Synopsis : Save money. Take your winter losses now. Unite weak colonies or those headed by dodgy queens … and some thoughts on poly nucs for overwintering.
With apologies to Winston Churchill:
“Now this is not the end. It is perhaps the beginning of the end.” 1
And even a cursory look through couple of colonies will confirm this. They are shifting from their summer labours to the late summer preparations for winter.
The signs are easy to spot.
Colonies with ample super space are beginning to backfill the broodnest with nectar. You can see it sparkling in the sun.
Backfilled cells (and a drone or two)
You also see this when the colonies have nowhere else to store fresh nectar, but my supers are disappointingly full of space this year 2 ) so they’re opting to keep it close. The brood pattern can look a bit spotty, but the queen is ‘missing’ the cells because they’re already full.
Most of my east coast colonies have stopped, or almost stopped, rearing drones. There are still plenty of drones about but they’re not producing any more this season.
This makes sense. Drones are ‘expensive’ in terms of the resources (pollen, nectar, time, workers) needed to rear them and the chance that they will successfully complete a mating flight this late in the season is limited.
They’re not chucking them out yet though. On a warm afternoon the distinctive sound of a thousand drones going out ‘on the pull’ fills the air.
Ever the optimists 😉 .
Colonies are still strong and busy. They contain a lot of brood, but the laying rate of the queen is slowing and – presumably 3 – they will very soon start rearing the long-lived winter bees that will take the colony through to next spring.
Take your winter losses now
And, as the colonies segue from producing summer bees to winter bees, I’m also starting to plan for the winter. This involves preparing the colonies I want and getting rid of (i.e. uniting) those surplus to requirements or underperforming.
Synopsis : What can you do with the spare nucs and queens left after successful swarm control? After a ‘month of mayhem’, calm descends on the apiary and there are queens to mark, colonies to unite and – thankfully – a bit more time for everything.
The first half of the beekeeping season – yes, for me at least, more than half of it has gone already – started very slowly. The long, cold early Spring seemed to delay colonies from making swarm preparations, though they certainly built up strongly by foraging hard when conditions were suitable and there was a lot of pollen in the boxes.
And, because colonies were strong and running out of space, when things finally warmed up everything went a bit mad.
Fortunately, my apiary visit at the beginning of this week suggests that the ‘month of mayhem’ is over and it should now all be plain sailing until the end of the season.
No longer do I feel as though I’m playing ‘catch up’ all the time, juggling a dozen metaphorical plates to get a good honey crop and not lose swarms, desperately searching for spare equipment, or cursing my lack of frames, or dummy boards or – most recently – those little plastic ‘candy’ caps for JzBz queen introduction cages 1.
Calm after the storm
And, appropriately, these apiary visits were periodically interrupted by some spectacular cloudbursts … but, as I drove home in the calm afterwards it was clear both I and the bees had weathered the storm and things were looking good for the summer honey and the remainder of the season.
Synopsis : Supersedure – the replacement of the queen without a brood break or a queenless period – is an important colony survival mechanism. How is it induced and can the beekeeper take advantage of it?
Supersedure is the replacement of the queen – due to age or infirmity – by a new one reared in the same colony. Significantly the colony is at no point queenless, and may actually have two laying queens during the overlap period. Ted Hooper (in his Guide to Bees and Honey) states that 5% of colonies with two year old queens – at least of the strain of bees he used – actually have two queens in the colony in the autumn and they can often be found laying on the same frame.
I rarely inspect colonies in the autumn and have never seen two queens in a colony, let alone on the same frame. However, I’m well aware the process goes on undetected … or at least undetected until the following spring.
I’ll check a colony in mid-August and find the clipped, marked laying queen I expect. However, the following April – well before the swarm season starts here – I’ll find an unmarked and unclipped queen heading the colony 1.
Synopsis :“It’s good to learn from your mistakes. It’s better to learn from other people’s mistakes.” Here are some related ones of mine and the lessons I (again) learned from them.
This is the 50th post of the year. Usually 1 this is the week in which I write some erudite words 2 about the season in retrospect.
What went well, what could have gone better and what was an unmitigated disaster. The highs and the lows, together with a smattering of the in-between bits that actually constitute the majority of the beekeeping year.
Writing these review-type posts is quite enjoyable 3. I have to go back through my hive notes which inevitably brings back a flood of memories of warmer days, heavy supers, lost hive tools and unmated queens.
Laden foragers returning …
These notes are succinct – rarely more than ~10-20 words – littered with acronyms but surprisingly informative. At least they are when you take into account their dates and the timing of the development cycle of workers, drones and queens.
And, as a bonus, they are also legible.
I’ve mentioned before that I take my hive inspections records on a digital recorder in the apiary and then transfer them to a spreadsheet with the company of a coffee 4 later.
Testing, testing, one, two three
Whilst this approach misses the immediacy of a scribbled note on a sheet of paper under the hive roof, it does allow me to easily refresh my memory before the next apiary visit.
It also means they don’t blow away, get damp, eaten by slugs or require me to have a functioning pen in my beesuit … the recorder lives in the bee bag, so is always available.
By looking at the hive records in advance I’m reminded that – for example – I need more supers for hives #23 and #27, that the former had a good open queen cell on frame 7 (OC/7 in the notes) which should now be sealed 5 and that nuc #13 has a recently mated queen who will need finding (!), clipping and marking.
And by looking at the same records in mid-December, with the temperature plummeting outside, I can see how the season progressed week-by-week in my three main apiaries.
The nuc was sold a fortnight later, the queen in #23 eventually emerged but was lost before she got mated (or perhaps on her way back) and supers filled so rapidly that I regretted not adding more at once.
It was a great year for honey, the best since returning to Scotland in 2015.
But that can wait until the review of the season … which will now be next week 6.
Impressions vs. reality
I give a lot of talks on beekeeping. Whilst a talk might be about bait hives, swarm control or queen rearing, the questions afterwards can be more wide-ranging. It is quite fun to get questions on apparently random beekeeping topics (I’ve done ’ask the expert’7 panels at beekeeping conventions which are enjoyable; for one question and four panel members you get six different answers and a good-natured argument … no wonder we run out of time).
Some of the more ‘left field’ questions can be a challenge and require a degree of lateral thinking. I’m more than happy to acknowledge that I’m sometimes stumped for an answer … I understand the question, but I cannot explain why whatever happened 8, er, happened.
However, the very fact that I’m asked for an opinion at all suggests that I give the impression I know what I’m talking about 9 when it comes to almost any subject about honey bees.
Even if you just restrict the topic to the hive, its contents and what’s happening in it on a week-to-week basis, the apparent impression some have of my understanding can be wildly different from reality.
I know that because of my hive notes.
And I’m acutely aware of this because I’ve just re-read them … 😉 .
Perhaps I’m not being entirely fair. If you read the entries for any individual week in isolation it’s clear I sometimes don’t have a scooby 10 what’s happening in the hive.
It’s obvious because as well as acronyms there’s a dusting of ??? throughout the notes 11.
Not every hive and certainly not every week (thankfully), but more often than I’d like.
However, the regular repeat visits combined with the utter predictability of honey bee development, and comparison with adjacent hives, usually allows me to work out what’s happening with some certainty.
I think the take home message 12 here is that hive notes are veryuseful. Even if you don’t quite understand what’s happening in the hive, record what you see.
At the next visit, or the one after that, it should start to make sense.
And, when you re-read them in midwinter with the benefit of knowing what happened time, tea and a roaring stove, you’ll at least learn what to do in the same situation next year.
Or what not to do 🙁 .
But, there remains this disconnect between that impression of insightful understanding and the day-to-day reality of some of my apiary visits.
These are are not always as polished and assured as I’d like …
Photo by Roberto Prusso from 1913
… frankly, they can sometimes be a bit of a train wreck.
I reassemble the hive leaving the queen in a JzBz cage in my pocket.
Hives are inspected in the wrong order, meaning I might have to re-open one again to the understandable irritation of the bees.
I leave the hive tool inside a hive and can’t find another, or put it in the wrong pocket of my beesuit so it falls through the hole, down the inside of the leg and into my boot.
An elusive unmarked queen is found on my third run through the brood box … at exactly the same time as I find a suicidally psychotic worker inside my veil. I have insufficient hands to hold the frame, the queen and the worker (though, truth be told, I’m probably not intending to just ’hold’ the worker if she’s that agitated). The queen is abandoned until the following week.
Many are reassuringly ‘composed and unruffled’; I open the box, the bees are wonderfully calm. The queen is on the second frame I check, but the first had eggs anyway so I didn’t need to see her. However, since I found her and she’s mated and laying well, I mark her and clip her wing. The colony barely notice her absence and I run her gently back in between two brood frames to get on with her business.
Returning a marked and clipped queen – not distressed, just sauntering down between the frames
This is the beekeeper I’d like to always be … not that other ham-fisted muppet in an ill-fitting beesuit.
Here are a couple of queen-related examples from the season just gone. At the time I was flummoxed. In retrospect I’ve learned a few important lessons.
Or re-learned those that I had been taught already … and subsequently forgotten 😉 .
A tale of several queens
Almost all of my swarm control these days uses the nucleus method. In comparison to the widely-taught Pagden artificial swarm it only requires an additional nuc box. In my experience, it is almost totally foolproof as long as:
you take care to only leave a single queen cell in the hive; remember, this requires a visit one week after removing the queen. They cannot swarm if you leave just one cell.
you don’t make the nuc too strong; if you do there’s a chance it might swarm anyway.
My colony #7 contained an ageing but really lovely queen. I’d used her last year for queen rearing and hoped to do so again. At the start of May I’d obviously tempted fate by noting … ’Strong. Lovely BP. PC only … graft next week’14.
Lovely BP (brood pattern)
And, of course, the next week (the 8th of May) there were a couple of big, fat, 3-4 day old (i.e. open) queen cells and it was clear they were making plans to vamoose. I made up a nuc (number #47) with the old queen and moved her to a distant apiary.
One cell was left in box #7.
This box had overwintered with a nadired super and the original queen had snuck down in April and laid it up. Irritatingly, she’d chosen the frames of drone comb … not the end of the world because the queen was so good, but I didn’t want the new queen to do a repeat performance so moved the super above the queen excluder (QE). I discussed this in Early season inspections back in April – go there for all the gory details.
Drones emerging above a QE is a recipe for carnage as they try and squeeze through 15, so I added a thin eke that included an upper entrance. The drones could fly from this and, in due course, they did.
Hive with an upper entrance
In the meantime, the new queen should have emerged and got mated … but she was nowhere to be found. There were polished cells in the brood box and the colony was behaving as though it was queenright.
On the 12th of June I decided to give it ’one more week’ and, eventually, I then found her in the supers on the 19th, together with several frames of open brood.
Since there was no sealed brood she had presumably been slow getting mated and only started within the last week or so. I clipped and marked her and returned her to the brood box.
But she didn’t stay long.
My notes on the 21st of July include the comment ’no eggs’ (there had been on the 12th) and at the end of the month I found a new laying queen in the box.
She’s still there … or was when I last checked the colony (’lovely, well-tempered bees’ I was pleased to record in my notes) in mid-September. I presume the previous one hadn’t been ‘up to scratch’ and so was superseded sometime in mid-July .
When I removed the supers (unsurprisingly disappointingly light 🙁 ) and the plastic QE I found the latter had a couple of cracks in it. Although these didn’t result in any gaping holes, it’s possible the QE deformed sufficiently to let the queen through.
Lesson No. 1 – try and avoid using those inexpensive cheap plastic QE’s. A framed, wired excluder costs less than three jars of honey and is a good investment. I bought more at the start of this season, but still didn’t have enough.
You know it makes sense
However, I suspect the queen didn’t get into the supers through the QE.
I expect she instead returned from her last mating flight and entered the hive via the upper entrance. It’s not at all unusual for returning queens to end up in the wrong hive altogether, so simply mistaking an upper for the lower entrance is understandable.
Lesson No. 2 – ideally avoid upper entrances altogether on hives containing virgin queens, or at least orientate them to the opposite side of the hive.
What happened to the nuc?
The original queen was moved to another apiary in nuc #47 created during swarm control. A fortnight later (22/5/22) they were moved to a full hive 16 and three weeks later (12/6/22) I found a single charged queen cell in the middle of a central frame.
Although I suspected supersedure (ageing queen, single QC etc.) I’d seen the queen and she was still laying well. I therefore transferred the frame with the open cell to a neighbouring queenless and poorly tempered hive in the same apiary. She emerged, was mated and laying well by late July … and is heading the colony through this winter.
However, back to hive #47 … they attempted to swarm ~10 days later. Since the queen was clipped the swarm returned to the hive, but the queen was lost 🙁 .
I knocked back all but one of the charged open cells and guesstimated that she would emerge on the 6/7th of July. On my next inspection (on the 5th), the queen was quacking in the cell 17. My maths suggested she should be mated around the 20th but I didn’t open the box again until the last day of July when I found her laying well.
And it was about then that things started to go ‘pear-shaped’18.
Hands like feet
I fumbled the first couple of attempts at picking up the queen to mark her.
In my defence … it had been a long afternoon. This was the last of about 15 colonies I’d inspected and the supers were very heavy. It was hot, the sun was bright and I was really tired.
I’d removed the supers and set them aside, lifted the QE and found the unmarked laying queen after just a couple of minutes.
The first attempt at picking her up was pretty reasonable, albeit unsuccessful, but the second was badly botched. She skittered across the frame, clambering over and under the workers without giving them a chance to move aside.
Lesson No. 3 – when it comes to picking up queens, if at first (or at the most, second attempt) you don’t succeed, do not’try, try and try again’. Close the box, leave her for another day when both she and you will be calmer.
Of course, I persevered 🙁 .
On the third attempt she took off, seemingly in slow motion, but still too fast for me. She circled around, briefly landed on my shoulder, lifted off again and then – like Baron von Richthofen – was obscured by the dazzling sun.
I never saw her again.
But it gets worse …
I’ve had queens fly off before. In my experience they often (perhaps over 50% of the time) manage to return to the hive. They fly poorly and often crash land in the grass. It’s therefore important not to stampede about like a herd of wildebeest, but instead to calmly reassemble the hive and quietly retreat.
Ideally without moving your feet.
I managed the former but not the latter, cursing my failure to learn from ‘Lesson No. 3’ … it is not the first time that I’ve attended that lesson 🙁 .
I rarely inspect hives in August. This hive was on the other side of Scotland and I didn’t open it again until I removed the supers during the summer honey harvest at the end of the month. With only one and a bit filled supers there were relatively few bees above the QE … but there was a queen.
At least, there was evidence that there had been a queen present as there was a ~5 cm patch of brood on opposing faces of two of the super frames.
Small patch of brood – all of about the same age – in a super
I didn’t see the queen, and only discovered the brood as I shook the bees off the frames to remove them for extraction.
It was a patch of similarly aged brood; there were no younger larvae or eggs, and only a few cells were capped. It must have been laid 7-9 days previously.
Remember, I’d not opened the hive in the last 23 days.
There was no upper entrance and the QE was wired.
And the final lesson today
I ended up uniting the hive over a QE with a known queenright colony. I simply laid some newspaper over the top bars of the latter, added a QE to hold it in place and added the ’is-there-or-isn’t-there-a-queen-in-this-box?’ upper brood box onto which I shook the bees from the remaining super frames.
Newspaper and queen excluder
I do not understand the brood in the super.
The brood pattern indicated it was laid by a queen (rather than laying workers – in which case it would be scattered all around the frame). However, the age of the brood suggested she had only laid for a day or so. The brood looked like worker, but I didn’t photograph the frame until it was back in the extracting room and it was a bit bashed about by then.
My best guess is that the queen that flew away landed back on top of the open stack of supers next to the hive. However, that was over three weeks earlier. If it was the original laying queen that I’d failed to mark (or even pick up) then why didn’t she continue laying at the same rate?
Why the fortnight’s hiatus?
And why did she stop laying having only just started?
I’m afraid we’ll never know.
Which doesn’t mean that there’s not a lesson from this sorry debacle:
Lesson No. 4 – if a mated and laying queen does fly off, check the hive again one week later. If she’s back she’ll be laying and all will be well. If she’s missing in action there will be queen cells, but no remaining larvae young enough to rear queens from. Knock back all the cells you don’t want and let them get on with things 19.
One final queen
If you rewind about 1500 words you might remember that I found two good open queen cells in box #7. The one I didn’t leave in that hive I used to requeen an adjacent hive (#6).
Waste not, want not 😉 .
A week previous I’d already started swarm control on colony #6 by removing the queen to a nuc. I’d intended to let them requeen themselves 20 but the availability of a good queen cell from much better stock was too good an opportunity to miss.
I knocked back all the queen cells in hive #6, confident that there were no larvae young enough start as queens.
I added the frame from #7 with the queen cell and she emerged on about the 17th of May. She was mated and laying well by the 12th of June … probably earlier but I hadn’t checked at the intervening visit as I’d been taking three full supers of spring honey from the hive. I got a further three full supers of summer honey 9 weeks later.
The bees are well tempered and productive. They went into the winter very strong … headed by the same queen.
Sometimes, actually most of the time, everything ’just works’ 🙂 .
And a final word
The tale of misadventures recounted above was probably the only truly shambolic part of my beekeeping year in 2022 21. It was just a coincidence that it all originated from one hive. Some of it was self-inflicted, but other bits were just dumb luck.
Shambolic, but not catastrophic, and it all ended OK.
And I learned some valuable lessons.
Again 🙂 .
The opening quote, “It’s good to learn from your mistakes. It’s better to learn from other people’s mistakes”, is attributed to Warren Buffet.
A few readers signed up to receive notifications either about new posts or comments added to the post last week will have received repeat emails sometime on Tuesday evening. These were seemingly due to a hiccup in the server software and outside my control. With thanks to those who brought this to my attention, and apologies to the recipients. The current commenting and notification software is becoming ‘unfit for purpose’ due to subscriber numbers. I have plans to change, both along with some other developments, sometime next year.
Synopsis: There is a sexual arms race between the queen and the drones she mates with. The queen needs to mate with multiple drones to maximise colony fitness. Conversely, it’s in the interest of individual drones to reduce the number of additional partners who mate with the queen. Recent studies have demonstrated that drones reduce repeat mating flights by impairing the eyesight of the queen. Potential implications of this for practical beekeeping are discussed.
Honey bee queens are described as polyandrous 1 because they copulate with multiple drones during one or more mating flights taken shortly after emergence.
It takes longer to mate with multiple drones than it does to mate with one, but this time is minimised by reducing the number of mating flights. Rather than leaving the hive, mating once, returning and then repeating the process, the queen flies some distance to a drone congregation area and copulates with multiple drone before returning to the hive.
One of many …
I’ve discussed the location and locating drone congregation areas previously and the distances the queens and drones respectively fly to reach these (which are different to avoid inbreeding).
Between the queen returning from the mating flight and the onset of egg laying there is a delay of a few days. During this period the queen is storing the sperm from the drones in her spermatheca. These are the sperm storage organs within which sperm stays active for years … a necessity as, after the onset of laying, the queen will not go on any more mating flights.
Perhaps surprisingly, only about 3-5% of the sperm transferred from each drone is stored by the queen.
I hope that makes you wonder why she bothers mating with so many drones … it should.
Polyandry and hyperpolyandry
Just before I explain why she only stores 3-5% of the sperm from each of several drones, rather than storing it all from one twentieth the number (and thereby reducing the risks of longer mating flights) of drones, I need to explain the poly bit of polyandry.
How many drones does the queen mate with?
The usual figures quoted are in the high teens, with a range extending from single digits into the low forties. These numbers are determined using a variety of different techniques, at least some of which are likely to underestimate the actual number of drones.
Here’s one I made earlier …
Think of it like this, if you have a large population of something – like beekeepers – how many would you have to ‘sample’ to find one called ’David’.
Not many, it’s a common name.
But what about ’Atlas’ or ’Zebedee’?
You’d have to sample a lot more apiarists to find any with these rarer names, though I bet they’re out there somewhere. You might even have to use a different way to screen the population.
And it’s the same when determining the numbers of drones that the queen mates with.
Search and ye shall find – detecting rare patrilines
When you use a method that specifically looks for rare patrilines – essentially genetically distinct offspring fathered by different drones – you can find them. This suggests that the queen probably mates with more than the 15-19 drones usually quoted, and that hyperpolyandry is perhaps a better term to describe the mating behaviour of queen honey bees.
So now we’ve defined what the poly in polyandry means … but we still don’t know why the queen risks all those aerial shenanigans to mate with so many different drones.
By mating with multiple drones she ensures that the workers in the colony are genetically diverse. This genetic diversity increases the rather-difficult-to-grasp concept of colony ‘fitness’. In this instance fitness is used to mean a combination of adaptability, resistance to stress or pathogens, increased foraging activity, better overwinter survival etc.
The bottom line is that colonies that are headed by queens that are mated with very many drones (50+) produce more brood, have better disease resistance and have many other desirable traits (that benefit both the colony and the beekeeper).
The final piece of this introductory jigsaw I need to mention is that drone sperm is used randomly. It’s not a case of ‘first in, last out’. The 3-5% of sperm stored from each drone is mixed thoroughly in the spermatheca.
This makes sense in light of the comments above about colony fitness. If the sperm were used in batches from each drone you’d have cohorts of young bees being produced that had reduced genetic diversity, thereby potentially compromising colony fitness.
It takes two to tango
But let’s think about the poor drones for a moment.
Drones have two fates (excluding getting eaten by a bee eater); they either die while mating with a queen, or they get turfed out of the hive and starve to death towards the end of the season.
If the drone fails to mate with a queen he’s genetic dead end.
If he does mate with a queen there’s a good probability that the genes he carries will be passed on to the following generation.
There is therefore a lot of competition for the queen in the drone congregation areas (DCA).
The drones, once sexually mature, fly every (suitable) day to several DCAs, one after the other. In addition, they fly relatively short distances from the hive to maximise their time within the DCAs.
Heat map of the landscape used by drones – bright spots are DCA’s
This competition is intense, and it doesn’t stop once the drone has mated (and died).
If a queen mates with a relatively small number of drones – let’s say 10 for the sake of argument – the chance of the sperm from any one of those drones being used to fertilise an egg is much greater than if the queen had mated with 50 drones.
The fewer drones the queen mates with the better the chances that the genes from any one of her successful suitors will be passed on to the following generation.
Paradoxically, it therefore benefits the drone 3, if the queen mates with fewer other drones.
And, remarkably, drones have evolved a way to reduce the number of additional drones that a queen mates with.
A sexual arms race
Before I describe the mechanism, it’s worth emphasising here that best interests of the colony are served by the queen mating with many drones, but those of the drones are best achieved by limiting the polyandrous activity of the queen.
These two processes are therefore in direct competition.
There are some additional subtleties.
If the drone simply prevented the queen from mating again 4 it would be detrimental if that drone was the first with which the queen mated. The resulting colony would have little genetic resilience and would be unlikely to survive.
Any one drone must therefore allow the queen to mate with sufficient other drones to ensure colony fitness.
In addition, the more mating flights that a queen goes on, the greater the chances she will be predated by a passing bird, or get lost on the return flight.
From the drones point of view it would probably be beneficial for the queen to go on only one mating flight, but that she mates with sufficient (but no more than that) drones on that flight.
And finally, before I get to the mechanism by which all this is achieved – a compromise solution, like all the best solutions – I’ll remind you that studies have shown that queens go on about 5 mating flights spread over 3, usually successive, days.
Love is blind
At least, too much love is … 😉
Liberti and colleagues have recently published a snappily titled paper on how drones reduce the number of mating flights taken by a queen. The paper is Open Access so you can get all of the nitty-gritty details I don’t have time, energy or intelligence to include in the summary below.
The paper is:
Seminal fluid compromises visual perception in honeybee queens reducing their survival during additional mating flights by Joanito Liberti et al., (2019) eLife 2019;8:e45009
As with all science, the results published in this paper were a continuation of earlier studies of queen honey bees. In particular, these included studies by some of the same authors who had showed that seminal fluid contained proteins that had the ability to interact with neurons.
In addition, in Drosophila melanogaster (the fruit fly, and genetically best studied insect) there was evidence to suggest that seminal fluid promotes fast oviposition and reduces the willingness of females to seek additional copulations.
Drosophila mating in captivity
Now, Drosophila mating behaviour is very different to that of honey bees, but there was clearly a precedent here in which some of the components of seminal fluid – the ‘carrier’ that keeps sperm alive and motile and protects against pathogens – influenced subsequent mating in insects.
Or the lack of mating.
The study by Liberti et al., involves an elegant combination of hardcore molecular gene expression analysis coupled with electroretinography 5 and field work. I’ll skip briefly through the first two of these and provide a bit more detail on the last.
Analysis of gene expression
Virgin queen bees were instrumentally inseminated with seminal fluid (i.e. no sperm) or a control saline solution. Subsequent analysis of the brains of the bees – using a method called RNA-Seq which allows the qualitative and quantitative changes in gene expression to be accurately determined – demonstrated reproducible changes in the gene expression of dozens of genes.
Venn diagram of differential gene expression in instrumentally inseminated queen bees
Detailed analysis of which genes had changed in expression showed that several so-called signalling and metabolic cascades were modified in response to seminal fluid, and many of these mapped to the phototransduction pathways i.e. those involved in sight.
Several of the genes that were detected encoded proteins that were implicated in the conversion of light into the electrical signals in photosensitive electrical cells.
Inevitably, that one sentence has probably confused half the readers that have persevered to this point in the post …
Essentially what this means is that there are components within drone seminal fluid that change the ability of the queen to perceive light, or to see.
So, do they?
Visual perception of queens
The gene expression studies in this paper are complicated (for a molecular biologist). The electroretinography is an order of magnitude more complicated for this molecular biologist to understand … but here goes.
Electroretinography involves measuring the electrical signals generated by particular neurones that are connected to the compound eyes and ocelli 6. This allows the consequences of the changes in gene expression to be determined in terms of the vision of the queen bee.
These studies showed that queens instrumentally inseminated with seminal fluid had lower responses to low frequency flickering light, and that that this response (or lack of response) increased on the second day after insemination.
There were additional changes in the response of the ocelli in queens inseminated with seminal fluid.
Taken together, these results show that queens exposed to seminal fluid experience reduced visual performance.
They are not blinded, but their vision is impaired.
Does this visual impairment have any influence on their mating behaviour?
Mating flight behaviour
Finally, we come to something that’s a bit easier to comprehend, not least because I’ve previously discussed the technology used – the RFID tagging of individual bees to monitor their flight frequency and duration.
RFID-tagged queens (34 in total) were instrumentally inseminated (either mock, or seminal fluid or semen) and subsequently monitored when going on mating flights. Those receiving either seminal fluid or semen were more likely to get lost on these flights, and repeatedly triggered the hive entrance sensors, suggesting they were disorientated by sunlight after leaving the hive.
Of the 21 queens that returned, 81% went on mating flights of more than 7 minutes which was considered a conservative threshold for a completed mating flight i.e. flight to a DCA, mating(s) and return to the hive, and about 50% laid worker brood.
Notably, of the 17 queens that went on ‘successful’ (by duration, not necessarily by outcome) mating flights, those receiving the control saline solution left 1-2 days later than those that had received seminal fluid or semen.
Seminal fluid and semen induce alterations of mating flight behaviour in honeybee queens
These results show that exposure to seminal fluid induces significant changes in queen mating flight behaviour, presumably as a consequence of the alteration to the vision of the queen.
Therefore, the implication from these results is that proteins in the seminal fluid of drones impairs the visual perception of queens, thereby reducing the likelihood that the queen will embark on additional mating flights.
Queens that had already mated (or been instrumentally inseminated in this study) were more likely to get lost on subsequent mating flights, and embarked on these flights earlier.
But what about swarming?
The hive – or a natural nest site – is a low-luminance environment. Queens do not need fully functional eyesight once they have returned from their mating flights. In the hive communication is non-visual, mediated by pheromones, contact, vibrations and sound.
However, although a queen only goes on a few mating flights, she will also leave the colony if it swarms.
Swarm of bees
What are the implications for the this study on the eyesight of queens during swarming?
This isn’t really discussed in the paper, but I think there are two likely scenarios:
the changes in visual perception by the queen are transient and return to ‘normal’ after a few days, weeks or months
swarming is a fundamentally different activity in which thousand of bees leave the hive and for which accurate vision is not needed by the queen.
There’s a world of difference between embarking alone on a mating flight of several kilometres and having to return to the exactly the same location, and leaving on a one-way trip with a swirling mass of attendees with dozens of scout bees leading the way.
Further studies will be needed to determine whether the changes in vision are transient or permanent, as well as to identify the ‘active ingredient’ in seminal fluid that is responsible for the degradation of the mated queen’s vision.
I also think further studies will be required to determine the relationship between dose and timing of the response.
How long does it take for the reduction in visual perception? If the first and second mating flight are taken on successive days is the “return rate” greater than if they are taken a few days apart?
How many drone matings are needed to reduce the visual acuity of the queen? I would predict that this would be a number consistent with the lower estimates of polyandrous matings needed to generate fitness in the resulting colony.
And implications for practical beekeeping?
Perhaps none directly, though I’m interested in the answers to the questions I posed in the paragraphs above.
In an area with low drone densities and those with shall we say ‘variable’ weather – such as my apiaries on the west coast of Scotland (or for that matter, any beekeepers living in remote northerly areas with just a few hives) – is colony fitness compromised by reduced matings?
An isolated apiary
Conversely, is mating success lower because more queens fail to return from subsequent mating flights that they have to take to try and mate with enough drones?
Can mating success and colony fitness be increased by boosting drone numbers?
And is this achievable at a scale meaningful to a small-scale beekeeper?
If a measurable increase in mating success took a 1000-fold increase in drone numbers it’s probably not achievable.
However, if all it took was an extra frame of drone comb in every hive in the apiary, then that’s quick win.