Category Archives: Beekeeping

Superinfection exclusion

Alpha

Beta

Gamma

Delta 

The majority of readers will identify these as the current circulating variant strains of Covid 1. The World Health Organisation decided upon this naming system as being easier and more practical to discussed (sic) by non-scientific audiences 2.

All viruses vary, and viruses with genomes made from ribonucleic acid (RNA) vary more than those which have deoxyribonucleic acid (DNA) genomes. This is because the enzymes that replicate RNA virus genomes do not have an error correction facility. 

The virus that causes Covid-19 is an RNA virus and so is Deformed wing virus (DWV), probably the most significant virus to bees and beekeepers (other than those who have Covid that is).

Virus variation

Why does virus variation matter? 

Or, asking the same question in a more roundabout way, why don’t RNA viruses evolve error correcting enzymes (after all, the DNA viruses have these … can it be that difficult?).

If the enzyme makes errors then that’s surely a bad thing?

Actually … for the particular ‘lifestyle’ that these viruses practice, errors and variation are a good thing.

They benefit the virus.

But you know all this already, even if you don’t think you do.

Covid cases caused by the delta variant

The SARS-Cov2 delta variant now accounts for at least 99% of cases of Covid-19 in the UK. It accounted for just 0.1% of cases in late February.

The delta variant is much more transmissible. It carries errors, or mutations as they’re more correctly known, that – for whatever reason – means it can be passed from person to person much more efficiently 3.

These mutations benefit the virus and allow it to spread further and faster 4.

If the mutations (‘errors’) that the virus acquires are beneficial – by increasing transmission, by expanding the cell, tissue or host range, by helping evade the immune response in a partially vaccinated population (!) for example – then the virus will successfully replicate and produce more viruses carrying the same mutation.

And a bunch of additional ones as well … acquired during the last round of replication.

Strains and types

At some point a virus acquires sufficient mutations from an earlier incarnation that it’s identified as a distinct strain.

For example, SARS-Cov2 is ~82% identical at the genome level to SARS-Cov1 which caused the SARS pandemic in 2003 5. SARS-Cov2 did not evolve from SARS-Cov1, but they share a common ancestor. They are different strains or types of coronavirus.

There are no hard and fast rules that define when a virus is considered a different strain or type. Often it’s historical, reflecting the geographic origin, or the source from which the virus was isolated. Different strains may exhibit different phenotypes – host range, transmission, disease etc. – but don’t have to.

For example (before we get back to honey bee viruses) there are three ‘types’ of poliovirus that are about 80% identical at the genetic level. They all cause exactly the same disease (poliomyelitis) and they replicate in an identical manner – same cell, tissue and host range for example. However, to the human immune system they ‘look’ different. The immune response to poliovirus type 1 will not protect you from infection with poliovirus type 3. That’s why the poliovirus vaccine contains a mixture of all three types, to protect you from all polioviruses.

You can even get infected with two types of poliovirus simultaneously, and the virus can replicate in the same cells in your gut … or, if you’re unfortunate, your brain.

I’ll return to dual infections shortly as it’s an important topic … and related to the study I’m going to discuss.

Deformed wing virus

There are two types of DWV, designated type A and type B 6.

Originally these had names that reflected their original isolation.

DWV type A was termed Deformed wing virus and was isolated from honey bees displaying the characteristic symptoms of developmental deformities shown in the image below.

DWV type B was termed Varroa destructor virus type 1 and was isolated from the ectoparasitic mite Varroa destructor.

It “does what is says on the tin” … DWV symptoms in a recently emerged worker

These viruses are very similar to each other. They are something like 85% identical at the level of the RNA genome. More importantly than this genetic identity (or perhaps similarity would be a better term to use here) is the fact that they appear to cause very similar diseases in honey bees.

Although early studies suggested there were some differences in their virulence, more recent work from Prof. Rob Paxton in Germany, from my lab, and from Dr. Eugene Ryabov and colleagues in the USA suggests these two types of DWV are actually very similar, at least in pathogenesis.

There do appear to be some differences, with the suggestion that type A does not replicate in Varroa whereas (full disclosure, the following study is from my lab) type B does. Undoubtedly, the other genetic differences between the types will confer some subtle variation in phenotype (effectively what they ‘do’), but – as far as beekeeping is concerned – they should probably be considered the same.

A protective, non-lethal type A DWV? 

All of which made a 2015 colony-level study 7 of DWV infection rather intriguing.

This reported the survival of colonies that were infected with a “non-lethal” type B strain which were protected from infection with the “lethal” type A strain 8. The authors summarised the significance of this study like this:

We propose that this novel stable host-pathogen relationship prevents the accumulation of lethal variants, suggesting that this interaction could be exploited for the development of an effective treatment that minimises colony losses in the future.

At the time there was a flurry of excitement and discussion about this 9

Superinfection exclusion

They proposed that the mechanism that prevented the infection with the type A strain was superinfection exclusion.

Virologists love mechanisms … 🙂 

Which brings me back to virus variation. 

Imagine a population of variant viruses trying to infect a new host … like a bee.

Survival of the fittest – selection for better replicating viruses from a mixed population

In mixed infections, a virus that has an advantage over the others in the population ends up ‘winning’ the competition for the resources of the host. They therefore make more progeny viruses.

One of the advantages could be that the virus simply replicates faster

Another – more subtle, but the same outcome – is that the virus prevents other viruses from infecting the same cell (and, by extension, host).

By excluding competing viruses it effectively ‘wins’ the competition.

Superinfection exclusion – one virus (type) can prevent infection by related but different viruses

And some viruses do exactly this using a variety of cellular mechanisms.

For example, many viruses turn off the expression of the cellular receptor (think of this as the door) they use to enter the cell. If there’s no receptor (no door) then another virus cannot enter.

With no other viruses to compete with in the same cell there can only be one type of virus produced 10.

There are other mechanisms as well, but we’ll stick with the receptor one as it’s easy to comprehend.

Superinfection of a cell containing a virus that has the ability to turn off the cellular receptor it uses will effectively exclude the second virus from replicating … hence superinfection exclusion.

What don’t we know about DWV?

A lot 🙁

We don’t know how it gets into cells. We don’t know a huge amount about its replication and we know precious little about the way it interacts with the cellular machinery (the ‘stuff’ in the cell that the virus hijacks to make more viruses) of the host. 

However, since 2015 we do know that all the types of DWV that have been carefully studied appear to be more or less equally virulent. None appear to be ‘non-lethal’ as claimed for the type A virus in the superinfection exclusion paper.

This prompted us to look in a bit more detail at the consequences of dual or sequential infections with DWV in the laboratory. 

Is there a precedence at work?

In mixed infections, does one virus always ‘win’ and predominate in the new virus population?

In sequential infections, does it matter the order in which the viruses are acquired?

And mixed infections are pretty much the norm for DWV infection. All bees, whether previously exposed to Varroa or in Varroa-free regions, appear to have low levels of DWV already present. If parasitised by the mite, these bees must experience a mixed infection.

In addition, studies we published several years ago 11 showed that recombinant viruses – essentially hybrids between type A and type B DWV – often predominated in heavily Varroa-infested colonies 12.

If mixed infections cannot occur, how do such hybrids form?

Some of the answers to these questions are in our recently paper published in the ISME Journal. Gusachenko, O. et al., (2021) First come, first served: superinfection exclusion in Deformed wing virus is dependent upon sequence identity and not the order of virus acquisition. ISME J (2021). https://doi.org/10.1038/s41396-021-01043-4

Mixed DWV infections

I don’t propose to give a pupa-by-pupa account of the studies we conducted. You can read the paper – it’s open access and (because Olesya ‘Alex’ Gusachenko, the lead author, did most of the writing) relatively easy to comprehend 😉

But here are a few highlights.

Over the last few years we have produced reagents that allow us to produce almost ‘pure’ stocks of type A, type B or hybrid type A/B 13 strains of DWV.

At least 99.99% of these stocks are of one DWV type. Note that there will still be variation within this population as the replication errors probably generate one mutation per virus in the population. We therefore refer to these virus stocks as near clonal.

Injection of honey bee pupae with any of these viruses resulted in very similar levels and kinetics of replication – all the viruses replicate as far and as fast as each other.

In mixed injections, when two viruses were administered simultaneously, both replicated to equivalent levels. 

We therefore found no evidence for the dominance of one strain over another.

Sequential DWV infections

But it got more interesting when we did sequential injections. We did these by injecting with one virus, waiting 24 hours and then injecting with a second virus.

Using type A and type B DWV both viruses had replicated to similar high levels (billions of virus per pupa) within 48 hours, irrespective of the order of addition. 

If superinfection exclusion was operating we would have perhaps expected type A to have prevented or reduced the replication of type B. However, that didn’t appear to be the case.

Competition between sequential infecting DWV isolates. VVV is type B, VDD is type A and VVD is a hybrid between them.

But, when we looked at sequential infections between type A and a type A/B hybrid we did see that replication of the second virus was delayed.

Delayed, but not stopped altogether.

It would take a complete post to describe the figure above 🙁 . We’ve quantified the virus present 5-7 days after sequential injections with type A (VDD), type B (VVV) or a hybrid virus (VVD) 14.

The columns labelled VDD→VVV or VVV→VDD show the viruses and order of addition. The dots represent the amount of virus present at 5 or 7 days post injection. When the viruses were more similar to each other – for example, the VVV→VVD or VVD→VVV pairs on the right – there was a greater impact on the replication of the virus added second.

The same but different

We extended these studies to look at sequential infections with two viruses that only differed by 4 nucleotides (the building blocks) of the 10,140 nucleotides in the RNA genome of DWV i.e. 99.6% identical.

Cunningly, these four differences allowed us to unambiguously identify which virus was replicating.

In this part of the study the virus added second did not replicate to detectable levels. 

So … our data clearly demonstrates that viruses that were more similar to each other were more likely to inhibit replication during sequential infections.

In addition, no individual virus type was dominant over any others. 

This didn’t look much like classic superinfection exclusion to us.

Red or green viruses

Not content with generating graphs and tables we went on to take photographs of virus infected pupae. 

You can’t beat a nice colour image when trying to impress the peer reviewers 😉 .

Remember that DWV is too small to see with even the most powerful light microscope. You could fit several billion on the head of a pin.

We therefore engineered the virus genome to ‘show’ us where it was replicating.

Green bees

We did this by introducing an additional gene that fluoresced green or red when under UV light. I’ve discussed green viruses before … the red version uses similar technology, but using a different fluorescent reporter gene.

DWV replication (showed by green fluorescent signal) in the head, wing and abdomen of honey bee pupae

Using the red or green viruses we showed very similar results to those described above. When we superinfected with a genetically similar virus, its replication was inhibited. When it was genetically more divergent it could replicate (and we could visualise it as red or green foci of infection in a variety of tissues of the developing pupa).

Red and green viruses

We also infected bee with the red and green viruses simultaneously. Most of the fluorescent foci of infection were red or green, but a small number were both red and green. 

Green (EGFP) and red (mCherry) expressing DWV coinfecting a honey bee pupa. Arrow indicates dually infected cells.

The most likely explanation for having both colours overlapping in the photograph was because the virus were replicating in the same cells in the honey bee pupa.

Since this was exactly the sort of situation that was needed to generate recombinants (hybrids or chimeras) between the two different DWV viruses we specifically looked for them 15.

And there were lots and lots of recombinants …

Recombination between DWV viruses. The size and position of ‘bubbles’ indicate the location and number of junctions.

The bubble plot above shows the location and frequency of junctions. One virus is plotted on the horizontal and one on the vertical axis. It’s a sort of two-dimensional map of the virus. Think of a junction as where one virus ends and the other starts. They are located throughout the DWV genome – hundreds of them.

This suggests that pupae infected with both type A and type B DWV will act as ‘factories’ for the production of thousands more different hybrid variants between the two viruses.

Most of these hybrids will grow poorly.

Many will be uncompetitive.

But some – like the delta variant of SARS-Cov2 – might be more transmissible.

And some could be more pathogenic.

Or – the nightmare scenario – both 😯 .

What’s this got to do with practical beekeeping?

Every time a beekeeper moves bees about s/he is also moving viruses about.

This happens when you move bees to out apiary, when selling a nuc or when importing a queen.

Double brood ...

Moving viruses (and bees) to a new apiary …

This will contribute to the constant mixing of DWV variants that occurs when bees drift between hives, when drones mate with queens, when phoretic Varroa jumps onto a bee that is robbing a collapsing colony.

There’s a difference of course.

All those bee-driven mixing events are local and small scale … a few bees and a few miles.

But if you import a nuc from Greece via Northern Ireland both the distance and number of bees (and hence number of viruses) is much greater.

Of course, most of this mixing will just generate more mixtures of viruses.

It will also generate more recombinants.

But there’s always the possibility it might throw up a highly virulent, highly transmissible variant.

Which would not be a ‘good thing’.

And if it does, a ‘non-lethal type A strain’ (should such a thing actually exist) is not going to help prevent infection by the mechanism of superinfection exclusion I’m afraid 🙁 .

Without doubt the best way to prevent infection is to minimise the mite numbers in your colonies. This is a subject I’ll be tackling again in a couple of weeks.

But, before I go, do we understand how the more closely related strains of DWV prevent superinfection? 

Yes … probably, and it’s all to do with the immune response of the bee

I’ll discuss this in the future as it’s a mechanism that could be exploited to produce bees immune to the ravages of DWV.


 

Queen introduction

I’m probably less qualified to write about queen introduction than almost any other aspect of beekeeping. This is not because I’ve not introduced any queens. Quite the opposite, it’s something I do more or less routinely many times a season. 

The reason(s) I’m really not qualified to discuss the topic are:

  • I almost exclusively use the method I first used and I’ve not done any side-by-side comparisons with other methods to determine which work ‘best’. I have a method that works well enough i.e. somewhere between most of the time and almost always. That’s good enough for me.
  • I’m not aware of any recent scientific studies on the subject so cannot use those to make informed decisions – or interpretations – of why some methods work and others don’t 1.

Nevertheless, not being qualified has never stopped me before 2 and it’s a topic that some beekeepers struggle with and many beekeepers worry about.

Successful introduction ...

Successful introduction …

So here goes …

Art or science?

David Cushman/Roger Patterson make the point that: 

” … you can have two colonies in the same condition, in the same apiary, on the same day and if you introduce a queen in the same condition into each, one will succeed and the other will fail.”

This doesn’t mean that 50% of introductions fail (although it reads that way). What he/they mean is that there appears to be no rhyme or reason why one succeeds and the other does not.

On another day, both might succeed … or both might fail 🙁

Is it therefore an art or a science?

I don’t know. All you can do is get the basics correct and cross your fingers …

For understandable reasons, beekeepers feel rather precious about their queens. In particular, beekeepers who do not rear their own queens (and so have no spares waiting in the wings) can get a bit paranoid about queen introduction. 

What if it goes wrong?

The colony will potentially be left irretrievably queenless and – if you purchased the queen – you’ll be £40 out-of-pocket 3.

If you do rear your own queens you can perhaps be a bit more blasé about queen introductions. Potentially you can also do the sort of side-by-side comparisons I mentioned above … though there aren’t many studies where this has been done in a rigorous way. 

Most seem to find a method that works for them and then stick with it … which is what I’ve done and what I’m going to describe.

This is what I mean by ‘get the basics correct’.

I’ll also mention an alternate method I irregularly use for what I consider to be really difficult situations and/or really valuable queens.

But before we get into the methodology, it’s worth making some general comments about the state of the recipient colony and the queen being introduced.

Is the colony really queenless?

Trying to introduce a new queen into a colony that is not actually queenless will not end well.

One or both of the queens will probably not survive the experience. Either the workers will reject (and slaughter) the incoming queen, or the queens will fight and may both be damaged and lost.

It is therefore important that the recipient colony is queenless.

By queenless I mean that there is no queen present.

I do not mean no laying queen present. If you try and introduce a new queen into a colony with a failed (non laying) queen or a virgin (unmated) queen you will have problems.

Sod’s Law is explicit in these instances … the valuable new mated laying queen will be lost 🙁

Queen above the QE

A virgin queen (in this instance on the wrong side of the queen excluder)

The very best way to be sure the colony is queenless is to remove the current queen before introducing the new one. That necessitates finding the queen in the first place. 

What if you can’t find the queen but you’re sure that the colony is queenless?

Well, there are only two possibilities if you can’t find the queen, these are:

  1. The colony is queenless … you’re good to go.
  2. The colony is not queenless … but you’ve looked so hard for so long they’re now disturbed and running manically around the frames, getting more and more agitated and angry. Neither the bees or you are any sort of state to allow the queen to be discovered. Close the hive up. Have a cup of tea. Try again tomorrow.

I discussed methods of determining whether the colony is queenright (though not by extrapolation, the opposite i.e. queenless – see below) last season. Towards the end of that post I described the addition of a ‘frame of eggs’ to determine if the colony is queenright or not. I won’t repeat all the details here.

If the colony draw queen cells on the introduced frame then you can be sure that the colony is queenless. See (1) above … you’re good to go 🙂

Not queenless, but not queenright

That same post describes the concepts of queenright and queenless.

A colony that is queenright has a mated queen capable of laying fertilised eggs (though she may temporarily not be laying, for example due to a dearth of nectar).

A queenless colony contains no queen.

But there’s an intermediate stage … or potentially two intermediate stages if you allow me a little leeway.

A colony containing a failed queen that’s either not laying at all (and not going to restart), or only laying drone (unfertilised) eggs is neither queenright not queenless. This colony will not draw queen cells on the introduced frame. You cannot safely introduce a new queen into such a colony before first finding and removing the failed queen.

A colony containing laying workers will also not 4 produce queen cells from the introduced frame of eggs. 

Laying workers ...

Laying workers …

A colony with laying workers behaves as though it’s queenright but is actually queenless. It’s not really an intermediate stage, but the consequences are the same. Again, they are highly unlikely to accept an introduced queen.

Deal with the laying workers first and then requeen … and good luck, laying workers can be a nightmare 🙁

OK … let’s assume the colony really is queenless … what’s the easiest way to introduce a new queen?

Add a sealed queen cell

Almost without exception, a queenless colony can be requeened by adding a sealed queen cell. The virgin queen will emerge, go on one or two mating flights and return and head the colony. This method of queen introduction is almost foolproof in my experience. 

Where do you get the queen cell from? Another colony, your mentor, a friend in your beekeeping association, a local queen rearer … necessity is the mother of invention 5.

Assuming the cell is a natural queen cell … cut the queen cell out of the comb with a generous amount of surrounding comb. Don’t risk damaging the queen cell. Keep it vertical … there are stages during development when the pupa is susceptible to damage. Ideally choose and use a cell 24-48 hours from emergence as they’re a lot more robust late in the development cycle.

Use your thumb to make an indentation towards the top of a frame near the centre of the broodnest, above some capped and emerging brood. Using the generous ‘edge’ of comb surrounding your chosen queen cell push this into the indentation so the cell is secure. Close up the colony and a) check for emergence in 48 hours or so 6 and b) a fortnight later for successful mating.

Adding a grafted queen to a colony

If the cell is from a grafted larvae it is even easier … press the plastic cell cup holder into the comb and push the frames together. I describe this in a recent discussion of grafting.

How successful is this method of ‘queen’ introduction?

I’d estimate at least 85%.

A very small percentage of queen cells fail to emerge (or rather, the queen fails to emerge from the cell … but you knew what I meant 😉 ).

A slightly larger percentage of queens fail to mate (or fail to return from a mating flight). But, even in a bad season, it’s rarely more than 10-15%.

The new queen is accepted by the colony because she emerged there and they all live happily ever after 😉 .

What?

I know, I know … that’s not really queen introduction.

You’re right. But it works. Very well.

These are the two methods I use for queen introduction.

Candy-plugged queen cage

I have a large supply 7 of JzBz queen introduction and shipping cages. 

JzBz queen cages

JzBz queen cages

I really like them because they were free they are reusable, they have a tube-like entrance that can be plugged with candy/fondant and they have a central region to protect the queen from aggressive workers outside the cage. 

Some cages offer no areas of refuge for the queen and workers can damage the queen through the perforations. Avoid cages that are all perforations.

The JzBz cages can be purchased with a removable plastic cap (shown below the cage in the image). These fit over the end of the tube and can seal the cage until you judge the colony is likely to gracefully receive the new queen … as described below 8.

JzBz queen introduction and shipping cage

Using a JzBz cage for queen introduction:

  • Plug the tube of the JzBz cage with queen candy or fondant. Queen candy can be purchased commercially and kept frozen for long periods. I almost always use fondant these days as I have spare boxes of the stuff from autumn feeding.
  • Add a short piece of wire or a cocktail stick through the perforations at one end of the cage to hang the cage – entrance tube pointing downwards – between two frames. Do this before adding the queen to avoid risking skewering the queen at a later stage 9
  • Place the queen in the cage without any attendants (see below for comments on removing them). Close and seal the cage. Seal the candy tube with the plastic cap.
  • Hang the cage in the centre of the broodnest, above some emerging brood. Leave the colony for 24 hours.

The idea here is that the colony gets the chance to accept the new queen without getting the opportunity to slaughter her.

Look for signs of aggression

Colonies that have been queenless for a few hours (say 2-24) before adding the new queen are usually very willing to accept a replacement. Adding a queen immediately after removing the old queen is likely to result in some aggression to the caged queen.

Check the colony after 24 hours. I usually lift the cage out and place it gently on the top bars to observe the interaction of the workers and the queen.

Checking for aggression

If the colony show no aggression to the caged queen – look for bees trying to sting through the cage or biting at the cage – then remove the plastic cap and re-hang the cage between the frames.

If they show aggression leave them another 24 hours and check again 10

Once you remove the cap the queen will be released by the workers after they eat through the candy/fondant. This takes just a few hours. 

Check again a week later to ensure the colony has accepted the queen.

Nicot introduction cage

I use the method described above for almost every queen I introduce. 

The only exception is if I have to requeen a colony that has previously not accepted a queen using the method described above. Usually such a colony will also be broodless (just based on the timings of determining they are queenless and failing once to successfully introduce a queen). 

Under these circumstances I use a Nicot queen introduction cage.

Nicot queen introduction cages

I find a frame from another colony with a hand-sized patch of emerging brood. The comb needs to be level so that the cage can sit on top without gaps for the queen to escape.

Then do the following:

  1. Remove all the bees from the frame and place the Nicot cage over the brood using the short plastic ‘legs’ to hold it into the comb 11.
  2. Secure the cage in place using one or two elastic bands.
  3. Introduce the queen through the removable – and eminently losable 12 – door.

In practice it’s easier to do this in the order 3-1-2 … place the queen on the frame, cover with the cage and then secure it with the elastic band.

Add the frame and cage to the hive, locating it centrally. Push the frames together. 

The emerging workers will immediately accept the queen and feed her. Other workers will feed the queen through the edges of the cage.

One corner of the cage has an entrance tunnel that can be filled with candy/fondant. I don’t think I’ve ever used this. In my experience the colony releases the queen by burrowing under one edge of the cage after a few days. If they don’t, check and remove the cage a week later.

I don’t think I’ve ever failed to successfully introduce a queen using one of these cages, but it’s a relatively small sample size.

Thorne’s sell a metal mesh version of this cage that has integral ‘legs’. I’ve not used it, but the principle is the same. Keep it in a box or the sharp cut metal edges will butcher your fingers – it’s difficult picking up queens with heavily bandaged digits.

You could also ‘fold’ your own from mesh floor material. One with deeper ‘sides’ could be pushed down to the midrib of the comb, so reducing the chances of the bees burrowing under the edge of the cage.

Mated or virgin? 

I use the JzBz cage for introducing either mated or virgin queens. I’m not aware of any significant difference in the acceptance rate between them. 

However, it’s worth noting that acceptance is dependent upon essentially ‘matching’ the expectations of the colony with the state of the queen. 

A virgin queen will be less likely to be accepted by a colony from which a mated laying queen has recently been removed. Leave them 24-48 hours. 

Likewise, I remove nearly mature queen cells from a colony I’m requeening with a mated queen. I don’t want to risk an early-emerged virgin queen from ‘raining on the parade’ of the introduced queen.

I’ve only used the Nicot cage for mated queens. Since the latter is usually used for a broodless colony I want the minimum possible delay before there is new brood in the colony.

Alone or with attendants?

If you purchase a queen and receive her by post there will be a few workers caged with her.

I always remove these although some suggest that they do not adversely influence acceptance rates 13. I remove them because I’m a bit paranoid about viruses … these workers come from an ‘unknown’ hive (quite possibly not the same one that the queen came from) and will carry a potentially novel range of Deformed wing virus variants (and possibly others as well).

I don’t want these in my hive so I remove the workers

It’s also worth noting that Wyatt Mangum has an interesting report in American Bee Journal indicating that the presence of attendants significantly increases the acceptance time 14 for an introduced queen 15. In some cases the presence of attendants resulted in the colony showing aggression for longer than it took for the bees to eat through the candy plug … that’s not going to end well for the queen.

The safest way to remove attendants is to open the caged queen in a dim room with a single closed window. The bees will fly to the window (perhaps with a little encouragement).

A mated queen probably will not fly at all and can be re-caged. A virgin queen can fly well and will also end up at the window. Gently grab her by her wings and re-cage her.

You can do all this in the apiary … it requires confidence and dexterity. I know this because I recently tried it with a virgin queen in my apiary, using lashings of overconfidence and hamfistedness.

She flew away 🙁

Inevitably you can buy a gadget to help you with this – the queen muff

Conclusions

There is always a slight risk that queen introductions will not be successful. The queen pheromones have such a fundamental role in colony maintenance that disrupting them – or suddenly changing them – may lead to rejection. 

However, the methods described above are sufficiently successful that I’ve not found the need to look for better alternatives. They’re also sufficiently fast that I’m not tempted to try some of the ‘quick and dirty’ approaches 16 to save time.

Finally, it’s worth noting that it is usually easier to requeen a nucleus colony than a full hive. If I ever bought one of those €500 breeder queens I’d introduce her to a nuc first and then unite the nuc back with the original colony.

But that’s not going to happen 😉


 

Fainting goats … and queens

Myotonia congenita is a genetic disorder that affects the muscles used for movement. Myotonia refers to the delayed relaxation of these skeletal muscles, resulting in a variety of obvious symptoms including temporary paralysis, stiffness or transient weakness.

In humans these symptoms are often manifest as difficulty in swallowing, gagging and frequent falls. Children are affected more than adults. One of the most dramatic manifestations are the falls (‘fainting’) that can occur as a result of a hasty movement. 

Although physiologically distinct, ‘fainting’ is a reasonably accurate description of the sudden loss of movement and the transient nature of the disorder. Like fainting, loss of movement is usually quickly resolved. However, unlike fainting, myotonia congenita involves muscular rigidity or stiffness, so more closely resembles catalepsy.

Genes

There are two types of myotonia congenita, termed Thomsen disease and Becker disease, both of which are usually associated with mutations in the gene CLCN1 1. This encodes a chloride channel (a ‘hole’ through the cell membrane that allows the transfer of chloride ions) critical for muscle fibre activity. 

Cartoon of a transmembrane chloride channel.

With loss-of-function mutations in CLNC1 the muscle fibre continues to to be activated. When stimulated, for example if the fibre is triggered to suddenly contract for jumping or running (or  to stop a fall), the muscle fibre is hyper-excitable and continues to contract, and shows delayed relaxation

Around 1 in 100,000 people exhibit myotonia congenita, though it is about ten times more common in northern Scandinavia. Treatment involves use of a number of anticonvulsant drugs.

The same loss-of-function CLCN1 mutation in humans is seen in symptomatically similar horses, dogs … and goats.

Goats

In the late 19th century four goats were imported to Marshall County, Tennessee. Their strange behaviour when startled was first described in 1904 and defined as a congenital myotonia by Brown and Harvey in 1939. 

The eponymous Tennessee fainting goat

These pre-war studies formed the basis of of our understanding of both the physiology and genetics of myotonia congenita, though the specific mutation in the CLCN1 gene was only confirmed several years after it had been identified in humans.

Since then myotonic goats have become an internet staple, with any number of slightly distressing (for me at least, if not for the goats) YouTube videos showing their characteristic fainting when surprised or frightened 2.

Don’t bother watching them.

If you want to see a fainting goat in action watch little ‘Ricky’ jump up onto a swinging seat on the National Geographic website.

It’s a perfect example.

He jumps up, gets a mild fright as the swing moves, goes stiff legged and simply rolls over and falls to the ground. A few moments later he’s back on his feet again, looking slightly shaken perhaps, but none the worse for wear.

Queens

All of that preamble was to introduce the topic of fainting queens. 

A fainting queen

This was a subject I’d heard about, but had no experience of until last week.

Periodically it gets discussed on Beesource or the Beekeepingforum – usually the topic is raised by a relatively small-time amateur beekeeper (like me) and it gets a little airtime before someone like Michael Palmer, Michael Bush, Hivemaker or Into the Lion’s Den 3 shuts down the conversation with a polite “Yes, I see it a few times a year. They recover”, or words to that effect.

Since these commercial guys handle hundreds or perhaps thousands of queens a year I think we can safely assume it’s a relatively rare phenomenon. 

Since I don’t handle hundreds or thousands of queens a year – and you probably don’t either – I thought the incident was worth recounting, so you know what to expect should it ever happen.

And to do that I have to first explain the fun I had with the first of the two queens in the hive I was inspecting.

A two queen colony

It was late afternoon and I was inspecting the last of our research colonies in the bee shed.

The hive had two brood boxes and a couple of supers. Nothing particularly surprising in that setup at this time of the season; the colony was quite strong, the spring honey had been extracted and a couple of supers had been returned to the hive for cleaning.

However, it wasn’t quite that straightforward. 

The lower brood box had been requeened ~3 weeks earlier with a mature queen cell from one of my queen rearing attempts. I’d seen that the virgin had emerged and restricted her to the lower box at my last visit. 

I’d added a queen excluder (QE) over the lower box with the intention of removing all the old frames above the QE once the brood had emerged.

However, at that last visit I’d ended up with a good looking 4 ‘spare’ virgin queen. Although I had no need for her at the time, and no time to make up a nuc 5, I decided to put her in a fondant-plugged introduction cage in this upper box.

This ‘upper’ queen couldn’t fly and mate in the week I was away, but I reasoned that I could merge the colony with the bottom box if the ‘lower’ queen failed to mate 6.

So, after adding the virgin queen to the top box I added a second QE and the two supers.

She can fly …

Having removed the supers and the upper QE I carefully inspected the upper box looking for the virgin queen who had been released from the cage

No sign of her 🙁

I went through the box again.

Time to try some of the ‘queen finding tricks’.

I moved three frames out of the way having examined them very carefully. The remaining 8 frames were then spaced out as four, well separated, pairs. I let the colony settle for a few minutes and then looked at the inner face of each pair of frames.

No sign of her 🙁

I looked again … nada, rien, niets, nunda, dim byd and sod it 7.

The obvious conclusion was that the colony had killed the queen after releasing her from cage. 

How uncharitable.

I reassembled the upper brood box and lifted it off the lower QE, in preparation to leave it outside the shed door while I went through the lower box. 

As I carried the brood box to the door I briefly looked up and saw a 8 virgin queen climbing up the inner pane of one of the shed windows, flapping frantically and fast approaching the opening that would allow her escape.

For obvious reasons I have no photographs of the next few minutes.

Bee shed window ...

Bee shed window …

For those unfamiliar with the bee shed windows, these have overlapping outer and inner panes, so are always open. They provide a very effective ‘no moving parts’ solution to clearing the shed of bees very quickly.

Which was the very last thing I wanted at that moment 😉

… rather well

I had a brood box and hive tool in my hands, the shed door was wide open, there was all sorts of stuff littering the floor and the virgin queen was inches away from making a clean getaway.

It’s worth noting that when virgin queens are disturbed and fly they almost always return to the hive. However, the hives in the shed have a single entrance and all the hives were already occupied with queens. I couldn’t let her fly and hope for the best … it probably wouldn’t end well.

By balancing half the brood box on an unoccupied corner of an adjacent hive roof I made a largely ineffective swipe for the queen, but disturbed her enough she flew away from the window in spirals around my head.

I    s  t  r  e  t  c  h  e  d    to reach the shed door and pulled it close, so reducing the possible exits from eight to seven. A small victory.

I put the brood box safely on the floor, leaning at an angle against the hive stand 9, and abandoned the hive tool.

The next 5 minutes were spent ineptly trying to catch the queen. When she wasn’t flying around the shed (where the lighting isn’t the best) she usually made for the same window.

The one behind the hive with four supers stacked on top 🙁

After a few more laps of the shed, dancing around the precariously balanced brood box and reaching around the hive tower for the window, I finally caught her.

And caged her 10.

I’m looking for publisher for my latest book, ‘Slapstick beekeeping’. If any readers know of a publisher please ask them to contact me.

After all that I should have had a little rest. I’d had enough excitement for the afternoon 11.

But there was still the queen in the bottom box to find and mark.

Feeling faint

The queen in the bottom box was mated and laying well. 

I made a near-textbook example of finding her 12.

After moving aside a few frames I should have announced (to the non-existent audience), She’s on the other side of the next frame … ” (the big reveal) ” … ah ha! There you are my beauty!”.

Holding the frame in one hand I checked my pockets for my marking cage 13.

All present and correct.

I then calmly picked her up by her wings. She was walking towards me, bending slightly as she crossed over another bee, so her wings were pushed up and away from her abdomen.

A perfect ‘handle’.

I didn’t touch her abdomen, thorax or head.

A swooning queen

And, as soon as I lifted her from the frame, she fell into a swoon and ‘dropped dead’.

This is an ex-parrot

Her wings were extended to the sides, her abdomen was curled round in a foetal position and she appeared completely motionless.

It is pining for the fjords

I dropped her into the marking cage and took the photo further up the page.

It was 6:49 pm.

For several minutes there was no obvious movement at all. Her legs and antennae were immobile. She showed no sign of breathing.

I gently shook her out onto a small piece of Correx on a nuc roof to watch and photograph her. I picked her up by the wing and held her in my palm … perhaps she needed some warmth to ‘come round’.

Was that a twitch?

Or was that me shaking slightly because I’d inadvertently killed her? 

Several more minutes of complete catatonia 14 passed … and then a gentle abdominal pulsing started.

This was now 10-11 minutes after I’d first picked her up.

Which got a bit stronger and was accompanied by a feeble waggle of the antennae.

And was followed a minute or so later by a bit of uncoordinated leg flexing.

And after 15 minutes she took her first steps.

It looked like she’d been on an ‘all nighter’ and was still rather the worse for wear.

I slipped her into a JzBz queen cage, sealed it with a plastic cap, and left it hanging between a couple of brood frames.

From picking her up to placing the caged queen into the brood box had taken 24 minutes.

Caged queen after fainting (and recovering … more or less)

I reasoned that if …

  • she fully recovered they’d feed her through the cage and I could release her the following morning
  • I’d released her immediately and she’d acted abnormally the colony might have killed her off
  • she did not recover I would at least be able to find the corpse easily ( 🙁  ) and so could confidently requeen the colony (with the virgin I’d tucked away safely in my pocket)

The following morning the cage was covered in bees and she looked just fine, so I released her. 

Somewhere under that lot is the recovered queen – still caged

She walked straight down between the frames as though nothing untoward had happened.

I didn’t have the heart to mark and clip her … I didn’t want to risk her ‘fainting’ again and, if she had, didn’t have the time to hang around while she recovered 15.

So was this ‘fainting’ myotonia congenita?

I suspect not.

Another name for the Tennessee fainting goat is the ‘stiff-legged’ goat. This reflects the characteristic rigidity in the limbs when the muscles fail to relax. The queen’s legs were curled under her, rather than being splayed out rigidly.

However, this interpretation may simply reflect my near complete ignorance of the musculature of honey bees 😉

However, I do know that the basics of muscle contraction and relaxation are essentially the same in invertebrate and vertebrate skeletal muscle. There are differences in the innervation of muscle fibres, but the fundamental role of chloride channels in allowing muscle relaxation is similar.

Therefore, for this fainting queen to be affected by myotonia congenita she should have a mutation in the CLCN1 gene encoding the chloride channel.

Although the honey bee genome has been sequenced a direct homolog for CLCN1 appears not to have been identified, though there are plenty of other chloride channels present 16

The majority of the 60 or so mapped mutations associated with myotonia congenita (in humans) are recessive. Two copies of the mutated gene (in diploids, like humans or female honey bees) are needed for the phenotype to occur.

Of course, drones are haploid so it should be easier to detect the phenotype.

I’ve never heard of drones ‘fainting’ when beekeepers practise their queen marking skills on them. Have you?

Repeated fainting

I’ll try to mark and clip this queen again.

It will be interesting to see if she behaves in the same way 17.

A quick scour of the literature (or what passes for the ‘literature’ on weird beekeeping phenomena i.e. the discussion fora) failed to turn up examples of the same queen repeatedly fainting.

Or any mention of daughter queens showing the same behaviour.

All of which circumstantially argues against this being myotonia congenita.

However, there are many other causes of sudden fainting (from the NHS website):

  • standing up too quickly – (low blood pressure)
  • not eating or drinking enough
  • being too hot
  • being very upset, angry, or in severe pain
  • heart problems
  • taking drugs or drinking too much alcohol

… though I can exclude the last one as my bees are teetotal 😉

So, there you have it, a brief account of a cataleptic queen … and her recovery.


Notes

A fortnight after the events described above I clipped and marked the queen. I did everything the same – picked her up by the wings in the shed (so again not exposed to bright sunlight – which may be relevant, see the comment by Ann Chilcott).

She (the queen) didn’t faint. She behaved just like the remaining 4 queens I marked on the same afternoon.

So no repeat of the ‘amateur dramatics’ 🙂

DIY queen cell incubator

You can please some of the people all of the time, you can please all of the people some of the time, but you can’t please all of the people all of the time … so said John Lydgate (1370-1450).

And he wasn’t wrong.

This is something I’m particularly aware of writing a weekly post on beekeeping. Much like my talks to beekeeping associations, the ‘audience’ (in this case the readership) ranges from the outright beginner to those with way more experience than me.

An article, like the one last week, on transporting your first nuc home and transferring it to a new hive, is unlikely to be of much interest to an experienced beekeeper.

Conversely, a post on something esoteric – like Royal patrilines and hyperpolyandry – is probably going to be given a wide berth by someone who has recently started beekeeping 1.

There’s no way I can write something relevant, interesting and topical for the entire breadth of experience of the readers 2

Going by the popularity of certain posts it’s clear that many readers are relatively inexperienced beekeepers.

The post entitled Queen cells … don’t panic! contains little someone who has kept bees for five years doesn’t or shouldn’t already know 3. Nevertheless, it is one of the most popular pages over the last couple of years. It has already been read more times this year than all previous years 4.

I suspect the majority of these thousands of viewings are from new(ish) beekeepers.

If you’re in this group then I suggest you look away now 😉 5

I’m going to discuss a pretty focused and specialised topic of relevance to perhaps a fraction of 10% of all beekeepers

The 10%

When I started beekeeping I was certain I would never be interested in queen rearing.

In fact I was so certain that, when repeatedly re-reading Ted Hooper’s book Bees and Honey, I’d skip the chapter on queen rearing all together. 

By ‘queen rearing’ I mean larval selection, grafting, cell raisers, cell finishers, mini-nucs, drone flooding etc. 

Queen cells from grafted larvae … what a palaver!

What a palaver!

All I wanted was a few jars of honey.

Oh yes, and slightly better tempered bees.

And perhaps a nuc to overwinter ‘just in case’.

What about a queen or two ‘spare’ for those swarms I miss?

A year or two later I had the opportunity – through the generosity of the late Terry Clare – to learn the basics of queen rearing and grafting

A week later I had a go on my own.

Amazingly (though not if you consider the tuition) it worked 🙂 . I successfully reared queens from larvae I’d selected, transferred, produced as capped cells and eventually got mated.

It was probably the single most significant event in my experience as a beekeeper. I got my nuc to overwinter and I’ve gradually improved my bees through selecting from the best and requeening the worst. I know how to produce ‘spare’ queens, though need them less frequently as my swarm control has also improved 😉  6

I don’t know what proportion of beekeepers ‘actively’ rear their own queens. I suspect it’s 10% or less.

But even that select group aren’t the target audience for this post.

The target audience are queen rearers who need to incubate queens or queen cells for protracted periods (hours to days) without constant access to mains electricity.

Let me explain

The peripatetic beekeeper

I live on the remote west coast of Scotland 7 but keep the majority of my bees in Fife. 

My apiaries in Fife are 30-40 minutes apart, and I drive past one on my way to my main apiary (in St Andrews). If I need a ‘spare’ queen in an out apiary (and have one in St Andrews) it adds over an hour to what is already a four hour beekeeping commute.

That’s an hour of my life I’ll never get back and something I’d really like to avoid 8.

On the west coast beekeepers and bees are very thin on the ground. I’ve just started queen rearing here and (again) have a 45 minute commute between apiaries 9. I’m working with another beekeeper and larvae are sourced from one and the cells are raised in another.

You can move frames of larvae about if you keep them warm and humid – a damp tea towel works well – at least if the times/distances are not too great.

But there’s an added complication … this area is Varroa free and I don’t want to be moving potentially mite-infested frames into the area. Nor do I want to deplete any of the donor colonies of brood frames.

All I want to move are a few larvae … but they’re a lot more fragile and sensitive.

So … two slightly unusual situations.

It seemed to me that my life would be a lot easier if I had some sort of portable queen and queen cell incubator.

My trusty honey warming cabinet

More than most events in beekeeping, the timing of the various stages of queen rearing is very clearly defined. You graft day old larvae and use the cells 10 days later. This timing currently defines the dates of my trips … except that sometimes there are diary clashes.

If my apiary with the cell raising colony was a mile away I could just go later in the day. 

But it’s not … 🙁

Before I started this (temporary) life as a travelling beekeeper I’d sometimes needed to incubate queen cells that were near to emergence. Once the cell is capped you can put it in an incubator, either until you use it as a capped cell, or until the virgin queen emerges. You then requeen a colony using the recently emerged virgin queen.

This was clearly another option to make the diary clashes less of an issue – raise the cells and then incubate them (outside the hive) until emergence, and then use the queens.

I’d already used my trusty honey warming cabinet to incubate queen cells. When I built this I used an Ecostat chicken egg incubator element rather than a 100 W incandescent bulb. The Ecostat heaters are thermostatically controlled and do a pretty good job of maintaining a stable temperature, anywhere between the high 20’s (°C) and about 55°C.

A day in the life of my honey warming cabinet (click for explanation of fluctuations)

There were two minor issues … the incubator needed a 240 V mains supply and was about the size of my car 10.

Honey warming cabinet. The Apiarist

Honey warming cabinet …

However, it’s perfect if you need to incubate 800 queen cells at once 😉

What I needed was a smaller, more portable, ‘battery’ – or at least 12V – powered version … 11

Beekeepers have short arms and deep pockets

One obvious solutions was to use a commercially available hen egg incubator. Brinsea are one of the market leaders and I know several beekeepers who use them as queen cell incubators. 

Although they are usually mains powered, they actually have an integral transformer and run at 12V, so could be powered from a car cigarette lighter socket. Temperature and humidity are controlled. They start at about £80 and would need modifying to accommodate queen cells, or Nicot cages containing queens.

The beekeeping-specific commercial solution is the Carricell.

Carricell queen cell incubator

These are manufactured in New Zealand in three sizes – for 40, 70 or 144 queen cells. Swienty (and presumably others) sell the 70 cell variant 12 over here for €636 13.

Excluding VAT 🙁

Beekeepers are notoriously commendably parsimonious. Since I have an alter ego named Dr. Bodgit, it seemed logical to try and build my own.

For a little less that €636 …

And ideally less than £80 😉

But first I needed to know more about the influence of temperature on queen cell development.

Temperature and development

The usual temperature quoted for the broodnest is about 35°C. Numerous studies have shown that, although the temperature is never constant, it is always in the range 33-36°C 14

It is reasonably well known that temperature can influence the development time of honey bees. At lower temperatures, development takes a little bit longer.

More significantly, Jürgen Tautz and colleagues showed almost two decades ago that honey bee workers reared (as pupae) at low temperatures have behavioural deficiencies 15.

For example, workers reared at 32°C showed reduced waggle dance activity when compared to bees reared at 36°C. Not only were they less likely to dance to advertise a particular nectar source, but they would dance less enthusiastically, performing fewer dance circuits.

In tests of learning and memory – for example associating smells with syrup rewards – bees reared as pupae at 32°C were also impaired when compared to bees reared at 36°C.

Tautz also demonstrated that bees reared at the lower temperature were more likely to go ‘missing in action’. They disappeared at a faster rate from the hive than the bees reared at the higher temperature. This strongly suggests their compromised memory or learning also had a negative influence on their survival. For example, in predator evasion, flight duration or the ability to find the hive.

OK … so temperature is really rather important for worker development.

Perhaps very accurate thermostatic control will be needed?

But what about queens?

There are good reasons to think that queen development might not be quite as sensitive to lower temperatures.

Queen cells are relatively rarely found in the centre of the broodnest. Those that are are often considered to be ‘supersedure cells‘, though location alone is probably not definitive.

Where are queen cells more usually found?

At the periphery of the broodnest, decorating the lower edges of the frame and even protruding down into the space below the bottom of the comb.

Queen cells

Queen cells …

Logic suggests that these might well experience lower temperatures simply by being at or near the edge of the mass of bees in the cluster. 

Perhaps queen development is less temperature sensitive?

Fortunately, I don’t need to rely on (my usually deeply flawed) logic or informed guesses … the experiment has been done 16.

Chuda-Mickiewicz and Samborski incubated queen cells at 32°C and 34.5°C. Those incubated at the lower temperature took ~27 hours longer to emerge than those at 34.5°C (which emerged at 16 days and 1 hour after egg laying).

However, of the variables measured, this was the only significant difference observed between the two groups. Body weights at emergence were similar, as were the spermathecal volume and ovariole number.

In both temperature groups ~90% of (instrumentally) inseminated queens started laying eggs.

So perhaps development temperature is not so critical (for queens after all).

The cheque queen is in the post

Finally, I expected my bodged incubator would also be used to transport mated queens. There’s good evidence that these are very robust 17. After all, you can get them sent in the post 18

Again, the experiment has been done 🙂

Survival of adult drones, queens and workers at 25°C, 38°C and 42°C

Jeff Pettis and colleagues investigated the influence of temperature on queen fertility 19 and concluded that incubation within the range 15-38°C are safe with a tolerance threshold of 11.5% loss of sperm viability 20

In addition, Pettis looked at the influence of high or low temperatures on adult viability (see graph above). Queens and workers survived for at least 6 hours at 25°C or 42°C. In contrast drones, particularly at high temperatures, ‘dropped like flies’ 21.

Stand back … inventor at work

Version 1 of the incubator was built and has been used successfully.

Queen cell incubator – exterior view (nothing to see here)

It consists of a polystyrene box housing a USB-powered vivarium heating mat. This claims to offer three heating levels – 20-25°C, 25-30°C and 30-35°C – though these are not when confined in a well-insulated box where it can reach higher temperatures. I’m not sure I believe the amperage/wattage information provided and don’t have the equipment to check it.

I run it from a 2.1A car USB socket, or a similar one that plugs into the mains.

The battery pack in the picture above runs the Raspberry Pi computer that is monitoring the temperature 22. It’s important to have accurate temperature monitoring and to do some trial runs to understand how quickly the box warms/cools. In due course all this wiring can either be omitted or built in … but it wouldn’t be a proper invention unless it looked cobbled together 😉

Not a lot to see here either …

Inside the box is a lot of closed cell foam – some crudely butchered to accommodate Nicot queen cages – sitting on top of a large ‘freezer block’. This acts as a hot water bottle. There’s also a plastic tray holding some soggy kitchen towel to raise the humidity.

Define ‘success’

The box has been used for the following:

  • transfer grafted larvae from an out apiary to a cell raising colony an hour away. Success defined by getting the grafted larvae accepted by the cell raiser.
  • transport queen cells up to 7 hours by car 23. Success defined by requeening colonies with the cells.
  • transport and maintain virgin queens for 7-10 days. These emerged in the incubator and then accompanied me back and forth before being used. All are now in hives and out for mating.

While powered – either in the house or the car – the box is easy to maintain at an acceptable temperature for extended periods, though it takes some time to reach the operating temperature.

An afternoon collecting and distributing queen cells to an out apiary

Even when opening the lid as queen cells are added/removed the temperature fluctuates by no more than 2-3°C. The graph above was generated from temperature readings taking queen cells from one apiary to another.

I’ll describe maintaining queens for extended periods in an incubator (with no attendant bees) in a future post.

The future

This really is a bodged solution.

At the moment the temperature has to be changed manually to keep it within the 32-35°C range. This might only be every few hours, depending upon how frequently the box is opened.

The combination of the insulation and the ‘hot water bottle’ freezer block means it can be left unattended overnight.

However, it really needs to have automatic temperature control. This should be trivial to add but will require more time than I have at the moment and for the box to be empty. It’s accompanying me on an exotic holiday to Glenrothes for the next three days 24 and will be in use for much of July as I start to make up nucs for overwintering.

So … as promised, an inelegant but working solution for a fraction of the 10% of beekeepers who rear queens. 

At a fraction of the price of a commercial one 🙂


 

Your first bees

June is a good time to start keeping bees.

The long, cold, dark winter is a distant memory. The uncertainties of spring – the unseasonably warm days in March, the April (snow) showers, the “will they, won’t they” doubts over spring build up (in a cold year) or early swarming (in a warm one) – are over. 

If you did a ‘start beekeeping’ course in the winter then waiting until June to get bees might feel like a lifetime, but it actually makes a lot of sense.

You miss the roller coaster ride that spring sometimes provides. In a bad year, starvation or swarming can leave you without bees by the end of May 🙁

Instead, you benefit from better (more settled) weather, stronger colonies and at least three months to get to confidently work with your bees as you – hopefully – get some summer honey and prepare them for the winter ahead.

Buy local bees

There are compelling reasons to buy local bees. By this I mean queens reared locally.

More locally reared queens …

Not Greece or Italy 1, imported in large batches and dropped into a box of ‘local’ workers, all of whom will be replaced within a month. These are effectively bees from southern Europe and are quite possibly not suited to Cumbria or Essex 2.

Several scientific studies have shown that locally reared bees do better than imports, particularly when overwintering. 

But the benefits don’t end there. If you buy bees locally you’ll probably buy them from a local beekeeper 3. I’ve proposed before that this could be your mentor … and that, ideally, you could have helped split the nuc from a strong colony, watched it develop and then purchased it.

But that’s not always possible. Mentoring is time consuming and dependent on the organisation of the local beekeeping association, to say nothing of simple geographic factors 4 or Covid and social distancing.

When you buy local bees you should expect to get some of the ‘back story’ on the colony. When was the queen grafted, when did she start to lay? 

If you do agree to buy bees from a local beekeeper, don’t then go and then buy them from someone else. Preparing nucs is time-consuming and involves committing resources from honey production or making increase. At the very least, a beekeeper reserving a nuc for you probably means s/he is turning other potential purchasers away. Have some courtesy.

A 5 frame nuc when sold should contain a frame of stores, a laying queen (!) – clipped or marked if requested  – and 3-4 frames of brood in all stages.

There should be sealed brood in the colony laid by the queen heading the colony.

OK, enough preamble … what about the practicalities of getting the bees home, installing them in a hive and doing your first inspection?

Transporting bees

If you are collecting your nuc from a local apiary it will probably already be sealed up for transport. The entrance should be sealed securely and the frames should be wedged in place so they won’t flap around during transit. I use closed cell foam blocks for this, but it may not be necessary in some smaller nuc boxes.

Preparing a nuc for transport. Note the foam block to secure the frames.

You might not be provided with a strap, so bring your own. Ratchet straps are probably overkill for a nuc, but they certainly do the job. Gaffer tape works well, as do these ‘no moving parts but can I remember how they work?’ hive straps.

Standard hive straps

If you collect them at the beginning or end of the day there will be more bees in the box and fewer foragers out, er, foraging.

It’s always good to actually get the bees you’re paying for 😉

More importantly, it’s also cooler at the start or end of the day, which is one less thing to be concerned about when transporting bees. Since you’re buying locally you won’t be transporting the bees far. That being the case, it’s usually sufficient to make sure there’s good airflow under the open mesh floor, without using a travel screen.

If you move bees in the heat of the day expect to have to use some sort of mesh screen over the top of the frames. The last thing you want is overheating and stressed bees. 

Mesh and staples

Actually, that’s the penultimate thing.

The last thing you want is the combs melting and collapsing … avoid this at all costs.

Escapees

Secure the nuc in the car 5 so that it can’t tip over. The frames should be in line with the direction of travel.

It’s not the end of the world if they’re perpendicular to travel, but it reduces the ‘frame flap’ when accelerating and decelerating. 

I often put the bees on the car seat, strapped in place with a seat belt, with a sheet or two of newspaper underneath the OMF to stop getting nectar or pollen on the nappa leather upholstery my filthy car from soiling the nuc box.

I’ve moved dozens of nucs like this and never had a problem.

Drive carefully.

You might find one or two bees “escaping”. In my experience these are more likely to be ‘hitchhikers’ who were underneath the open mesh floor, rather than Houdini-like bees that have circumvented the sealed entrance of the nuc 6.

Stop and let them out at the earliest opportunity … it’s safer and they’re more likely to get back to the home apiary.

If you’re 10 miles away from the apiary their fate is probably sealed 🙁

Opening the hive entrance

Bees can be a bit disoriented and distressed after a car journey.

Therefore, don’t be in a rush to open them up too soon.

I always place them in the location they are going to be permanently sited and leave them for at least half an hour.

Then, and only then, I gently open the hive entrance.

If you do it as soon as you arrive the bees may come flooding out … if you leave them to settle they will be much calmer.

Correx, the beekeepers friend ...

Correx, the beekeepers friend …

Don’t bump or rock the hive.

Don’t wrestle with the sealed entrance.

Hopefully the 30+ minutes recuperation time has allowed you to work out a strategy to open the hive entrance with the minimum disturbance possible.

Those rotating entrance disks have got a lot to commend them 🙂

Ideally you want the bees to be barely aware that the entrance is now open when it wasn’t a moment before … for example, there’s usually no need for smoke 7.

Remember, the bees know nothing about their new environment. You want them to explore it at their own pace, rather than releasing a few thousand agitated bees all at once.

Open the entrance so the bees can come and go, but don’t leave a cavernous maw gaping that they might struggle to defend,

Take a few steps back and enjoy watching the first orientation flights of your new bees.

And that’s it for the day … leave them in peace.

Transferring the nuc to a full hive

At this time of the season the bees will rapidly outgrow a 5 frame nucleus hive. If you leave them in there too long the queen will run out of space to lay and they’ll start to think about swarming.

Remember that overcrowding is one of the (many) triggers for swarming and, once they’ve decided to go, it can be very difficult to stop them.

Here's one I prepared earlier

Here’s one I prepared earlier … an overcrowded overwintered nuc in April

Therefore you need to transfer them to a full-sized hive within – at most – a few days of acquiring them 8.

You will need a full hive – floor, brood box, crownboard and roof – together with five or six (or 7 for the new Abelo boxes I see) frames with foundation fitted 9.

Frame orientation – frames from nuc in red, new foundation in grey

Since this is probably also the first time you are going to open the nuc (and, if it’s not, why did you look earlier? See the final section of this post.) you’ll also need a beesuit, hive tool and smoker.

  • Move the nuc gently to one side and place the new floor and brood box where the nuc was, with the entrance facing the same direction.
  • Gently smoke the nuc. Just a couple of puffs near the entrance should be more than sufficient. You don’t need to ‘kipper them’.
  • Transfer the 3-4 frames of brood one at a time, placing them next to each other in the new hive. By all means have a brief look at each side of the frames, but place them in the new hive in the same orientation with regard to their neighbours. The goal here is that the brood nest is not unduly disturbed.
  • Flank these with a frame or two of foundation and then add the frame of stores.
  • If I’m arranging the frames the ‘warm way’ i.e. parallel to the hive entrance, I’ll place the occupied brood frames closer to the entrance. This helps the colony defend the entrance. If the frames are perpendicular to the entrance (the cold way) I place them in the middle of the hive 10.

Add the crownboard and roof. 

All done.

Feeding the colony

Probably the first dilemma faced by a new beekeeper is whether to feed the recently re-hived nucleus colony. 

This is what beekeeping is all about … making judgement calls based upon the strength and state of the colony, in the context of the local environment and with an understanding of what the weather is going to be like over the next week or two.

Get used to it … you’ll be making a lot of decisions like this 😉

Here are a couple of scenarios …

  1. Unseasonably cold weather with lots of rain and an understrength nucleus colony.
  2. Warm, settled weather with a very strong nucleus colony in an environment with abundant forage.

The first must be fed for it to survive, let alone thrive.

The second may well not need feeding at all.

It’s best to err on the side of caution and feed nucs if there’s any doubt they will not have enough nectar to draw fresh comb and expand the brood nest. 

This spring – at least since late May – the nectar flow has been exceptional and I’ve not fed any nucs. All have drawn comb ‘for fun’, often drawing successive frames one after another that I’ve rotated into the box.

If the colony does need feeding I prefer to use a contact feeder (a plastic bucket with a fine mesh grille in the lid inverted over the brood nest) containing 1:1 (by weight) syrup made of granulated sugar and water.

Welcome to your new home … nuc ‘promoted’ to hive with contact feeder in place

The aim it to imitate a good nectar flow rather than allow the bees to store large amount of syrup stores. You want them to draw new comb and rear lots of new brood.

I place the contact feeder directly over the top bars, separated by a couple of wooden spacers. I do this because most of my crownboards lack central holes. Use a spare super to enclose the contact feeder.

I think my contact feeders are ‘half gallon’ ones … they are just big enough to take a mix of 2 litres of water and 2 kg of sugar 11. If the weather remains poor, or the nectar remains elusive (you could always ask the local beekeeper you bought the nuc from … another advantage of buying local bees 😉 ), then it will do no harm to give them a second ‘half gallon’ of syrup to help them build up.

Do not spill syrup in the apiary. It encourages robbing and your new colony may not be able to defend itself. If in doubt, again err on the side of caution … reduce the entrance size of the hive.

Inspections and enjoyment

On a warm, calm, settled day you should conduct your first colony inspection. Nucs, even recently promoted ones in a full hive, are usually a pleasure to inspect. There are sufficiently small numbers of bees that you should be able to see what’s going on relatively easily.

Don’t worry about finding the queen. If there are eggs present and no sealed queen cells then she will be in the hive.

Marked queen surrounded by a retinue of workers.

They’re not always this obvious …

It’s always a bit risky making assurances like that as I can think of several scenarios when I would be wrong.

If there are eggs present then there was a queen in the hive within the last 3 days 12.

If there are sealed queen cells present then it’s possible that the hive has swarmed.

But what about eggs being present together with unsealed queen cells?

That'll do nicely

That’ll do nicely …

There are two obvious explanations, one of which is much more likely for a new beekeeper with their first colony:

  • The colony was dead set on swarming and has swarmed without waiting for the queen cell to be sealed. This happens, but it’s unlikely to occur with a nucleus colony just moved to a new hive 13.
  • The queen has very recently died – or, more accurately, been killed – and the bees are rearing new queen cells under the emergency impulse,

New beekeepers are understandably enthusiastic … but they can be clumsy.

It’s not unusual for a queen to be damaged or killed during a colony inspection by an inexperienced beekeeper 14. It’s easy to squidge the queen between the sidebars of the frame and the brood box, perhaps because she’s rushing about after the colony was smoked too much, or between frames when returning them to the hive.

If you can’t find the queen you can’t be sure where she is.

Accidents happen.

This was almost certainly the fate of my first ever queen which disappeared a week or two after I bought my nuc … and I thought I was being so careful 🙁

Which brings me to my last couple of points. 

Do not inspect the colony more than necessary.

Once every seven days is sufficient. Don’t meddle. Let them get on with things. When they get to 7-8 frames of brood add a queen excluder and a super. 

Observe and enjoy them … from a distance. 

Congratulations … you’re now a beekeeper 🙂


 

Little dramas

This post was originally titled Drama queens.

Apposite … it’s mostly about queens.

However, the term drama queen refers to someone who overreacts to a minor setback 1 … which is almost the complete opposite of what I’m intending to discuss.

Instead, this post is about the – sometimes unseen – little dramas in the apiary. Things that go wrong, or could go wrong but eventually go OK because you gently intervene … or often because you don’t intervene at all 😉

It’s also about observing rather than doing. It’s sometimes surprising what you see, and – with a little application – you can learn something about your bees 2.

Of course, in the end some things do not end well … but there’s no point in being a drama queen about it 😉

Swarmtastic

There’s a certain predictability to the beekeeping year. It’s dictated by the climate and latitude, by the forage available, by the need for bees to reproduce (swarm) and by our efforts as beekeepers to corral them and keep them producing honey 3.

All of which means that June has been pretty manic. 

After a record-breakingly cold spring things finally warmed up. Here in Scotland this was 2-3 weeks into May.

Since then it’s been a near-constant round of queen rearing, swarm control, making up nucs and adding supers. Most of the OSR supers are now off, meaning that I’ll be hunched over the extractor for hours when I’m not with the bees 🙁

All the OSR near my bees is well and truly over – this lot is sadly just out of range

The rapid warming in late spring triggered a lot of swarming activity. I found my first charged queen cell on the 18th of May and, in at least one or two colonies, at every subsequent inspection since then.

Visits to the apiaries have been hard work. Inspecting a double brood colony with four full supers involves a lot of lifting 4.

And the lifting is necessary because I need to check whether there are any queen cells in the brood chamber.

I know some beekeepers simply prise the two brood boxes apart and expect to see queen cells at the junction.

That certainly works … sometimes.

However, I’ve found several colonies with queen cells in the middle of frames, or otherwise in positions I would not see them if I just looked at the interface between the boxes. 

Queen cell … and what else?

And I would still have to remove the supers to prise the brood boxes apart.

Although I’ve invested in some better quality hive tools, I’d need a crowbar to separate the boxes if there was 80 kg of supers on top 5.

So, if I have to take the supers off, I might as well look through the box carefully.

More haste, less speed

But before I fire up the smoker and start rushing around prising off crownboards I always try and simply observe what’s happening in the apiary.

Are all the colonies equally busy? If it’s the time of day when the new foragers are going on orientation flights are any colonies much less active? Have they had a brood break?

Which direction are the bees flying off or returning from? Has the main forage changed?

Are there any drones on orientation flights yet?

What’s happening at the hive entrances?

Is there pollen going in?

Any sign of fighting?

Or robbing?

It’s surprising what a few minutes observation can tell you about the local forage, the state of the colonies and their relative strength.

If you’ve not already read it (and even if you have) it’s worth finding a copy of At the Hive Entrance by Prof. H. Storch 6. The book’s strap-line is “How to know what happens inside the hive by observation on the outside”. Recommended.

And, now and again, you notice something unusual …

Queen under the open mesh floor

Like – in my peripheral vision – a single bee flying out from underneath an open mesh floor.

My queens are generally clipped. If the colony swarms the queen often finds her way back to the hive stand after crashing – very unregally 7 – to the ground. She crawls up the leg of the stand and ends up underneath the open mesh floor (OMF).

The bees then join her. It’s not unusual to find a large cluster of bees under the hive floor, with lots of activity, and lots of bees flying to and fro from underneath the OMF 8.

But last Friday, by chance I noticed a single bee and this prompted me to investigate.

A quick peek confirmed that there wasn’t a swarm under the OMF.

But there was a queen.

I spy with my little eye … you can just see the marked and clipped queen under this Abelo floor.

Almost completely alone.

I presume the colony had swarmed, the queen had got as far as she could and the swarm had eventually abandoned her and returned to the hive. 

When I inspected the colony I found a single sealed queen cell and confirmed that the queen I found was the one that was missing.

This colony was one of my ‘middle third’ ones 9i.e. destined for requeening with better stock if I had any spares.

There’s a near-to-eclosion queen cell under there …

I did.

I had half a dozen ‘spare’ queen cells almost ready to emerge from grafting at the start of June. I removed the queen cell in the hive and carefully checked I’d not missed any others. I then added the grafted cell, seating it in a thumb-sized depression over some brood. She will have emerged the following day and might even be mated when I check early next week.

Had I not seen the bee emerge from under the floor I’d have never otherwise checked. There are always a few bees under an OMF, but it’s rare to find a queen all alone there.

Queen in the grass

In another apiary the previous week I’d found a satsuma-sized cluster of bees in long grass about 10 metres from the hives. The application of a little gentle smoke and some prodding around with my index finger resulted in a clipped and marked queen calmly walking up onto my hand.

Microswarm? … or more likely the remains of a much larger one …

Again, I wouldn’t have seen this had I not been taking my time checking the hive entrances and the activity in the apiary. I was being even more leisurely than normal as there was rain threatening and I was trying to decide whether to start the inspections or not

Because of the known state of other colonies in the apiary – most were nucs with virgin or recently-mated queens – it was obvious which colony the queen had come from. 

The ‘threatening rain’ looked like it would soon become a certainty. I ran the queen in through the front entrance of the hive and the remaining bees eventually returned to the hive, fanning madly at the entrance.

Bees fanning at the entrance

When I next checked the hive the queen had gone 🙁

There was no sign the colony had swarmed, but there was a recently opened queen cell in there. I assumed there’s a newly emerged virgin queen running about in there with ‘blood on her hands’ having done away with the original queen.

We’ll find out next week.

Again, a few minutes just watching things in the apiary meant I found the queen. Had I not done so I’d have only seen the end result – a queenless colony – not the events that led to it.

Preventative and reactive swarm control

I should emphasise that the majority of my colonies are a little more under control than the two described above, both of which clearly attempted to swarm.

In both cases the clipped queen saved the day, even though she may not have lived to fight another day.

My swarm control (and success thereof) this season has been in stark contrast to last year’s ‘lockdown beekeeping’.

Then the priority was minimising travel and guaranteeing I wasn’t haemorrhaging swarms that might cause problems for the the public or other beekeepers.

I therefore used the nucleus method of swarm control on all my colonies. I implemented it well in advance of the peak swarming period. By doing so, I undoubtedly weakened my colonies. I produced less honey and did no queen rearing.

But I didn’t lose a single swarm 🙂

This year the priority has been to maintain strong colonies. Some are being used for honey production 10 and others are being split to make up nucs.

Inevitably a few have got a little ‘overcooked’ … but the clipped queen has usually ensured the bees remain in the hive.

I don’t think I’ve lost a swarm, but I have lost a few queens.

Queen in the cage

One of my colonies went queenless in mid May. This was well before I’d got any spare queens – mated or otherwise. I’d hoped that they would rear another, but it was too cold for the new queen to mate and the colony started to look a little pathetic.

I considered uniting them but, for a variety of reasons, never got round to it.

When I finally had a spare mated queen (in early June) I popped her into a JzBz introduction cage. I’d already plugged the tube with candy and placed a plastic cap over the end. 

The bees could feed the queen through the cage, but could not release her.

This is my usual method for queen introduction. I check the cage a day or so after hanging it between the frames. If the bees are showing aggression to the queen I leave it and check again 24 hours later.

Once they’re no longer showing any aggression I remove the plastic cap. The bees chew through the candy and release the queen.

Job done 🙂

I then leave the colony at least a week before inspecting, by which time I expect to see eggs and larvae.

JzBz queen introduction & shipping cage with removable plastic cap

On returning a week after removing the plastic cap I was dismayed to find the queen still in the cage. Most of the candy had gone, but there was a plug at one end that was rock hard. Clearly the bees had been unable to release her.

The colony had now been broodless almost a month. Brood pheromone is really important in suppressing laying worker activity in the hive. Queen pheromone is no substitute for brood pheromone 11 and I was very concerned about the additional lost week due to my stupidity 12.

But there was no point in being a drama queen … I opened the cage and gently released the queen onto a seam of bees. Five days later there are eggs and larvae (and the queen) in the hive, though I also think there are a few laying workers as there’s a smattering of drone pupae in worker cells (a classic sign).

Fingers crossed 🙂

Queen failure

The final ‘little drama’ was played out in full view over almost two months. Its eventual unsatisfactory conclusion was largely due to my procrastination … though I suspect a swallow or house martin may have hastened events at the end.

In late April, during one of the rare warm days it was possible to actually open a colony, I noticed some strange egg laying behaviour in one hive. 

The colony was queenright. The queen was marked and clipped and laying. However, although she was laying single eggs in worker comb, she was laying multiple eggs in about 10% of cells, almost all of which were in drone comb.

A fortnight or so later she was still doing the same thing. Even if it wasn’t obvious to me, it was clearly obvious to the bees that the queen was failing as they started a couple of queen cells. Here’s an enlargement of an earlier photo in this post – blue arrows mark single eggs, red arrows indicate multiples.

SIgns of a failing queen

I removed the queen and added a near-mature queen cell from my first round of grafting. She had emerged when I next checked, but was not yet laying (and I didn’t bother looking for her).

But, unlike the queen stuck in the cage, this didn’t have a happy ending.

By early June there was no sign of the queen and I fear she failed to return from a mating flight. There’s a big pond bear the apiary and it’s a magnet for swallows and house martins 13.

I added a frame of open brood (including both young larvae and eggs) in the hive, but they ignored it 14.

Frames showing the characteristic dispersed bullet brood of laying workers

When I next checked it was clear there were laying workers and I cut my losses and shook the colony out. 

In retrospect what should I have done? 

I should have united the colony in mid-May.

It was obvious then – at least to the bees – that the queen was failing. I’d never seen a queen laying singles in worker comb 15 but multiples in drone cells. 

Uniting would have immediately provided both brood pheromone and a laying queen. This would have suppressed the development of laying workers.

My notes go something like:

  • 18/5 – Still laying singles in worker and multiples in drone. Weird. QC looks like supersedure. Give them a week.
  • 26/5 – Q out. Didn’t check further. Decision time next week.
  • 3/6 – Strange. Increasing drone brood. Behaving queenright. Decision time next week.
  • 12/6 – Laying workers. Shook them out. Will I ever learn? EEJIT 16

The second rule of beekeeping

Anytime I write Decision time next week (or variants thereof, like Give them another weekin two successive weeks then it’s almost always going to end in tears 🙁

If it happens three times in succession it’s a nailed on certainty.

The first rule is – of course – Knocking off queen cells is not swarm control 😉


 

More from the fun guy

Great fleas have little fleas upon their backs to bite ’em,
And little fleas have lesser fleas, and so ad infinitum.

Augustus de Morgan’s quote from A Budget of Paradoxes (1872) 1 really means that everything is preyed upon by something, which in turn has something preying on it.

The Flea, engraving from Robert Hooke’s Micrographia (1665)

As a virologist I’m well aware of this.

There are viruses that parasitise every living thing.

Whales have viruses and so do unicellular diatoms. All the ~30,000 named bacteria have viruses. It’s likely that the remaining 95% of bacteria that are unnamed also have viruses.

There are even viruses that parasitise viruses. The huge Mimivirus that infects amoebae 2 is itself parasitised by a small virophage (a fancy name for a virus that infects viruses) termed Sputnik.

Whether these interactions are detrimental depends upon your perspective.

The host may suffer deleterious effects while the parasite flourishes.

It’s good for the latter, but not the former.

Whether these interactions are detrimental for humans 3 also depends upon your perspective.

The deliberate introduction of rabbit haemorrhagic disease virus to Australia benefitted sheep farmers who were plagued with rabbits … but it was bad news for rabbit farmers 4.

Biocontrol

Beneficial parasitism, particularly when humans use a pathogen to control an unwanted pest, is often termed biocontrol, a convenient abbreviation for biological pest control.

There are numerous examples; one of the first and best known is control of greenhouse whitefly infestations with the parasitoid wasp Encarsia formosa.

Tomato leaf with whitefly nymphs (white) parasitized by E. formosa (black).

One of the benefits of biocontrol is its self-limiting nature. The wasp will stop replicating once it runs out of whitefly to parasitise.

A second benefit is the specificity of the interaction between the host and whatever is administered to control it; by careful selection of the biocontrol agent you can target what you want to eradicate without lots of collateral damage.

Finally, unlike toxic chemicals such as DDT, the parasitoid wasp – and, more generally, other biocontrol agents – do not accumulate in the environment and cause problems for the future.

And, with all those benefits, it’s unsurprising to discover that scientists have investigated biocontrol strategies to reduce Varroa mite infestation of honey bee colonies.

It’s too early for an aside, but I’ll make one anyway … I’ve discussed the potential antiviral activity of certain fungi a couple of years ago. That wasn’t really biocontrol. It was a fungal extract that appeared to show some activity against the virus. Although that story has gone a bit quiet, one of the authors – Paul Stamets – is also a co-author of the Varroa control paper discussed below.

Biocontrol of Varroa using entomopathogenic fungi

Entomopathogenic means insect killing 5. There are several studies on the use of insect killing fungi to control Varroa 6, with the most promising results obtained with a variety of species belonging to the genus Metarhizium

Metarhizium produces asexual spores termed mitospores. The miticidal activity is due to the adhesion of these mitospores to Varroa, germination of the spore and penetration by fungal hyphae 7 through the exoskeleton of the mite and proliferation within the internal tissues.

A gruesome end no doubt.

And thoroughly deserved 🙂

Although Metarhizium is entomopathogenic it has a much greater impact on Varroa than it does on honey bees. This is the specificity issue discussed earlier.

It is for this reason that scientists have continued to explore ways in which Metarhizium could be used for biocontrol of Varroa.

But there’s a problem …

Although dozens of strains of Metarhizium have been screened, the viability – and therefore activity – of the mitospores is significantly reduced by the relatively high temperatures within the colony.

The spores would be administered, they’d show some activity and some Varroa would be slaughtered. However, over time treatment efficacy would reduce as spores – either administered at the start of the study, or resulting from subsequent replication and sporulation of Metarhizium on Varroa – were inactivated.

As beekeepers you’ll be familiar with the limitation this would impose on effective control of mites.

Varroa spend well over half of their life cycle capped in a cell while it feeds on developing pupae. Anything added to kill mites must be present for extended periods to ensure emerging mites are also exposed and killed.

This is why Apiguard involves two sequential treatments of a fortnight each, or why Apivar strips must be left in a hive for more than 6 weeks.

In an attempt to overcome these limitations, scientists are using directed evolution and repetitive selection to derive strains of Metarhizium that are better able to survive within the hive, and so better able to control Varroa than the strains they were derived from.

Good news and bad news

Like many scientific papers on honey bees 8 those with even a whiff of ‘saving the bees’ get a lot of positive press coverage.

This often implies that the Varroa ‘problem’ is now almost solved, that whatever tiny, incremental advance is described in the paper represents a new paradigm in bee health.

This is both understandable and disappointing in equal measure.

It’s understandable because people (not just beekeepers) like bees. News publishers want ‘good news’ stories to intersperse with the usual never-ending menu of woe they serve up.

It’s disappointing because it’s a variant of “crying wolf”. We want the good news story to describe how the impact of Varroa can now be easily mitigated.

It gets our hopes up.

Unfortunately, reality suggests most of these ‘magic bullets’ are a decade away from any sort of commercial product.

They will probably get mired in licensing problems.

And they may not be any better than what we currently use.

You finally end up as cynical as I am. This might even force you to read the original manuscript, rather than the Gung ho press release or the same thing regurgitated on a news website.

And, if you do that, you’ll better understand some of the clever approaches that scientists are applying to the development of effective biocontrol for Varroa.

We’re not there yet, but progress is being made.

V e r y   s l o w l y.

The paper I’m going to discuss below is Han, J.O., et al. (2021) Directed evolution of Metarhizium fungus improves its biocontrol efficacy against Varroa mites in honey bee colonies. Sci Rep 11, 10582.

It’s freely available should you want to read the bits I get wrong 😉

Solving the temperature-sensitivity problem of mitospores

The strain of Metarhizium chosen for these studies was M. brunneum F52. This had previously been demonstrated to have some efficacy against Varroa. Almost as important, it can be genetically manipulated and there was some preliminary evidence that its pathogenicity for Varroa – and hence control potential – could be improved.

Genetic manipulation covers a multitude of sins. It could mean anything from selection of pre-existing variants from a population to engineered introduction of a toxin gene for destruction of the parasitised host.

In this study the authors used directed evolution of a population of Metarhizium to select for strains with more heat tolerant spores.

Directed evolution of Metarhizium to select mitospores with increased thermotolerance

This is not genetic engineering. They grew spores under stressful conditions and increasing temperatures. Hydrogen peroxide (H2O2) , a mild mutagen, was added in some cases. Nutritional stress also increases population variation. Spores selected using nutritional stress are better able to withstand UV and heat stress.

The optimal growth temperature for the strain of Metarhizium they started with was 27°C. By repeated selection cycles at increasing temperatures they derived spores that grew at 35°C, the temperature within a colony.

Ladders and snakes

A well known phenomena of repeated selection in vitro (i.e. in a test tube in the laboratory, though you actually grow Metarhizium on agar plates) is that a pathogen becomes less pathogenic.

It was therefore unsurprising that – when they eventually tested the thermotolerant spores – only about 3% of the Varroa that died did so due to Metarhizium infection.

Field selection after directed evolution of Metarhizium in the laboratory

They therefore modified the repetitive selection, but this time did it on Varroa-infested colonies in the apiary. Mites that died from Metarhizium mycoses 9 were used as a source to cultivate more Metarhizium.

They were therefore selecting for both thermotolerant (because the experiments were being conducted in hives at 35°C) and pathogenic fungi, because they only cultivated mitospores from Varroa that had died from mycoses.

And it worked …

Amplification of Varroa mycoses by Metarhizium. Black arrows indicate the treatment dates.

After four rounds of selection over 60% of the mites that died did so because they were infected with Metarhizium.

All very encouraging … but note I was very careful with my choice of words in that last sentence. I’ll return to this point shortly.

Before that, here’s the ‘proof’ that the strain selected by directed evolution (which they termed JH1078) possessed more thermostable spores.

Thermostable spores

They measured this by recording the percentage that germinated. At 35°C ~70% of JH11078 spores germinated compared to only ~45% of the M. brunneum F52 strain they started with.

But it’s not all good news

My carefully chosen “60% of the mites that died” neatly obscures the fact that you could get a significant increase in mites dying of Metarhizium, but still have almost all the mites in the hive surviving unscathed.

The authors continued repeated Metarhizium monthly treatments for a full season after the selection experiments described above. The apiary contained 48 colonies, 24 received Metarhizium JH1078 and the remainder received no treatment.

Did Metarhizium treatment stop the well documented increase in Varroa levels observed in colonies not treated with miticides?

Varroa levels in Metarhizium treated and untreated (control) colonies.

Er … no.

They describe this data (above) as showing a ‘delay’ in the exponential increase in Varroa … but acknowledge that it ‘did not totally prevent it’.

Hmmm … looking at the error bars in the last few timepoints I’d be hard pressed to make the case that there was any significant difference in Varroa increase caused by treatment.

And while we’re here look at the mite infestation rate … 10-25 mites per 100 bees.

These are catastrophically high numbers and, unsurprisingly, 42 (~88%) of the 48 colonies – whether treated or untreated – died by the end of 2018, succumbing to “Varroa, pathogen pressure and intense yellow jacket predation”

There was some evidence that colonies receiving Metarhizium treatment survived a bit longer than the untreated controls, but the end results were the same.

Almost every colony perished.

Metarhizium vs. oxalic acid

Typically a paper on a potential improved biocontrol method for Varroa would do a side-by-side comparison with a widely used, currently licensed treatment.

There’s only one comparative experiment between Metarhizium and dribbled oxalic acid treatment. It’s buried at the end of the Supplementary Data 10. In it they show ‘no significant difference’ between the two treatments.

Frankly this was a pretty meaningless experiment … it was conducted in June 2020 when colonies would have been bulging with brood. Consequently 90% of the mites would have been hidden under the cappings. They assayed mite levels only 18 days after a single application of Metarhizium or oxalic acid.

Although it showed ‘no significant difference’ – like the “60% of the mites that died” quote – it obscures the fact that most mites were almost certainly completely untouched by either treatment.

What does this study show?

This study involved a large amount of work.

The directed evolution in the laboratory is a very nice example of how the combination of phenotypic selection and natural variation can rapidly yield new strains with desirable characteristics.

Combination of this with in vivo selection for enhanced pathogenesis successfully produced a novel strain of Metarhizium with some of the features desirable for biocontrol of Varroa.

However, in the apiary-based studies the majority of the colonies, whether treated or not, died.

This shows that, although scientists might have made a promising start, they are still a very long way from having an effective biocontrol solution for Varroa.

Unmanaged Varroa replicates to unmanageable levels

One of the Supplementary Data figures illustrated the Varroa drop per month from colonies in the research apiary.

Cumulative mite drop per colony for the month of July 2018

This is relatively late in the study, July 2018. These hives were established from commercial packages of bees in April 2017. They were either treated with the experimental Metarhizium spores or were untreated controls for the 15 months between April 2017 and July 2018 11.

Look at those Varroa numbers!

This is the mite drop just after the peak of the season. Brood levels would be close to maximum in their short, warm summer 12. The majority of the mite population would have been safely tucked away feasting on developing brood.

This is not the mite drop after miticide treatment … it’s just the drop due to bee grooming, natural mite mortality and the general ‘friction’ in the hive.

The average is 2866 mites dropped per month per hive 😥

Maybe nothing could have saved hives as heavily infested as these? 13

Don’t wait for Metarhizium … be vigilant now

These numbers – of mites and dead colonies – are a stark warning of the replication potential of Varroa and the damage is causes our bees.

Left untreated, Varroa will replicate to very high levels.

Colony mortality – either directly due to the mite and viruses, or indirectly due to the weakened colonies succumbing to robbing – is a near-inevitable consequence.

I’ve discussed the importance of Varroa management repeatedly over the years. It’s a topic I’ll be returning to again – probably in August when it starts to become a necessity.

In the meantime, keep an eye on the mite levels in your own colonies as they get stronger during the season.

While you’re doing that think of the scientists who are looking for practical, effective and environmentally-friendly strategies to control Varroa. Understand that these studies are time-consuming, progress is glacial incremental … and they might not work anyway.

Of course, if we finally manage to develop a suitable Metarhizium-based mite control strategy then bees and beekeepers will not be the only beneficiaries.

Metarhizium has its own parasites. Some of the best characterised of these are small RNA viruses.

If beekeepers are sprinkling billions of Metarhizium spores over their colonies every year then these viruses will be having a great time 😉


 

Supering

Something short and sweet this week 1 … though perhaps ‘tall and sweet’ would be preferable as I’m going to discuss supering.

The noun supering means ‘the action or practice of fitting a super to a beehive’ and dates back to 1840:

Duncan, James. Natural History of Bees Naturalist’s Library VoI. 223   The empty story which is added, may be placed above, instead of below the original stock, and the honey will thus be of a superior kind. This mode of operating is called super-ing, in contra-distinction to nadir-ing.

I don’t quite understand the description provided by here. Adding a super underneath the colony (original stock) is unlikely to lead to it being used as a honey store. Bees naturally store honey to the side and above the brood nest.

And does James Duncan mean the honey is superior because it’s better? Or is he using superior in its zoological sense meaning ‘at or near the highest point’? 2

So … let’s get a few definitions out of the way first.

  • Supering – the addition of a super to a hive, which could be either:
    • Top-supering – adding a super to the top of a stack of existing supers, or
    • Bottom-supering – adding a super below any existing supers, but above the brood box(es) 
  • Nadiring – the addition of a super below an existing brood box (which won’t be mentioned again in this post 3.

Supering … click for legend

I prefer the term top- or bottom-supering as the alternative over- or under-supering could be misinterpreted as the amount of supers being excessive or insufficient.

Which is better – top- or bottom-supering?

Let’s get the science out of the way first.

There’s an assumption that bottom supering should be ‘better’ (in terms of honey yield) as it reduces the distance bees have to travel before they are relieved of their nectar. 

A study conducted two decades ago by Jennifer Berry and Keith Delaplane 4 showed that – in terms of the amount of honey stored – it makes no statistical difference whether top- or bottom-supering is used.

This study was conducted at the University of Georgia (USA). It used 60 hives – 3 different apiaries each containing 10 hives over two distinct nectar flows. 

Note the deliberate inclusion of the term ‘statistical’ above … the bottom-supered hives did end up with ~10% more honey in total but, considering the scale of the experiment, this was not statistically significant. 

To determine if this difference was real you’d need to do a much larger scale experiment.

This was not simply weighing a few hives with the supers added on top or below … each colony used was balanced in terms of frames of brood, numbers of bees and levels of stores in the brood box for each nectar flow. That’s not my idea of fun when it would involve a few thousand colonies 🙁   5.

The Berry & Delaplane study reached the same conclusion as earlier research by Szabo and Sporns (1994) who were working in Alberta, Canada 6. They had concluded that the failure to see a significant difference in terms of honey stored was because the nectar flows were rather poor. However, this seems unlikely as the Berry & Delaplane study covered two nectar flows, one of which was much stronger than the other (measured in terms of honey yield).

Before we leave the science there’s a minor additional detail to discuss about the Berry & Delaplane study. All their hives consisted of a single Langstroth brood box with a honey super on top underneath the queen excluder (refer to C. in the figure above).

This first honey super was termed the ‘food super’. The remaining supers were the ‘honey supers’. It’s not clear from the description in the paper whether the queen ever moved up to lay in the ‘food super’. I’m assuming she did not.

That being the case, the bottom supering employed by Berry & Delaplane is probably not quite the same as understood by most UK beekeepers.

When I talk about bottom-supering (here and elsewhere) I mean adding the super directly above the box that the queen is laying in (refer to A. in the figure above).

Whether ‘true’ bottom-supering leads to increased honey yields I’ll leave to someone much stronger than me. It’s an experiment that will involve a lot of lifting … and a lot of hives 😉

Which brings us to other benefits associated with where the super is added …

Benefits of bottom supering

I can think of two obvious ones.

The first is that the frames are immediately above the warmth of the broodnest. This might help get new foundation drawn a bit faster. However, if the flow is so good you’re piling the supers on it’s likely that the bees will draw comb for fun.

Note also the comments below about frame spacing and brace comb. I start new supers with 11 frames and subsequently reduce the number to 9. To avoid brace comb it’s easier to get undrawn supers built when there are no other supers on the hive. However, if that’s not possible I usually bottom-super them … it can’t do any harm. 

The second benefit is that by bottom-supering the cappings on the lowest supers always stay pristine and white. This is important if you’re preparing cut comb honey. It’s surprising how stained the cappings get with the passage of hundreds of thousands of little feet as the foragers move up to unload their cargo in top-supered colonies. 

Benefits of top supering

Generally I think these outweigh those of bottom-supering (but I don’t make cut comb honey and I’d expect the sale price of cut comb with bright white cappings trumps any of the benefits discussed below).

The first is that it’s a whole lot easier on your back 🙂

No need to remove the stack of supers first to slide another in at the bottom. This is a significant benefit … if the colony needs a fourth super there’s probably the best part of 50 kg of full/filling supers to remove first 7

Lifting lots of heavy supers is hard work. A decade ago I’d tackle three full supers at a time without an issue.

More recently, honey seems to be getting much denser 😉 … three full supers, particularly if on top of a double brood box, are usually split into two (or even three) for lifting. 

Secondly, because top-supering is easier it’s therefore much quicker.

Pop the crownboard off, add another super, close up and move on. 

Some claim an additional benefit is that you can determine whether the colony needs an additional super simply by lifting off the crownboard and having a peek. That might work with a single brood box and one super 8, but it’s not possible on a double brood monster hive already topped with four supers 9.

Of course, all of the benefits in terms of ease of addition and/or lack of lifting are null and void if you are going to be inspecting the colony and therefore removing the supers anyway.

Frame spacing in supers

Assuming a standard bee space between drawn, filled, capped honey stores, the more frames you have in the super the smaller the amount of honey the super will contain. 

This might never be an issue for many beekeepers.

However, those that scale up to perhaps half a dozen hives soon realise that more frames per super means more time spent extracting. 

That’s exactly what happened with me. My epiphany came when faced with about 18 supers containing almost 200 frames and a manual (hand cranked) three-frame extractor 🙁

By the next nectar flow I’d invested in an electric 9 frame radial extractor and started spacing my frames further apart.

That first ‘semi-automated’ honey harvest paid for the extractor and my physique became (just) slightly less Charles Atlas-like.

With undrawn foundation I start with a full box of 11 frames. However, once drawn I space the frames further apart, usually 9 per super. The bees draw out deeper comb and fill it perfectly happily … and I’ve got less frames to extract 🙂

I know some beekeepers use 8 frames in their supers. I struggle with this and usually find the bees draw brace comb or very uneven frames. This might be because our nectar flows aren’t strong enough, but I suspect I’ve spaced the frames too far apart in one go, rather than doing it gradually.

Frame alignment of supers

Speaking of brace comb … remember to observe the correct bee space in the supers. Adding a super with mismatched frame numbers will result in brace comb being built at the junction. The same thing happens if frames are misaligned.

Frame spacing and alignment in the supers.

Inevitably this brace comb ends up fusing the two supers together and causes a ‘right mess’ 10 when you eventually prize them apart.

And you’ll have to because they’re probably too heavy to lift together.

Brace comb

Brace comb …

The example above is particularly bad due to the use of misaligned foundationless super frames. The comb is, as always, beautiful … and unusually in this example the bees built from the bottom upwards.

Note that the frame alignment between adjacent boxes does not appear to apply to the brood box and the first super. At least, it doesn’t when you’re using a queen excluder. I presume this is because the queen excluder acts as a sort of ‘false floor’. It disrupts the vertical bee space sufficiently that the bees don’t feel the need to build lots of brace comb.

You can use castellations to space the frames in the supers. I don’t (and got rid of my stock of used and unused castellations recently) as they prevent re-spacing the frames as needed 11. The bees quickly propolise up the frame lugs meaning the frames are effectively immovable without the application of significant force.

Oops ...

Oops …

Like with a hive tool … or if you drop the super 🙁  12.

Caring for out of use supers

After drawn brood comb, drawn supers are probably the most valuable resource a beekeeper has.

You can’t buy replacement so it makes sense to look after it.

Of course, having written the sentence above I realised I was almost certainly wrong. A quick Google search turned up this Bad Beekeeping post from Ron Miksha who described commercially (machine) produced drawn comb.

Three Langstroth-sized combs are €26 😯 

There’s also this stuff … 

OK, so I stand corrected. You can buy replacement drawn comb, but a single super will cost you about €78 13 so they should be looked after.

Empty drawn supers should be stored somewhere bee, wasp and rodent-free. I store mine in a shed with a solid floor underneath the stack and a spare roof on top. 

Late November in the bee (storage) shed …

I have friends who wrap their supers in clingfilm … not 30 cm kitchen roll, but the metre wide stuff they use in airports to wrap suitcases 14.

Wax moth infestation of drawn supers is generally not a problem. They much prefer used brood frames. However, it makes sense to try and make the stacks as insect-proof as possible.

Caring for in use supers

If the supers are full of bees and honey then the drawn comb is only the third most important thing in the box.

Don’t just pile the supers on the ground next to the hive. The lower edges of the frames will be festooned with bees which will get crushed. You’ll also pick up dirt from the ground which will then be transferred to the hive.

Instead, use an inverted roof. Stand the super(s) on it, angled so they’re supported just by the edges of the roof. This minimises the opportunities for bees to get squashed.

If you’re removing a stack of supers individually (because they’re too heavy to lift together) do not stack them up in a neat pile as you’re very likely to crush bees. It’s better to support the super on one edge, propped up against the edge/corner of the first super I removed.

Again, this minimises the chances of crushing bees. It’s distressing for the beekeeper, it’s definitely distressing for the bee(s) and it’s a potential route for disease transmission.

The multi-purpose Correx hive roof

Once the supers are emptied of bees but full of capped honey you’ll need to transport them home from the apiary. I use spare Correx hive roofs to catch the inevitable drips that another more caring member of the household would otherwise discover 🙁

These Correx hive roofs aren’t strong enough to stack supers on. I always ensure there’s at least one or two conventional roofs in each apiary to act as temporary super stands during inspections.

Final thoughts

Tidy comb

At the end of the season it’s worth tidying the super frames before stacking them away for the year.

Before - brace comb

Super frames before tidying and storage

I use a hive tool to scrape off any bits of brace comb from the top and bottom bars of each frame. I also use a breadknife to level up the face of the comb. The combs are then arranged in boxes of nine and stored away for the winter.

A small amount of time invested on the supers saves time and effort doing much the same thing when you need them.

Drone foundation in supers

Over 50% of my supers are drawn from drone foundation.

There are two advantages to using drone foundation in the supers. The first is that there’s less wax and more honey; it takes less effort for the bees to build the comb in the first place and the larger cell volume stores more honey.

In addition, with less surface area in each cell, it’s at least theoretically possible to get a greater efficiency of extraction 15.

The second benefit is that bees do not store pollen in drone comb. In a strong colony you sometimes get an arch of pollen stored in the bottom super, and this is avoided by using drone comb.

Drone comb in super

That doesn’t mean that they’ll necessarily fill the comb with nectar. Quite often they just leave an empty arch of cells above the brood nest 🙁

The major problem with using drone comb in the supers occurs when the queen gets above the queen excluder. You end up with my million drones fiasco and a lot of comb to melt down and recycle.

The super frame shuffle

Bees often draw and fill the central frames in the super before those at the sides. This can lead to very unevenly drawn comb (which can be ‘fixed’ with a breadknife as described above), and grossly unbalanced comb when extracting.

Full super ready for extraction

Full super ready for extraction …

To avoid this simply shuffle the outer frames into the centre of the super and vice versa. The frames will be much more evenly filled.

Spares

If you have an out apiary, keep spare supers in an insect-proof stack in the apiary.

Spare supers … only one now, on hive #29

Alternatively, keep spares under the roof but over the crownboard. As a strong nectar flow tails off, or if the weather is changeable, it might save a trip back to base, or having to carry yet another thing on your rounds.


Note

I’ve now done the calculation … 11 National super frames have an area of ~5500 cm2 which would require 6.5 Langstroth-sized sheets of drawn commercial comb. At the prices quoted above (€26 for three) that would only cost about €56 … but you’d still have to slice’n’dice them into the frames.

Hmmm … almost 3000 words … not so short and sweet after all 🙁

Radar love

The average beefarmer in the UK is probably somewhere in their mid-60’s 1. This means that in 1973, when the Dutch rock band Golden Earring had their only notable chart success Radar love, they were about 18.

Bear with me …

As 18 year olds they probably wore denim flares and loud shirts with spearpoint collars. They would go to the local disco to meet similarly-attired members of the opposite sex (whose shorter hair may have been their only distinguishing feature).

They knew when and where to meet … the weekly Saturday night (obviously 2 ) disco.

There was no point in turning up at 10 in the morning … the disco was closed 🙁

Similarly, despite their ‘cool threads’, wearing them to the launderette would have resulted in almost certain disappointment … the dance partners they were seeking weren’t likely to be found doing the laundry 🙁

No, the disco was the place to go. 

Radar love would have been on the playlist. It reached the top 10 in the charts in many countries.

Hold that thought … we’ll return to Radar love in a few minutes … 3

The birds and the bees

Of course, these young beefarmers didn’t just go to the disco to dance

Oh no.

They had an ulterior motive 😉

They knew that they had a good chance of meeting a like-minded (and similarly attired) member of the opposite sex who was also ‘looking for love’.

These meetings were effectively ritualised … a particular time and place.

Let’s forget the bell bottoms and hippie shirts now … I only added that detail so that any readers who know an ageing beefarmers can have a little giggle imagining them dressed for the disco 😉 

OK, back to the disco … metaphorically.

The disco is not fundamentally dissimilar to the lek used by male grouse 4

Greater sage-grouse at a lek, with multiple males displaying for the less conspicuous females

A lek is defined as a location where males congregate to compete and mate with females. Importantly, there are no direct benefits – such as food or territory – that the females gain from attending the lek 5.

How do the males know where to congregate?

Grouse tend to live for several years 6. Older grouse know where the lek is because they attended last season. Juveniles probably tag along and learn from their elders despite the fact they are too immature to mate, or lack the social dominance (or plumage 7 ) to compete.

As a consequence of this male hierarchy the location of the lek is invariant.

The birds congregate at the same place each year.

One of the features of leks is that males show high levels of fidelity to a single lekking site.

So now we know something about the birds … what about the bees?

Drones congregate in particular – rather ill defined – landscape features called drone congregation areas (DCA’s).

These, like a black grouse lek, are stable from day to day and year to year.

The drones compete (for the queen, though not directly with each other by displaying) and offer the queen no territorial or food benefits … meaning that DCA’s are effectively insect leks 8

Drone congregation areas

There are studies going back well over 50 years on DCA’s. There are no hard and fast rules that define their location (at least to humans … thankfully virgin queens have no problems finding them). However, you can sometimes hear them; they sound like a small swarm, the noise caused by thousands of drones circling 5-40 metres above the ground in a swirling, traffic cone-shaped, perhaps a 100 metres or more in diameter.

How do drones know where to congregate? There is no male hierarchy 9. An individual drone lives for just a few weeks and perishes before winter. 

The location must be somehow ‘hard-coded’ in the environment. Effectively a set of features that – once located – attract the drones back repeatedly until they either mate with a queen, or die trying 10.

Many studies have attempted to identify DCA’s – geographic features on the ground, sheltered from strong winds, a dip in the horizon etc. These have tended to produce rather mixed results.

I don’t think we’re anywhere close to being able to point to an intersection of two hedges and say “Over there … that’s where drones will congregate”.

An alternative approach is to go fishing for DCA’s.

Literally. 

Having identified a number of potential DCA’s from landscape analysis, you can dangle a virgin queen from a helium balloon and sample the drone density in each of the areas.

It sounds a lot simpler than it is … there’s a nice account by Aude Sorel in Bee Culture if you’re interested.

By definition, the drone congregation areas are the ones you trap the most drones in.

Right?

Well, possibly not.

Perhaps the very method used to sample the drones attracted them there in the first place? 

It’s been known since the 1960’s that high concentrations of queen mandibular pheromone can attract drones to almost any location – in one notable example, even 800 metres out to sea 11.

If you use bait, how can you be certain that the areas you define are ‘real’. 

A better way to define a DCA would be to observe individual drones accumulating in a particular area … to watch them leaving the hive, fly the tens or hundreds of metres to the same place they flew to yesterday, and record them ‘strutting their funky stuff’.

Have you ever tried to follow a drone in flight?

They’re strong and fast. They need to be to outcompete other drones when chasing the queen.

It’s almost impossible to track them across the apiary, let alone over the hedge, across two fields and into the lee of a copse.

But scientists can now do exactly that … using a technique called harmonic radar tracking.

The title of this post should now make a bit more sense … it’s the use of radar to find where drones go ‘looking for love’ 😉

Harmonic radar tracking

A harmonic radar system emits a stimulus signal. This signal is picked up by a harmonic tag (the transponder) which uses the low frequency stimulus energy to generate a second harmonic which is then re-radiated back out to a receiving system.

The harmonic signal emitter/receiver is portable … if you’ve got a lorry.

Harmonic radar emitter and detector – with Rothamsted Manor in the background.

Fortunately, the transponder is tiny … small and light enough to be glued to the back of a bee.

Drone with harmonic radar transponder attached.

Harmonic radar has been used to study orientation flights in honey bees 12, to track Asian hornets, and to follow butterfly flight paths 13 (amongst other things).

And now it’s been used to map drone congregation areas by tracking the flights of individual drones from the hive.

Harmonic radar is a relatively short range system. You can’t track transponder-tagged insects flying miles away. The effective range is just a few hundred metres for most systems.

However, for drone congregation areas this shouldn’t be a major limitation. Drones generally fly shorter distances to mate than queens (an evolutionary mechanism to avoid inbreeding) and DCA’s have often been found near to apiaries 14.

Tracking drones by harmonic radar

The study, by Woodgate et al., was published a couple of weeks ago in iScience. The full reference is:

Woodgate et al., Harmonic radar tracking reveals that honeybee drones navigate between multiple aerial leks, iScience (2021), https://doi.org/10.1016/j.isci.2021.102499

It’s available under open access (i.e. free, for anyone) and I recommend you read it if you’re interested.

I’m just going to pick out a few highlights.

During two sequential seasons the authors tracked over 600 flights by at least 78 drones. These included 19 first flights (orientation flights) and – for four drones – 6-8 consecutive flights, including their first ever orientation flight.

Orientation flights were typically observed as multiple loops in different directions, centred on the hive from which the drone originated.

Drone orientation flights

The average duration of these orientation flights was ~13 minutes and the drones observed only took one or two before changing their flight pattern (see below) and seeking drone congregation areas.

Worker bees typically take more (~6) orientation flights than drones. Presumably foragers need to ‘map’ the hive location better because they may end up returning to it (and they’ve failed if they don’t) from any location.

As we’ll see in a minute, drones tend to use particular ‘flyways’ which are probably determined by landscape features. Drones also may return to a different hive to the one they set out from.

Identifying drone congregation areas by harmonic radar tracking

Scientists love ‘heat maps’.

These are a graphical way of depicting levels of activity of one kind or another.

If you overlay the flights by every transponder-tagged drone in each of the two years of this study you generate a map (like C and E shown below). In this study they used a ‘white to red’ scale where the paler the colouration, the more drones were detected in that particular point on the map.

You can easily see the hive location (points 1, 2 and 3) as all flights originated there.

Heat map of the landscape used by drones.

Actually, C and E are a bit confusing because they include the orientation flights which are centred on the hives. If you exclude these you end up with the heat maps D and F on the right.

From these the authors could detect particular areas where the drones tended to concentrate … these are proposed to be the drone congregation areas. There were four within range of the harmonic radar system – A-D above (confusingly labelled on images D and F).

There are a few obvious features of these proposed DCAs:

  1. They are in approximately (but not exactly) the same position in the two study years.
  2. The frequency with which they were visited changes. A is visited less frequently in the second year (panel F) than in the first (panel D).
  3. The most distant DCA (at least that could be mapped in this study) was ~600 metres from the hive. 
  4. Each DCA had a roughly symmetrical ‘core’ of 30-50 metres, significantly smaller than many drone trapping studies suggest..

One thing that was noticeable by comparison of the orientation flights and the proposed DCAs was that they did not overlap.

So how do the drones ‘find’ the DCA if they don’t discover them on an orientation flight?

Flyways, straight and convoluted flights

Heat maps are cumulative data.

It was also possible to look at the individual flight paths of drones on their way to and from a DCA (in exactly the same way as they mapped orientation flights).

Analysis of these showed that drones adopted two distinct types of flight – an approximately straight, direct flight interspersed with periods of convoluted, looping flight. There are lots of pictures of these in the paper but, rather than showing another published image, here’s my “no expense made spared” diagram of these two patterns of flight.

Drone flight paths showing distinct direct and convoluted elements.

The convoluted flight defines the drone congregation areas. In these the drones showed very distinctive behaviour – the further they were from the centre of the DCA the more strongly they accelerated back towards the centre. 

Drone flight paths (inevitably) overlapped in DCAs.

However, they also overlapped in the straight line flight. Drones tended to use particular flyways from the hives to, and between, the DCAs.

Scientists have previously identified (or at least suggested the existence of) these flyways that drones use to travel to and from the hive and the DCAs 15

However, what they had previously not identified was that drones often visit more than one DCA in a single (potential) mating flight.

In 20% of the flights analysed drones visited more than one DCA. 

Finally, drones tended to only spend about 2 minutes flying around very fast (at ~5 m/s rather than the sedate ~3 m/s they fly around the hive at 16 ) within the proposed DCA.

This suggests that drones might routinely patrol several DCAs in a single flight, moving on unless a queen is present.

Harmonic radar mapping the flights of virgin queens

I’ve often preceded the term ‘drone congregation area’ in the text above with the word ‘proposed’. A DCA has a very specific meaning that describes the places where drones congregate to attempt to mate with a virgin queen.

None of the studies above showed queen mating, or even the presence of a queen.

But, of course, the authors tried that as well.

They transponder-tagged queens (94 in total) and tracked their orientation flights and mating flights (26 in total). The orientation flights were remarkably similar to those of the drones; the average number of these flights was 3 and no queen went on more than 6 orientation flights.

Unfortunately the tracking of queen mating flights was less successful 17.

Queens flew out of range (I’ll return to this shortly), the transponder fell off, or parts of the flight were not picked up by radar. Some of the queens ‘followed’ (or for which tracking was attempted) did get mated, but not apparently in the DCAs identified during the flight tracking of drones.

This type of study clearly needs further work …

Conclusions

Drone congregation areas could be detected using harmonic radar tracking of transponder-tagged drones. Unlike other well-studied lekking areas, males (drones) did not display lek fidelity, but instead visited several in rotation 18.

The DCAs are a consequence of drones exhibiting a convoluted flight pattern in particular locations. The conservation of the flyways – the routes taken by the drones – between DCAs suggest they might contribute to the location of the DCAs.

Understanding what defines these flyways might allow better prediction of DCA locations.

Previous studies have shown that queens tend to fly further to DCAs than drones, presumably to avoid inbreeding. One possibility is that tagged queens in this study might have been more likely to visit the four DCAs identified if they were placed in mating nucs situated further away from this study site.

But, of course, they could have then flown off in a different direction altogether 🙁

Finally, it’s worth noting that a different pattern of queen mating activity had been described for dark, native (Apis mellifera mellifera) and near-native bees. This is apiary vicinity mating (AVM), and is nicely described by Jon Getty on his website

I now have some native black bees. I’m also experiencing the worst spring of my entire beekeeping career for queen mating. I am increasingly interested in AVM as a mechanism for saving the queen from drowning or freezing to death while attempting to reach a DCA 🙁


 

Hard graft

Regular readers will have seen this image before …

Swarmy weather? I don’t think so …

… as I used it (with the same legend) towards the end of the post last week. 

I spoke too soon 🙁

The temperature on the 17th and 18th briefly reached 17.5°C … which was enough.

Grrrr …

But I’m getting ahead of myself.

Good morning America Glenrothes

I’m fortunate to live in a stunningly beautiful and remote part of the country. I open the blinds in the morning to panoramic views of the Morvern hills across a narrow sea loch. There are no houses in direct sight and – even when it’s damp 1 – it’s an idyllic scene.

Good morning Morvern …

But although I live here, most of my bees still live in Fife, so I have a commute to look after them and stay in convenient 2 hotels.

Opening the curtains on these trips provides a somewhat less salubrious view.

Uninterrupted views of the Macdonald’s drive-in

But at least I don’t have to cook my own breakfast, which is but a short walk away 🙂

As you can see from the photo above, it’s been raining overnight.

To make these trips economically rational 3 it’s necessary to book them several weeks in advance.

Despite the use of supercomputers, the BBC’s medium to long-range weather forecasts seem little more than guesswork. It’s worth remembering that a weather forecast competition over several weeks was won by a team that predicted ‘tomorrow will be like today’ for the duration of the event 4.

And for beekeeping, there’s a significant difference between 12°C, light drizzle with strong winds and 13°C, intermittent sunshine and gentle breezes.

The latter makes opening hives a relatively straightforward proposition … careful and quick, but the bees will cope just fine.

In contrast, the former makes everything rather hard work.

And this morning we’ll graft delicate larvae no larger than a comma on a page …

And these are exactly the conditions that greeted me when I did my first round of grafting on the 10th of May.

The weather is probably the major problem of long distance beekeeping. You have to be prepared for anything.

Queenright cell raising – the Ben Harden system

I’ve discussed grafting and using the Ben Harden queenright cell raising system extensively before. 

My Ben Harden setup was in the bee shed.

As it turned out, this was a (disappointingly rare) stroke of genius.

A strong, double brood colony had been modified be the replacement of 7 frames in the upper box by two ‘fat dummies‘. These have the effect of concentrating the bees in the gap between them. 

In this space were two frames containing pollen, one frame of young larvae 5 and the cell bar frame, into which I would be grafting larvae.

Ben Harden setup and pollen patties

This box sits on top of a queen excluder, below which was a single brood box (containing the queen) literally overflowing with bees 6. Positively bulging at the seams.

Since I didn’t have frames with sufficient pollen in them I’d also supplemented the colony with pollen substitute (a pollen pattie) which they were happily devouring. 

The hive also had a couple of half-full supers. These contained lots of bees but rather disappointing amounts of nectar.

The queen providing the larvae was in a nuc box in the same apiary. I’d been feeding this colony syrup and pollen to ensure the young larvae were well fed 7.

Grafting

The day for grafting dawned cool, grey and drizzly.

Great 🙁

I ended up doing the grafting in the passenger seat of the car, wearing a headtorch. I kept the larvae warm and humid using a damp piece of kitchen paper draped over those I’d already transferred from the comb to the plastic cups in the cell bar frame.

After gently inserting the cell bar frame into the space in the centre of the Ben Harden setup and filling the feeder in the fat dummy with syrup, I added a clearer board and then replaced the two supers.

The intention was to empty the supers into the cell rearing box, guaranteeing a huge number of bees would be there to help raise the queens.

Ben Harden cell raiser with clearer and supers

After another evening of junk food and a disappointingly similar breakfast I checked the grafts the next day for ‘acceptance’.

10/10 …

You do this by – ever so gently – lifting the cell bar frame from the centre of the Ben Harden setup and looking for a 5-6mm collar of fresh wax built around the lower lip of the Nicot cup into which the larvae have been grafted.

Amazingly, considering the dodgy conditions and the fact that this was my first attempt at grafting for a couple of years, all the larvae appeared to have been accepted 8. I didn’t brush any of the bees off and I certainly didn’t prod about in the densely packed bees on the frame … but things looked good.

So I closed the hive up and went off to inspect some other colonies in the rain before driving back to the west coast.

Coffee mishaps and colony inspections

I returned to the east coast about 8-9 days later to add the queen cells to nucleus colonies.

The ~150 mile journey didn’t go well. In mid-slurp the lid came off my mug, depositing a lap-full of lukewarm coffee over me. 

Never mind. The route I take goes through some ‘modesty-ensuring’ remote countryside. It was a five minute task to leave the trousers drying over the boxes of frames in the back of the car.

Since I had no spares I donned my beesuit and continued on the journey.

The weather improved as I drove east. I checked an apiary in mid-Fife where all was well and finally arrived at my main apiary in mid-afternoon.

It was a lovely day 🙂

So lovely one of the colonies had swarmed 🙁

There were actually two small swarms hanging about a metre apart in the willow trees I’d planted around the apiary 9

I didn’t really have time to think about the swarm … we needed a few hundred early stage drone pupae for work so went through the colonies to find these first.

These were quick ‘n’ dirty inspections … I checked every frame, but not every cell or every nook and crannie … 

  • brood in all stages?
  • eggs?
  • stores?
  • any charged queen cells?
  • temper, behaviour, stable on the comb?
  • anything weird or strange? 10
  • next please …

I didn’t check the hive I’d set up for queen rearing, or any of the nucs on site that contained virgin queens. However, all of the other colonies were queenright as determined by the presence of eggs and the absence of (obvious 11 ) queen cells.

Drone brood was either present in relative abundance – in the strong colonies – or notable by its absence. This should not be unexpected to those of you who read the post on drones last week.

To the tune of ‘Ten green bottles’ … all together now, ‘Ten capped queen cells hanging on a frame …’

And I still had 10 queen cells in the cell raising colony, all now capped and ready to use the following day 🙂

And the swarm?

The swarm (either of them if there were actually two) wasn’t really big enough to be a prime swarm. These contain a mated queen and ~75% of the workforce from the hive. None of the hives appeared short of bees and I’d found no (obvious 12 ) charged queen cells.

However, I’d not checked the queen rearing colony – packed full of bees and fed copious amounts of syrup – and one of the colonies on the site was very bad tempered 13.

Poor temper is often a sign of a queenless colony.

Anyway, back to the swarm.

I dropped each clump of bees into a separate nuc box containing a frame of drawn comb and a couple of additional frames. I left these in the shade until late afternoon when I’d finished with the other colonies.

Two into one do go

By late afternoon most of the swarm bees from one of the nuc boxes had abandoned it and joined the other nuc box. It was pretty clear that there was only one ‘swarm’ and that it had got separated when settling at the bivouac.

The bees were leaving the queenless box and joining the queenright one.

I checked the willow where the swarm was found. 

Small amounts of wax where a swarm settled

There were small amounts of wax deposited on the leaves and stem of the willow. I suspect that the swarm may therefore have been there overnight 14 but can’t be sure.

I ended the afternoon by putting the hived swarm on a hive stand in the apiary.

Before leaving I checked the bad tempered colony (which I was intending to split into nucs the following day).

During my fumblings I managed to get a few bees into my beesuit pocket 15.

The one with the hole in it from my razor-sharp hive tool.

That opened onto my leg.

Which was unprotected by trousers due to my fumblings with the coffee 9 hours earlier 🙁

Ouch 🙁

Getting nuked

The weather the following day started bright but rapidly degenerated.

That lot is about 10 minutes away … and approaching fast

By the time I’d got the nuc boxes prepared – feeders, frames, stores, dummy boards, entrance blocks, labels, straps – it was 11°C and there was rain quickly approaching from the west.

The first four nucs were prepared from the ‘bad tempered’ hive (#6). I decided it was wise to get this over and done with before the heaven’s opened.

Despite going through the box twice I failed to find a queen. Perhaps she went with the smallest prime swarm ever?

I divided the frames (by brood and bees, not number of frames) into four approximately equal nucs and added a queen cell to each. 

Here’s one I produced earlier … or helped produce

Each queen cell was removed from the cell bar frame, the adhering bees gently brushed off (with a handful of weeds) and pressed into a thumb-sized indentation in the comb, just underneath the top bar of the frame.

I then carefully pushed the frames together (avoiding crushing the cell) and closed the nuc box up.

As I opened the next hive to be split the rain started …

I should design a beesuit with an integrated sou’wester

… and the wind lessened, meaning the rain stayed.

And it rained for most of the afternoon.

Rain did not stop play

In the words of the late Magnus Magnusson “I’ve started, so I’ll finish”.

And it was miserable.

For the second time in two days I was soaked.

As those of you who have hunched over open hives in the rain will know, it’s your back, shoulders and hood that catch the worst of it.

This time my trousers stayed mostly dry … 

Nucs in the rain

The high point of the afternoon (and, let’s face it, the bar was pretty low) was the realisation that housing the cell raiser in the bee shed was an inspired choice.

When adding queen cells to nucs you either have to detach them in advance from the cell bar frame and keep them warm somewhere convenient, or collect them in turn.

Five gone, five to go … queen cells reared in a Ben Harden cell raiser

I had nowhere to keep them warm, so was returning to the Ben Harden setup to retrieve them one at a time. Since it was warm and dry in the shed I could leave the frame balanced (as shown above) still festooned with bees and fetch each cell as needed.

Had they been outside I would have had to stop.

It was difficult enough making up the nucs in the rain, one hand holding a frame, the other lifting the roofs on and off. 

It would have been impossible to juggle the cell raiser and cell bar frame as well.

But I eventually finished and moved half a dozen of the nucs to another apiary 16. I put the Varroa trays underneath 17, filled the feeders with syrup and opened the entrances a half inch or so to allow the bees to fly.

Half a dozen nucs, all in a row

And then I returned to the main apiary to tidy up.

And the swarm?

I still don’t know where the swarm came from 18.

I checked it between downpours. 

Despite opening the box very gently, with almost no smoke, the bees ‘balled’ the queen and killed her. I found her in the middle of a golf ball-sized clump of bees on the floor. 

Queen being ‘balled’ … it didn’t end well

After dislodging some of the bees with my fingers I found her, laying on her side, as dead as a dodo. You can just see her in the photo above., slightly below the middle of the image by the edge of the mesh.

Why did they do this?

I’ve inspected dozens of swarms the day after hiving them and don’t ever remember having this happen before.

Perhaps it was the poor weather? Maybe my ‘very gently’ wasn’t gentle enough?

The queen was unmarked and (obviously) unclipped.

To me, she looked like a virgin queen, rather than a slimmed down mated queen 19

There were two nucs in the apiary containing virgin queens. I didn’t inspect either, but a quick peek through the plastic crownboard showed both still appeared to contain bees. The size of the swarm, although small (as swarms go) looked much larger than the size of these nucs.

I’ll check again next week …

I added a queen cell to the swarm and set off for home.

Chasing the setting sun

It’s a beautiful commute, across Rannoch and through Glencoe, chasing the setting sun. 

And my trousers were finally dry 😉


Note

I’ve already grossly exceeded my self-imposed word count this week. This is not meant as a practical guide to queen rearing 20. For those interested in queen rearing – the most fun you can have with a beesuit on 21 – there are lots of articles here with the nitty gritty practicalities. Try these for starters … queen rearing, an introduction to the Ben Harden system, setup and cell raising.