The nucleus method

Almost all beekeeping associations – and most books – teach Pagdens’ artificial swarm as the recommended method of swarm control. It is tried and tested and reasonably dependable. However it can be a bit tricky to grasp for inexperienced beekeepers.

At least part of the problem is you have two hives that look the same, one on the original site, one adjacent. Conducted properly, the adjacent hive is moved to the other side of the original a week or so into the process.

Teaching this in a poorly lit, draughty church hall in late January, facing the audience with the inevitable confusion over left and right, and getting ‘new’ and ‘old’ hives mixed up, often bamboozles the beginner 1. Or the instructor ūüėČ

Here’s an alternative … the nucleus method of swarm control.

There she goes ...

There she goes …

General principles

This method is simplicity itself. When the colony looks as though it’s preparing to swarm you remove the queen, some stores and some bees into a nucleus hive.

This keeps the queen safe in case things go awry with the original colony.

You then return a week later and remove all but one queen cell in the original colony. The virgin queen emerges, mates, returns and starts laying.

A month or so after starting the original colony is headed by a new queen and you have a ‘spare’ building up in the nucleus box. You can overwinter this, sell it, give it away or – after removing the queen – unite it back with the original hive.

And that’s it … I said it was simple ūüôā

Here is a more complete account.

Equipment needed

It goes without saying that the nucleus method of swarm control needs a nucleus (nuc) hive 2. Any sort of 5 frame nuc is suitable. Nucs are incredibly useful, so they are a good investment. If you’re buying one for the first time get polystyrene as they’re lighter, better insulated and much better for overwintering bees in. I’ve reviewed poly nucs a few years ago. There are even more makes to choose from now.

I’d recommend not using a¬†two frame nuc as there’s not really enough room for stores and colony expansion 3.

Two frame nuc box

Two frame nuc box … a bit too small for the nucleus method of swarm control (but usable at a pinch)

In addition to the nuc you’ll need five frames that are compatible with your nuc and hive. Ideally, one or two of these should be drawn comb, but don’t worry if you just have foundation. A dummy board can also be useful. Like nucs, you can almost never have too many dummy boards.

Honey bee development

To properly understand honey bee swarm control you really need to understand the timing of the development cycle of queen bees.

Honey bee development

Honey bee development

Queen cells have a characteristic appearance. Unlike the horizontally-oriented worker cells, larvae destined to become queens hatch from eggs laid in vertically-oriented queen cells. After three days as eggs and a further five days of larval development the queen cell is sealed.

A colony will usually swarm on or soon after 4 the queen cells are sealed.

~3 day old queen cell ...

~3 day old queen cell …

This is why it is recommended that colony inspections are conducted at seven day intervals. If the colony is thinking of swarming you’ll find an unsealed cell (because there were none last week when you inspected and they take 8 days to be sealed) and you can immediately start swarm control.

Day 1 – Making up the queenright nucleus colony

If you find one or more unsealed queen cells at a routine inspection … don’t panic. You’re prepared, you’ve done your homework and you have the necessary equipment.

  1. Stuff the entrance of a nucleus hive with grass and place it near the colony 5.
  2. Remove one of the outer frames from the colony (you’ve probably already done this to give yourself room for the inspection) as this should have a good amounts of sealed and unsealed stores.
  3. Check again that the queen isn’t on this frame of stores (unlikely) and that it doesn’t contain any queen cells (again unlikely).
  4. Gently transfer the frame of stores plus all the adhering bees to the nucleus box.
  5. Continue the inspection and find the queen. Be gentle, don’t rush, don’t use too much smoke.
  6. Ideally you want the queen on a frame with some sealed and emerging brood. If you are lucky you’ll find her on a suitable frame.
  7. Gently transfer the queen and the frame she is on to the nucleus box. It is very important that this frame has no queen cells on it. Check very carefully. Destroy any you find.
  8. Your nuc colony is now queenright and has two frames of bees. Push the frames against the side wall of the nuc box, leaving a wide gap.
  9. Into this gap shake a further two frames of bees. Foragers are likely to leave the nuc and return to the original hive. You do not want the box to be short of young bees. If in doubt shake a further frame of bees into the gap in the nuc 6.
  10. Add a frame of drawn comb if you have it then fill the box with foundation. Add a dummy board if needed. Gently place the crownboard and roof on the nuc, secure everything with a strap and turn your attention to the colony.

Notes

  • The purpose of this exercise is to establish a small colony with stores, a laying queen, space to lay and sufficient bees to support her and the brood being reared. Remember stores, queen, bees, space and no queen cells¬†you won’t go wrong.
  • You will usually find the queen on a frame with eggs and young larvae. It’s very important that this frame does not have any queen cells on it.
  • Ideally you want the queen on a frame of emerging brood. This offers a number of advantages
    • The young bees will immediately strengthen the population supporting the queen
    • The vacated cells can be used by the queen to lay eggs (so reducing the need for drawn comb, or for the bees to build new comb)
    • The nuc colony will go through a period with no sealed brood and you can take advantage of this for Varroa management if needed (I’ll deal with this in another post)
    • It’s unlikely (due to the age of the other brood) to have a queen cell on it
  • One of the most common problems encountered with this method of swarm control is making up (or ending up) with a nuc that is not strong enough. A weak nuc will be unable to defend itself against robbing or wasps. There’s very little chance of weakening the original hive too much.
  • One way to avoid losing foragers from the nuc is to move it to an out apiary more than 3 miles from the original hive.
  • If you do leave the nuc in the same apiary check it a couple of days later. The bees should have chewed their way out through the dried grass. If they haven’t, pull a bit out at the corner of the entrance to encourage them to fly.

Day 1 – Preparing with the queenless colony

  1. Inspect every frame in the colony. Destroy all large queen cells 7. Anything that looks like the queen cell in the picture above should be destroyed. The idea here is to only leave queen cells containing very small larvae.
  2. Mark the frames containing these remaining selected queen cells using a drawing pin or pen.
  3. Push the frames together, add two frames of foundation, add the crownboard and close up the colony.
Here's one I prepared earlier

Here’s one I prepared earlier

One week later – Ensuring the queenless colony does not swarm

The timing and thoroughness of this inspection is important. Don’t do it earlier. Or later. Don’t rush it and don’t leave more than one queen cell.

  1. Inspect the colony and look for queen cells on the frames you marked a week earlier. These had very young larvae in them then and so will now be sealed 8.
  2. Select one queen cell to keep. Just one. Which one? Choose one that is large, well-shaped and has a sculptured exterior.
  3. Destroy all the other queen cells on this frame. All of them! If you need to remove the bees to see the frame better either brush them off gently or blow gently on them. Do not shake the bees off the frame as this might damage the developing queen.
  4. Gently return the frame with the selected queen cell to the box.
  5. Inspect all other frames in the colony (not just the ones you marked last week) and destroy all of the queen cells you find.
  6. You can shake the bees off these other frames to be sure of finding all other queen cells.
  7. Remember that some queen cells will be unsealed 9 … destroy them all.
  8. Return all the frames to the colony. Close it up and leave it for at least two weeks before inspecting again (see below).
Sealed queen cell ...

Sealed queen cell …

Notes

  • The purpose of this return visit is to leave the colony with only a single queen cell.
  • Because you removed the queen a week ago there are no other suitably aged young larvae or eggs for the colony to rear queens from.¬†Therefore, the colony¬†cannot produce multiple casts (swarms headed by virgin queens).
  • The nucleus method of swarm control often leaves the queenless colony very strong 10, if you leave more than one queen cell the colony may produce casts.
  • What if the queen gets lost on a mating flight? Shouldn’t I leave two queen cells? Just to be on the safe side?¬†No. If there’s a problem with the queen getting mated you’ve still got the old queen tucked away safely in the nuc box.
  • Queen cells that are large, well shaped and sculptured have received a lot of attention from the workers and so presumably contain a well-fed and good quality queen 11.
  • Don’t be tempted to inspect the colony in less than two weeks. Ideally leave them for three weeks. If you inspect too early there’s a chance that the queen may not have had a chance to mate and start laying (so the point of inspecting is missed) or – worse – that she returns from her mating flight as you have the box open and is then confused or lost.
  • Don’t meddle! Look for pollen being taken into the colony.
  • Have patience. Bees have been around for a few million years. They would not be this successful if they weren’t pretty good at getting queens mated …
  • Finally, particularly if the weather is poor, check the nuc as well. Ensure that it has sufficient stores. With reduced numbers of bees there’s a chance they could starve if the bees cannot forage (in which case the queen in the main colony is going to struggle to get out and mate as well).
Everynuc

Everynuc …

Pros and cons of the nucleus method of swarm control

With the exception of vertical splits almost all of my swarm control uses this nucleus method 12. I particularly like the nucleus method because I have lots of nuc boxes ( ūüôā ) and because it leaves manageable single-entrance hives rather than double height, multiple entrance stacks.

Almost all of the foraging bees are left with the original colony so the nectar-gathering capacity is not significantly reduced.

I almost never use the Pagden artificial swarm, largely because it ties up too much equipment.

Pros

  1. Limited amount of extra equipment needed – five frames and a nuc box … both of which are useful anyway.
  2. The old queen is kept safe and out of the way.
  3. Simple to implement, with just two visits at fixed times.
  4. Reasonably easy to understand the manipulations involved.
  5. No heavy lifting.
  6. You generate a nucleus colony to give away or to build up for overwintering.

Cons

  1. You need to find the queen.
  2. You need to find all the queen cells and use your judgement as to their age and quality.
  3. Unless you remove the nuc to an out apiary there’s a good chance lots of the bees will return to the original hive. Make sure you add enough at the start and be prepared to add more if you check the nuc after a day or two and find it heavily depleted.
  4. If you don’t want to make increase the nuc is a little more difficult to unite back with the original colony 13.

Give it a go … what could possibly go wrong?


 

Superorganism potential

The term superorganism can be used to refer to a colony of honey bees. The term gained prominence in the mid/late noughties having been reintroduced by the world-renowned myrmecologist 1 E.O. Wilson.

Bees, like ants (myrmex, “ant”, from the Greek¬†őľŌćŌĀőľő∑őĺ), are social insects in which there are divisions of labour. Different individuals within the colony perform different tasks. Some of these roles are defined by the castes in the colony – queen, worker and drone in a colony of honey bees for example – and some are defined by physiological differences between individual members of the same caste.

The term superorganism describes the entirety of the colony and is defined as a group or association of organisms which behaves in some respect like a single organism.

Essentially, a superorganism has characteristics and behaviours that the individuals within the colony – due to caste or physiological specialisation – do not exhibit.

The superorganism operates as a unified entity, collectively working together to maintain and reproduce the colony.

Division of labour and temporal polyethism

Drones and queens have relatively straightforward roles in the colony. Drones, like teenage boys, lounge around eating and thinking about sex. The queens are egg-laying machines.

An egg laying machine

An egg laying machine

Although there’s undoubtedly work involved in laying your bodyweight in eggs at the height of the season, the real work in the colony is – appropriately – done by the workers.

Worker bees exhibit temporal polyethism i.e. they display different patterns of behaviour depending upon their age. They have a maturational schedule in which they sequentially undertake age-correlated roles in the colony:

  • Young bees work in the hive in a series of roles starting with cell cleaning (days 1-2), nursing developing larvae (nurse bees; days 3-11) and wax production (days 12-17).
  • After two to three weeks the workers undergo significant physiological changes (weight loss, changes in immune function, reduced stress resistance) which prepare them for a productive life outside the hive. During this period the bees transition through a period when they act as guard bees.
  • Older bees (the ‘flying’ bees) perform a range of foraging activities including water carrying, pollen collection and nectar gathering.

And then they die in the field ūüôĀ

Behavioural plasticity

This behavioural maturation is controlled by a so-called negative feedback loop between vitellogenin (Vg 2) and juvenile hormone (JH).

Nurse bees have high Vg levels which are reduced at the transition to foraging. Conversely JH levels increase with the onset of foraging (I know this sounds counterintuitive). These changes are responsible for a range of physiological changes in the worker bee.

Behavioural maturation in worker bees

Behavioural maturation in worker bees

But it’s not as simple as that. High Vg levels can block JH synthesis, so delaying maturation and foraging. Similarly, JH may reciprocally inhibit Vg synthesis and induce early foraging.

Clearly that last couple of sentences indicates that worker maturation is not an invariant process. It doesn’t always occur after 2-3 weeks.

In fact, the maturation or ageing process in honey bees is a very interesting phenomenon.

Ageing exhibits seasonal variability and remarkable plasticity.

Nurse bees can survive for at least 130 days and overwintering bees may survive up to 280 days. Clearly ageing in bees is a remarkably variable process. Overwintering bees ‘mature’ into either nurse bees or foragers. Presumably this has evolved as an effective mechanism of allowing spring colony build up (by having sufficient bees for the different roles) once environmental conditions improve.

In addition, there is another striking feature of the maturation process of honey bees.

Under certain social environmental conditions maturation is reversible.

This reversible maturation can be demonstrated by removing the nurse bees from the hive. Under these conditions some of the younger foragers revert, both behaviourally and physiologically, to nursing tasks. JH levels drop and Vg levels increase.

Old foragers are unable to undergo this rejuvenation.

Reversible maturation in worker bees

Reversible maturation in worker bees

Which finally and in a¬†round the houses¬†way gets me to the subject I meant to cover in the first place this week …

Brood and the superorganism

The honey bee colony superorganism not only contains a queen, workers and drones. It also contains brood. In the following text I’ll use the term brood as a collective noun meaning all the eggs, unsealed larvae and sealed pupae in the colony (unless otherwise specified).

Is the brood a component of the superorganism?

It certainly is.

Laying workers ...

Laying workers …

Remember previous discussion of laying workers. These are workers that lay unfertilised eggs which develop into drones. Egg laying by workers is suppressed by pheromones produced from unsealed brood 3. Therefore brood does influence the behaviour of the colony 4.

If the complete colony – brood, workers, drones and a queen – is a superorganism, which components of the colony, individually or together, have the potential to form the superorganism?

And why should this matter?

Swarming and the superorganism

During swarming, either naturally during colony reproduction, or during manipulation by the beekeeper, the ‘superorganism’ is broken up.

During natural swarming the (old) mated queen leaves the colony with 60-75% of the workers to establish a new colony. By the time the swarm leaves, the original colony – which has all the eggs, larvae and brood (obviously) – is usually already well on the way to rearing a new queen. The (new) virgin queen emerges, gets mated, and the colony has successfully reproduced.

Many of the colony manipulation methods that are used to prevent the loss of natural swarms exploit the potential of the components in the colony to form a complete new colony.

Most ‘artificial swarms’ work by breaking the colony – the superorganism – into two parts:

  1. The queen and the ‘flying’ bees. Even young bees can fly, so the term ‘flying’ bees refers to the older bees from the colony that have matured sufficiently to leave the hive.
  2. The nurse bees and all the brood.
Swarms, splits and superorganisms

Swarms, splits and superorganisms

These two parts both have the potential to create a new colony.

The queen and the flying bees that form the swarm (or the queenright part of an artificial swarm) occupy a new site (or hive 5), draw comb in which the queen lays, the larvae are fed 6, pupate and emerge. At the same time, foragers collect the necessary nectar and pollen to maintain the new colony.

The swarmed colony (i.e. the queenless part of an artificial swarm) contains ample stores and the nurse bees. What they don’t have is a queen. But they do have eggs and young larvae. The nurse bees select and feed one or more of these young larvae with copious amounts of Royal Jelly. A few days later a virgin queen emerges, matures, mates and returns to the colony to start laying eggs.

Sealed queen cell ...

Sealed queen cell …

Therefore both natural and artificial swarms exploit the potential in both parts of the original colony to eventually reproduce the colony.

No potential

Not all components of the colony have the potential to give rise to a new colony or superorganism. A solitary queen doesn’t even have the ability to feed herself properly, let alone double up for egg laying and nursing larvae duties.

This comes as a surprise to some people.¬†If you frequent any of the online discussion forums you’ll sometime see questions posted like this:

What sort of hive do I need to buy to put a queen bee in to make honey?

Followed by some polite, or not so polite, responses saying that there’s a little bit more to beekeeping than that 7.

The ‘flying’ bees alone, in the absence of a queen, also have no potential. They can lay eggs (as laying workers, see above), but since the eggs are unfertilised the colony will be doomed. It’s not unusual for a queen from an artificial swarm (or from a cast) to fail to return from a mating flight, so condemning the workers in the hive to oblivion.

Swarms and behavioural plasticity

The classic artificial swarm involves moving the nurse bees and the brood to a new site, leaving the queen and the flying bees in the original location.

You do this so that the flying bees that have orientated to the position of the original hive – whether out in the field actively foraging or in the moved hive – eventually return and so become separated from the nurse bees and the brood.

In doing this you remove the urge to swarm and you weaken the queenless hive.

The majority of those flying bees are foragers.

And this is where behavioural plasticity is essential. remember that the artificial swarm predominantly contains foragers, not the nurse bees needed to feed developing larvae.

Some of these foragers undergo rejuvenation to produce wax or to become nurse bees. These build new comb and, in a few days, feed larvae that have hatched from the eggs laid by the queen.

This behavioural plasticity contributes to the potential of the artificial swarm to produce a new colony or superorganism.

A small swarm ...

A small swarm …

Do the same processes happen in natural swarms?

That requires a discussion of the worker composition of swarms which is not straightforward and will have to wait for another day ūüėČ


 

Unknown knowns

If there’s one thing that can be almost guaranteed about the beekeeping season ahead it’s that it will be unpredictably predictable. I can be pretty sure what is going to happen, but not precisely¬†when it’s going to happen.

These are the unknown knowns.

The one thing I¬†can be sure about is that once things get started it will go faster than I’d like … both in terms of things needing attention now (or yesterday ūüôĀ ) and in the overall duration of the season.

So, if you know what is coming – spring build up, early nectar flow, swarming, queen rearing, splits, summer nectar flow, robbing, uniting, wasps, Varroa control and feeding colonies up for winter – you can be prepared.

As Benjamin Franklin said …

By failing to prepare, you are preparing to fail

Preparation involves planning for the range of events that the season will (or could) produce.

It also involves ensuring you have additional equipment to¬†cope with the events you’ve planned for.

Ideally, you’ll also have sufficient for the events you failed to include in your plans but that happened anyway ūüėČ

Finally, it involves purchasing the food and treatments you need to manage the health and winter feeding of the colony 1 .

So what do you need to plan for?

Death and taxes 2

The two utterly dependable events in the beekeeping season are – and this is likely to be a big disappointment for new 3 beekeepers –¬†Varroa control and feeding.

Not an outrageous early spring honey crop, not ten weeks of uninterrupted balmy days for queen rearing, not even lots of swarms in your bait hives (freebees) … and certainly not supers-full of fabulous lime or heather honey.

Sorry ūüėČ

So … plan now how you are going to feed the colony and how you are going to monitor and manage mites during the season.

Feeding usually involves a choice between purchased syrup, homemade syrup or fondant. I almost exclusively use fondant and so always have fondant in stock. I also keep a few kilograms of sugar to make syrup if needed.

Buy it in advance because you might need it in advance. If it rains for a month in May there’s a real chance that colonies will starve and you’ll need to feed them.

Early June 2017 ...

Early June 2017 …

I’ve discussed mites a lot on this site. Plan in advance how you will treat after the summer honey comes off and again in midwinter. Buy an appropriate 4 treatment in advance 5. That way, should your regular mite-monitoring indicate that levels are alarmingly high, you can intervene immediately.

Having planned for the nailed-on certainties you can now turn your attention to the more enjoyable events in the beekeeping year … honey production and reproduction.

Honey production

Preparing for the season primarily means ensuring you have sufficient equipment, spares and space for whatever the year produces.

In a good season – long sunny days and seemingly endless nectar flows – this means having more than enough supers, each with a full complement of frames.

How many is more than enough?

More supers

More supers

Here on the east coast of Scotland I’ve not needed more than three and a bit per hive¬†i.e. a few hives might need four in an exceptional summer (like 2018). When I lived in the Midlands it was more.

Running out of supers in the middle of the nectar-flow-to-end-all-nectar-flows is a frustrating experience. Boxes get overcrowded, the bees pack the brood box with nectar, the queen runs out of laying space and the honey takes longer to ripen 6.

Without sufficient supers 7 you’ll have to beg, borrow or steal some mid-season.

Which is necessary because … it’s¬†exactly the time¬†the equipment suppliers have run out of the supers, frames and foundation you desperately need.

And so will all of your beekeeping friends …

Ready to extract

Ready to extract …

Not that you’ve necessarily got the time to assemble the things anyway ūüėČ

Don’t forget the brood frames

You’ll need more brood frames every season. A good rule of thumb is to replace a third of these every year.

There are a variety of ways of achieving this. They can be rotated out (moving the oldest, blackest frames to the edge of the box) during regular inspections, or you can remove frames following splits/uniting or through Bailey comb changes.

Irrespective of how it’s achieved, you¬†will need more brood frames and – if you use foundation – you’ll need more of that as well.

Foundationless frames

Foundationless frames …

And the suppliers will sell out of these as well ūüôĀ

But that’s not all …

You will also need sufficient additional brood frames for use during swarm prevention and control and – if that didn’t work – subsequent rescue of the swarm from the hedge.

Swarmtastic

In a typical year the colony will reproduce. Reproduction involves swarming. If the colony swarms you may lose the bees that would have produced your honey.

You can make bees or you can make honey, but it takes real skill and a good year to make both.

And to make both you’ll need spare equipment.

Pagdens' artificial swarm ...

Pagdens’ artificial swarm …

Knowing that the colony is likely to swarm in late spring, you need to plan in advance how you will manage the hive to control or prevent swarming. This generally means providing them with ample space (a second brood box … so yet more brood frames) and, if that doesn’t work 8, manipulating the colony so that it doesn’t swarm.

Which means an additional complete hive (floor, brood box, yet more brood frames, crownboard, roof) if you plan to use¬†Pagdens’ artificial swarm.

Alternatively, with slightly less equipment, you can conduct a vertical split which is essentially a vertically orientated artificial swarm.

Or you can use a nucleus (nuc) box to house the old queen … a very straightforward method I’ll discuss in more detail later this season.

Bait hives and skeps

I don’t like losing swarms. I’ve previously discussed the responsibilities of beekeepers, which includes not subjecting the general public to swarms that might harm or frighten them, or establish a colony in their roof space.

But I do like both attracting swarms and re-hiving swarms of mine that ‘escaped’ (temporarily ūüėČ ). I always set out bait hives near my apiaries. If properly set up these efficiently attract swarms (your own or from other beekeepers) and save you the trouble of teetering at the top of a ladder to recover the swarm from an apple tree.

But if you end up doing the latter you’ll need a skep 9 or a nice, light, large poly nuc box to carefully drop the swarm into.

Paynes nuc box ...

Paynes nuc box …

Don’t forget the additional brood frames you will need in your bait hive or in the hive you eventually place the colony in the skep into ūüėČ

Planned reproduction

You’re probably getting the idea by now … beekeeping involves a bit more than one hive tucked away in the corner of the garden.

Not least because you really need a minimum of two colonies.

A quick peek inside the shed of any beekeeper with more than 3 years experience will give you an idea of what might be needed. Probably together with a lot of stuff that isn’t needed ūüėČ

Storage shed

Storage shed

By planned reproduction I mean ‘making increase’¬†i.e. deliberately increasing your colony numbers, or rearing queens for improving your own stocks (or those of others).

This can be as simple as a vertical split or as complicated as cell raising colonies, grafting and mini mating nucs.

By the time most beekeepers get involved in this aspect of the hobby 10 they will have a good idea of the additional specialised equipment needed. This need not be complicated and it certainly is not expensive.

I’ve covered some aspects of queen rearing previously and will write more about it this season.

3 day old QCs ...

3 day old QCs …

Of course, once you start increasing your colony numbers you will need additional brood boxes, supers, nuc boxes, floors, roofs, stands, crownboards, queen excluders and – of course – frames.

And a bigger shed ūüėČ


Colophon

The title of this post is an inelegant butchering of part of a famous statement from Donald Rumsfeld, erstwhile US Secretary of Defense. While discussing evidence for Iraqi provision of weapons of mass destruction Rumsfeld made the following convoluted pronouncement:

Reports that say that something hasn’t happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns‚ÄĒthe ones we don’t know we don’t know. And if one looks throughout the history of our country and other free countries, it is the latter category that tend to be the difficult ones.

The unknown known

The unknown known

If you can be bothered to read through that lot you’ll realise the one thing Rumsfeld¬†didn’t mention are the unknown knowns.

However, as shown in the image, this was the title of the 2013 Errol Morris documentary on Rumsfeld’s political career. In this, Rumsfeld defined the¬†“unknown knowns” [as] “things that you know, that you don’t know you know.”

Perhaps unsurprisingly Condoleezza Rice, Secretary of State, claimed that Rumsfeld¬†doesn’t know what he’s talking about.” ... though she wasn’t referring to the unknown knowns.

 

Spring starvation

A very brief post this week to highlight the dangers of unseasonably warm weather early in the season. February 2019 has entered the record books as the first ‘winter’ month in which the temperature exceeded 20¬įC (on at least the 25th and 26th¬†in the UK). It’s also been a record with the daily temperature (highs … we’ve had some hard frosts as well) exceeding the historic average daily temperature on almost every day of the month.

Fife temperatures, February 2019

Fife temperatures, February 2019

Even here in Fife on the East coast of Scotland, the weather has been very warm and sometimes even sunny. The graph above shows the daily maximum temperature compared to the monthly average (dashed line).

The contrast with this time last year is very striking. The big winter storm called Anticyclone Hartmut (aka the Beast from the East) arrived in the last week of February.

The Beast from the East ...

The Beast from the East …

We had six foot deep snow drifts blocking the road to the village and there wasn’t a bee to be seen.

Crocus and snowdrop

Fast forward exactly 12 months and the bees are piling in the pollen and flying well for an extended period. Around here this early pollen probably comes from crocus, snowdrop, hazel and alder, perhaps with a bit of gorse as well which flowers throughout the season.

Brood rearing will have started in earnest. The large amounts of pollen being collected is a pretty good indicator that all is well in the hive, that the queen is starting to ramp up her egg laying rate and the numbers of hungry larvae are increasing.

There’s no need to open the hive to check for brood. Indeed, hive inspections (here at least) are probably at least 6 weeks away.

However, don’t ignore the colonies. The increase in brood rearing is a time when stores levels can quickly get critically low. There’s not a huge range of nectar sources about at the moment and the combination of a warm spell, increasing amounts of brood and a subsequent deterioration in the weather can rapidly result in colonies starving.

Hefting or a sneak peak

If you’ve been regularly hefting the hive to check its weight you should have a reasonable ‘feel’ for what it should be, and whether it’s significantly lighter. More accurately, but also more trouble, you can use luggage scales to record the week-by-week reduction over the winter.

It’s possible to determine whether there are sufficient – or at least some – stores by looking through a perspex crownboard at the tops of the frames.

Emptied bag of fondant

Emptied bag of fondant

Many of my hives went into the winter with the remnants of the autumn-fed fondant still present on the top bars. With a perspex crownboard it’s a trivial task to check if these stores have been used and – if they have – to heft the hive to see if they need more.

Fondant topups

Several hives have already had a fondant topup of about a kilogram placed directly onto the top of the frames. Alternatively, the hives with the Gruyere-like Abelo crownboards 1 get a fondant block slapped directly over the hole above the most concentrated seams of bees.

Fondant absorbs moisture from the atmosphere so you need to protect the faces of the fondant block not accessed by the bees. There are all sorts of ways to do this. A strong plastic bag with a slot or flap cut in the bottom is more than adequate.

Better still is to dole out the fondant into plastic food containers you’ve diligently saved all year. These are reusable, come in a variety of sizes and – ideally – are transparent. You can then easily see when and if the bees need a further topup.

Time for another?

Time for another?

I usually slice up a block of fondant and fill these food containers in midwinter, wrap them in clingfilm and carry them around in the back of the car for my occasional apiary visits. If a hive needs more stores I remove the clingfilm and simply invert the container over the bees.

Do remove the clingfilm! Bees tend to chew it up and drag it down into the brood nest, often embedding it into brace comb. It can be a bit disruptive during cool weather early-season inspections to remove it … hence the suggestion to use a strong plastic bag earlier.

Continued vigilance

Most of my hives will have had at least a kilogram of fondant by the end of February this year. One or two are likely to have had significantly more. I’ll keep a note of these in my records as – all other things being equal – I’d prefer to have frugal bees that don’t need fussing with over the winter.

As the days get longer and the season continues to warm the queen will further increase her laying rate. Until there are both dependable foraging days and good levels of forage there remains the chance of starvation.

Colonies are much more likely to starve in early spring than in the middle of a hard winter. If the latter happens it’s either due to poor winter preparation or possibly disease. However, if they starve in early spring it is probably due to unseasonably warm weather, a lack of available forage, increasing levels of brood and a lack of vigilance by the beekeeper.

Don’t delay!

If a colony is worryingly light don’t wait for a warm sunny day to feed them. Adding a block of fondant as described above takes seconds.

Everynuc fondant topup

Everynuc fondant topup

If a colony needs stores add it as soon as possible.

If it’s cold the bees will be reasonably lethargic and you may not even need to smoke them. I’ve only fired up the smoker once … to topup a colony of psychotic monsters ‘on loan’ from a research collaborator who shall remain nameless.

I managed to add the fondant without using the smoker but they then chased me across the field to thank me ūüôĀ


 

Hanging around

I’ve recently discussed the misnamed ‘phoretic’ phase in the life cycle of¬†Varroa destructor. Here we’ll briefly explore some features of this important, but non-reproductive, phase. It’s important because, as I’ll show, it influences subsequent mite reproduction.

I won’t rehash the life cycle of¬†Varroa¬†in detail as I’ve covered it previously.¬†Varroa is an ectoparasite of honey bees. It reproduces in capped cells, feeding on the developing pupa. A mated female mite enters the cell a few hours before capping and she and her incestuously mated daughters are released when the bee emerges.

The longer pupal development takes, the more progeny mites are produced, so Varroa has evolved to preferentially infest drone brood.

A smorgasbord of viruses

As an ectoparasite of honey bees, Varroa is responsible for the transmission of a smorgasbord of pathogenic viruses to the developing pupa. Subsequent virus replication, particularly by the aptly-named deformed wing virus, can result in developmental deformities.

Worker bee with DWV symptoms

Worker bee with DWV symptoms

Emerging workers with deformities are rapidly ejected from the hive. Other infested workers, with high viral levels, have reduced longevity. This is probably what accounts for the majority of overwintering colony losses. It may also explain so-called ‘isolation starvation‘.

The ‘phoretic’ phase

Mites outside capped cells are termed ‘phoretic’ mites. Recent studies have indicated that these mites are feeding on the workers to which they are attached. The same studies have shaken the long-held assumption that¬†Varroa feeds on haemolymph 1 by rather neatly demonstrating that it is the¬†fat body tissue of the bee that is the¬†plat du jour.

The duration of the ‘phoretic’ phase is dependent upon the state of the colony. Since it is defined as the phase in which mites are¬†not associated with developing pupae, in a broodless colony¬†all the mites are ‘phoretic’. Under these circumstances mites remain ‘phoretic’ until either brood is produced, or they fall (or are groomed) off and drop through the open mesh floor.

The duration of the ‘phoretic’ phase

In colonies with ample brood the ‘phoretic’ phase is, on average, 6 days in length. The range often quoted is 4 – 11 days. The absolute figure must depend upon a number of factors. These include the chance of a mite encountering a late-stage larva. This is presumably influenced by the amount of suitable-aged brood in the colony and – because there is a division of labour in the hive – the type of bee upon which the mite is riding around the colony on.

For the purpose of this post we’ll consider bees of three ages – newly emerged, nurse bees and foragers. Newly emerged bees (days 1-2 post emergence) clean cells and nurse bees (days 3-11) feed developing larvae. Older bees are involved in wax production (days 12-17) and foraging (>18 days until death).

Logic would dictate that mites would ‘choose’ 2 to associate with bees that bring them into contact with developing larvae of the right age to infest.

Do they?

Hanging around with nurses

Xie et al., (2016)3 assembled artificial colonies containing equal numbers of new bees, nurse bees and foragers, all suitably marked so their age was known. These colonies were provided with a queen, open brood and stores. At the start of the experiment the colonies had 1500 bees and low Varroa levels.

The scientists then introduced 200 ‘phoretic’ mites from another colony 4 and left the colonies for 48 hours. They then age-sorted the bees and harvested all the ‘phoretic’ mites by washing them off in alcohol.

'Phoretic' mites prefer nurse bees

‘Phoretic’ mites prefer nurse bees

On average, ~16% of the nurse bees had ‘phoretic’ mites attached. In contrast, only ~10% of the foragers and ~5% of the new bees had mites. These studies involved seven individual experiments, in two countries and two separate years, using a different source colony for the mites. The statistics are significant.

So mites prefer nurse bees.

Is this ‘simply’ 5¬†because the nurse bees are more likely to bring the mite into close proximity with a suitably-aged larvae?

Or does associating with, and presumably feeding on, nurse bees have other benefits for the mite?

Mite fecundity and fitness

Fecundity is the reproductive productiveness 6 of an organism.

We’ve obliquely tackled this subject recently. Using an in vitro¬†artificial ‘feed packet’ system, Ramsey and colleagues demonstrated that mites fed on the fat body of bees laid more eggs i.e. they had higher fecundity.

Xie¬†et al., also tested fecundity of ‘phoretic’ mites from newly emerged bees, nurse bees and foragers. They did this by manually harvesting mites after a 3 day ‘phoretic’ phase, adding them to a pre-pupa and then counting the number of progeny female mites 9 days later.

Mite fecundity and fitness

Mite fecundity and fitness

‘Phoretic’ mites from nurse bees exhibited higher fecundity (more female offspring), higher fitness (more mature female offspring) and lower infertility (female mites that did not generate offspring).

So evolution has elegantly resulted in ‘phoretic’ mites associating with the right type of bee to bring them close to developing larvae (upon which they reproduce)¬†and¬†made them better able to reproduce once they get there.

Why do Varroa mites prefer nurse bees?

This is the title of the Xie et al., paper.

Xie et al.,¬†sort of answer the question they posed in the title. What they don’t do is explain¬†why ‘phoretic’ mites on nurse bees are more fecund. However, the recent Ramsey paper suggests that this may be because nurse bees have a larger fat body and higher levels of vitellogenin.

If they’re better fed perhaps they produce more viable offspring? 7.

Another known unknown (semiochemicals)

How do mites detect the differences between new, nurse and older bees?

Perhaps they ‘smell’ different?

Mites preferentially infest drone brood because it produces a range of methyl and ethyl esters of straight-chain fatty acids, in particular methyl palmitate.

Similarly, the preference for nurse bees might be explained by their production of another¬†semiochemicals 8. If we could identify this semiochemical it might be possible to create a ‘sponge’ soaked in it that attracted all the mites in the colony.

A bit simplistic, but you get the idea.

In reality, it’s likely that nurse bees are identified by the relative strengths of a range of semiochemicals produced by bees of different ages.

In reality it’s also likely that dropping a ‘sponge’ soaked in¬†eau de nurse bee into the colony could unbalance all sorts of other events in the hive … ūüôĀ

I told you it wasn’t simple.


Rattus norvegicus

Rattus norvegicus

Hanging Around is the fifth track on Rattus norvegicus, the 1977 debut album of one of the finest rock/punk bands of all time, The Stranglers. The album also includes the incomparable Peaches and (Get a) Grip (On yourself), both of which were released as singles.

No more heroes from the same year, but a different album, is also a classic by the same band.

You had to be there … I was ūüėČ

 

 

Winter chores

After two weeks of mites, their diets and pedantry we’ll take a break this week for some practical beekeeping.

Or at least as close as you can get to practical beekeeping when it’s been as cold as -8¬įC.

Midwinter is a time to prepare for the season ahead, to stock up on new equipment during the winter sales, build more frames, plan the strategy for swarm control and think about stock improvement.

And – if you’re anything like as disorganised as me – it’s also the time to tidy up after the season just finished.

Which is what we’ll deal with today.

Tidy the shed

The original research apiary and bee shed is now under an access road for a new school. Fortunately, we managed to rescue the shed which has now been re-assembled in the new apiary.

In the longer term these sheds could together accommodate at least a dozen full colonies. However, in the shorter term it has allowed me to rationalise the storage, giving much more space to work with the colonies in the larger shed.

Supers and brood in the storage shed have all been tidied (see below) and are in labelled stacks ready to use. The other side of the store contains stacks of floors, split boards, clearers and roofs.

It’ll get messier as the season progresses, but it’s a good start.

I also spent a couple of weekends making some minor improvements to the bee shed following the experience last season.

The lighting has been increased and repositioned so it is ‘over the shoulder’ when doing inspections. On a dull winter day it is dazzlingly bright 1 but I fear it will still not be enough. I’m looking at creating some reflectors to direct the light better.

I’ve also used a few tubes of exterior sealant to block up all the holes and cracks around the edge of the shed roof. Last season was a bad one for wasps and we were plagued with the little stripy blighters.

Tidy the frames

Two of the most valuable resources a beekeeper has are drawn super frames and capped stores in brood frames.

Look after them!

I often end up uniting colonies late in the season, but then overwinter the bees in a single brood box. This means I can end up with spare frames of sealed stores. These should be protected from wax moth and mice (or anything else) as they are really useful the following year for boosting colonies that are light on stores or making up nucs.

Drawn supers can be used time and time again, year after year. They also need to be protected but – if your extraction is as chaotic as mine – they also usually need to be tidied up so they are ready for the following season.

I load my extractor to balance it properly, rather than just super by super. Inevitably this means the extracted frames are all mixed up. Since frames are also often drawn out unevenly this leaves me with a 250 piece jigsaw with billions of possible permutations, but only a few correct solutions.

Little and large - untidy frames and a breadknife

Little and large – untidy frames and a breadknife

And that’s ignoring all the frames with brace comb that accumulate during a good flow.

So, in midwinter I tidy up all the cleared super frames, levelling off the worst of the waviness with a sharp breadknife, removing the brace comb, scraping down the top bar and arranging them – 9 to 11 at a time 2 – in supers stored neatly in covered stacks.

And, if you’ve got a lot, label them so you know what’s where.

An hour or two of work on a dingy midwinter day can help avoid those irritating moments when – in the middle of a strong flow – you grab a super to find it contains just five ill-fitting frames, one of which has a broken lug.

The wax removed during this tidying up is usually lovely and white. Save it for making soaps, cosmetics or top-quality candles.

Wax extraction

Brood comb has a finite life. After about three years of repeated¬†brood rearing¬†cycles it should be replaced. Old comb contains relatively little wax but what’s there can be recovered using a solar or steam wax extractor. This also allows the cleaned frames to be re-used.

Processing a few dozen brood frames with a solar wax extractor during a Scottish winter is an exercise in futility. For years I’ve used a DIY steam wax extractor which worked pretty well but was starting to fall apart. I therefore recently took advantage of the winter sales and purchased a Thorne’s Easi-steam 3.

The Easi-steam works well and with a little further processing generates a few kilograms of wax for making firelighters or¬†trading in¬†… and a large stack of frames for re-use.

Remember to keep a few old dark brood frames aside for using in bait hives. 

Keep an eye on your bees

In between all these winter chores don’t forget to check on your bees.

There’s not a lot to do, but these checks are important.

Make sure the entrances are clear, that the mouse guards 4 are in place and that the roofs are secure.

Storm Eric brought us 50-60 mph winds and a couple of my¬†hives lost their roofs. These had survived a couple of previous storms, but the wind was from a different direction and lifted the roofs and the bricks stacked on top. I got to them the following day but we’ll have to wait until the season warms up to determine if there’s any harm done.

Fondant top up

Fondant top up

Finally, as the days lengthen and it gets marginally warmer colonies should have started rearing brood again. Make sure they have sufficient stores by regularly ‘hefting‘ the hive. If stores are low, top them up with a block or two of fondant. This should be placed directly over the cluster, either over a hole in the crownboard or on the top bars of the frames.


 

Pedantically not phoresy

The life cycle of the ectoparasitic mite Varroa destructor essentially consists of two stages. The first is within the capped cell, where reproduction takes place. The second occurs outside the capped cell when the recently-mated female progeny mites matures while riding around the colony attached to a nurse bee.

Almost without exception this second stage is termed the phoretic phase.

It isn’t.

Phoresy

Phoretic is an adjective of the word phoresy. Phoresy is derived from the French¬†phor√©sie¬†which, in turn, has its etymological origins in the Ancient Greek word¬†ŌÜőŅŌĀő∑ŌÉőĻŌā.

And¬†ŌÜőŅŌĀő∑ŌÉőĻŌā means¬†being carried.

Which partly explains why the correct definition of the word phoresy is:

An association between two organisms in which one is carried on the body of the other, without being a parasite [OED]

Phoresy has been in use for about a century, with the word phoretic first being recorded in the Annals of the Entomological Society of America (25:79) in 1932:

It is possible, as suggested by Banks (1915), that such young mites are phoretic, being carried about from place to place on the host’s surfaces.

And, no, they weren’t discussing¬†Varroa.

“Without being a parasite”

These are the critical words in the dictionary definition of phoresy which makes the use of the word phoretic incorrect when referring to mites on nurse bees.

Because mites on nurse bees are feeding Рor at least a significant proportion 1 of them are.

They are therefore being¬†parasitic and so shouldn’t be described as phoretic.

Om, nom, nom 2

Last week I discussed the recent Samual Ramsey paper presenting studies supporting the feasting of Varroa on the fat body of bees.

In the study they harvested bees from a heavily mite-infested hive and recorded the location on the bee to which the mite was attached.

The majority were attached to the left underside of the abdomen. More specifically, the mite was wedged underneath the third abdominal tergite 3.

What were they doing there? Hiding?

Yes … but let’s have a closer look.

Ramsey and colleagues removed some of the mites and used a scanning electron microscope to examine the attachment point on the bee. Underneath the tergite there is a soft membrane. The imprint of the body of the mite was clearly visible on the membrane.

Varroa feeding location on adult bee

Scanning EM of Varroa feeding location on adult bee

The footpads of the mite were left attached to the membrane (left image, white arrows), straddling an obvious wound where the mouthparts had pierced the membrane (black arrow). Between them, the inverted W shape is presumably the imprint of the lower carapace of the mite.

The close-up image on the right even shows grooves at the wound site consistent with the mouthparts of the mite.

These mites were feeding.

Extraoral digestion

Varroa belongs to the order (a level of classification) Mesostigmata. Most mesostigmatids feed using a process termed extraoral digestion.

Extraoral digestion has also been termed ‘solid-to-liquid’ feeding. It involves the¬†injection of potent hydrolytic enzymes which digest solid tissue, converting it to a semi-solid that can be easily ingested. It can reduce the time needed to feed and it increases the nutrient density of the consumed food.

If¬†Varroa fed on haemolymph it wouldn’t need to use extraoral digestion. Instead it would need all sorts of adaptations to a high volume, low nutrient diet. Varroa¬†doesn’t have these. It has a simple tube-like gut parts of which lack enzymatic activity … implying that digestion occurs elsewhere.

A picture is worth a thousand words

Do the images of feeding mites support the use of extraoral digestion?

EM cross-section of Varroa feeding

EM cross-section of Varroa feeding

The image above 4 shows the cross-section of a Varroa (V), wedged under the tergite (Te), feeding through a hole (arrow in the enlargement on the right) in the membrane (M). The fat body (FB) is immediately underneath the membrane. The scale bar is incorrectly labelled 5.

A close-up of the wound site shows further evidence for extraoral digestion.

Feeding wound at higher magnification

Feeding wound at higher magnification

Beneath the wound site (C, arrow) are remnants of fat body cells (white arrow) and bacteria (black arrow; of two types, shown in D). A closer look still at the remnants of the fat body (E and F) shows cell nuclear debris (blue arrows) and lipid droplets (red arrows).

These images are entirely consistent with extraoral digestion of fat body tissue by feeding Varroa. The presence of bacteria near the wound suggests that bacterial infection may result from Varroa feeding, possibly further contributing to disease in bees.

So, pedantically it’s not phoresy

So-called phoretic mites, unless they’re on the thorax or head of the bee, are not really phoretic. They are being carried about, but they are also likely¬†feeding. By definition that excludes them from being phoretic.

Instead they are ectoparasites of adult bees.

What are the chances that beekeepers will stop using the term phoretic?

Slim to none I’d predict 6.

And, of course, it doesn’t really matter what the correct term for them is.

What’s more important is that beekeepers remember that it’s at this stage that mites are susceptible to all miticides.

The June gap

But it’s also worth thinking about the potential impact of brood breaks.

During brood breaks all the mites in the colony must be ‘phoretic’.

Generally, the majority of the mites in a hive are in capped cells. Depending upon the stage of the season, the egg-laying rate of the queen and other factors, up to 90% of the mites are associated with developing pupae.

But as the laying rate dwindles more and more mites are released from cells and become ‘phoretic’, unable to find a suitable late-stage larva to infest.

And which bees do the mites associate with?

Nurse bees primarily, for reasons I’ll discuss in the future. But – spoiler alert – one of the reasons is likely to be that they have a larger fat body.

So, a mid-season brood break (e.g. the ‘June gap’) is likely to result in lots more nurse bees becoming both the carriers¬†and¬†the dinner of the mite population.

Some or many of the nurse bee cohort may perish, perhaps from damage to the fat body or from the viruses acquired from the mite. However, bees exhibit phenotypic plasticity, meaning that older bees can revert to being nurse bees when the queen starts laying again.

Late season brood breaks

In late summer mite levels are usually at their highest in the hive. A brood break occurring now will release a very large number of mites to parasitise the adult bee population.

Presumably these mites select the bees best able to support them 7.

And which bees are these? The nurse bees of course. But it’s also worth remembering that there are¬†key physiological similarities between nurse bees and winter bees. Both have low levels of juvenile hormone and high levels of vitellogenin (stored in the fat body).

So I’d bet that the ‘phoretic’ mites during a late season brood break would also preferentially associate with any early-produced winter bees.

Furthermore, once the queen starts laying again – perhaps in early/mid-autumn – the winter bees being produced would be subjected to the double-whammy of high levels of mite infestation and potential damage from ‘phoretic’ mites.

Practical considerations

More work is required to model or actually measure the impact of late season brood breaks, high levels of ‘phoretic’ mites, nurse bee numbers and winter bee development.

Compare two colonies of a similar size with a similar mite load, treated at the same time in early autumn with an appropriate miticide. If one of them experienced a late summer brood break (pre-treatment) and consequent high levels of ‘phoretic’ mites, does this reduce the chances of the colony surviving overwinter?

Who knows? Lots and lots of variables …

Fundamentally, it remains important to treat colonies early enough to protect the winter bee population. You’ve heard this from me before and you’ll hear it again.

However, it’s something to think about and I can see ways in which it might influence the strategy and timing of mite control used. I’ll return to this sometime in the future.


 

Chewin’ the fat

A little over a year ago reports started to circulate of a study showing that Varroa feed on the fat body of bees rather than on haemolymph.

Having worked in Glasgow through the early noughties the title of this post was a no-brainer and an outline draft was written in December 2017.¬†However, the peer-reviewed paper wasn’t published until last month, so it’s only now we’ve got the chance to judge the study and consider its implications.

Varroa feed on hameolymph, right?

Historically this was the accepted dogma. However, the experimental data supporting this conclusion – based upon labelling bees with radioactive isotopes and seeing what the mites acquired after feeding – was really not definitive. The experiments had been done in the 1970’s and the specificity of the labelling was a bit dubious. In addition, during the intervening period scientists had determined that, unlike vertebrate blood which is rich in cells and nutrients 1, haemolymph has little of either and is actually a pretty lousy food source.

In addition, and somewhat more circumstantially, Varroa control using chemotherapeutics fed to bees (and subsequently taken up by the mite during feeding) had been relatively disappointing.

Perhaps these chemicals weren’t getting to the right tissues of the bee?

Perhaps¬†Varroa don’t feed on haemolymph after all?

The Ramsey study

This new study reports three independent experiments that, together, indicate that¬†Varroa actually feed on the fat body of bees, rather than on haemolymph. The paper is so-called ‘open access’, so anyone can access it and therefore I’ll just provide a synopsis of the important bits.

The questions Samual Ramsey and colleagues attempted to answer were:

  1. Where on the bee do mites feed? Is it primarily or exclusively near the fat body?
  2. When Varroa feeds, what host tissues are ingested?
  3. What sort of diet is required to maintain Varroa and allow their reproduction in vitro2.

Location, location, location

The authors counted phoretic mites on 104 bees. Over 95% of them were located on the underside of the body, predominantly on the left side of the bee, under the tergite or sternite3 on the third metasomal segment (i.e. the second visible segment of the abdomen).

Mite location on nurse bees

Mite location on nurse bees

This position is consistent with feeding on the fat body tissues which are most abundant under the inner ventral surface of the metasoma.

Seeing red

Bees were fed with Nile red, a lipophilic fluorescent stain that preferentially accumulates in the fat body. They co-fed bees with uranine, a differently coloured fluorophore that accumulates in the haemolymph. They then allowed mites to feed on the fluorescently labelled bees and subsequently photographed the mites under fluorescent light.

The rationale here was straightforward. If the mites fed on the fat body they would stain red due to taking up the Nile red stain.

Mites visualised after feeding on fluorescently labelled bees

Mites visualised after feeding on fluorescently labelled bees

Which they did.

It was notable that the red stain predominantly accumulated in the rectum and gut of the mite (image O above). The authors conducted all sorts of controls to confirm that the stains actually stained what they were supposed to – you can view these in the paper.

Babies!

In the final part of the study the authors maintained mites in vitro (in an incubator), feeding them on a diet containing increasing amounts of fat body or haemolymph. These are tricky experiments and in some way the least satisfactory part of the study.

Two results suggest that fat body was beneficial or essential to the mites. Firstly, only mites that had 50% or more fat body in the diet survived for 7 days. Secondly, there was a dose response to the amount of fat body in the diet and fecundity. Mites on a 100% fat body diet exhibited 40% fecundity, the highest level observed in the study.

What can we conclude from the Ramsey study

Of the three experiments presented, the Nile red fat body stain uptake by mites is reasonably compelling.

The feeding position study is essentially correlative, but there could be other interpretations of the data. For example, that location on the bee might be the least accessible to a ‘grooming’ bee. Perhaps it’s a survival mechanism?

Survival and fecundity in¬†in vitro studies wasn’t great. However, in defence of the authors, fecundity of mites under natural conditions can be as low as 40% and is not higher than 80%. Not all mites have baby mites. Thankfully.

Only 20% of the mites survived one week under in vitro conditions, even on a 100% fat body diet. In contrast, mites fed haemolymph alone died within 48 hours. This poor level of survival was surprising and suggests other essential components of the diet were probably missing.

Other published studies have shown reasonable survival of Varroa for at least 3 days, with at least one report of mites surviving on flowers for up to 7 days.¬†I’m also aware that other laboratories can maintain mites¬†in vitro for longer than 7 days without using any honey bee-derived components in the diet.

Hang on … what is the fat body anyway?

The fat body is multi-functional. It has been compared to the vertebrate liver and adipose tissue. It acts as a major organ for nutrient storage, energy metabolism and detoxification of things like pesticides.

Vitellogenin made by and stored in the fat body reduces oxidative stress and is associated with extending the longevity of overwintering bees. The fat body also has critical roles in metamorphosis.

So, not only multi-functional, but also very important.

Significance of the results … is this a game changer?

This paper has been discussed online as a ‘game changer’. That’s probably a bit strong. Whilst the fluorescent stain uptake study is reasonably convincing it must be remembered that it was conducted on adult¬†bees.

Do mites on pupae also feast on the fat body?

This will have to be determined in the future. It’s a more difficult experiment of course.

The other two studies, and a number of additional small observations I’ve not discussed here, are certainly supportive, but not alone hugely convincing. The¬†in vitro study in particular will be interesting to compare with (currently unpublished) studies from other laboratories that do not use honey bee fat bodies in their mite feeding and maintenance diet.

Practical matters

Does it matter what part of the bee the mite feeds on?

Clearly it does for the mite, but what about the beekeeper?

I think this study is significant for the beekeeper for two reasons Рthe first will only be relevant if and when lipophilic miticides are developed, the second matters right now.

  1. Strategies are being developed to add highly specific miticides to the diet of bees which are then delivered to Varroa when the mite feeds. To date, these have been rather underwhelming in their performance. If Ramsey is right, modification of these miticides to make them lipophilic (like the Nile red fluorphore) will concentrate them in precisely the right place to ensure the mites get a lethal dose.
  2. A key product of the fat body is vitellogenin. The long-lived overwintering bees have high levels of vitellogenin. Mites feeding on, and depleting, the fat body would be expected to result in reduced vitellogenin levels in the bee 4. This would explain why high Varroa levels are associated with reduced longevity of winter bees and consequently increased overwintering colony losses.

The most important take home message

To prevent mites that feed on fat bodies from damaging vitellogenin production miticides have to be used early enough to protect the winter bees.

In the paper Ramsey makes the statement:

Simple reduction of mite loads late in the season to decrease the¬†overwinter parasite load may not be enough, as it still allows for the mites to damage tissue critical to the process of overwintering …

Instead …

A treatment schedule that includes treatment in late summer or early fall before mites can significantly damage fat body in developing winter bees would likely be more effective.

Which is¬†precisely the point I’ve made previously about treating early enough to protect winter bees.

What the Ramsey paper adds is the piece of the jigsaw possibly explaining why late summer treatment is so important.


Colophon

Chewin’ the Fat was a four-series Scottish comedy sketch show. It was broadcast from 1999 to 2002, with further Hogmanay specials until 2005. The show had a recurring cast of characters and sketches including¬†The Big Man,¬†The Banter Boys,¬†The Lighthouse Keepers,¬†Ballistic Bob and¬†Taysiders in Space.

Gonna no' dae that

Gonna no’ dae that – The Lighthouse Keepers

Chewin’ the Fat was filmed in and around Glasgow (where I worked at the time) and the characters parodied a range of local ‘types’ … pretentious Kelvinsiders,¬†Glaswegian gangsters,¬†narcissistic golfers, The man from Kilmacolm,¬†and shellsuit-wearing, chain-smoking, hard-drinking Glaswegian neds.

It was a bit rude and definitely an acquired taste. Without subtitles, some of the scenes would probably have been unintelligible south of the border.

Flawed floors

I’m a fan of Abelo poly National hives. They’re reasonably robust, well-insulating, correctly dimensioned 1 and pre-painted.

Abelo poly National hives ...

Abelo poly National hives …

I’ve been using these boxes for well over a year now and will review them shortly.

The review will be generally positive.

Abelo floor and entrance reducer

Abelo floor and entrance reducer

‘Generally’ as I really don’t like the floors. They are by far the weakest part of the hive design and have a number of, er, flaws making them poorly suited to my¬†beekeeping 2.

Rather than ‘taint’ a future review with negative comments on these flaws floors I’ll deal with them in this post and ignore them in the future 3.

The poly hive retails at about £125 for a hive with 2 supers. The Abelo floor alone costs £25.

What’s the floor for?

At its most basic the floor serves as something to stand a compatible brood box on.

But it does more than that.

It allows the bees to enter and exit and it often has features that¬†discourage the entry of other animals … like mice.

These days open mesh floors (OMF) are commonplace, allowing mites dislodged by grooming or miticides to fall out and away from the colony.

But, if you think about it in a bit more detail you realise that the floor does other things as well and therefore needs additional features:

  • it’s what’s handled if you’re bodily picking up the entire hive
  • it needs to have an entrance that is¬†easily and securely sealed for transporting hives
  • there is often an integrated landing board (for the beekeeper, rather than the bees)
  • for convenience it should have a¬†Varroa¬†tray to monitor mites that fall through the OMF
  • if used when vaporising oxalic acid-containing treatments¬†it needs to be reasonably ‘gas tight’

How does the Abelo poly National floor 4 meet these requirements?

First, the good points

The Abelo floors are sturdy, ready-painted and nicely cast (molded? moulded? formed?) from dense poly. The paint (all mine are green or yellow though they may do blue as well) is tightly bonded to the poly surface and doesn’t easily wear away. I think the white patches in the picture below were there from manufacture, not from use.

Abelo floor - drone'e eye view

Abelo floor – drone’e eye view

The floors have an reasonable area of mesh, securely held in place. The mesh area isn’t as great as some wooden floors, but is at least as good as my homemade kewl floors.

On either side of the floor, on the underside, there is a recessed handhold that really helps in lifting hives. These recesses are also convenient anchoring points for an elasticated bungy to hold the roof in place 5.

Worms-eye view of an Abelo floor

Worms-eye view of an Abelo floor

Probably the¬†best feature of these floors is that they’re fully compatible with other National hive components. I’ve mixed them with cedar or¬†Swienty poly brood boxes and they fit perfectly. The interface between the boxes is flat, the correct dimensions and pretty hard-wearing.

Entrance blocks

Abelo do tend to design rather ‘fiddly’¬†equipment and they’re very keen on ventilation.

They usually include these fiddly design features to allow increased ventilation – or at least the option for it.

The entrance block is in two parts (see photo above). A grey plastic reversible full-width block that drops into two vertical slots on either side of the landing board. One way up the entrance is reduced to ~8cm wide. Inverted and the entrance is sealed.

Well, sort of sealed ūüôĀ

There are four vertical ventilation holes that remain open on either side of the entrance block. Are these really needed? After all, the ventilation provided by the OMF far exceeds the little bit extra through the entrance block.

There’s a second green 6 plastic slider that can be added to the entrance block to provide an integral mouse guard. Or – more options – if inverted it can be used to further reduce the entrance to¬†one bee width¬†(or closed off altogether).

Ventilation and Varroa trays

Returning to the underside of the floor, the weakest part of the design is the Varroa tray.

Abelo floor Varroa tray - inserted

Abelo floor Varroa tray – inserted

The tray is unpainted polystyrene, square with a shallow lip. It slots into a recess in the underside of the floor, supported by two metal runners.

The area of the tray is approximately 75% of the floor area of a National brood box. With a full colony, some of the¬†Varroa¬†will fall outwith this area. This isn’t a major issue, but it could lead to underestimating the mite load in the colony.

The tray slides in and out easily, facilitated by a small protruding handle on the underside.

Abelo Varroa tray half withdrawn

Abelo Varroa tray half withdrawn

Unfortunately, there are some large gaps around the tray when it’s in place. If you sublimate oxalic acid a significant proportion of the vapour escapes around the edges of the Varroa tray.

The gaps around the tray are awkwardly shaped, so it’s not straightforward to plug them … other than with foam blocks perhaps. It’s also not possible to easily temporarily replace the tray with a Correx sheet. If you did it would need holding in place so potentially putting you too close to the hive and clouds of escaping oxalic acid vapour.

Resourceful beekeepers will work out solutions to these problems, but it would have been better if the defects weren’t designed into the floor in the first place.

Abelo floor, Varroa tray inverted

Abelo floor, Varroa tray inverted

And, before you ask, inverting the tray does not significantly seal off the gaps!

Poly Varroa trays

It is possible to make reasonably ‘vapour-tight’ poly¬†Varroa¬†trays. For example, the Thorne’s Everynuc has one that slots neatly in place. I’ve used these dozens of times and there is very little loss of vapour in my experience.

However, the Abelo floor (and the Everynuc Varroa tray) has the additional problem of being unpainted polystyrene. These very quickly become stained, with pollen, bee faeces and all of the usual rubbish that falls through the floor.

Abelo poly Varroa tray

Abelo poly Varroa tray

This staining makes counting Varroa much more difficult.

Again, a couple of coats of white gloss paint would seal the surface of the tray. However, this rather undermines the attraction of the ready-painted Abelo hives ūüôĀ

Alternatively, you could source some white Correx sheet to make an insert that would be easy to draw a grid on, count Varroa in and clean.

And, inevitably, easy to lose.

Floors done well

In summary, the problems with these Abelo floors are three-fold.

  1. Intentionally (the entrance block) and unintentionally (the Varroa tray) leave too much ventilation to conveniently be used when sublimating oxalic acid. The success of these depends upon retaining the vapour within the hive while it condenses on internal surfaces. Allowing it to leak out excessively simply makes the treatment less effective.
  2. Even if you don’t control¬†Varroa by oxalic acid vaporisation the¬†Varroa tray gets dirty quickly and is difficult to clean.
  3. Finally, it’s not possible to securely fix the entrance for transporting colonies, other than by using loads of gaffer tape. Even if you do, the large landing board on these floors makes strapping hives together awkward.

Most of my hives have homemade kewl floors. These probably cost about ¬£6 each to make and have none of the problems listed above. They offer additional benefits as the L-shaped entrance ‘tunnel’ prevents mice from entering the hive and reduces robbing by wasps.

Kewl floor and Correx landing board ...

Kewl floor and Correx landing board …

These DIY floors have a simple, easy to clean, Correx¬†Varroa tray that is much more ‘gas-tight’ than the Abelo design. An L-shaped wooden entrance block can be screwed in place for transport and the landing board is effectively integral to the floor, replaceable if damaged and does not project in a way that inhibits strapping hives together for transport.

Cedar floor and plywood tray ...

Cedar floor and plywood tray …

Kewl floors are unsuited to being used in the bee shed. For these hives we use slightly modified cedar floors made by Peter Little of Exmoor Bees and Beehives. These have a ply removable Varroa¬†monitoring tray that provides an excellent ‘gas-tight’ fit when sublimating. These floors are not inexpensive, but they are very well made.

Cedar floor with closed monitoring tray

Cedar floor with closed monitoring tray

Considering the quality of the rest of the Abelo National hives, these floors are a disappointment. I use them if I’ve run out of everything else and I kick myself when I discover – as I did a few weeks ago – that there are still some in use when the midwinter mite treatment is needed.

What do you call a stack of Abelo poly floors ...

What do you call a stack of Abelo poly floors …


Colophon

Hooke's microscope

Hooke’s microscope

Floor and flaw are homonyms, two words that sound the same but have different meanings.¬†Floor, meaning in this context the¬†‘base of any cavity’ probably dates back to Old English (Anglo Saxon) ~317AD.¬†Flaw in comparison is a young upstart, with the first recorded use being by¬†Robert Hooke in 1665. Hooke was, amongst other things a microbiologist, and he used the word flaw in his book, Micrographia, which is about his observations using a microscope (and telescopes). Hooke was the first to use the word ‘cell’ following microscopic examination of plant cells, which have walls, because the appearance reminded him of honeycomb.

Making mead

Every year, usually around Christmas, I make a batch of mead.

About a year later I bottle the mead and leave it to mature.

A year or more later I start drinking the mead … if it’s drinkable ūüėČ

If at first you don’t succeed …

The last couple of batches have been, if not spectacular, certainly very drinkable.

I expect them to improve further with age 1 and so have tucked them away for special occasions over the next 12-18 months … or longer 2.

Clearly this isn’t a quick process.

The early batches I made were pretty rough. Some were ditched at – or rather just before – bottling. However, I’ve now settled on a recipe (which means found … I claim no originality for it) that has worked well for at least three batches in a row.

Here it is.

Equipment

You’ll need a small amount of equipment, all of which is readily available from a brewing and winemaking store. I’ve used Hop and Grape, but there is lots of choice online. In England, Wilkinsons is also a good source of inexpensive brewing supplies.

  • Demijohn
  • Airlock
  • Rubber bung
  • Siphon (or simple piece of tubing)
  • Bottles
  • Good sized saucepan
  • Funnel
Ready for fermentation ...

Ready for fermentation …

Recipe

  • ~4lb of well-flavoured honey
  • 1 mug of cold tea
  • 1 teaspoon of citric acid
  • 1 teaspoon of yeast nutrients
  • 5g of good quality white wine yeast. I’ve had the most success with Lalvin D47.
  • 5 litres of still bottled water
Fermenting mead ...

Fermenting mead …

Preparation

  1. Prepare a mug of tea. Use boiling water and one tea bag, leave it to go cold and discard the tea bag. While it’s cooling prepare the yeast starter and sterilise everything.
  2. Add the yeast to a clean glass containing 100ml or so (quantity isn’t critical) of warm water at ~40¬įC. Stir to disperse the yeast and leave at room temperature to rehydrate.
  3. Add the honey to the saucepan and add about 2 pints of water. Warm over a gentle heat, stirring regularly to completely dissolve the honey. It doesn’t need to get hotter than ‘hand hot’. Once the honey is completely dissolved take the saucepan off the heat and allow to cool. While that’s happening prepare the demijohn.
  4. Thoroughly sterilise a demijohn. I use crushed Campden tablets as I’m ‘old skool’, there are probably newer and better ways to do this now. At the same time sterilise a rubber bung for the demijohn, a funnel and an airlock. Rinse the cleaned demijohn very well (tap water) and then add ~1 pint of bottled water.
  5. To this demijohn, using the funnel, add the honey mix, the cold tea, citric acid and the yeast nutrients. The temperature should now be around 30¬įC.
  6. Add the yeast starter. There will still be a considerable volume of the demijohn still empty (see the image above).
  7. Add the bung and, holding the bung tightly in place, shake the demijohn very vigorously.
  8. More, shake it some more. I don’t know if it really helps, but it feels like you’re doing something important and constructive ūüėČ
  9. Replace the bung with an airlock part-filled with bottled water.
  10. Place the demijohn somewhere out of the way to ferment. The temperature (at least for Lalvin D47) needs to be 15-20¬įC but not any higher or it can produce ‘off’ flavours. I wrap the demijohn in bubble wrap or old blankets to help keep the temperature stable 3.¬†It needs to be out of the way as you don’t want to move it and disturb things during fermentation.
  11. Bubbles will start in 6-18 hours. Initial fermentation can be very vigorous which is why lots of headspace was left at the beginning.
  12. After 48-72 hours fermentation will have steadied to about one bubble every few seconds. The sound is hypnotic ūüôā Once fermentation has steadied remove the airlock, top up with water to within 1″ of the neck of the demijohn and replace the airlock.
  13. Let fermentation continue. After 2-3 months fermentation will have almost or completely stopped. The demijohn will have a thick layer of yeast settled at the bottom of the bottle.
  14. Avoiding the yeast layer, siphon the mead into a new, sterilised demijohn. Don’t disturb the yeast layer … don’t worry about not getting every last drop out of the demijohn.
  15. Top up the new demijohn with ~1:3 w/w honey in warm water (i.e. 227g of honey dissolved in 750ml of water). Replace the airlock. Fermentation will start again.
  16. Once fermentation has completely finished – this takes a variable length of time – the mead should be crystal clear 4.
  17. Bottle the mead. Test it (of course!) and leave it somewhere dark and cool to mature for several months.

Additional notes and comments

Mead

Mead

This is a very basic guide to making mead. That’s because, despite making it for a few years, I’m still very much a beginner. There are hundreds of guides and at least as many recipes online. Read a few, but then just have a go … don’t get bogged down in the minutiae. If you can’t find Lalvin D47 use generic white wine yeast.

Use well-flavoured honey. Don’t use something bland or insipid. Many people use heather honey for mead though the best batches I’ve made have always been with a good midsummer mixed floral honey.

Using the recipe above the last few batches have cleared perfectly. One or two early attempts remained cloudy after racking it off and I remedied this by adding a bit of bentonite.

I’m a bit of a heathen and usually use 500ml “Grolsch-type” bottles, which are more properly termed swing-top bottles. If you’re intending to compete in your association annual honey show make sure you use the correct type of bottle … which¬†will not¬†be a swing top ūüėČ

Whatever bottle style you use make sure it is made of¬†clear¬†glass … you want the lovely golden amber colour of the mead to shine through.

I’ve no idea of the alcohol content as I’ve lost my hygrometer. Lalvin D47 can tolerate 14-16% alcohol which gives you an idea of the upper limit it will reach.

I know the stuff I’ve made is reasonably potent. Test your mead¬†in moderation. If you like the flavour I’d recommend¬†NOT guzzling the entire bottle in one sitting … particularly if you use standard volume (75cl) wine bottles 5.

Remember that you can’t sell alcohol without a licence.

Drink it with friends and sell them lots of honey when their defences are lowered ūüėČ

Have fun