But an ideal wrap-up session to a starting beekeeping course would be the account of a real first year from a new beekeeper.

What were the problems? How did they attempt to solve them? What happened in the end?

This asks a lot of a relatively inexperienced beekeeper. Not least of which is good record keeping (but of course, they learnt this on the course the previous year 😉 ).

However, the comparison between the ‘textbook’ account delivered during the course with the ‘sweating in a beesuit’ reality of someone standing by an open hive feeling totally clueless is very enlightening.

Sweating in a beesuit

With sufficient preparation you could even turn it into a quiz to test what the trainees have understood.

I’ve seen several ‘starting beekeeping’ courses. All have had some of the things described above. None have had all of them. Most have included superfluous information, or in some cases, dangerous misinformation.

Which brings neatly me to the question of who should teach the course?

If you can do, if you can’t teach

Ensuring that everything is covered at the right time, avoiding duplication and maintaining the correct emphasis takes skill for one person. For a group of individuals it requires a lot of preparation and strict instructions not to drift off topic.

You might have noticed that many experienced beekeepers like to talk.

A lot.

A course handbook becomes an essential – both to help the students and as a guide to keep “on message” for the tutors.

Often it is some of the most experienced beekeepers who teach these courses.

Some are outstanding. Others less so.

Their years of experience often means they take for granted the subtleties that are critical. The difference between play cups and a 1-2 day old queen cell. A reduced laying rate by the queen. How to tell when there is a nectar flow on, and when it stops.

All of this, to them, is obvious.

They forget just how much they have learned from the hundreds of hives they have opened and the thousands of frames they have examined. They’ve reached the stage when it looks like they have a sixth sense when it comes to finding the queen.

Queen rearing course

Listen up Grasshopper!

As Grasshopper says to the old, blind master 10 “He said you could teach me a great knowledge”.

Possibly.

But sometimes they’ve retained some archaic approaches that should have been long-forgotten. They were wrong then, they still are. Paint your cedar hives with creosote. Use matchsticks to ventilate the hive in winter. Apistan is all you need for Varroa control.

 

Matchless matches

If any readers of this post have had these suggested on a course they are currently attending then question the other things that have been taught.

Get a good book that focuses on the essentials. I still think Get started in beekeeping by Adrian and Claire Waring is the best book for beginners that I’ve read 11.

Get a good mentor … you’re going to need one.

And good luck!


 

Polyandry and colony fitness

Honey bees are polyandrous. The queen mates with multiple drones during her mating flight(s). Consequently, her daughters are of mixed paternity.

In naturally mated queens there is a relationship between the number of patrilines (genetically distinct offspring fathered by different drones) and the ‘fitness’ of a colony.

Colony fitness

A ‘fit’ colony is one that demonstrates one or more desirable traits (those that benefit the colony … and potentially the beekeeper) such as better population growth, weight gain, resistance to pathogens or survival.

If you analyse the molecular genotype of the worker offspring you can determine which patriline they belong to. If you genotype enough workers you start to see the same patrilines appearing again and again. The more patrilines, the more drones the queen mated with 1.

Shallow depth of field

One of many …

Naturally mated queens mate with ~13 drones. Depending upon the study a range from as low as 1 to as high as 40 (and exceptionally into the high 50’s) has been demonstrated, though different studies all tend to produce an average in the low- to mid-teens.

There is a well-established link between polyandry and colony fitness 2. Essentially, the more genetically diverse a colony i.e. the larger the number of patrilines, the fitter that colony is.

The benefits of polyandry

Why should colonies with increased genetic diversity be fitter?

There are a number of hypotheses that attempt to explain why intracolonial genetic diversity is beneficial. These include the increased behavioural repertoire of the worker bees, a reduced production of diploid drones (which would otherwise be produced due to the single-locus sex determination system) and an increased resistance to a wide range of parasites and pathogens 3.

Parasites and pathogens are an extremely effective evolutionary selective pressure. Several studies from David Tarpy and Thomas Seeley have shown that increased polyandry results in better resistance to chalkbrood and American foulbrood.

But what about Varroa? It’s a new pathogen (evolutionarily speaking) to honey bees and there is evidence that the resistance mechanisms observed are genetically determined 4.

Does polyandry contribute to Varroa resistance? 

Would increased polyandry result in improved resistance to mites?

Limits of polyandry and natural resistance

Why is the average number of drone matings in the low teens?

If polyandry is beneficial – and there’s no doubt it is – then surely more patrilines (hyperpolyandry) would be even more beneficial?

How could this be tested?

Naturally mated queens only very rarely exhibit 30+ drone matings. Not only are these colonies hard to find, but they are so rare that doing any sort of statistical analysis of the improved (or otherwise) fitness is probably a non-starter.

Perhaps there’s an alternative way to approach the question? Rather than look at individual colonies within a mixed population, why not study the overall level of polyandry within a population that demonstrates resistance?

For example, do queens that head colonies of untreated feral bees that exhibit a demonstrated enhanced resistance to Varroa, the most important pathogen of honey bees, exhibit higher levels of polyandry?

Two relatively recent scientific papers have tackled these questions. Both have produced clear answers.

Drones : if more is better, is lots more better still?

Yes.

Keith Delaplane and colleagues used instrumental insemination (II) of virgin queens to produce queens ‘mated’ with 15, 30 or 60 drones. Sperm was collected from 1, 2 or 4 drones from 15 donor colonies, mixed thoroughly and used for queen insemination.

Full-sized colonies were requeened with the II queens and left for 6 weeks 5 after which sampling started. Over two seasons a total of 37 colonies (with 11, 13 and 13 colonies respectively headed by queens ‘mated’ with 15, 30 and 60 drones) were tested at approximately monthly intervals.

Testing involved visual analysis of colony strength 6 and comb construction. Mite levels were measured using standard alcohol wash of ~300 bees at mid- or late-summer timepoints.

Brood frame with a good laying pattern

The results of this study are commendably brief … just 8 lines of text and two tables. I’ll summarise them in just a couple of sentences.

Colonies headed by queens ‘mated’ with 30 or 60 drones produced significantly more brood than the colony headed by the queen ‘mated’ with only 15 drones. Conversely, significantly more colonies headed by queens mated with only 15 drones had a higher level of mite infestation 7.

Natural Varroa resistance and polyandry

One of the best studied populations of feral bees co-existing with Varroa are those in the Arnot Forest in New York State. These are the bees Thomas Seeley and colleagues study.

These colonies live in natural holes in trees at low density through the forest. The colonies are small and they swarm frequently. Their spatial distribution, size and swarminess (is that a word?) are all evolutionary traits that enable resistance, or at least tolerance, to Varroa and the pathogenic viruses the mite transmits.

I’ve discussed Seeley’s studies of the importance of colony size and swarming previously. I don’t think I’ve discussed his work on spatial separation of colonies, but I have described related studies by Delaplane and colleagues.

Essentially, by being well-separated, mite transmission between colonies (e.g. during robbing) is minimised. Similarly, by existing as small colonies that swarm frequently Iwith concomitant brood breaks) the mite population is maintained at a manageable level.

Marked queen surrounded by a retinue of workers.

Her majesty …

Do the Arnot Forest Varroa-resistant 8 bees exhibit especially high levels of polyandry, suggesting that this contributes their survival?

No.

Seeley and colleagues determined the number of patrilines in 10 Arnot Forest colonies using the same type of genotyping analysis described earlier. They compared these results to a similar analysis of 20 managed honey bee colonies located nearby.

On average, Arnot Forest queens had mated with ~18 drones (17.8 ± 9.8) each. In contrast, queens in managed colonies in two nearby apiaries had mated with ~16 and ~21 drones. These figures are not statistically different from each other or from the natural mating frequencies reported for honey bees in other studies.

Hyperpolyandry and colony fitness

The first of the studies confirms and extends earlier work demonstrating the polyandry (and in this instance hyperpolyandry i.e. at an even greater level than seen normally) increases colony fitness – at least in terms of colony strength and Varroa resistance.

Delaplane and colleagues hypothesise that the increased mite resistance in hyperpolyandrous (30 or 60 drones) colonies may be explained by either:

  • the importance of extremely rare alleles (gene variants), which would only be present in colonies in which the queen had mated with a very large number of drones.
  • the presence of beneficial non-additive interactions between genetically-determined traits e.g. grooming and hygienic behaviour and reduced mite reproduction.

Neither of which are mutually exclusive and both fit at least some of the extant data on natural mite resistance. Discriminating between these two hypotheses and teasing apart the variables will not be straightforward.

Absence of hyperpolyandry in naturally mite-resistant colonies

At first glance, the absence of the hyperpolyandry in the mite-resistant Arnot Forest bees studied by Thomas Seeley and colleagues appears to contradict the studies using the instrumentally inseminated queens.

The Arnot Forest bees exhibit the same level of polyandry as nearby managed colonies, and for that matter, as colonies studied elsewhere. They are mite-resistant but the queen has not mated with an increased number of drones.

In other studies 9, naturally mated colonies exhibiting different levels of polyandry (within the normal range) showed no correlation between Varroa levels and queen mating frequency.

Perhaps it’s surprising that the Arnot Forest queens hadn’t mated with fewer drones considering the extreme separation of the colonies (when compared with managed colonies). The colony density within the Forest is approximately one per square kilometre.

However, at least during the peak swarming and mating period in the season, drone availability is rarely limiting.

This is because drones are not evenly spread in the environment. Instead, they accumulate in drone congregation areas (DCA) to which the queen flies for mating.

What limits polyandry?

Polyandry is beneficial and, apparently, hyperpolyandry is more beneficial. However, queens mate with 10 – 20 drones, rather than 50 or more. Why is this?

Queen mating is a risky business. The queen has to fly to the DCA, mate with multiple drones and then return to the hive. She may make one or several mating flights.

I’ve discussed how far drones and queens fly to reach the DCA previously. Most drones fly less than 3 miles and 90% of matings occur within about 5 miles of the virgin queen’s hive. The queen probably flies further to the DCA.

All the time she is travelling to and from the DCA, and all the time she is present within it mating, she’s potentially at risk from hungry house martins, swallows, bee eaters (!) or from thunderstorms.

Or simply from getting lost.

Additionally, a number of honey bee pathogens are transmitted between drones and queens during mating. Hyperpolyandrous queens 10 are therefore at risk from these sexually transmitted diseases 11.

It’s therefore likely that the level of polyandry observed in honey bees has evolved as a consequence of the beneficial pressures polyandry brings balanced by the risks associated with mating multiple times.

Practical beekeeping

Although the two studies described here don’t have an immediate relevance to day-to-day practical beekeeping, it’s worth remembering that poor queen mating is regularly blamed for queen failures e.g. queens that develop into drone layers during the winter.

I’m going to write about drones later this year so for the moment will just make these points:

  • drone production is maximised to generate sexually mature drones for the swarming season
  • after eclosion, drones need to mature before being able to mate
  • drones live about 30 days and their sperm volume, though not necessarily viability, decreases as they age

Together this means that late in the season – perhaps late July or early August (though this will vary depending upon location) – the number of drones will decrease.

More significantly, the drones will be ageing.

In turn this means that late-mated queens may not mate with as many drones, or that the matings may not result in insemination.

Most beekeepers will be aware of queens that apparently ‘run out of sperm’ and become drone layers.

However, there may be less obvious problems with late-mated queens. I’m not aware of any studies on seasonality of queen mating and polyandry. However, I would not be at all surprised if they exhibited a reduced level of polyandry.

And, as described above, these colonies are likely to exhibit reduced fitness.

Something else to consider when deciding whether to unite a colony late in the season or hope the last of your virgin queens mates successfully …


 

Resolutions

It’s that time of the year again. The winter solstice is long passed. Christmas has been and gone. The New Year is here.

Happy New Year 🙂

And New Year is a time to make resolutions (a firm decision to do or not to do something).

There is a long history of making resolutions at the turn of the year. The Babylonians promised to pay their debts and return borrowed objects at their New Year. Of course, their year was based on a lunar calendar and started with the first crescent moon in March/April, but the principle was the same.

Many New Year’s resolutions have religious origins … though the more recent trend to resolve to “drink less alcohol” or “lose weight are somewhat more secular.

About 50% of people in the western world make New Year’s resolutions. This figure is up from ~25% in the 1930’s. Perhaps success increases uptake?

Popular resolutions include improvement to: health (stop smoking, get fit, lose weight), finance or career (reduce debt, get a better job, more education, save more), helpfulness (volunteer more, give more to charity) or self (be less grumpy, less stressed, more friendly) etc.

But since this is a beekeeping website it is perhaps logical to consider what resolutions would lead to improvements in our beekeeping.

Beekeeping resolutions

The short winter days and long, dark nights are an ideal time to develop all sorts of fanciful plans for the season ahead.

How often are these promptly forgotten in the stifling heat of a long June afternoon as your second colony swarms in front of you?

The beekeeping season starts slowly, but very quickly gathers pace. It doesn’t take long before there’s not enough time for what must be done, let alone what you’d like (or had planned) to do.

And then there are all those pesky ‘real life’ things like family holidays, mowing the lawn or visiting relatives etc. that get in the way of essential beekeeping.

So, if you are going to make beekeeping resolutions, it might be best to choose some that allow you to be more proactive rather than reactive. To anticipate what’s about to happen so you’re either ready for it, or can prevent it 1.

Keep better records

I’ve seen all sorts of very complex record keeping – spreadsheets, databases, “inspection to a page” notepads, audio and even video recordings.

Complex isn’t necessarily the same as ‘better’, though I’ve no doubt that proponents of each use them because they suit their particular type of beekeeping.

Objective and subjective notes

My notes are very straightforward. I want them to:

  • Be available. They are in the bee bag and so with me (back of the car, at home or in the apiary) all the time. If I need to refer to them I can 2. They are just printed sheets of A4 paper, stuffed into a plastic envelope. I usually write them up there and then unless I forget a pen, it’s raining and/or very windy or I’m doing detailed inspections of every colony in the apiary. In these cases I use a small dictation machine and transcribe them later that evening.
  • Keep track of colonies and queens. I record the key qualitative features that are important to me – health, temper, steadiness on the comb etc. – using a simple numerical scoring system. Added supers are recorded (+1, +1, -2 etc) and there’s a freeform section for an additional line or two of notes. Colonies and queens are uniquely numbered, so I know what I’m referring to even if I move them between apiaries, unite them or switch from a nuc box to a full hive.
  • Allow season-long comparisons ‘at a glance’. With just a line or two per inspection I can view a complete season on one page. Colonies consistently underperforming towards the bottom of the page usually end up being united in late August/early September.
  • Include seasonal or environmental jottingsMay 4th – first swift of the year”, “June 7th – OSR finished”, “no rain for a fortnight”. These are the notes that, over time, will help relate the status of the colony to the local environment and climate. If the house martins, swallows and swifts are late and it’s rained for a month then swarming will likely be delayed. Gradually I’m learning what to expect and when, so I’m better prepared.

Monitor mites

Varroa remains the near-certain threat that beekeepers have to deal with every season. But you can only deal with them properly if you have an idea of the level of infestation.

Varroa levels in the colony depend upon a number of factors including the rate of brood rearing, the proportion of drone to worker brood and the acquisition of exogenous mites (those acquired through the processes of drifting and robbing).

Pupa (blue) and mite (red) numbers

In turn, these factors vary from colony to colony and from season to season. As I discussed recently, adjacent colonies in the same apiary can have very different levels of mite infestation.

Additional variation can be introduced depending upon the genetically-determined grooming or hygienic activity of the colony, both of which rid the hive of mites.

Since the combined influence of these factors cannot be (easily or accurately) predicted it makes sense to monitor mite levels. If they are too high you can then intervene in a timely and appropriate manner.

Quick and effective ways to monitor mite levels

Any monitoring is better than none.

Easy counting ...

Easy counting …

There are a variety of ways of doing this, some more accurate than others:

  1. Place a Correx tray under the open mesh floor (OMF) and count the natural mite drop over a week or so. Stick the counts into the National Bee Unit’s (appropriately named) Varroa calculator and see what they advise. There are quite a few variables – drone brood amounts, length of season etc – that need to be taken into account and their recommendation comes with some caveats 3. But it’s a lot better than doing nothing.
  2. Uncap drone brood and count the percentage of pupae parasitised by mites. The NBU’s Varroa calculator can use these figures to determine the overall infestation level. The same caveats apply.
  3. Determine phoretic mite levels by performing a sugar roll or alcohol wash. A known number of workers (often ~300) are placed in a jar and the phoretic mites displaced using icing sugar or alcohol (car screenwash is often used). After filtering the sugar or alcohol the mites can be counted. Sugar-treated bees can be returned to the colony 4. Infestation levels of 2-3% (depending upon the time of season) indicate that intervention is required 5.

Does what it says on the tin.

Overwinter nucs

If you keep livestock you can expect dead stock.

Unfortunately colony losses are an inevitability of beekeeping.

They occur through disease, queen failure and simple accidents.

Most losses are avoidable:

  • Monitor mites and intervene before virus levels threaten survival of the colony.
  • Check regularly for poorly mated or failing queens (drone layers) and unite the colony before it dwindles or is targeted by wasps or other robbers.
  • Make sure you close the apiary gate to prevent stock getting in and tipping over hives … or any number of other (D’oh! Slaps forehead 🙄 ) beekeeper-mediated accidents).

But they will occur.

Corpses

Corpses …

And most will occur overwinter. This means that as the new season starts you might be missing one or two hives.

Which could be all of your colonies if you only have a two 6.

Replacing these in April/May is both expensive and too late to ensure a spring honey crop.

Winter colony losses are the gift that keeps on giving taking.

However, if you overwinter an additional 10-25% of your colonies as 5 frame nucs (with a minimum of one), you can easily avoid disaster.

Here's one I prepared earlier

Here’s one I prepared earlier

If you lose a colony you can quickly expand the nuc to a full hive (usually well before a commercially-purchased colony would be ready … or perhaps even available).

And if you don’t lose a colony you can sell the nuc or expand your colony numbers.

Sustainable beekeeping

If you’ve not watched Michael Palmer’s The Sustainable Apiary at the National Honey Show I can recommend it as an entertaining and informative hour for a winter evening.

Michael keeps bees in Vermont … a different country and climate to those of us in the UK. However, his principles of sustainable beekeeping without reliance on bought-in colonies is equally valid.

Overwintering nucs requires a small investment of time and money. The former in providing a little more care and attention in preparation for winter, and the latter in good quality nucleus hives.

I reviewed a range of nuc boxes six years ago. Several of these models have been discontinued or revised, but the general design features to look for remain unchanged.

Here's three I prepared earlier ...

Everynuc poly nucs

Buy dense poly nucs for insulation, make sure the roof isn’t too thin and flimsy and choose one with an entrance that can be readily reduced to a “bee width” 7. Choice (and quality) has improved over the last 5-6 years but I still almost exclusively use Thorne’s Everynuc. I bought 20 a few seasons ago and remain pleased with them, despite a few design weaknesses.

Beekeeping benefits

I do all of the above.

Having learned (often the hard way) that my beekeeping benefits, these habits are now ingrained.

I had about 20 colonies going into the 2019/20 winter, including ~20% nucs. All continue to look good, but it won’t be until late April that I’ll know what my winter losses are.

In the meantime I can review the hive notes from last season and plan for 2020. Some colonies are overwintering with very substandard queens (generally poor temper) because they’re research colonies being monitored for changes in the virus population 8. They will all be requeened or united by mid/late May.

My notes mean I can plan my queen rearing and identify the colonies for requeening. I know which colonies can be used to source larvae from and which will likely be the cell raisers. The timing of all this will be influenced by the state of the colonies and the environmental ‘clues’ I’ve noted in previous years.

Capped queen cells

Capped queen cells

Of course, things might go awry before then, but at least I have a plan to revise rather than making it up on the spur of the moment.

I learned the importance of mite monitoring the hard way. Colonies unexpectedly crashing in early autumn, captured swarms riddled with mites that were then generously distributed to others in the same apiary. Monitoring involves little effort, 2-3 times a season.

So these three things don’t need to be on my New Year’s resolution list.

Be resolute

More people make New Year’s resolutions now than 90 years ago.

However, increasing participation unfortunately does not mean that they are a successful way to achieve your goals.

Richard Wiseman showed that only 12% of those surveyed achieved their goal(s) despite over 50% being confident of doing so at the beginning of the year.

Interestingly, success in males and females was influenced by different things. For men, incremental goal-setting increased the success rate 9 (I will write hive notes on every apiary visit, rather than Keep better notes). For women, the peer pressure resulting from telling friends and family increased success by 10%.

More generally, increased success in achieving the goals resulted from:

  • Making only one New Year’s resolution – so perhaps the three things above is overly ambitious?
  • Setting specific goals and avoiding resolutions you’re previously failed at.

My New Year’s (beekeeping) resolutions?

Since I’m a man, the chance of achieving my goals is not influenced by peer pressure so I’m not publishing them. We’ll have to see in 12 months whether I’m in the 12% that succeed … or the 88% that fail 😉