The gentle art of beekeeping

High summer.

The swarm season had been and gone. The June gap was over. Grafts made at the peak of the swarm season had developed into lovely big fat queen cells and been distributed around nucleus colonies for mating.

That was almost six weeks ago.

From eclosion to laying takes a minimum of about 8 days. The weather had been almost perfect for queen mating, so I was hopeful they’d got out promptly, done ‘the business’, and returned to start laying.

That would have been about a month ago.

Good queens

I’d spent a long morning in the apiary checking the nucs and the colonies they were destined for. In the former I was looking for evidence that the queen was mated and laying well. That meant looking for nice even frames of sealed worker brood, with some – the first day or two of often patchy egg laying – now emerging.

Brood frame with a good laying pattern

It was warming up. More significantly, it was getting distinctly close and muggy. I knew that thunderstorms were predicted late in the afternoon, but by late morning it already had that oppressive ‘heavy’ feel to the air. Almost as though there wasn’t quite enough oxygen in it.

Never mind the weather, the queens were looking good. 90% of them were mated and laying well.

Just one no-show. She’d emerged from the cell, but there was no sign of her in the nuc, and precious few bees left either.

Queenless nucs often haemorrhage workers to nearby queenright colonies (or nucs), leaving a pathetic remainder that may develop laying workers. There’s no point in trying to save a colony like that.

Actually, it’s not even a colony … it’s a box with a few hundred abandoned and rapidly ageing workers. Adding resources to it – a new queen or a frame of eggs and young larvae – is almost certainly a waste of resources. They’d better serve the colonies they were already in. The remaining workers were probably over a month old and only had another week or two before they would be lost, ‘missing in action’, and fail to return from a foraging flight.

If you keep livestock, you’ll have dead stock.

These weren’t dead stock, but they were on their last legs, er, wings. I shook the workers out in front of a row of strong colonies and removed the nuc box so there was nowhere for them to return. The workers wouldn’t help the other colonies much, but it was a better fate than simply allowing them to dwindle.

Spare queens

Most of the nucs were going to be used to requeen production colonies. A couple had been promised to beginners and would be ready in another week or so.

Midseason is a good time to get a nuc to start beekeeping. The weather – the predicted (and seemingly increasingly imminent) afternoon thunder notwithstanding – is more dependable, and much warmer. The inevitably protracted inspections by a tyro won’t chill the brood and nucs are almost always better tempered than full colonies. In addition, the new beekeeper has the pleasure of watching the nuc build up to a full colony and preparing it for winter. This is a valuable learning experience.

Late season bramble

Late season bramble

It’s too late to get a honey crop from these midseason nucs (usually, there may be exceptional years) but that’s probably also good training for the new beekeeper. An understanding that beekeeping requires a degree of patience may be a tough lesson to learn but it’s an easier one than discovering that an overcrowded nuc purchased in April, swarms in May, gets really ratty in June and needs a new queen at the beginning of July.

But, after uniting the nucs to requeen the production hives it turned out that I had one queen spare.

Which was fortunate as I’d been asked by a friend for an old leftover queen to help them improve the behaviour of their only colony. Rather than give them one of the ageing queens she could have the spare one from this year.

A queen has a remarkable influence over the behaviour and performance of the colony. Good quality queens head calm, strong colonies that are a pleasure to work with. But it’s not all good genes. You can sometimes detect the influence of a good new queen in a poor colony well before any of the brood she has laid emerges. I assume this is due to pheromones (and with bees, if it’s not genetics or pheromones I’m not sure what else could explain it – ley lines, phase of the moon, 5G masts nearby?).

Go west, young(er) man

My friend lived about 45 minutes away. I found the queen in the nuc, popped her into a marking cage and placed her safely in light shade at the back of the apiary while I rearranged the nuc for uniting over a strong queenright colony.

Handheld queen marking cage

Handheld queen marking cage

A few minutes later I’d recovered the queen, clipped her and marked her with a white Posca pen. I alternate blue and white (and sometimes yellow if neither of those work or can be found) and rely on my notes to remind me of her age should I need to know it. I’m colourblind and cannot see – or at least distinguish – red and green, either from each other or from lots of other colours in the hive.

I transferred the marked queen into a JzBz queen cage and capped the exit tube. Of all the huge variety of queen introduction cages that are available these are my favourite. They’re also the only ones I was given a bucket of … something that had a big part to play in influencing my choice 🙂

JzBz queen cages

JzBz queen cages

I put the caged queen in the breast pocket of my beesuit, extinguished the smoker and tidied up the apiary. It was warm, dark and humid in the pocket – for an hour or so she would be fine.

Actually, it was getting increasingly humid and the heaviness in the air was, if anything, getting more oppressive.

What I’d really like now would be a couple of large mugs of tea … I’d inspected a dozen large colonies and nearly the same number of nucs. The colonies that needed requeening had been united with the nucs (having found and removed the ageing queens) and I’d neatly stacked up all the empty nuc boxes in the shed. Finally, I’d retuned all the supers, some reassuringly heavy, and left everything ready for the next inspection in a fortnight or so 1.

That’s a lot of lifting, carrying, bending, squinting, prising, turning, rearranging and then gently replacing the crownboard and the roof.

Not really hard work, but enough.

Actually, quite enough … I’d really like that cuppa.

Was that thunder? Way off to the west … a sound so faint I might have imagined it. There were towering cumulus clouds building along the horizon.

Cloud

Threatening

Time to get a move on.

With the car packed I lock the apiary gate and set off.

West.

Leaving the flat agricultural land I climbed gently into low rolling hills. The land became more wooded, restricting my view of the thunderheads building, now strongly, in the direction I was heading. The sun was now intermittently hidden between the wispy clouds ahead of the storm front.

Could you do me a favour?

The bad weather was still a long way off. I’d have ample time to drop the queen off, slurp down a cuppa and be back home before any rain arrived. If my friend was sensible she’d just leave the new queen hanging in her cage in a super. The workers would feed her until the weather was a little more conducive to opening the hive and finding the old queen.

I pull into the driveway and my friend comes out to meet me. We share beekeeping chat about the weather, forage, the now-passed swarm season, the possibility of getting a nuc for next season 2.

“Could you perhaps requeen the colony? I’m really bad at finding the queen and they’ve been a bit bolshy 3 recently. I’ll put the kettle on while you’re doing it.”

I did a quick mental calculation … weighing up the positives (kettle on) and the negatives (bolshy, the distant – but approaching – thunder) and was surprised to find that my yearning for a cuppa tipped the balance enough for me to agree to do it.

I returned to the car for my smoker and some queen candy which I used to plug the neck of the JzBz cage. At the same time I also found a small piece of wire to hang the cage between the frames from.

“They’re in the back garden on the bench by the gate to the orchard.”

I look through the kitchen window across the unkempt lawn (was the mower broken?). Sure enough, there was a double brooded National hive topped with two supers on a garden bench about 30 metres away.

“I’ll stay here if you don’t mind … they gave me a bit of a fright when I last checked them.”

Sure. No problem. I’ve done this a hundred times. White, no sugar and, yes, I’d love a cookie as well.

Be properly prepared

I stepped into the back garden and fired up the smoker. It was still warm from being used for my own bees and the mix of cardboard, woodshavings and dried grass quickly started smouldering nicely. A couple of bees had come to investigate but had just done a few laps of my head and disappeared.

But they returned as I walked across the lawn.

And they brought reinforcements.

By the time I was half way across the lawn I’d been pinged a couple of times. Not stung, but the sort of glancing blow that shows intent.

A shot across the bows, if you like.

I didn’t like.

I pulled the veil over my head and zipped it up quickly, before rummaging through my pockets to find a pair of gloves. Mismatched gloved. A yellow Marigold for my left hand and a thin long-cuff blue nitrile for my right. It’s an odd look 4 but an effective combination. The Marigold is easy to get on and off, and provides ample protection.

Nitriles ...

Nitriles …

The nitrile is a bit of a nightmare to get on when it’s still damp inside. Another couple of bees dive bomb my veil, one clinging on and making that higher pitched whining sound they make when they’re trying to get through. I brushed her off with the Marigold, turned the nitrile inside out, blew into it to inflate the fingers, and finally got it on.

Why two different gloves? Two reasons. I’d lost the other Marigold and because nitriles are thin enough to easily pick a queen up with, and that’s what I’d been doing most of the morning.

And hoped to do again shortly when I found the old queen in the agitated colony.

Opening hostilities

I approached the hive. It was a strong colony. Very strong. It was tipped back slightly on the bench and didn’t look all that stable 5. I gave them a couple of puffs of smoke at the entrance and prised the supers up and off, placing them propped against the leg of the bench.

I was faintly aware of the smell of bananas and the, still distant, sound of thunder. It probably wasn’t getting any closer, but it certainly wasn’t disappearing either.

The thunder that is.

The smell of bananas was new … it’s the alarm pheromone.

Actually, it’s one of the alarm pheromones. Importantly, it’s the one released from the Koschevnikov gland at the base of the sting. This meant that one or two bees had already pressed home a full attack and stung me. Felt nowt. Presumably they’d hit a fold in the beesuit or the cuff of the Marigold.

Or my adrenaline levels were sufficiently elevated to suppress my pain response.

I was increasingly aware of the number of really unpleasant bees that were in the hive.

And, more to the point, coming out of the hive.

But I was most aware that I was only wearing a single thickness beesuit in the presence of 50,000 sociopaths with a thunderstorm approaching. Under the suit I had a thin short sleeved shirt and a pair of shorts.

It might be raining in half an hour … this could get ugly.

It was late July, it was a hot day, my bees are calm. I wasn’t dressed appropriately for these psychos.

I felt I needed chain mail … and an umbrella.

Time for a rethink

I gave the hive a couple of larger puffs from the smoker and retreated back to the car, ducking under and through – twice – some dense overhanging shrubs to deter and deflect the bees attempting to hasten my retreat.

Ideally I’d have put a fleece on under the beesuit. That makes you more or less impervious to stings.

Did I mention it was a warm day in July? No fleece 🙁

However, I did have a beekeeping jacket in the car. This is what I wear for most of my beekeeping (unless I’m wearing shorts). I removed the jacket hood and put it on over the beesuit, remembering to transfer the queen to the outer jacket pocket. I also found another nitrile glove and put it on to be double gloved.

“The queen’s not marked”, my friend shouted to me as I walked back across the garden, “Sorry!”

Now you tell me …

I See You Baby

I See You Baby

I returned to the hive. To reduce the immediate concentration of bees, I split the two brood boxes off the floor, placing each several metres away on separate garden chairs. I balanced the supers on the original floor to allow returning foragers and the increasing maelstrom of flying bees to have somewhere to return if needed.

And then I found the unmarked queen.

As simple as that.

Amazingly, it was on the first pass through the second brood box.

Each box was dealt with in the same way. I gently split the propolis sealing the frames together – first down one side of the box, then the other. I removed the outer frame, inspected it carefully and placed it on the ground leaning against the chair leg. With space to work I then methodically went through every frame, calmly but quickly.

I didn’t expect to find her so easily. I wasn’t sure I’d be able to find her at all.

It helped that she was huge and pale. It helped that she was calmly ambling around on the frame, clearly confident in the knowledge that there were 50,000 acolytes willing to lay down their lives to protect her.

Her confidence was misplaced 🙁

Veiled threat

And then a bee got inside the veil.

This happens now and then. I suspect they sneak through the gap where the zips meet at the front or the back. There are little Velcro patches to hold everything together, but it was an old suit 6 and the Velcro was a bit worn.

There are few things more disconcerting that 50,000 psychos encouraging a Ninja worker that’s managed to break through your defences and is just in your peripheral vision. Or worse, in your hair. With a calm colony you can retreat and deal with the interloper. You have to take the veil off. Sometimes you have to take the suit off.

Removing the veil would have been unwise. Perhaps suicidal. I retreated a few yards and dealt with the bee. It was never going to end well for one of us 🙁

Reassemble in the reverse order

Returning to the original bench, I removed the supers that were now festooned with thousands of bees, balancing them against the leg again. I found a pencil-thick twig and used it under one corner of the floor to stop everything wobbling. Both brood boxes were returned, trying to avoid crushing too many bees at the interface. A combination of a well aimed puff or two of smoke, brushing the bees away with the back of my hand and placing the box down at an angle and then rotating it into position reduced what can otherwise cause carnage.

I hung the new queen in her cage between the top bars of the central frames in the upper box, returned the queen excluder and the supers and closed the hive up.

It took 15 minutes to avoid and evade the followers before I could remove the beesuit safely. I’d been stung several times but none had penetrated more than the suit.

I finally got my cup of tea.

Confidence

This was several years ago. I took a few risks towards the end with the queen introduction but got away with it. The colony released the queen, accepted her and a month or so later were calm and well behaved.

I was lucky to find the queen so quickly in such a strong colony. I didn’t have to resort to some of the tricks sometimes needed to find elusive queens.

Ideally I’d have left the queen cage sealed to see if they were aggressive to her, only removing the cap once I was sure they’d accept her. This can take a day or two, but you need to check them.

There was no way I was going back into the hive and my friend definitely wasn’t.

The rain and thunder never arrived … like many summer storms it was all bluster but eventually dissipated as the day cooled.

This was the worst colony I’ve ever handled as a beekeeper. At least for out and out, close quarter, bare knuckle aggression. By any measure I’d have said they were unusable for beekeeping. I’ve had colonies with followers chase me 300 metres up the meadow, though the hive itself wasn’t too hot 7. This colony was an order of magnitude worse, though the followers were less persistent.

I suspect that aggression (or, more correctly, defensiveness) and following have different genetic determinants in honey bees.

Lessons

  • Knowing when to retreat is important. Smoking them gently before I returned to the car for a jacket helped mask the alarm pheromone in the hive and gave me both time to think and renewed confidence that I was now better protected.
  • Confidence is very important when dealing with an unpleasant hive. It allows you to be unhurried and gentle, when your instincts are screaming ‘get a move on, they’re going postal’.
  • Confidence comes with experience and with belief in the protective clothing you use. It doesn’t need to be stingproof, but it does need to protect the soft bits (my forearms, ankles and face react very badly when stung).
  • Indeed, it might be better if it’s not completely stingproof. It’s important to be aware of the reactions of the colony, which is why I prefer nitrile gloves to Marigolds, and why I never use gauntlets.
  • Many colonies are defensive in poor weather or with approaching thunderstorms. If I’d known just how defensive this colony were I’d have planned the day differently.
  • The unstable ‘hive stand’ would have agitated the bees in windy weather or during inspections.

Bad bees

It turned out the colony had been purchased, sight unseen, as a nuc the year before. By the end of the season it had become unmanageable. The supers had been on since the previous summer and the colony hadn’t been treated for mites.

They appeared healthy, but their behaviour was negatively influencing their management (and the upkeep of the garden). Beekeeping isn’t fun if you’re frightened of the bees. You find excuses to not open the hive, or not mow the lawn.

The story ended well. The new queen settled well and the bees became a pleasure to work with. My friend regained her confidence and is happy to requeen her own colonies now.

She has even started using proper hive stands rather than the garden bench … which you can now use for relaxing on with a mug of tea and a cookie.

While watching the bees 🙂


 

A virus that changes bee behaviour

Particle physicists might not agree, but I think that evolution is the most powerful force in the universe. It is responsible for the fabulous diversity of life, for everything from the 6,000,000 kg Pando clonal colony of quaking aspen covering 43 hectares of the Fishlake National Forest in Utah, to the teeniest of tiniest of viruses.

As a microbiologist I’m acutely aware of the role evolution has played in the genetic arms race between hosts and pathogens. This is what is responsible for the multi-faceted immune system higher organisms carry – the antibodies, the lymphocytes, the complement and interferon responses, and everything else.

In turn, the fast replicating bacteria and viruses have evolved countermeasures to subvert these immune mechanisms, to switch them off entirely or to decoy them into targeting the wrong thing. This ‘arms race’ has gone on since well before the evolution of multicellular organisms (~600 million years ago) … and continues unabated.

Evolution is powerful for one simple reason; if a particular genetic combination 1 ‘works’ it will be passed on to the progeny. If a virus evolves a way to resist the immune response of the host, or to spread between hosts more efficiently, then the trait will be inherited.

Molecular mechanisms and behavioural changes

Some of changes work at the molecular level, invisible without exquisitely sensitive in vitro analysis; protein A binds to protein B and, in doing so, stops protein B from doing whatever it should have be doing. These are important but often very subtle.

Rabies: Slaying a mad dog, 1566 illustration from Wellcome Images

Other changes are far more obvious. Take rabies for example (or don’t, it’s not recommended as it has a near-100% case fatality rate) … the primary host of the rabies virus are carnivorous mammals. Infection causes gross behavioural changes that facilitate virus transmission. The animal becomes bolder and much more aggressive, resulting in virus transmission through biting.

Recent studies have elegantly demonstrated that this (also) is an example of protein A binding to protein B at the molecular level, it’s just that the phenotype 2 is very much more marked.

A protein on the surface of the virus resembles a snake venom toxin and has the ability to bind to nicotinic acetylcholine receptors present in the central nervous system of the mammalian host. These receptors ‘do what they say on the tin’ and bind the neurotransmitter acetylcholine. If the virus protein binds the receptor the response to acetylcholine is blunted and this, in turn, leads to hyperactivity, one of the key behavioural responses caused by rabies viruses.

That’s enough about mad dogs.

If virus-induced behavioural changes are so obvious, why haven’t lots of different examples already been identified and characterised?

Sniffles

Part of the problem is the blurring of distinctions between overt behavioural changes and the direct symptoms induced due to the virus replicating.

Human rhinovirus, the aetiological agent of the common cold, causes upper respiratory tract infections. You get a runny nose and you sneeze a lot.

Gesundheit

Your behaviour changes.

However, it’s generally accepted that the sneezing and runny nose are a result of the physiological response to infection, rather than a virus-induced behavioural response to facilitate transmission.

It’s worth noting that all that “stuff” that comes out of your nose contains infectious virus, so it’s perhaps an artificial distinction between the general symptoms of sickness and evolutionarily-selected host behavioural changes caused by the virus.

Which in a roundabout way …

… allows me to finally introduce the topic of bee viruses that cause host behavioural changes involved in their transmission.

Or, rather, one bee virus that does this … though I’m certain that there will be more.

Israeli Acute Paralysis Virus (IAPV) is an RNA virus transmitted horizontally by direct contact between bees, or while feeding on developing pupae, by the parasitic mite Varroa destructor. It was implicated as a causative agent of Colony Collapse Disorder (CCD), though really compelling evidence supporting it as the primary cause never materialised.

It’s a virus UK beekeepers should be aware of, but unworried by, as it is extremely rare in the UK.

A recent paper has shown two behavioural changes in response to IAPV infection in honey bees. One of them – that facilitates horizontal transmission between colonies – is also partially explained at the molecular level.

The paper was published a couple of months ago:

Geffre et al., (2020) Honey bee virus causes context-dependent changes in host social behavior. Proc. Natl. Acad. Sci. USA 117:10406-10413. 3

I’m going to focus on the results, rather than the methods, though the methods are rather cool. They used barcoded bees to allow the automated image analysis of every bee in a colony for some of the studies where they had introduced known IAPV infected individuals.

Responses of nestmates to IAPV infected bees

Imagine watching a few hundred waggle dances and being able to recount the position, distance and response of every bee ‘watching’ 4 the dance, and then being able to summarise the results.

Over five days.

Non-stop.

Including nights (and yes, bees do still waggle dance at night – a subject for the future).

The scientists orally infected groups of 30 bees with a sub-lethal dose of IAPV, marked them and released them into an observation hive. They then recorded their movements around the hive and their interactions with other bees in the colony. In particular, they focussed on trophallaxis interactions where one bee ‘feeds’ another.

Trophallaxis is also considered to be a method of communication in the hive and has been implicated in disease transmission.

The authors love their whisker plots and statistical analysis.

Who doesn’t? 😉

However, they generally make for rather underwhelming images in a bee blog for entertaining reading. Here .. see what I mean …

Number of trophallaxis interactions per hour.

Suffice to say that the results obtained were statistically significant.

They showed that the infected bees in the colony actually moved about the colony more than their nestmates. Conversely, they were engaged in fewer trophallaxis interactions i.e. it appeared as though they were being ‘ignored’ by their nestmates.

Were they really being ignored altogether or did their nestmates approach them, detect something was amiss and move away?

Antennation

Antennation is the mechanism by which bees recognise nestmates. They use the sensitive chemoreceptors on their antenna to detect cuticular hydrocarbons (CHC) which are distinctive between bees from different hives.

Antennation is a precursor to trophallaxis.

After all, bees do not want to feed a foreigner, or exchange chemicals involved in communications, or even potentially risk being exposed to a new pathogen.

Good as the barcoding and camera system is, it’s not good enough to record antennation within the observation hive. To do this they manually 5 recorded antennation events between IAPV-infected bees and nestmates in cages in the laboratory 6.

In these studies IAPV-infected bees were engaged in the same number of antennation events as control bees. This strongly suggests that the nestmate could detect there was something ‘wrong’ with the IAPV-infected individuals. In support of this conclusion, the authors also demonstrated that bees inoculated with a double stranded RNA (dsRNA) stimulator of the honey bee immune response were also also antennated equally, but engaged in less trophallaxis interactions.

Therefore, these studies appear to show that nestmates exhibit a behavioural response to IAPV-infected bees (and bees with elevated immune responses, recapitulating their response to pathogen infection) that is likely to be protective, reducing the transmission of horizontally acquired viruses.

It’s worth noting two things here.

  1. There were no virus transmission studies conducted. It’s assumed that the lack of trophallaxis reduces virus transmission. That still needs to be demonstrated.
  2. This response is not induced by the virus on the host. It’s a response by nestmates of the host to virus infected individuals (or individuals that present as ‘sick’). As such it’s not the same as the rabies example I started this post with.

Virus-induced behavioural responses

But do the IAPV-infected bees behave differently when they come into contact with other bees who are not their nestmates?

After all, IAPV is a pathogenic virus and its continuing presence within a population (not just a single hive) depends upon it being spread from hive to hive.

For a highly pathogenic virus this is very important. If you spread from bee to bee within a hive and kill the lot you also go extinct … this partly explains the mechanism by which highly virulent viruses become less virulent over time.

But back to IAPV. What happens when IAPV-inoculated bees interact with bees from a different hive?

For example, what would happen if they drifted from one hive to another in a densely populated apiary? Drifting is a significant contributor to the spread of bees between adjacent colonies – studies show that 1% of marked bees drift to adjacent hives over a 3 day window. This partially accounts for the genetic mix of workers (up to 40% are unrelated to the queen that heads the colony) in a hive, a fact generally unappreciated by beekeepers.

The authors first showed that IAPV-infected bees could apparently leave and return to the hive with a similar frequency as uninfected foragers. Their flying was not compromised.

They then resorted again to recording interactions in the laboratory between IAPV-infected bees or control dsRNA-inoculated bees and workers from a different hive.

This was where it gets particularly interesting.

Hello stranger

The dsRNA-immunostimulated bees (remember, these induce a generalised immune response characteristic of a ‘sick’ bee) were treated aggressively by unmatched workers from a different hive.

In contrast, the IAPV-infected bees (which were ‘sick’ and would have been undergoing immunestimulation caused by the IAPV infection) experienced significantly less aggression than both uninoculated workers (which induced an intermediate response) and the dsRNA-inoculated.

This strongly suggests that IAPV is somehow able to modulate the appearance or behaviour (and one often determines the other) of the host to make it more acceptable to an unmatched worker.

They extended this study to conduct “field-based assays at the entrances of three normally managed honey bee colonies”, monitoring whether IAPV-infected bees were more likely to be accepted by the guard bees at the entrance of the hive.

They were. The IAPV-infected bees received a less aggressive reception and/or entered the hives much more easily than the controls.

But what about proteins A and B?

Good question.

The behavioural alterations described above must be explainable in terms of the molecular changes that IAPV induces in the bees. By that I mean that the virus must make, or induce the making of, a chemical or protein or other molecule, the presence of which explains their acceptance by the foreign guard bees.

And the obvious candidates are the cuticular hydrocarbons (CHC) that are recognized during antennation, which I introduced earlier.

And here the story leaves us with some tantalising clues, but no definitive answer.

The scientists demonstrate that there were marked differences between the CHC profile of IAPV-infected and control bees. Again, they used their favoured whisker plots to show this, but collated all of the CHC data into an even more difficult to explain scatter plot of linear discriminant analysis.

CHC profiles (relative abundance) shown using linear discriminant analysis.

The key take home message here is that for each of the CHC’s analysed there were differences in both the quality and relative abundance between the control bees, bees immunestimulated with dsRNA and the IAPV-infected bees.

These differences were so marked that you can see distinct clustering of points in the analysis above … these bees ‘look’ 7 different to the guard bees that antennate them.

This is a great story.

It’s as yet incomplete. To complete the understanding we will need to know which of those CHC’s, or which combination, when suppressed (or overrepresented) induce the guard bees to say “Welcome, step this way … “.

We’ll then of course need to find out how IAPV induces the change in CHC profile, which takes us right back to protein A and protein B again.

Ever the pedant

Much as I like this science I’d perhap argue that, again, the virus isn’t directly inducing a behavioural change in the host.

What it’s doing is inducing a behavioural change in the response to the infected host (by the guard bee). So perhaps this again isn’t quite the same as the rabies example we kicked off with.

A behavioural change in the host might include IAPV-infected bees drifting more, or drifting further. Alternatively, perhaps a colony with widespread IAPV infection could more easily indulge in robbing neighbouring colonies as they would experience less aggression from guard bees.

Smaller is better ...

Reduced entrance to prevent robbing …

I can see immediate evolutionary benefits to a virus that induced these types of behavioural changes. It’s not an original idea … the late Ingemar Fries suggested it in a paper two decades ago 8.

I’m also certain that researchers are looking for evidence supporting these types of directly-induced behavioural changes caused by viral pathogens in honey bees.

All religion, my friend, is simply evolved out of fraud, fear, greed, imagination, and poetry

Edgar Allen Poe may or may not have said this.

However, while we’re on the thorny subject of pathogen-induced behavioural changes in the host, it might be worth mentioning a couple of more controversial areas in which it has been proposed.

In the snappily titled paper “Assortative sociality, limited dispersal, infectious disease and the genesis of the global pattern of religion diversity” Fincher and Thornhill argue 9 that the wide diversity of religions in the tropics (compared to temperate regions) is driven by infectious disease selecting for three anti-contagion behaviours; in-group assortative sociality; out-group avoidance; and limited dispersal. It’s an interesting idea and I’m pleased I don’t have to test it experimentally. Their argument is that these three behavioural changes select for fractionation, isolation and diversification of the original culture … and hence the evolution of religions.

Conversely, perhaps microorganisms induce religious behaviours (rather than religion per se) that facilitate their transmission. This is exemplified in the entertainingly titled paper “Midichlorians – the biomeme hypothesis: is there a microbial component to religious rituals?” by Panchin et al., (2014). They argue that microbes – and they are really thinking about the gut microbiota here – might be able to influence their hosts (humans) to gather for religious rituals at which both ideas (memes) and infections are more easily transmitted.

Perhaps something to think about when mindlessly spinning out all that summer honey in the next few weeks?

Party, party

I think it’s fair to say that both the papers in the section above have some way to go until they achieve mainstream acceptance … if they ever do.

Furthermore, the general area in which parasites, bacteria and viruses, induce changes in the behaviour of their hosts’ is really in its infancy. We are aware of a lot of behavioural changes, but few are understood at the molecular level 10. As such, we often don’t know whether the association is correlative or causative.

Evolution is certainly a powerful enough selective force to ensure that even extremely subtle benefits to the pathogen may become a genetically-fixed feature of the complex interaction it has with the host.

Respiratory viruses, such as the common cold, Covid-19 and influenza infect millions of people globally and are readily transmitted by direct or indirect contact.

That’s why most of the readers of this post have a face mask nearby and a bottle of hand sanitizer ‘at the ready’. Or should.

Direct transmission benefits the virus as it does not have to survive on a door handle, milk bottle or petrol filling pump.

But direct transmission requires that people meet and are in close contact.

And a paper 10 years ago demonstrated that infection with influenza virus resulted in increased social interactions in the 48 hours post-exposure, compared with the same period pre-exposure 11.

It’s amazing what viruses can do … or might do … or (just look around you) are doing.


 

Bigging up nucs

The phrase bigging up [somebody or something] means saying they are very good, usually in public 1. It is slang and used informally and usage has increased significantly in the last couple of decades.

The term bigging in bigging up meaning promotion, is relatively new. However, the same word can be traced back to Middle English and (a bit more more recently) obsolete Scottish, when it meant build.

Two days work bigging a brick wall in the Braidfoots house 2.

Anyone who has used nucs, for queen mating or swarm control for example, is likely to big them up … as in sing their praises. Small enough to need only limited resources to start them, large enough to function as a self-contained and resilient colony etc.

However, in this post I’m going to discuss bigging up nucs in the older meaning of the phrase … building them up from a nuc to a full colony.

Which could also, of course, be considered as promoting them 😉

Problems with history and latitude

One of the perils of writing about beekeeping in the UK is the variation in the season between the south and the north of the country.

Just as you can’t be prescriptive in any one location about when certain events in a particular beekeeping year occur – e.g. swarming, winter bee production, broodlessness – it’s also pretty obvious that the season is longer 3 at lower latitudes.

It’s therefore not possible to say ‘in late May’ or ‘by mid-June’ nucs will start to be overcrowded 4. Not only does this depend upon the local climate, but it is also significantly influenced by how the nucs were prepared.

If the nuc was established for swarm control, started with the old queen and 1-2 frames of brood, it is likely to have built up rapidly and will quickly overrun the box if not dealt with promptly.

Alternatively, if the nuc was used for queen mating, started with a sealed cell (or virgin queen) and a frame of emerging brood, it will build up less fast as the queen has to get out and mate and then start laying.

Overcrowding

Whatever the history (or the latitude), at some point the colony will grow to be too large for the box. Then, but ideally earlier (so you are prepared), you need to decide what you are going to do with them.

With experience you can judge overcrowding by gently popping the lid up and peering through the thin plastic or polycarbonate crownboard. 

I use Thorne’s Everynucs which have an integral feeder at one end of the box. When they start building brace comb in the feeder they need to be given more space.

Here's one I prepared earlier

Here’s one I prepared earlier

The colony above is overwintered and very clearly overcrowded. The photo was taken in the third week of April (in Scotland). By mid-season, a colony that crowded would have probably swarmed.

Comb in feeder

The photo immediately above was taken in late June this year. The nuc was set up in mid-May for swarm control with the queen and just one frame of emerging brood.

However, in the intervening six weeks I had already removed two or three frames of sealed brood (but not adhering bees) to boost other colonies, replacing the frames with a mix of drawn comb and foundation, all of which had been drawn and filled again.

Nucs can build up very fast … be warned.

Decision time

Nucs are really versatile. Your choice includes (but isn’t restricted to):

  1. Overwintering the nuc
  2. Expanding the nuc into a full hive
  3. Uniting the nuc with a queenless colony
  4. Removing the queen and uniting the nuc with a queenright colony
  5. Leaving it too late and letting them swarm 🙁

I’m not going to discuss the last option, but it is an inevitability if the colony is healthy and there’s a reasonable amount of forage in the area. 

One more week’ for a nuc is usually not worth risking.

Overwintering nucs deserves a post of its own (and has been covered some time ago 5). It’s worth noting that nucs started in May for swarm control or for queen mating require a lot of maintenance if they are not to outgrow their accommodation by the end of the season. You need to regularly remove bees and brood or the colony will swarm.

It is much better to start nucs later in the season for overwintering.

Before doing anything with the nuc it is worth confirming that the queen appears well mated and is laying well 6. She should be producing frame after frame packed with brood. In new(ish) comb you can easily tell her quality based upon the presence of even sheets of brood, with relatively few missed cells.

Good laying pattern from queen in 5 frame nucleus

The frame above is from a nuc this spring. The majority of the missed cells, at least at the top of the frame, are due to the wires in the foundation.

Returning a marked and clipped queen to a nuc

And, while you’re at it, use this opportunity of the last inspection of the nuc to mark and clip the queen (if she isn’t already). It’s always easier to find a queen in a nuc – fewer bees, less frames to hide on the other side of etc.

From nuc to a full brood box

This is about as easy as it gets and should take no more than 5 minutes if you have everything to hand.

  1. Move the nuc a metre or so away from its original location.
  2. Place a new floor and a brood box on the original site.
  3. The brood box should contain a couple of frames of drawn comb if you have them, or frames with fresh foundation. Place one next to each side wall (see note below for comment on warm and cold way).
  4. If the floor has open mesh I slide in the Varroa tray. I do not want the bees to be distracted by smells from other ‘potential’ routes into the hive.
  5. Open the nuc using a very small amount of smoke 7.
  6. Remove the dummy board from the nuc and gently separate the frames if they’re propolised together.
  7. Transfer each frame to the new brood box maintaining their position and orientation relative to the neighbouring frames. Arrange the frames from the nuc close to the new hive entrance (see below).
  8. Ideally , make sure the queen is seen … just to give you confidence 🙂
  9. Move the second new frame of drawn comb or foundation to ‘sandwich’ the frames from the nuc.
  10. Fill the rest of the box with frames containing drawn comb or new foundation.
  11. Replace the dummy board removed in #6 above.
  12. Add syrup if needed – see below.
  13. Replace the crownboard and roof.
  14. Reduce the entrance to help the colony defend their new, much larger, residence.

Feeding

If there is a good nectar flow you may not need to feed the colony. If you’ve used new foundation rather than drawn comb then they probably will need feeding. It’s important they draw new comb so the queen can continue laying uninterrupted. This ensures they build up rapidly.

Use thin syrup (1:1 by weight of sugar and water) in a contact feeder. 

I usually give nucs a gallon or so of syrup to help them draw comb. They use this surprisingly fast. Check them every 48 hours. 

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

My crownboards lack holes, so I place the contact feeder directly above the top bars, separated by a couple of spare frame bottom bars. I add a super to ‘house’ the contact feed and then close the hive up.

Defending the hive

All of my full-sized hives are arranged warm way. This means the frames are parallel with the entrance of the hive. The alternative, cold way, has the frames perpendicular to the entrance.

To help the small colony defend the new large box they are in, the nucleus frames should be located close to the hive entrance.

The hive entrance is on the left with the frames arranged ‘warm way’.

Initially, these are the frames that are covered in bees, so providing a deterrent to any potential robbers.

It may also help to reduce the size of the hive entrance so the bees only need to defend an inch wide hole, rather than the full width of the box.

If your hives are organised cold way’ the same requirements apply – arrange the bees near to the entrance and reduce the entrance width. For example, place the frames in the centre of the hive, flanked on each side by three new frames, and leave a narrow central entrance open.

Finally, do not slop syrup around all over the place when feeding them. It’s a near-certain way to encourage robbing (particularly if there’s a shortage of nectar).

Uniting the nuc with a queenright or queenless colony

I can deal these two together because the only difference is where the queen is in the stacked boxes at the end of the procedure.

Collect together the things you will need:

  • A new brood box
  • Two sheets of newspaper
  • Six frames of drawn comb or foundation

Queens

If the hive and the nuc are both queenright you must remove the unwanted queen 8.

Typically this is when you have used the nucleus method of swarm control. The colony has reared a good new queen and the old queen in the nuc is now surplus to requirements.

Alternatively, the colony might have generated a sub-standard or poorly mated queen and you want a single united colony headed again by the original queen.

If the old(er), unwanted queen is still laying OK consider offering her to someone else in your association. Remove the queen, does not necessarily mean sacrifice her. 

Caged queen with attendants

Place the queen in a introduction cage with some attendant workers and some candy. Put her somewhere safe (the breast pocket works for me) and give her to someone who needs her more than you do … perhaps in exchange for a nice bottle of merlot 9 😉

Don’t risk leaving two queens in the same box and hoping the ‘better’ one (i.e. the one you want) will survive the ruckus that will happen. 

Sod’s Law dictates that the queen you want will not make it … particularly if it’s late in the season, she’s particularly good or she’s otherwise precious.

Uniting

I generally move the nuc to the hive it is being united with. Waft some smoke at the hive entrance, remove the roof and gently lift the corner of the crownboard. Add a second gentle puff of smoke into the gap and let the bees move down.

Remove the crownboard and gently lay two intact sheets of newspaper flat over the tops of the frames. It helps to remove brace comb from the top bars as it can puncture the newspaper and lead to premature mixing and a bit of a melee.

In the good old days a single page from a broadsheet 10 newspaper was sufficient. These days I think you have to read the Financial Times to achieve this

Assuming you’re not Gordon Gekko, a hedge fund manager or derivatives trader you will probably need two slightly overlapping sheets. Don’t bother about moving all the bees off the top bars – they’ll move down soon enough once you put the newspaper on.

If it’s windy use your initiative, recruit a helper or evolve at least one additional limb to hold the newspaper in place.

Add a second empty brood box on top.

Make a small hole (about the size of the o in hole) in the sheet using your hive tool, somewhere near the middle, above a gap between two frames. You can just see the hole above the curve of the hive tool here …

Newspaper, second brood box and a very small hole

Add two or three frames of drawn comb or foundation. Transfer all the frames from the nuc to the new brood box, as before, maintaining their order and orientation. Fill the rest of the box with frames, shake in the last bees from the nuc box and close the hive up.

Just checking!

As before, if you are uniting a queenright nuc with a queenless hive, it’s always good to be certain the queen was on one of the frames transferred to the new box.

Have patience

Hives usually have sufficient stores at this time of the season. If both boxes are light you might have to feed them syrup (to help them draw comb) or fondant (just to tide them over until the nectar flow starts).

Leave them to it. There’s nothing to be gained by ‘having a peek’. The bees will chew their way through the newspaper in 24-48 hours.

Successful uniting ...

Successful uniting …

Look out for a pile of shredded newspaper falling through the open mesh floor and, after a week, continue inspections as normal.

Miscellaneous final thoughts

If the recipient hive is broodless it will end up with lots of space and empty frames. Under those circumstances I usually unite them down to a single box. Rather than adding additional frames to the top box I use a fat dummy to fill the space.

Uniting a nuc with a full colony

Uniting a nuc with a full colony …

A block of polystyrene tightly wrapped in a bin bag works just as well 11.

A week after uniting them rearrange the brood-containing frames with pollen and stores into a single box and remove the empty frames and unwanted second brood box.

Lost bees

How will the bees reorientate to the new location?

Don’t worry. The bees from the nuc will discover that everything is changed when they have to muscle their way through the lower brood box to reach the hive entrance. They will quickly reorientate to the new hive.

Some of the workers from the nuc will have been out foraging when you rudely removed their home. They will, in time, move to a nearby hive and blag their way in 12

Where has the house gone?

You can speed this process up by removing the hive stand the nuc was on. With nowhere to land they quickly find an adjacent hive. If I unite colonies in poor weather (or just before rain starts 13) I’ll try and minimise the number of stranded bees by doing this.

For the same reason I prefer not to unite late in the afternoon to give the bees time to relocate. 

Supers

When I was younger and much better organised I’d clear the supers in advance on the recipient hive. I’d visit the apiary 24 hours before I intended to unite them and add a clearer board. When preparing the recipient colony I’d put the (now emptied) supers aside, unite the colonies and then add the supers back on top (all on the same visit). 

These days I’m definitely older and usually less well organised 🙁

Newspaper and queen excluder

If I’ve forgotten to clear the supers I’ll also unite the bees in the supers over the nuc. I separate them with newspaper as before and add a queen excluder to stop the queen moving up into the supers.

All that then remains to do is tidy up the apiary and go home for a cup of tea.

Time to tidy up and go home


 

Barcoding bees

Every jar of honey I prepare carries a square 20mm label that identifies the apiary, batch, bucket and the date on which is was jarred. The customer can scan it to find out about local honey … and hopefully order some more.

The label looks a bit like this:

Scan me!

This is a QR code.

You’ll find QR codes on many packaged goods in the supermarket, on bus stop adverts, on … well, just about anything these days.  QR codes were first used in 1994 and are now ubiquitous.

QR is an abbreviation of quick response.

It’s a machine-readable two-dimensional barcode that is used to provide information about the thing it’s attached to.

QR codes contain positional and informational content. In the image above the three corners containing large squares allow the orientation to be unambiguously determined.

Within the mass of other, much smaller, black and white squares are several alignment points, an indication of the encoding 1 and the ‘information payload’. 

Large QR codes can contain more information and more error correction (so they can be read if damaged 2 ). Conversely, small QR codes contain reduced amounts of information and less error correction, but can still be used to uniquely identify individual things in a machine-readable manner.

A barcoded bee and barcode diagram.

And those ‘things’ include bees.

I am not a number 3

I had intended to write a post on how pathogens alter honey bee behaviour. This has been known about in general terms for some time, but only at a rather crude or generic level. 

To understand behavioural changes in more detail you need to do two things:

  • observe bees in a ‘natural setting’ (or at least as natural as can be achieved in the laboratory)
  • record hundreds or thousands of interactions between bees to be able to discriminate between normal and abnormal behaviour. 

And that isn’t easy because they tend to all look rather similar.

Lots of bees

How many of the bees above are engaging in trophallaxis?

Does the number increase or decrease over the next five minutes? What about the next hour?

And is it the same bees now and in an hour?

And what is trophallaxis anyway? 

I’ll address the last point after describing the technology that enables these questions to be answered.

And, since it’s the same technology that has been used to monitor the behavioural changes induced by pathogens, I’ll have to return to that topic in a week or two. 

Gene Robinson and colleagues from the University of Illinois at Urbana–Champaign have developed a system for barcoding bees to enable their unique identification 4.

Not just a few bees … not just a couple of dozen bees … every bee in the colony.

Though, admittedly, the colonies are rather small 😉

Each barcode carries a unique number, readable by computer, that can be tracked in real time.

So, unlike Patrick McGoohan, these bees are a number.

bCode

The scientists designed a derivative of the QR code that could be printed small enough to be superglued to the thorax of a worker bee. They termed these mini-QR-like codes bCodes 5. The information content of a bCode was limited by its size and the reference points it had to carry that allowed the orientation of the bee to be determined.

In total the bCode could carry 27 bits of data. Eleven bits (each essentially on or off, indicated by a black or white square) encoded the identification number, allowing up to 2048 bees to be uniquely numbered. The remaining 16 bits were the error-correction parity bits that had to be present to ensure the number could be accurately decoded.

If you’re thinking ahead you’ll realise that the maximum number of bees they could therefore simultaneously study was 2048. That’s about 1/25th of a very strong colony at the peak of the season, or the number of bees covering both sides of a two-thirds full frame of sealed brood.

It’s enough bees to start a one frame nucleus hive, which will behave like a mini-colony 6 and, in due course, expand to be a much larger colony.

And if you’re thinking a long way ahead you’ll realise the every barcode must be affixed to each bee in the same orientation. How otherwise would you determine whether the bees were head to head or abdomen to abdomen?

Labelling bees

This is the easy bit.

Each bCode was 2.1mm square and weighed 0.6mg i.e. ~0.7% of the weight of a worker bee. Honey bees can ‘carry’ a lot more than that. When they gorge themselves before swarming they ingest ~35mg of honey. 

The bCode therefore should not be an encumbrance to the bee (and they confirmed this in an exhaustive series of control studies).

A single frame of sealed brood was incubated and the bees labelled within a few hours of emergence. Typically, two batches of ~700 bees each were labelled from a single frame for a single experiment.

Each bee was anaesthetised by chilling on ice, the bCode glued in place (remember … in the same orientation on every bee) and the bee allowed to recover.

Labelling a single bee took 1-2 minutes.

Labelling 1400 bees takes several people a long time.

I said it was easy.

I didn’t say it was interesting.

Smile for the camera

I’ve not yet discussed the goal of the study that needed barcoded bees. It’s not really important while I’m focusing on the technology. Suffice to say the scientists wanted to observe bees under near natural conditions.

Which means a free-flying colony, on a frame of comb … in the dark.

Free-flying because caged bees do not behave normally.

On a frame of comb because they were interested in the interactions between bees under conditions in which they would normally interact.

And in the dark because that’s what it’s like inside a beehive (and it’s one of the features that scout bees favour when selecting a site for a swarm).

Camera and hive setup.

The scientists used an observation hive with a difference. It had an entrance to allow the bees to fly and forage freely and it contained a single sided, single frame. In front of the frame was a sheet of glass separated by 8mm from the comb. This prevented the bees from clambering over each other, which would have obscured the bCodes 7. Behind the frame was an 850nm infrared lamp to increase contrast, and the front was illuminated by several additional infrared lamps.

Bees cannot see light in the infrared range, so they were effectively in the dark.

The camera used (an Allied Vision Prosilica GX6600 … not your typical point and shoot) recorded ~29MP images every second. A typical experiment would involve the collection of about a million images occupying 4-6 terabytes of hard drive space 8.

The recorded images were processed to determine the temporal location of every bee with a visible (and readable) bCode. This was a computationally interesting challenge and involved discarding some data – e.g. barcodes that moved faster than a bee can walk or barcodes that fell to the bottom of the hive and remained motionless for days (i.e. dead bees). About 6% of the data was discarded during this post-processing analysis.

Trophallaxis

Which finally gets us to the point where we can discuss trophallaxis. 

Honey bees and other social insects engage it trophallaxis.

It involves two insects touching each other with their antennae while orally transferring liquid food. It occurs more frequently than would be required for just feeding and it has been implicated in communication and disease transmission

bCoded bees and trophallaxis

So, if you are interested in trophallaxis, how do you determine which bees are engaging in it, and which are just facing each other head to head?

In the image above the two bees in the center horizontally of the insert 9 are engaged in trophallaxis. The others are not, even those immediately adjacent to the central pair.

Image processing to detect trophallaxis – head detection.

This required yet more image processing. The image was screened for bees that were close enough together and aligned correctly. An additional set of custom computer-vision algorithms then determined the shape, size, position and orientation of the bees’ heads. To be defined as trophallaxis the heads had to be connected by thin shapes representing the antennae or proboscis.

And when I say the image … I mean all million or so images.

Bursty behaviour

And after all that the authors weren’t really interested in trophallaxis at all.

What they were really interested in was the characteristics of interactions in social networks, and the consequences of those interactions.

This is getting us into network theory which is defined as “Well out of my depth”

Transmission of things in a network depends upon interactions between the individuals in the network.

Think about pheromones, or honey, or email … or Covid-19.

It’s only when two individuals interact that these can be transmitted between the individuals. And the interaction of individuals is often characterised by intermittency and unpredictable timing. 

Those in the know – and I repeat, I’m not one of them – call this burstiness. 

If you model the spread of ‘stuff’ (information, food, disease) through a bursty human communication network it is slower than expected.

Is this an inherent characteristic of bursty networks?

Are there real bursty networks that can be analysed.

By analysing trophallaxis Gene Robinson and colleagues showed that honey bee communication networks were also bursty (i.e. displayed intermittent and unpredictable interactions), closely resembling those seen in humans.

However, since they had identified every trophallaxis interaction over several days they could follow the spread of ‘stuff’ through the interacting network.

By simply overlaying the real records of millions of interactions over several days of an entire functional community with an event transmitted during trophallaxis they could investigate this spread..  

For example, “infect” (in silico) bee 874 in the initial second and follow the spread of the “infection” from bee to bee through the real network of known interactions.

In doing this they showed that in a real bursty network, interactions between honey bees spread ‘stuff’ about 50% faster than in randomised reference networks. 

Why isn’t entirely clear (certainly to me 10, and seemingly to the authors as well). One obvious possibility is that the topology of the network i.e. the contacts within it, are not random. Another is that the temporal features of a bursty network influence real transmission events. 

Scientists involved in network theory will have to work this out, but at least they have a tractable model to test things on …

… and at a time when some remain in lockdown, when others think it’s all a hoax, when social distancing is 2m 11, when some are wearing masks and when prior infection may not provide protective immunity anyway, you’ll appreciate that ‘how stuff spreads’ through a network is actually rather important.

Stay safe


 

It’s the little things …

When I first started keeping bees colony inspections were a special occasion.

There was quite a bit of preparation beforehand, collecting together the paraphernalia the catalogues all described as essential for effective beekeeping. I’d fuss over the hives, sometimes opening them a second time (or twice in a weekend) to check things. I’d write up some notes afterwards that – like certain websites 😉 – tended to verbosity.

Despite this, things went well.

Honey happened.

Splits worked.

Swarms didn’t … or were re-hived.

Larvae were grafted and queens were mated.

Colony numbers increased. 

Ready for inspection … are you?

Inspections moved from being a special occasion to, at times, something of a chore. 

Never not enjoyable or not a learning experience, but not quite the event they’d once been. 

There were also a lot more of them.

Twenty or so a week, many more if you count the nucs and the mini-nucs some years.

During all this time I was learning a whole lot more about bees.

But as importantly, I was learning a lot more about keeping and managing bees.

The KISS principle

This US Navy acronym (for Keep it simple, stupid) means that things work best if they are kept uncomplicated.

And beekeeping, and particularly the essential weekly 1 inspections are one area where the KISS principle can be beneficial.

A combination of better (but less) preparation, greater efficiency during the time spent hunched over the hive(s) and improved (but less) record keeping, reflects improvements in my beekeeping over the last decade or so.

All of which have resulted in hive inspections again being a pleasure rather than a chore.

Most of these improvements are subconscious.

I’ve unknowingly ‘learned’ that doing things a particular way works better for me or the bees. None of the lessons have been learned the hard way – they’re definitely evolution, not revolution.

Described below are a few I’m aware of 2.

Remember, these suit my style 3 of beekeeping (whatever that is 🙂 ) and may not be relevant to you.

However, for all of the things listed below I’m aware the way I’ve done things has changed over time.

Or, I’m aware that the way I do things now seems to work well though I’ve no idea how I used to do them 😉

Preparation

My essentials now fit easily into my bee bag. Partly because I now need less and partly because they never live anywhere else.

Stuff that was in the bag but wasn’t used, was ditched long ago.

I now have two boxes (2 litre ice cream tubs) in the bag, one for “daily” items and one for “queen-related” things. Neither box is full.

There’s not much in the daily container. Hive tools are kept in the apiary in a bucket of washing soda, with a spare tiddler in the bee bag to cover the inevitable losses. I now always carry a roll of gaffer tape and some staple-free newspaper. The former has all sorts of uses and the latter is for uniting colonies. 

Staple-free to save the hassle of separating sheets, and potentially ripping them, when trying to unite colonies. You want one very small hole in the sheet … they’ll easily expand this and gently mingle.

The “queen” box contains things for grafting larvae (which haven’t changed since I last wrote about them, a lifetime ago) together with the things I need for queen marking and clipping 4.

The smoker and blowtorch live together in a metal box. I have matches in the “daily” box, but never use them. A blowtorch is a much better way to light a smoker properly.

Smoker fuel lives in a plastic tub. I’ve discovered that the plastic tubs sold full of suet balls make excellent containers for smoker fuel. They are square(ish), have a handle and a convenient tab to help prise up the lid. Altogether better than a honey bucket.

Two final things come under the heading ‘preparation’.

The first is learning to fuel and light the smoker so that it stays lit. Exactly how you achieve this depends upon the fuel you are using. Practice makes perfect.

Buy a large smoker, prime it with something that smoulders well (dried rotten wood for example), light it with a blowtorch and then pack it reasonably tightly with additional combustible material. Dried grass, animal bedding, woodturning shavings etc. Top the lot off with a handful of fresh grass. 

Once lit, stays lit … bigger is better

Once it’s going, my Dadant smoker will stay lit for one to two hours without more than the occasional squeeze of the bellows … or laying on its side if burning too fiercely.

It’s ironic that the more experience you get, the less you need the smoker … however the more experience you get, the more likely the smoker will actually work when you do need it 🙂

The final preparation involves reading the notes in advance from the last inspection … the ones that I made to remind me what will be needed next time I visit the apiary.

Don’t barbeque the bees 😉

Less is definitely more when you open the hive.

The less smoke, the less knocks, bumps or sudden jarring, the less squashed bees, the less adjusting and readjusting the frames … all of these make the inspection more useful and effective.

The bees (and the beekeeper) will be calmer.

They’ll be behaving better 5

… not running manically around the frame or pinging off your veil.

You’ll see a whole lot more and, after all, what else is an inspection for if it’s not to see things?

Smoking the colony does not mean kippering them 6.

One gentle puff at the hive entrance or under the open mesh floor is enough. However these both drive the bees up.

As useful, and arguably more so, is a gentle puff in the gap created when you first lifted the crownboard 7. This eases the bees away from the top bars of the frames, making your next task easier.

OK, let’s find the queen …

You need space to work and an orderly approach. 

Think about what you’re doing. The colony, with all its darkness, smells, sounds and vibrations, is pulled apart during an inspection. 

If I wanted to be anthropomorphic I’d say it’s a very distressing experience … like having a tornado ripping the roof off and rearranging the furniture while you were frying bacon and listening to some gentle jazz 8

But I’m not anthropomorphic. 

What you need to avoid is the bees getting defensive. That just makes the looking part of the inspection more difficult. 

And if the looking is difficult, finding the queen is going to be very tricky.

Except you don’t usually need to find the queen.

If the colony contains recently laid eggs and no queen cells you can be confident the queen is in residence and will remain so … so there’s no need to look for her. 

But if your inspection is gentle and methodical, and the colony remains calm, you’ll usually see her anyway 🙂

Frame management

Remove the dummy board, shake the bees off it (onto the top bars) and lay it aside 9.

Remove the outer frame. It probably contains stores and so it’s unlikely the queen is in residence. Check, then put it aside and get on with the inspection. 

But where and how do you ‘put it aside’? Standing on end, leaning against the leg of the hive stand? Preferably not.

Most of my hive stands are a frame-width wide so you can hang a frame by the lugs, secure in the knowledge that the frame cannot be knocked over, kicked or stood on.

But I usually don’t hang the frame by the lugs.

To do so takes two hands when you put the frame down, and two when you pick the frame up. If you don’t use two hands it’s a clumsy procedure and you need a very strong grip – there’s a risk of crushing bees on the side bars.

Whilst I do have two hands (!) it’s actually usually easier to balance the frame at an angle, supported on a frame lug and the sidebar on one end, and the bottom bars on the other. There’s less reaching involved and one lug can be used as a very effective handle.

Easy to put down and pick up

The frame is held clear of vegetation below the hive stand. The protruding lug provides excellent grip. It can be put down and picked up with one hand. 

When putting the frame down, gently place the lug on the further frame bar, slide the frame away from you until the further sidebar touches the hive stand (gently, allow the bees to move aside) then lower the bottom bar towards the nearer frame bar, gently moving the frame from side to side in a narrow arc. The bees will clear the lower bar rather than get crushed.

No crushed bees

It takes much longer to describe than to actually do.

If it’s blowing a gale, frames balanced like this might topple … but if it’s blowing a gale it’s really not an ideal day to be inspecting the colony.

Unless they’re in a bee shed 😉

Removing and returning frames

With space to work you can now start the inspection. 

The frames are probably propolised together. Even with good finger strength they can be difficult to separate. 

Hive tools ...

Hive tools …

Don’t try … use the hive tool, it’s what it’s for.

Gently break the propolis seal between every frame. Do all the frame lugs on one side first, then do the other. That way you don’t pass your hands repeatedly over the open hive, which can distress the bees make them defensive.

You don’t need to lever the frames far apart. Breaking the propolis seal only involves moving the frame a millimeter or two. The smaller the distance, the less chance a bee will sneak into the gap you’ve created and get crushed as you separate other frames.

Again, less is more.

With all the frames now ‘free’ you can do the inspection.

Slide the next frame a short distance along the frame runners into your working ‘gap’. You shouldn’t just lift the frame as bees at the interface with the adjacent frame will get “rolled” 10. Grip the frame by the lugs, inspect one face, turn, inspect the other face, turn again.

The frame is now in the same orientation as when it was lifted out of the hive. It can therefore be returned easily to minimise the disruption to the brood nest. By using the same routine for every frame the colony is reassembled with the minimum unnecessary disturbance.

Wrong

Don’t just put the frame back ‘near’ it’s neighbour and squeeze them altogether when you put the dummy board back at the end of the inspection. Return it so the Hoffman spacers directly contact the neighbouring frame. That way, no bees get crushed when additional frames are added back later in the inspection.

That’s better

You’ll find that you can gently return the frame, pushing the bees aside between the Hoffman spacers as you lower it into the hive. You have a better view (more light and an oblique viewing angle) when returning the frame into the gap than when the frame is hanging by the lugs in the hive. 

Gently shiggling 11 the frame from side to side as you lower it helps move the bees aside between the spacers.

By returning the frame right next to its neighbour you’ve also retained all your working space to move the next frame into.

You handle most frames only once, increasing the efficiency of your inspection but – more importantly – minimising the likelihood of crushing bees and agitating the colony.

Once through all the frames, you can even replace the removed frame of stores at the opposite end of the box to minimise further disturbance.

Finishing up

If there are supers on the hive there is probably a queen excluder separating them from the brood box. 

I’ve got a big stack of plastic queen excluders in the bee shed, but no metal wired, wooden framed ones. 

Framed wire QE ...

Framed wire QE …

That’s because all of the metal wired, wooden framed queen excluders are in use.

They are easier to remove and easier to replace on the hive. The bee space created by the frame prevents bees being crushed. The rigid frame means they can be replaced obliquely, then gently turned until square on the hive. In doing so, bees on the upper rim of the brood box are pushed aside, rather than squished below.

With the supers, crownboard and roof back in place there are only three things left to do:

  1. Make the hive secure. Will the roof stay on, and the hive stay upright, if there’s a gale … or a cow or deer ambles into it at night? The zephyr-like breeze when you inspect might be replaced with 50 mph gusts in 48 hours. Ratchet straps really do help, though tall stacks of boxes can still topple if top-heavy with honey.
  2. Put the smoker out. Plug it with grass and let it cool before putting it away. If you do this immediately after closing the last hive it will be ready by the time you …
  3. Write up the hive notes. Less really is more here. No verbiage 12. You need to record the current ‘state’ of the colony – strength, health, stores. Ideally, also record its behaviour – defensiveness, running (are the bees stable on the frame?) and unpleasant traits such as following. All of this can be achieved with a simple scoring system. An additional sentence of freehand might also be needed – “Defensive – don’t use for grafting”. Importantly, make sure you note down anything needed at the next visit … 

Objective and subjective notes

Which neatly takes us back to preparation.

I’m sure there are a million other things I do now that are an improvement on what I used to do. I’m also certain there are better ways to do some of the things I now do 13.

Are you aware of changes to your beekeeping practices that have improved things, for you or – more importantly – for the bees?


Notes

Today (10th July) is Don’t step on a bee day … that improves colony inspections as well 😉

If it quacks like a duck …

Quack

… it might be a trapped virgin queen.

I discussed the audio monitoring of colonies and swarm prediction last week. Whilst interesting, I remain unconvinced that it is going to be a useful way to predict swarming. 

And, more importantly, that replacing the manual aspects of hive inspections is desirable. I’m sure it will appeal to hands off beekeepers, though I’m not sure that’s what beekeeping is about.

However there was a second component to what was a long and convoluted publication 1 which I found much more interesting.

Listening in

If you remember, the researchers fitted hives with sensitive accelerometers and recorded the sounds within the hive for two years. Of about 25 colonies monitored, half swarmed during this period, generating 11 prime swarms and 19 casts.

In addition to the background sounds of the hive, with changes in frequency and volume depending upon activity, some colonies produced a series of very un-bee-like toots and quacks.

Have a listen …

The audio starts with tooting, the quacking starts around 8-9s, and there’s overlapping tooting and quacking from near the 21s mark.

Queen communication

I’ve previously introduced the concept of pheromone-based communication within the hive. For example, the mated queen produces the queen mandibular and queen footprint pheromones, the concentrations of which influence the preparation and development of new queen cells.

Tooting and quacking is another form of queen communication, this time by virgin queens in the colony.

It’s not unusual to hear some of these sounds during normal hive inspections, but only during the swarming season and only when the colony is in the process of requeening.

If you rear queens, and in my experience particularly if you use mini-mating nucs, you will regularly hear “queen piping” – another term for the tooting sound – a day or so after placing a mature charged queen cell into the small colony.

But we’re getting ahead of ourselves. 

How does the queen make these sounds?

Queen piping or tooting

Queen tooting has been observed. The queen presses her thorax tight down against the comb and vibrates her strong thoracic wing muscles. Her wings remain closed. The comb acts as a sounding board, amplifying the sound in the hive (and presumably transmitting the vibrations through the comb as well).

This doesn’t happen just anywhere … the virgin queen is usually near the cell she has recently emerged from. 

And this swarm cell is usually on the periphery of a frame.

This is because the laying queen only rarely ventures to the edges of frames, so the concentration of her footprint pheromone is lower in this area, eventually resulting in queen cells being produced there

In their study, accelerometers embedded in the periphery of comb were able to detect much stronger tooting and quacking signals, supporting the conclusions of Grooters (1987) 2 who had first published studies on the location of piping queens.

Queen tooting and quacking

Queen piping is usually recorded at around 400 Hz and consists of one or more 1 second long pulses, followed by a number of much shorter pulses. In previous studies the frequency of tooting had been shown to be age-related. It starts at ~350 Hz and rises in frequency to around 500 Hz as the virgin queen matures over several days.

Compare the image above with the audio file linked further up the post. The tooting is followed by an extended period of quacking, and then both sounds occur at the same time.

Going quackers

The duck-like quacking is presumably also made by queens vibrating their flight muscles while pressed up against the comb.

I say ‘presumably’ as I don’t think it has been observed, as opposed to heard.

The reason for this is straightforward, the queens that are quacking are still within the closed queen cell.

Quacking is a lower frequency sound (is this because of the confines of the queen cell, the way the sound is produced, or the ‘maturity’ of the queen’s musculature?) but has also been shown to increase in frequency – from ~200 Hz to ~350 Hz – the longer the queen remains within the cell.

Afterswarms = casts

Before discussing the timing of tooting and quacking we need to quickly revisit the process of swarming. I’ve covered some of this before when discussing the practicalities of swarm control, so will be brief.

  1. Having “decided” to swarm the colony produces swarm cells. Usually several.
  2. Weather permitting, the prime swarm headed by the original laying queen leaves the hive, on or around the day that the first of the maturing queen cells is capped.
  3. Seven days after the cell was capped the first of the newly developed virgin queens emerges. 
  4. If the colony is strong, this virgin also swarms (a cast swarm). Some texts, including the publication being discussed, call these afterswarms.
  5. Over the following hours or days, successively smaller cast swarms may leave the hive, each headed by a newly emerged virgin queen.

Not all colonies produce multiple cast swarms, but initially strong colonies often do.

From a beekeeping point of view this is bad news™. It can leave the remnants of the original colony too weak to survive and potentially litters the neighbourhood with grapefruit, orange and satsuma-sized cast swarms. 

Irritating 🙁

Whether it’s good for the bees depends upon the likelihood of casts surviving. The very fact that evolution has generated this behaviour suggests it can be beneficial. I might return to this point at the end of the post.

Tooting timing

The Grooters paper referred to earlier is probably the definitive study of queen tooting or piping. The recent Ramsey publication appears to largely confirm the earlier results 3, but has some additional insights on colony disturbance during inspections 4.

Here is the acoustic trace of an undisturbed colony producing a prime swarm and two casts.

Timing of tooting and quaking in a swarming colony

I’ve added some visible labels to the image above indicating the occurrence of tooting and quacking in an undisturbed naturally swarming colony.

  • The prime swarm exited the hive on the afternoon of the 13th. No tooting had been recorded before that date.
  • On the 17th tooting starts and increases in frequency over the next two days.
  • Quacking starts 6 hours after the tooting starts.
  • The first cast swarm (afterswarm) exits the hive on the 19th and is followed by a three hour break in tooting.
  • Tooting and quacking then continue until the second cast swarm on the afternoon of the 21st.

So, in summary, tooting starts after the prime swarm leaves and stops temporarily when the first cast leaves the hive. Quacking starts after the tooting starts and then continues until the last swarm leaves the hive.

Why all the tooting and quacking?

The timing of queen tooting is consistent with it being made by a virgin queen that has emerged from the cell. The cessation of tooting upon swarming (the first afterswarm) suggests that the virgin left with the swarm. The restarting of tooting a few hours later suggests a new virgin queen has been released from another cell and is announcing her presence to the colony.

In previous studies, Grooters had shown that replaying the tooting sound to mature virgin queens actively chewing their way out of a queen cell delayed their emergence by several hours. This delay allowed the attendant workers to reseal the cell and obstruct her emergence for several days.

These timings and the behaviour(s) they are associated with suggest they are a colony-level communication strategy to reduce competition between queens. 

The newly emerged virgin queen toots (pipes) to inform the workers that there is ‘free’ queen in the colony. The workers respond by holding back emergence of other mature queens. 

If all (or several) of the virgin queens emerged and ran around the hive simultaneously they would effectively be ‘competing’ for the hive resources needed for successful swarming i.e. the workers. 

By controlling and coordinating a succession of queen emergence, a strong colony has the opportunity to generate one, two or more cast swarms whilst sufficient workers remain in the hive. It presumably helps ensure the casts are of a sufficient size to give them the best chance of survival.

At what point does this succession stop or break down? One possibility is that this happens when there are insufficient workers to prevent additional virgin queens from emerging.

Unanswered questions

Why do mature virgin queens within the cell quack? It is clearly a response to tooting, rather than being standard behaviour of a soon-to-emerge queen. 

Hear! Hear the pipes are calling, Loudly and proudly calling (from Scotland the Brave)

Is the quacking to attract workers to help reseal the cell?

I suspect not. At least, I suspect there is a more pressing need to attract the workers. After all, wouldn’t it be easier for the queen to simply stop chewing her way out for a few hours? 

Isn’t there a risk that a quacking cell-bound queen might attract the virgin queen running around ‘up top’ who might attempt to slaughter her captive half-sister? 

Possibly, so perhaps the workers that are attracted to the quacking cell also protect the cell, preventing the loose virgin queen from damaging the yet-to-emerge queens.

This would make sense … if the virgin leaves with a cast, the workers that will remain must be sure that there will be a queen available to head the colony

And finally, back to the tooting. I also wonder if this has additional roles in colony communication. For example, what other responses does it induce in the workers? 

Does the increasing frequency of tooting inform the workers that the virgin is maturing and that they should ready themselves for swarming? Perhaps tooting above a certain frequency induces workers to gorge themselves with honey to ensure the swarm has sufficient stores?

In support of this last suggestion, studies conducted almost half a century ago by Simpson and Greenwood 5 concluded that a 650 Hz artificial piping sound induced swarming in colonies containing a single mobile (i.e. free) virgin queen.

Casts

The apparently self-destructive swarming where a colony generates a series of smaller and smaller casts seems to be a daft choice from an evolutionary point of view.

Several studies, in particular from Thomas Seeley, have shown that swarming is a risky business for a colony … and that the majority of the risk is borne by the swarm, not the parental colony. 

87% of swarmed colonies will rear a new queen and successfully overwinter, but only 25% of swarms survive. And the latter figure must only get smaller as the size of the swarms decrease. 

One possibility is that under entirely natural conditions a colony will not undergo this type of self-destructive swarming. Perhaps it is a consequence of the strength of colonies beekeepers favour for good nectar collection or pollination?

Alternatively, perhaps it reflects the way we manage our colonies. Ramsey and colleagues also record tooting and quacking from colonies disturbed during hive inspections. In at least one of these their interpretation was that there were multiple queens ‘free’ in the hive simultaneously, presumably because workers had failed to restrict the emergence of at least one virgin queen.

So, perhaps hive inspections that (inadvertently) result in the release of multiple virgin queens are the colonies that subsequently slice’n’dice themselves to oblivion by producing lots of casts.

I can only remember one colony of mine doing this … and it started days after the previous inspection, but that doesn’t mean the disturbance I created during the inspection wasn’t the cause.

I’d be interested to know of your experience or thoughts.


Colophon

The title of this post is derived from the Duck Test:

If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck.

This probably dates back to the end of the 19th Century. It’s a form of abductive 6 reasoning or logical inference. It starts with an observation or set of observations and then seeks to find the simplest and most likely conclusion from those observations. In comparison to deductive reasoning, logical inference does not lead to a logically certain conclusion. 

Inevitably, Monty Python stretched the logical inference a little too far in the Witch Logic scene from Monty Python and the Holy Grail:

What do you do with witches? Burn them! And what do you burn apart from witches? Wood! So, why do witches burn? ‘cos they’re made of wood? So; how do we tell if she is made of wood? Build a bridge out of ‘er! Ah, but can you not also make bridges out of stone? Oh yeah. Does wood sink in water? No, it floats! It floats! Throw her into the pond! What also floats in water? Bread! Apples! Very small rocks? Cider! Gra-Gravy! Cherries! Mud! Churches? Churches! Lead, Lead. A Duck! Exactly. So, logically… If she weighs the same as a duck, she’s made of wood… and therefore… a witch!

Listening to the bees – swarm prediction

Wouldn’t it be useful to know your colony was preparing to swarm?

With sufficient notice you could take preventative action.  You could conduct an artificial swarm or remove the queen to a nuc. With the major population of the hive now queenless the colony cannot swarm, though you will need to prevent casts by ‘discouraging’ too many virgin queens from emerging.

What is sufficient notice?

Certainly more than minutes or hours. You need to have time to collect the equipment you’ll need, you might need to wait until the rain clears, or you return from a long weekend in Rome (remember those?).

Inevitably, 2300 years ago Aristotle had both identified the problem (Are they about to swarm?) and found a way of answering the question.

When the flight of a swarm is imminent, a monotonous and quite peculiar sound made by all the bees is heard for several days 1.

Several days should be enough surely? The fact that you don’t see beekeepers hunched down by their hives listening intently suggests it’s not an entirely practical solution.

Depending where you live, the swarm season can extend from mid-April until mid-July. That’s a long time to be sat next to a hive with your ear glued to the brood box. 

Some sort of automated system is needed.

Woods’ Apidictor

In the 1960’s Edward Woods developed 2, patented and sold an electronic frequency analyser to “listen” to beehives. It incorporated analogue bandpass filters to screen out the background noise of the hive, focusing on the “monotonous and quite peculiar sound” (to quote Aristotle again) characteristic of a colony making swarm preparations.

Woods Apidictor

Woods sold about 300 Apidictors during the early 60’s. Analysing an individual colony took just minutes. In a 1965 article in Bee Craft Eddie Woods claimed that 60 colonies could be screened in 15 minutes.

In the right hands the Woods Apidictor was also accurate, predicting not only whether a colony was going to swarm, but also the particular stage it was at e.g. sealed queen cells present (presumably held back by bad weather), queenless colonies, superseding colonies, or even drone-laying queens 3.

One of the most impressive [demonstrations of accuracy] occurred when one purchaser complained that the instrument was “over-enthusiastic”. Our representative visited him and checked and predicted that seventeen out of twenty colonies in one apiary contained queen cells, even specifying the stage of development of the cells, a test which required only a few minutes. The manual examination, requiring hours, showed that indeed, the situation was as predicted. The three colonies which the instrument showed no swarm preparations were found to be clear. 4

Despite the fact that Woods only ever sold a limited number of Apidictors, the subsequent 60 years have seen continued interest in – literally – listening to the bees

The internet is littered with commercial and DIY solutions, all in various stages of development. I don’t intend to review them … Google is your friend. Make yourself a cuppa … there are over 2 million hits.

Importantly, the usefulness of this automation depends upon whether sounds in the hive are truly predictive of swarming, and our ability to identify the relevant sound that is predictive.

A monotonous and quite peculiar sound

When using sound as an indicator of swarming activity, false-positives will have us scurrying around performing artificial swarms when unnecessary, and false-negatives will mean the colony swarms.

Not the end of the world, but an irritation certainly.

So, what do we (or, more likely, our Raspberry Pi or Arduino-powered detectors) listen for? What is Aristotle’s “monotonous and quite peculiar sound”?

A recent paper by Martin Bencsik and colleagues addresses this and claims accuracy of greater than 90%, with successful swarming prediction up to 30 days prior to the event 5.

A beehive is a noisy environment. Some of the noises are constant, others vary during the day, or over longer periods. As the colony builds in strength during the early season the noise levels must increase. Similarly, the sound levels in the colony will be different at night than during a bright, sunny day with thousands of foragers working hard.

Late evening in the apiary

Late evening in the apiary

Many beekeepers will be aware of the sound a colony makes at night during a strong nectar flow. The entire hive hums as the workers drive off excess water prior to capping the cells. If you’ve not visited an apiary late on a calm, midsummer evening you should try; the smell of the honeysuckle in the hedgerow mingled with the scent of honey from the hive is a heady combination.

Toots and quacks and buzzes

In addition to the cumulative noises of tens of thousands of bees simply working in the hive, there are the noises individual bees make at certain times. 

Scout bees produce piping noises when doing their buzz runs as they encourage a swarm to leave the hive. Queens, in particular virgin queens, produce a variety of noises including duck-like quacks and piping before, during or after emergence. I’ll return to these in a future post as this paper also includes a lot of information on the timing and relevance of queen piping.

Marked queen surrounded by a retinue of workers.

If it quacks like a duck …

And if all that wasn’t sufficiently complicated there are additional acoustic signals such as the intermittent, but extensively repeated,’whooping‘ noise (and others), which may be similar to the ‘stop signals’ workers direct at dancing foragers advertising less than favourable locations.

All of which means you cannot just stick a microphone at the hive entrance and instantaneously determine whether they’re about to swarm.

In particular, the variable nature of sound over time needs to be taken into account. The steadily increasing background noise of a hive building up through the early spring and summer is probably not significant.

In contrast, a spike in the signal averaged over several hours or days is probably important, but there may also be characteristic sounds that – if present – indicate swarm preparation.

In the Ramsey paper the authors have used two machine learning techniques to analyse the sound from accelerometers (something that measures vibration) inside the hive.

Training data

Woods had identified a 250 Hz signal that he considered characteristic of a colony making swarm preparations. Modulation of this signal, which Woods termed “the warble”, in three test colonies was associated with swarming.

Ramsey and colleagues analysed the full spectrum using highly accurate accelerometers in about 25 hives, sampling continuously at 3 minute intervals, over a two year period. About 50% of these colonies swarmed during this time, generating 11 prime swarms and 19 casts.

This dataset was then analysed to find acoustic features characteristic of hives that did or did not swarm. Essentially the authors trained the algorithms to detect particular acoustic patterns that were – through empirical observation – associated with swarming (or not).

To do this they used two separate approaches:

The instantaneous alarm procedure.

In the first (the instantaneous alarm procedure) they took a one hour reading from the hive and then compared it to the trained data. By computationally analysing discriminant functions (i.e. acoustic features characteristic of swarming or non-swarming hives) they could determine whether the test colony fell within the “swarming” or “non-swarming” category.

In the diagram above they show the application of two discriminant functions, but the actual study used three. 

The second method used a much more complicated sounding three dimensional Fourier transform (conveniently abbreviated to 3DFT). In contrast to the first approach this involved analysis of the acoustic spectra collected over a ten day period.

3DFT sounds more complicated because it is more complicated. A Fourier transform converts a complex mix of signals into its individual components – for example, determining the individual volumes and frequencies (notes) in a musical chord. The diagram for this is a more colourful version of the one shown above, but is unlikely to help understand the process. If you insist you can view the original.

Application

Both methods were similar in that they used sound profiles collected from colonies known to have swarmed (or not) to define patterns characteristic of swarm preparation.

Interestingly, neither appear to show significant differences in the region of the spectrum Woods’ ‘warble’ occupied. 

Having trained the software they went on to analyse colonies in an unknown state in an attempt to predict swarming.

Using the instantaneous analysis 6 15 of 18 colonies that swarmed were correctly predicted, with no false positives in the colonies that did not swarm. Of those that swarmed, the prediction could be made an average of 22 days in advance of the first swarm leaving the colony. 

That sounds like a pretty convincing 90% prediction rate. However, looking at the primary data – all 33 Mb of supplementary figures – it is clear that many of the swarmed colonies produced “swarm-like” signals well after swarming, without repeated swarming. As the authors state “false positives are still triggered occasionally on an hourly basis, and this becomes exacerbated when the time duration of the season under scrutiny is extended to the rest of the summer”

So, it works OK for the first swarm of the year, but after that gives a lot of false positives.

It’s not clear from the figures what the range (or standard deviation) on the “22 day average warning” is. If it’s a range of 20-24 days that could be really useful, if it’s 3-45 days, less so.

Using the 3DFT methodology the authors could predict swarming in ~80% of colonies an average of 10±2 days before the swarm issued. Although this is a lower prediction rate, the clearly tighter time window might be more useful for practical beekeeping.

Again, the 3DFT approach produced signals that indicated swarming was imminent throughout the remainder of the season, often during periods of intense foraging. To exclude these the authors used averaged the night time values (midnight to 5am), rather than day-long assessments.

Take a deep breath

Overall, taking account of the false prediction rate and the false-positive triggering rate (the former being an overall incorrect prediction as to whether a colony will swarm, the second being ‘noise’ in the analysis when the threshold is reached), the authors favour the simpler “instantaneous” measurement method.

However, don’t be misled, this is not like Eddie Woods rocking up with his Apidictor, putting the stethoscope-like microphone on the side of the brood box and saying “take a deep breath”

These colonies are being constantly monitored, with accelerometers embedded in the frames, and the associated wiring dangling out of the brood box.

I have run colonies with embedded hive temperature and humidity monitors 7. The cabling is usually run under the crownboard and down between the frames. Along with 20,000 bees, it’s another thing that gets in the way during weekly inspections. In this paper Ramsey shows that the accelerometers can be fitted to any frame in the hive and still provide valid predictions. This offers the opportunity to perhaps use one of the ‘edge’ frames which would be more convenient than temperature monitors which have to be embedded in the centre of the brood nest.

I’m sure Woods’ Apidictor was not inexpensive in its day 8. This current implementation of in-hive technology, despite the advances in microelectronics and computing, uses accurate and sensitive accelerometers which are also not inexpensive 9. The apiary would need a power supply, computers and a way of transmitting a signal to the beekeeper (who is currently quaffing Barolo in a fancy trattoria anyway).

All of this is achievable.

But is it worth it?

And is it really needed?

Analogue beekeeping

The digital revolution and, most recently, the internet of things (IoT) has made monitoring “stuff” (like beehives, the house temperature, your fridge or coffee machine) inexpensive and relatively straightforward.

With smartphone apps you can be “in when you’re out” and get a warning that your colony is going to swarm … just as you sit down to lunch at Pierluigis.

The internet is littered with commercial and DIY hive monitoring equipment. Most of it is advertised, or at least promoted, as making beekeeping “easier”.

There’s the implication, stated or otherwise, that this type of automation reduces the need to conduct those pesky hive inspections.

But is that desirable? 

What about all the other things you check when inspecting a colony?

Nectar collection … how heavy are the supers? Yes, you can monitor this electronically as well with hive scales. But what about …

  • colony build up – how much space does the queen have to lay?
  • sufficient stores – are they going to starve if it rains for a week?
  • laying pattern of the queen – is she failing, is she a drone layer?
  • signs of disease
  • robbing etc.

I’m enthusiastic about technology but I’m not sure I’m enthusiastic about this technology. 

Beekeeping is in many ways, already ‘easy’. It’s also an intensely practical discipline.

A thorough hive inspection tells you a whole lot more about the colony than its likelihood of swarming.

I’d actually argue that the easiest thing to determine qualitatively is whether a colony is thinking of swarming. All of those other things listed above – and lots that aren’t – are both important and only acquired by standing hunched over the hive.

If your hive monitors discouraged you from checking colonies so often how would be ever learn, or know, these other important things?

Finally, in closing, I reckon I could open a colony in mid-April and – based upon its strength and knowing a little bit about the local nectar flows – predict with 90% confidence whether it will swarm later in the season 😉

What do you think? Are you in favour of automating some aspects of beekeeping? 


 

A June Gap

As far as the beekeeping season is concerned, we’ve had the starter and we’re now waiting for the main course. 

Like restaurants, the size of the ‘starter’ depends upon your location. If you live in an area with lots of oil seed rape (OSR) and other early nectar, the spring honey crop might account for the majority of your annual honey.

If you are in the west, or take your hives to the hills, you might have skipped the starter altogether hoping the heather is the all-you-can-eat buffet of the season.

Lockdown honey

In Fife they appear to be growing less OSR as the farmers have had problems with flea beetle since the neonicotinoid ban was introduced.

Nevertheless, my bees are in range of a couple of fields and – if the weather behaves – usually get a reasonable crop from it. My earlier plans to move hives directly onto the fields, saving the bees a few hundred yards of flying to and fro, was thwarted (like so much else this year) by the pandemic.

The timing of the spring honey harvest is variable, and quite important. You want it to be late enough that the bees have collected what they can and had a chance to ripen it properly so that the water content is below 20% 1.

However, you can’t leave it too late. Fast-granulating OSR honey sets hard in the frames and then cannot be extracted without melting. In addition, there’s often a dearth of nectar in the weeks after the OSR finishes and the bees can end up eating their stores, leaving the beekeeper with nothing 🙁

Judging all that from 150 miles away on the west coast where I’m currently based was a bit tricky. I had to timetable a return visit to also check on queen mating and the build up of all the colonies I’d used the nucleus method of swarm control on.

Ideally all in the same visit.

Blowin’ in the wind

I’d made up the nucs, added supers and last checked my colonies around the 17-19th of May. I finally returned on the 10th of June.

In the intervening period I’d been worried about one of my more exposed apiaries. I’d run out of ratchet straps to hold the hives together and was aware there had been some gales in late May.

Sure enough, when I got to the apiary, there was ample evidence of the gales …

How the mighty fall

The only unsecured hive was completely untouched and the bees were happily working away. However, one of the strapped hives had been toppled and was laying face (i.e. entrance) down. You can see the dent in the fence where it collided on its descent.

If she hadn’t already (and I expect she hadn’t based upon the date of the gales) I suspect the queen struggled to get out and mate from this hive 🙁

Nuked nucs

Two adjacent 8-frame nucs were also sitting lidless in the gentle rain. The lids and the large piece of timber they’d been held down with were on the ground. The perspex crownboards were shattered into dozens of pieces.

These bees were fine.

Both queens were laying and the bees were using the new top entrance (!) for entering and leaving the hive. They were a little subdued and the colonies were less well developed than the other nucs (see below). However, their survival for the best part of three weeks uncovered is a tribute to their resilience.

They were thoroughly confused how to get back into the hive after I replaced the lids 🙂

Slow queen mating

Other than extracting, the primary purpose of this visit was to check the queenright nucs from my swarm control weren’t running out of space, and to check on the progress of queen mating in the original colonies.

Queen mating always takes longer than you expect.

Or than I expect at least.

Poor weather hampered my inspection of all re-queening colonies but, of those I looked at, 50% had new laying queens and the others looked as though they would very soon.

By which I mean the colonies were calm and ‘behaved’ queenright, they were foraging well and the centre of the ‘broodnest’ (or what would be the centre if there was any brood) was being kept clear of nectar and had large patches of polished cells.

Overall it was a bit too soon to be sure everything was OK, but I expect it is.

However, it wasn’t too soon to check the nucs.

Overflowing nucs

In fact, it was almost too late …

With one exception the nucs were near to overflowing with bees and brood.

I favour the Thorne’s Everynuc which has an integral feeder at one end of the box. Once the bees start drawing comb in the feeder they’re running desperately short of space.

Most had started …

Here's one I prepared earlier

Here’s one I prepared earlier

I didn’t photograph any of the nucs, but the photo above (of an overly-full overwintered nuc) shows what I mean; the feeder is on the right.

The nucs had been made up with one frame of predominantly emerging brood, a few more nurse bees, two foundationless frames, a frame of drawn comb and a frame of stores.

They were now all packed with 5 frames of brood and would have started making swarm preparations within a few days if I hadn’t dealt with them.

Good laying pattern from queen in 5 frame nucleus

And the queens had laid beautiful solid sheets of brood (always reasonably easy if the comb is brand new).

Housekeeping and more swarm prevention

The beauty of the nucleus method of swarm control is that you have the older queen ‘in reserve’ should the new queen not get mated, or be of poor quality.

The problem I was faced with was that the new queens weren’t all yet laying (and for those that were it was too soon to determine their quality), but the older queen was in a box they were rapidly outgrowing.

I therefore removed at least three frames of brood 2 from each nuc and used it to boost the re-queening colonies, replacing the brood-filled frames with fresh foundation 3.

The nucs will build up again strongly and the full colonies will benefit from a brood boost to make up for some of the bees lost during requeening. Some of the transferred frames had open brood. These produce pheromones that should hold back the development of laying workers.

Finally, if the requeening colonies actually lack a queen (the weather was poor and I didn’t search very hard in any of them) there should be a few larvae young enough on the transferred frames for them to draw a new queen cell if needed.

I marked the introduced frames so I can check them quickly on my next visit to the apiary.

This frame needs to be replaced … but could be used in a bait hive next year

The additional benefit of moving brood from the nucs to the full colonies is that it gave me an opportunity to remove some old, dark frames from the latter.

Shown above is one of the removed frames. As the colony is broodless 4 and there’s the usual reduction in available nectar in early/mid June, many of the frames in the brood box were largely empty and can easily be replaced with better quality comb.

Everyone’s a winner 😉

Drone laying queen

One of the nucs made in mid/late May had failed. The queen had developed into a drone layer.

Drone laying queen

The laying pattern was focused around the middle of frame indicating it had been laid by a queen. If it had been laying workers the drone brood would be scattered all over the frames.

There was no reasonable or efficient way to save this colony. The queen was removed and I then shook the bees out in front of a row of strong hives.

I was surprised I’d not seen problems with this queen when making up the nucs in May 5. I do know that all the colonies had worker brood because the nucs were all made containing one frame of emerging (worker) brood.

Perhaps the shock of being dumped into a new box stopped her laying fertilised eggs. Probably it was just a coincidence. We’ll ever know …

Extraction

And, in between righting toppled hives, checking for queens, stopping nucs from swarming, moving a dozen hives/nucs, boosting requeening hives and replacing comb … I extracted a very good crop of spring honey.

Luvverrrly

Although I had fewer ‘production’ hives this season than previous years (to reduce my workload during the lockdown) I still managed to get a more than respectable spring harvest. In fact, it was my best spring since moving back to Scotland in 2015.

The crop wasn’t as large as I’d managed previously in Warwickshire, but the season here starts almost a month later.

A fat frame of spring honey

I start my supers with 10 or 11 frames, but once they are drawn I reduce to 9 frames. With a good nectar flow the bees draw out the comb very nicely.

The bees use less wax (many of my frames are also drawn on drone foundation, so even less wax than worker comb 6), it’s easier to uncap and I have fewer frames to extract.

Again … everyone’s a winner 😉

Not the June gap

Quite a few frames contained fresh nectar, so there was clearly a flow of something (other than rain, which seemed to predominate during my visit) going on. These frames are easy to identify as they drip nectar over the floor as you lift them out to uncap 🙁

In some years you find frames with a big central capped region – enough to usefully extract – but containing lots of drippy fresh nectar in the uncapped cells at the edges and shoulders. I’ve heard that some beekeepers do a low speed spin in the extractor to remove the nectar, then uncap and extract the ripe honey.

I generally don’t bother and instead just stick these back in the hive.

If there’s one task more tiresome than extracting it’s cleaning the extractor afterwards. To have to also clean the extractor during extracting (to avoid the high water content nectar from spoiling the honey) is asking too much!

Colonies can starve during a prolonged nectar dearth in June. All of mine were left with some stores in the brood box and with the returned wet supers. That, plus the clear evidence for some nectar being collected, means they should be OK.

National Honey monitoring Scheme

I have apiaries in different parts of Fife. The bees therefore forage in distinct areas and have access to a variety of different nectar sources.

It’s sometimes relatively easy to determine what they’ve been collecting nectar from – if the back of the thorax has a white(ish) stripe on it and it’s late summer they’re hammering the balsam, if they’ve got bags of yellow pollen and the bees are yellow and the fields all around are yellow it’s probably rape.

Mid-April in the apiary ...

Mid-April in a Warwickshire apiary …

But it might not be.

To be certain you need to analyse the pollen.

The old skool way of doing this is by microscopy. Honey – at least the top quality honey produced by local amateur beekeepers 7 – contains lots of pollen. Broadly speaking, the relative proportions of the different pollens – which can usually be distinguished microscopically – tells you the plants the nectar was collected from.

The cutting edge way to achieve the same thing in a fraction of the time (albeit at great expense) is to use so-called next generation sequencing to catalogue all the pollen present in the sample.

Pollen contains nucleic acid and the sequence of the nucleotides in the nucleic acid are uniquely characteristics of particular plant species. You can easily get both qualitative and quantitative data.

And this is exactly what the National Honey Monitoring Scheme is doing.

They use the data to monitor long-term changes in the condition and health of the countryside” but they provide the beekeeper’s involved with the information of pollen types and proportions in their honey.

National Honey Monitoring Scheme samples

Samples must be taken directly from capped comb. It’s a messy business. Fortunately the labelling on the sample bottles is waterproof so everything can be thoroughly rinsed before popping them into the post for future analysis.

I have samples analysed already from last year and will have spring and summer samples from a different apiary this season. I’ll write in the future about what the results look like, together with a more in-depth explanation of the technology used.

When I last checked you could still register to take part and have your own honey analysed.


Notes

Under (re)construction

Lockdown means there have been more visitors than ever to this site, with numbers up at least 75% over this time last year.

This, coupled with the need to upgrade some of the underlying software that keeps this site together, means I’m in the middle of moving to a bigger, faster, better (more expensive 🙁 ) server. I’m beginning to regret the bloat of wordpress over the lean and mean Hugo or Jekyll-type templating systems (and if this means nothing to you then I’m in good company) and may yet switch.

In the meantime, bear with me … there may be some broken links littering a few pages. If it looks and works really badly, clear your browser cache, re-check things and please send me an email using the link at the bottom of the right hand column.

Thank you

 

Does DWV replicate in mites?

Buckle up.

After a gentle tale of bad beekeeping last week 1 I think it’s time for a bit of science.

Does deformed wing virus replicate in Varroa mites?

Varroa destructor – focus stacked image

Actually, do any pathogenic virus of honey bees replicate in mites?

Does it matter?

Not really … in comparison to the 2.1 billion people who don’t have access to safe drinking water 2, it’s unimportant.

But if you’re interested in how viruses are transmitted between bees, or how the virus population evolves, then knowing whether the virus replicates in Varroa is important.

For example, perhaps replication in Varroa amplifies a particular sub-population of virus that are more virulent, or more transmissable?

Or causes bees to drift more, so spreading the virus more widely in the environment?

Behaviour-altering viruses are interesting. There has been recent a report that IAPV 3 changes the social behaviour of honey bees to potentially increase transmission 4.

So, if it does matter …

Why now?

Three things prompted me to write this post now:

  1. A recent paper on Black Queen Cell Virus replicating in Varroa was briefly discussed on the Bee-L mailing list. This paper repeated many of the errors of assumption in the historical literature  on virus replication in Varroa 5.
  2. The experiments done to address this question over the last couple of decades have been either contradictory or uninformative. Or both. Or just not very good 🙁
  3. We have just published a study 6 that specifically addresses whether deformed wing virus can replicate in mites. Inevitably 7 I think it’s the most complete answer to date but, as will become clearer, it raises more questions than it answers and I know we don’t yet understand the full story.

To understand the problem you need to have a little background on both viruses and Varroa. Our paper is on deformed wing virus (DWV) and I’ll almost exclusively be using this as an example. If I use the word ‘virus’ I mean DWV.

However, the generalities of the shortcomings in some of the historical studies and the way we tackled the problem is relevant to any virus of honey bees. In that regard, when I use the word ‘virus’ it could probably mean any virus of honey bees.

Background to viruses

Viruses are obligate intracellular parasites. They can only replicate inside a living cell. The majority of pathogenic viruses of honey bees have a genome composed of single stranded positive sense RNA.

I did remind you to buckle up? … here we go.

All single strand positive sense RNA viruses share a broadly similar replication strategy.

Virus replication – select for full size and legend.

The virus enters the cell and the genome is translated to make proteins. There are essentially two types of proteins made:

  • the structural proteins – these form the new progeny virus particles. They are what package the new virus genomes into particles (thereby protecting it from damage) to infect the next cell, or host.
  • the non-structural proteins – these proteins are the ‘motor’ that makes new virus genomes 8. They do not form part of the virus particle.

After translation the non-structural proteins replicate the virus genome. To do this they first make a single stranded negative-sense template from which they eventually copy hundreds or thousands of more positive-strands.

The positive strands (only) associate with the structural proteins to form new virus particles. These leave the cell and go on to infect another cell, or another bee.

It’s as simple as that 🙂

A few important things to remember:

  • negative strands are never present in the virus particle. Since they would be non-infectious the virus has evolved all sorts of elegant ways of excluding them from the particle.
  • there are lots of positive strands produced from each negative strand. A ratio of 1000:1 or higher is not unusual 9.
  • without the initial production of the non-structural proteins the virus cannot replicate.

Background to Varroa

I’ve discussed Varroa extensively in previous posts. A full description of the life cycle was presented in the post Know your enemy. For lots of juicy background detail please refer back to that post.

As far as this post is concerned the important facts are as follows:

  • Varroa feeds on developing honey bee pupae and, during the (misnamed) phoretic stage of the life cycle, on adult bees.
  • the mite ingests a rich ‘soup’ of cells and proteins from the bee. For a long time it was thought that the mite fed on haemolymph (effectively bee blood), but some currently favour the evidence that Varroa feeds on the fat body of bees. As far as this post goes, it’s irrelevant whether the mite feeds on haemolymph or the fat body 10.
  • when the mite feeds on a virus-infected bee is also ingests the virus.
  • when the mite subsequently feeds on a different bee (for example, to initiate another round of incestuous replication) it transmits some of the virus in its saliva to the new bee.

There, that wasn’t so bad was it?

Evidence for virus replication in Varroa

I’m not going to provide an exhaustive review the extensive literature here. It goes back to the mid-90’s and is pretty dull and rather hard going in places.

There are also lots of papers on DWV replication in bumble bees … does it?

Essentially the evidence for replication of viruses in mites is the presence of virus negative strands in the mite. Time and again this has been presented as “definitive proof” that the virus replicates in Varroa.

Does that seem reasonable?

You already know enough Varroa and virus biology to see the flaw in this conclusion.

Q. What did that mite last feed on?

A. A virus-infected pupa.

Q. And what was therefore present in abundance in that pupa?

A. Negative strands of the virus genome.

Just because viral negative strands are detectable in the mite does not mean that they were produced in the mite when (if?) the virus replicated.

Perhaps they were simply ingested with the soup of proteins and cells that the mite eats?

This is an error based upon a positive result. There is an assumption that the positive result tells you something … but it doesn’t, or at least it might not.

Evidence against virus replication in Varroa

This one is more subtle and – in contrast to the above –  is an error based on a negative result.

It’s always dangerous drawing scientific conclusions from negative results. Perhaps the experiment just didn’t work? Perhaps it wasn’t sensitive enough? This is why lots of controls are needed.

Scientists looked in detail at all of the proteins present in Varroa mites. They used a method called mass spectroscopy that detects tiny fragmented proteins which they identified by comparison with a database of known proteins.

Orbitrap ID-X Tribrid Mass Spectrometer

If one of the tiny fragments matches, there’s a reasonable chance that the entire protein was present. If lots of different tiny fragments match one protein there’s compelling evidence that the entire protein was present in the sample 11.

Using mass spectroscopy scientists detected the structural proteins of deformed wing virus. However, using the same methods, they could not detect the non-structural proteins.

Since the non-structural proteins were ‘absent’ the virus could not have been replicating in the mite as they are a prerequisite for replication.

Seems logical, but is again potentially wrong.

Perhaps the tiny protein fragments of the non-structural proteins of DWV are ‘sticky’ and remain associated with cellular fats and membranes 12 during the purification process?

What about controls? Did the authors demonstrate they could detect the non-structural proteins of a virus that does replicate in Varroa? Was the sensitivity of their assay sufficient to detect the levels of non-structural proteins expected to be present? Did they provide evidence they could detect other similarly low abundance proteins?

No.

Should honey bee viruses replicate in Varroa?

Viruses are obligate intracellular parasites. They depend upon proteins and processes in the cell for their replication. This often means that viruses are restricted to a very narrow range of hosts. Sometimes viruses will only replicate in certain tissues or cell types of a single host species.

Varroa and honey bees are both Arthropods, but belong to different classes (Arachnida and Insecta respectively) within this phylum. They are therefore rather distantly related.

This does not mean that a virus of honey bees cannot replicate in the mite. There are several human viruses that also replicate in the mosquito (Dengue, Yellow Fever, Zika for example) during transmission. However, it’s an interesting philosophical cul-de-sac which is distracting us from the main event.

Genetically engineered deformed wing virus

Keeping up?

Good.

Now we’re getting to the more exciting stuff 13.

For some time now my lab have been able to genetically engineer deformed wing virus. This means we can make changes to the virus that help us do interesting or informative experiments.

For example, Olesya ‘Alex’ Gusachenko in my team built a virus that expresses a protein that turns bees green.

Green bees

This is allowing us to look in detail at the specific tissues the virus replicates in, or at transmission of the virus between bees. I’ll discuss green bees again in the future.

To investigate whether deformed wing virus replicates in Varroa we used a virus that had been engineered to contain a tiny genetic tag. It was equivalent to altering 0.05% of the virus genetic material. This genetic modification had three really important features:

  • it was unique and was not present in any other strains of deformed wing virus
  • although present in the virus genome it did not change any of the characteristics of the virus 14.
  • it was easy to detect. Alex developed an assay that could detect really tiny amounts (probably less than 100 copies) of genomes that contained this modification.

An artificial diet for Varroa

The final thing I need to introduce is how to keep Varroa mites in the laboratory 15. The experts can maintain Varroa in incubators, feeding them on little drops of honey bee haemolymph in what are called feed packets.

We’re not experts. But we know people who are.

We collaborated with our friends Alan Bowman, Ewan Campbell and Craig Christie in Aberdeen University who helped us with the Varroa feed packet part of the experiment.

A mite-infested apiary in Aberdeen with Luke, from my lab, and Craig discussing craft beers.

Critically, Alan’s lab have developed a feed packet system that contains no honey bee material. They can maintain Varroa in the lab without feeding them on mushed up bees. This means we had total control over what our Varroa could eat.

The feed packet contents are a closely guarded secret 16 but will be published soon.

Enough! Enough! Does DWV replicate in mites?

This is how we did the experiment. We grew large amounts of our genetically-tagged virus in honey bee pupae.

We purified the virus and treated it with an enzyme called RNAse.

As described above, the genome of DWV is made from the chemical RNA. RNAse degrades and destroys RNA.

However, viruses are resistant to RNAse because the RNA genome is protected inside the structural protein coat that forms outer layer of the virus particle.

We treated the purified virus preparation with RNAse to remove all RNA that was not inside the virus particles. This contaminating RNA could otherwise compromise the experiment.

Importantly, RNAse degrades both positive and negative strand RNA molecules. Therefore, we could be certain that our virus input into the experiment contained no contaminating negative strand RNA (and confirmed this in several controls).

We then added our virus to the feed packets being used to maintain groups of ten Varroa. After 4 days we harvested the Varroa and extracted all the RNA from them. We also had control mites which were not fed our tagged virus, but were otherwise treated in an identical manner.

All the mites contained very large amount of DWV-specific positive strand RNA. This was unsurprising. Even if our tagged DWV did not replicate in mites they had been feeding on honey bee pupae packed with DWV only four days ago.

We then looked for the presence of negative strand RNA. Again, there were reasonable amounts present, entirely consistent with their previous diet of DWV-infected honey bees. The control mites contained good levels of negative strand RNA.

DWV replicates in Varroa

However, only the mites fed the tagged virus contained a variably weak but consistent signal for the unique genetic tag we had introduced.

We interpret that as very good evidence that DWV does replicate in Varroa.

Is this level of replication significant?

Significant in terms of what?

It’s significant in that this experiment demonstrates for the first time the de novo production of replication intermediates (the negative strand RNA) in mites.

I’m not unbiased ( 🙂 ) but I think this is some of the best evidence supporting DWV replication in Varroa. It also demonstrates the types of experiments that are probably needed to determine whether other honey bee viruses replicate in the mite. The presence of negative strands is not enough. As the figure above shows, at least in the case of DWV, the majority come from the bee pupa the mite last fed on and we have no way to determine whether they are newly replicated or not.

But is the replication significant in terms of the amplification of the virus?

The presence of this signal confirms that there is some replication of DWV in Varroa. The fact that the signal is weak suggests that virus replication is not very extensive or very fast.

For comparison, if we inject the equivalent of 10 DWV virus particles into a honey bee pupa 17 they will be replicate to produce 1,000,000,000 (one billion) viruses within 48 hours. Assuming a conservative ratio of positive to negative strands, these individual pupae would each contain a million copies of negative strand RNA two days after infection.

We have yet to fully quantify specific negative strand levels replicated in Varroa, but it looks a whole lot less than that to me.

These are technically very demanding experiments and will take some time to complete. In the meantime we can and should ask a more relevant question.

Is this replication significant in terms of the biology of the virus?

By ‘biology of the virus’ I mean things like differential amplification of specific variants of the virus in the mite, so changing the virus population. For example, does virus adaptation occur, selecting for DWV variants that are more transmissable by Varroa?

We don’t know yet, but at least we have a system which will allow us to test this.

Although we have additional genetically-tagged variants of DWV we can test in the future, in mixed infections one will only be consistently selected over the others if it has a growth advantage.

We don’t yet know such a growth advantage even exists and there might be better ways to determine if it does. These are not straightforward experiments to undertake.

Based upon the limited replication we see in mites I do not think that the replication is significant in terms of increasing the amount of infectious virus in the mite. In contrast, the very high level of replication in honey bees may well allow the evolution of particular strains with particular characteristics.

Where is the replicating virus in Varroa?

We treated the mite like a simple bag of RNA.

We didn’t determine whether the virus was present in muscle, or brain or the ovaries.

The location of the virus is really important.

If the virus is replicating in a tissue that facilitates transmission to the next bee 18, particularly if certain types of virus are being selected because they grow better there, then it might be significant.

Some tissues allow viruses to be transmitted, others do not.

For example, poliovirus is a very distant cousin of DWV. Poliovirus is transmitted faecal-orally 19 in contaminated water supplies. After ingestion it replicates really well in the small intestine. It then has a short distance to travel (!) until it is excreted again. So, the primary site of poliovirus replication (the gut), is ideal as it ensures an obvious route for transmission.

Actually, poliovirus replicates so well in the gut that in about 0.5% of infected people it escapes from the gut and enters the peripheral nervous system. It then travels to the spinal cord and finally reaches the brain.

Poliovirus replicates pretty well in the brain as well … so well that it destroys some of the grey matter causing paralytic poliomyelitis 20.

But, as far as the virus is concerned, the brain is a dead-end. There’s no way out. Virus that replicates in the brain can never infect another person. How could it get from the brain to a water supply?

What about DWV? Is DWV replicating in tissues that enables transmission to another host?

Replication in the gut, in salivary glands or possibly the ovaries would all be consistent with transmission (with the ovaries as a source for vertical transmission to progeny mites – though they have already fed at the same spot on the pupa so determining this might be difficult). However, if DWV is replicating in mite muscle or brain it may well be irrelevant in terms of honey bee virus biology as there’s no obvious way out of those tissues.

Questions and answers

We attempted to answer a seemingly simple question “Can DWV replicate in mites?

We think the answer is yes.

But, as you can see from the few paragraphs above, that short question and even shorter answer has generated lots more questions.

And some of them are much more difficult to answer than the one we tackled 🙁

Identifying the site(s) of virus replication in Varroa would normally require microdissection of a variety of different tissues. Is the virus present? Is it replicating?

But a virus that expresses a fluorescent green protein during replication should make things a lot more straightforward … but more on that some other time.


Notes

The paper containing this study is available – open access (i.e. free) – the full title and journal details are: Gusachenko et al., (2020) Green Bees: Reverse Genetic Analysis of Deformed Wing Virus Transmission, Replication, and Tropism. Viruses 12: 532.

The million drones fiasco

Accidents happen.

Sometimes they are due to stupidity, sometimes to forgetfulness, or sometimes they are just the result of plain dumb luck.

They’re also often caused or at least exacerbated by ‘local’ factors – like a rainstorm or a cancelled train preventing timely inspections. 

Or a countrywide lockdown necessitated by a global viral pandemic.

With the exception of the cancelled train my excuse for what follows is “all of the above” 😉

Social distancing

Beekeeping, like other activities involving livestock management, has been a permitted activity during lockdown. Beekeepers have been allowed to travel to their apiaries and to move bees for pollination etc

I was away when lockdown was imposed and opted 1 to stay where I was. For the first half of the season I’ve had to forego weekly colony inspections. I’ve not had the pleasure of watching the colonies build up, of queen rearing or of sweating profusely when shifting nectar-filled supers 🙁

Instead all my beekeeping – the first inspection of the season, the swarm prevention and the swarm control – have been squeezed into two visits, each of a few frantically busy days, in late April and mid-May.

And, inevitably, mistakes have been made.

Well, one mistake … that I’m currently aware of.

First inspections and swarm prevention

We’re late starters in Fife.

It’s not unusual to delay the full first inspection until the very end of April in this part of Scotland. A couple of years ago we had knee-high oil seed rape (OSR) ankle deep in snow at the end of April.

There seems little point in disturbing the colony if it’s too cold to have a leisurely look through the brood box. The bees get tetchy, the brood gets chilled and you don’t have time to look for the important things – like disease, or that elusive queen you failed to mark last autumn.

However, this season started well and I should have started colony inspections in the second week of April.

But by that time the world had changed dramatically …

I finally snatched a couple of days around the 25th of April to do the first inspections and swarm prevention all rolled into one … and coupled this with reducing my colony numbers by 50% to make management over the coming months easier 2.

I’ll discuss how I did all this in a couple of full-on days some other time. The end result was about a dozen united colonies, each topped with three supers, containing a good marked laying queen. Many of the colonies were very strong, with up to 15 frames of brood after uniting 3.

The colonies were strong and healthy. All were headed by a laying queen. I saw all but a couple of the queens 4 and clipped and marked all those I found that weren’t already 5.

Safely back in the hive

Three supers were overkill for the usual spring nectar flow. However, there was already a reasonable flow on and I wanted to give the colonies a good amount of space in the hope of delaying swarm preparations. 

Swarm control

Colonies usually start making clear their intent to swarm in the second half of May here. It varies a bit depending upon how advanced or otherwise the season is – one of those unknown knowns.

I kept in email contact with beekeeping friends about their own colony build up. By the time I received the first email saying charged queen cells were present (~16th of May) I was travelling back to do my own swarm control.

I decided to use the nucleus method whether queen cells were present on not.

Effectively I was going to implement preemptive swarm control on some colonies. By taking the queen out into a nuc the colonies would be forced to requeen, I’d then leave a single charged/capped queen cell and let them get on with it.

All looking good …

And for eleven of the colonies that’s precisely what happened. 

I removed the queen on a frame of emerging brood and shook some of the bees from a second frame into the nuc box. These were to be relatively small nucs but made sure each had a full frame of capped stores (saved from colonies at the first inspection). I also added a frame of drawn comb and two foundationless frames.

I sealed the nucs and moved them to another apiary.

Three of many … and hive number 29

Most of the brood boxes had play cups with eggs and about 50% had charged queen cells. There were no capped cells. I marked frames containing promising looking charged cells and closed the boxes up.

… and still looking good six days later

Six 6 days later I went carefully through every frame in the de-queened colonies.

One good queen cell, an old play cup and some rather old comb

All the boxes had good looking queen cells and I made sure I left just one in each colony. 

The nucs also all looked great when I checked them on the same day. 

New comb with queen already laying it up

The queens were laying well and the bees were drawing new comb. They would be fine for another few weeks. 

Come in Number 29, your time is up

One of the colonies proved more problematic.

Hive #29 … this had been left as a strong single brood colony on the 25th of April.

Three weeks later it was – unsurprisingly – still a strong single brood colony. The bees were busy and the supers were already filling nicely 7.

What was missing from the brood box in mid-May were eggs, larvae or capped brood 🙁

Had I inadvertently killed the queen 8 at the last inspection? The 21-22 day interval would have meant that all worker brood would have matured and subsequently emerged 9.

However, the temperament of the colony suggested it wasn’t queenless. The bees were calm, they were foraging well and bringing in good amounts of OSR pollen.

With a sense of dread I had a look in the supers …

Let there be drones

About 75% of my many super frames are drawn on drone cell foundation. For the same amount of wax – by weight – you store more honey. I also think there may be advantages when spinning it out in terms of honey recovery 10.

In addition, if you use drone cell comb immediately over the brood box, you dissuade a strong colony from storing an arch of pollen over the brood nest in the super … 

Drone comb in super

… though they do often leave cells empty, ready for the queen to lay.

But she can’t do that because she’s trapped under the queen excluder. 

Right?

Wrong 🙁

The middle few frames of the lower couple of supers were wall to wall capped drone brood and drone larvae. The queen was busy laying up some of the remaining space that wasn’t already filled with nectar.

I found the marked and clipped queen on the very first super frame I removed.

Sod it.

Snatching victory from the jaws of defeat

Perhaps.

Here was the dilemma. Hive #29 was strong and healthy but effectively queenless. Time was against me. I didn’t have the luxury of simply plonking her beneath the QE and checking the colony didn’t make swarm preparations in another three or four weeks 11

I’d already united all my other colonies and made up the nucs. I didn’t want to disassemble any of these to accommodate this colony.

With bad weather approaching in a few days I decided to make up a nuc with the queen and, in due course, donate a queen cell from another colony.

Which is what I did. 

An adjacent colony helpfully raised several very good looking cells which I knew were charged. One of these, on a frame holding a sideplate-sized patch of brood, was added to the colony just before the rain arrived.

Open the box, open the box

But on the same day I added the queen cell I also checked the supers thoroughly.

I wanted to make sure that every frame was drone foundation and that I’d not missed a queen cell drawn from any worker comb in the supers. That might have resulted in a virgin queen running about in my supers and, knowing my luck, squeezing through the QE and slaughtering the queen from the cell I’d just introduced. 

There were lots of “queen cells” in the supers. However all were little more than play cups drawn along the top edge of the drone comb, against the top bar. 

Lots of drone brood … but no real queen cells

None contained eggs. It was as though the bees, sensing the colony was now truly queenless, had known what to do but had no primary material to work with.

Over the next fortnight or so this hive was going to generate hundreds thousands lots of drones. Not in itself a bad thing – this was a good colony and the positve influence on local bee genetics might be beneficial.

However, all the drones would emerge in the supers and be prevented from exiting the hive due to the queen excluder.

When this happens the drones die in their droves stuck half way through the excluder.

This is a distressing sight and, for a drone, a demoralising experience (I would imagine 12).

Under normal circumstances I would simply return every 3-4 days, pop the lid off the hive and release them. This wasn’t possible living four hours away … 

… so I played the ‘get out of jail free’ card by adding a thin eke and upper entrance.

Upper entrance

When I next check the colony I expect the drone brood to have all emerged and, largely, left the supers. I hope there’s a mated laying queen in the bottom box and there should be some capped worker brood.

What there’s unlikely to be is three full supers of honey 🙁

With no worker brood being reared for at least 5 weeks the foraging workforce will be significantly depleted. I hope they manage to defend what they’ve already collected … time will tell.

What went wrong?

After finding the supers full of drone brood I wrote “dodgy” on both sides of the queen excluder frame as I replaced it with a plastic spare.

I assumed the queen had found a bent wire and   s  q  u  e  e  z  e  d  her way through to have a field day – actually three weeks – in the supers.

However, I think the explanation is more prosaic than that 13.

My notes indicated I’d not seen the queen in this hive during the April inspection. In this instance evidence of absence was not absence of evidence … there were lots of eggs and brood in all staged. The colony was queenright and the queen was in the right place.

At least before I opened the hive 😉

And this is where stupidity, forgetfulness and plain dumb luck played their part. I … 

  • stupidly botched the inspection, taking the strength and health of the colony as the most important signs that all was well, but …
  • forgot that the next inspection – when I would be making up nucs – would also need worker eggs in the brood box to rear new queens from.
  • There’s more … I also presumably forgot to thoroughly inspect the queen excluder before laying it to the side, allowing …
  • dumb luck to intervene when the queen scooted around to the other side of the excluder and so end up trapped in the supers when I reassembled the hive.

Mea culpa.

That’s my best guess anyway.

Did I do the right thing?

Hive #29 was the last to be inspected after a hard day of beekeeping in late April.

Coincidentally it was also the last to be checked in mid-May 14

This limited my options somewhat and I made a judgement call as to the best course of action. Doing what I describe above risks the queen failing to emerge or mate. It also potentially risks the box being robbed as the workforce diminish, particularly with the upper entrance I’ve added.

Both of these could lead to the loss of the hive, but the loss/problem would be all mine. At the time, standing there swearing sweating in my beesuit, gasping for a beer, it seemed like the safest bet. It also seemed like the responsible course of action in the middle of a global pandemic.

I chose not to just dump the queen back into the brood box, add the upper entrance and leave them to it. Had the colony subsequently swarmed 15 the problem might then have been someone else’s

Did I do the right thing?

We’ll know soon enough … 😉