Synopsis: How do eggs seem in locations the queen can’t attain?  Do these eggs produce employee or drone brood? If bees can transfer eggs, can they transfer them to queen cells?

Introduction

There was plenty of curiosity within the submit final week, and I’d prefer to thank readers who commented or contacted me instantly . Additional posts on the subject will seem earlier than queen rearing begins in earnest (or no less than right here in Scotland 😉 ).

Within the research I described final week, the queen was trapped on a specifically modified body behind a queen excluder.

Body sized queen ‘cage’.

Maybe extra accurately on this occasion it needs to be known as a queen includer because it prevented the queen transferring elsewhere within the hive.

Consequently, we may be sure that it was the queen that laid the eggs on the modified body.

Or can we?

Sure, we will .

Within the particular research described final week, the eggs hatched, the larvae developed, pupated and emerged as new queens. With one exception (Apis mellifera capensis – see under), employee bees can’t produce feminine progeny … and the ensuing queens I described final week had been positively feminine.

Nonetheless, in analogous circumstances, there are conditions during which eggs seem in places that the queen can’t attain.

How do the eggs get there?

Apis mellifera capensis

Let’s briefly cope with that exception first. The Cape honey bee (Apis mellifera capensis or, for comfort, Capensis) from South Africa.

Unusually, Capensis staff can lay unfertilised eggs which grow to be diploid feminine staff. Inside a colony, as much as 50% of the Capensis staff can lay eggs, and this has profound implications for honey bee biology. For instance, these eggs can be reared as new queens.

Free-living colony of Cape honey bees

The manufacturing of feminine diploid progeny from unfertilised employee eggs happens by a course of termed thelytokous parthenogenesis . There’s some suggestion this developed in Capensis to compensate for the excessive lack of queens on mating flights within the – famously windy – Western Cape area of South Africa.

With out these worker-laying staff, or extra accurately, diploid feminine laying staff, a colony that misplaced a virgin queen on a mating flight could be doomed.

Thelytokous parthenogenesis permits the rescue of an in any other case terminally-queenless colony.

While I’m positive some readers are wishing their bees had the identical ‘get out of jail free’ trick, and others are questioning why the trait isn’t current in all strains of Apis mellifera , I’m going to maneuver swiftly on as I threat disappearing down a rabbit gap of kin choice, social parasitism and gene GB45239 which – alone – accounts for the thelytokous phenotype.

Employee laying staff

If you happen to’ve saved bees for various years you’re most likely conversant in the irritating challenge of laying staff. In distinction to the Capensis worker-laying staff described above, regular laying staff lay unfertilised eggs which go on to grow to be haploid drones.

Frames displaying the attribute dispersed bullet brood of laying staff

All colonies comprise a low proportion of laying staff … they account for maybe 0.01% of the employee inhabitants. Visscher (1996) demonstrated that ~7% of the unfertilised (male) eggs in a colony had been laid by staff, not the queen. Nonetheless, evaluation of the grownup drone inhabitants (in a queenright colony) confirmed that just one in 1000 (0.1%) had been worker-derived.

These observations inform us two issues of relevance to the subject of whether or not bees transfer eggs:

• some eggs produced in a colony are laid by staff, not by the queen
• the overwhelming majority of worker-laid eggs are eliminated, or no less than don’t grow to be grownup drones

Research courting again to the late 80’s decided that staff can’t discriminate between larvae produced from eggs laid by queens and people from eggs laid by staff. This and different proof helps the existence of a policing mechanism – termed employee policing – during which eggs not laid by a queen are eliminated (and often devoured) by staff.

Employee policing explains the very small numbers of drones that originate from eggs laid by staff. I’ll talk about the mechanism by which staff differentiate between queen- and worker-laid eggs at another time, however it is going to be a shock to completely no-one that it includes queen pheromones.

Eggs in bizarre locations

Queens are creatures of behavior. They’re hardly ever discovered away from the brood nest. If you happen to discover a queen scuttling round on frames of shops on the periphery of the brood nest you may be fairly sure that you just’ve disturbed her by over-smoking the colony, or by being a bit hamfisted when eradicating or returning frames throughout an inspection.

Decelerate … bear in mind, extra haste much less pace.

Brood body

On good comb – by which I imply evenly drawn comb not already part-filled with nectar or pollen – queens have a tendency to put in concentric circles, producing rings of similarly-aged eggs, larvae and pupae. Conversely, they have a tendency to not lay particular person eggs on the excessive periphery of the brood nest, or in frames in any other case stuffed with shops.

They usually actually wrestle to put above the queen excluder.

So why is it commonplace to seek out eggs, larvae or pupae in tremendous frames?

Billy no-mates …

Virtually any time I extract greater than a half-dozen supers I anticipate finding one or two pupae there. If these are drone pupae – like the guy above – then the plain clarification is that it’s an egg from a laying employee that escaped employee policing.

Nonetheless, formally it might be a drone egg moved up by a employee from the brood nest into the tremendous.

Drone pupae are simple to elucidate.

In distinction, eggs, or employee pupae or occupied queen cells are both uninterpretable, or require a greater clarification. And, on events, you could find these within the supers as effectively.

Anecdotal experiences

There are experiences going again no less than to the start of the 19^th Century on eggs showing in places the place the queen has no entry. It’s value remembering that these experiences pre-date any understanding of employee policing, although laying staff had already been ‘noticed’ and described by Francis Huber .

Bee World 1936 … Do bees transfer eggs?

An article in Bee World from 1936 describes eggs showing in comb out of attain of a queen; for instance, in a hive during which the queen is tethered to a selected patch of comb (see additionally the experiments by Butler under), or in frames adjoining to a queen trapped in a cage. A number of of those experiences additionally describe bees carrying eggs.

Nonetheless, most of those largely anecdotal experiences contain employee brood, and many don’t exhibit the eventual emergence of the employees.

The writer of the Bee World article even means that some eggs on the periphery might be delayed in hatching as a result of their being in a cool a part of the comb. That’s an fascinating suggestion and never one thing I do know a lot about. I do know it’s doable to ship eggs by submit and presume the lowered temperatures there equally delays hatching.

Rather more fascinating than transferring eggs to rear employee brood is the chance that staff would possibly transfer eggs into not too long ago produced queen cells. Fortuitously, there are some scientific research finished on this space which assist handle the unique query of whether or not bees transfer eggs.

Scientific research of the origins of eggs in queen cells

In a queenright colony, the queen goes about her enterprise laying eggs in employee and drone comb.

Queen cups

If the colony is overcrowded and making swarm preparations, it’s presumed that the queen – encountering a queen cup in her travels – additionally lays an egg within the queen cup. A number of experiences describe this occurring in research utilizing remark hives.

Supersedure

If the queen is failing, by damage or outdated age, the colony might try to supersede her.

Colin Butler (1957) reasoned that each damage or outdated age might prohibit the mobility of the queen, and that both of those might induce supersedure.

Butler due to this fact investigated the manufacturing of queen cells in a colony during which the queen was tethered by a really skinny wire looped round her petiole (the slender waist that characterises member of the Hymenoptera).

This tethering prevented the queen from laying in cells, although she might nonetheless drop occasional eggs on the floor or rim of the drawn comb. Butler provisioned the hives containing the tethered queen with frames of younger larvae from which they had been anticipated to rear supersedure queens (if, that’s, restricted mobility did certainly induce supersedure).

Seventeen of 42 colonies containing tethered queens produced queen cells; 12 of those 17 had been traditional emergency cells, with the cell being drawn from employee comb. Nonetheless, the remaining 5 colonies had queen cups containing eggs.

Because the queen couldn’t attain the queen cups (as a result of her being tethered) the eggs should have been positioned within the cups by staff.

Had been they laid within the queen cups by laying staff, or had been they eggs laid or dropped by the queen and moved to the cups by staff?

Butler suggests the latter, stating that there was no proof of laying employee exercise within the hives (and ample open brood ought to suppress this exercise anyway).

Nonetheless, sadly we’ll by no means know. Not solely had been the experiments finished 70 years in the past this summer time, however Butler didn’t let the eggs hatch, develop and emerge. The tethered queens had been launched quickly after queen cells had been produced, and all colonies tore down the queen cells.

The emergency response

If the queen is killed or faraway from the colony, the ‘emergency response’ ends in staff rearing a number of substitute queens from eggs or very younger larvae.

Queen rearing below the emergency response is comparatively simple to review. It is usually the idea of nearly all of queen rearing strategies utilized by beekeepers.

There are two associated research by Mark Winston (like Butler and Huber, one other of the excellent honey bee researchers upon whose research plenty of our presently understanding of honey bee biology relies) which are related to the query “Do bees transfer eggs?”

These papers (Winston, 1979 and Punnett & Winston, 1983) deserve a full submit of their very own as they’re laden with fascinating observations of what occurs when the queen is faraway from a colony. That is related to sensible beekeeping … what do you assume occurs if you conduct a cut up, leaving one half all of a sudden queenless?

The 1979 paper was on Africanised bees, the later one on European honey bees. In each research, colonies had been de-queened and inspected each day for the situation, origin and timing of queen cell manufacturing. The age of eggs or larvae chosen for rearing of queens was decided by ‘counting again’ from the date/time at which any ensuing cells had been sealed.

Africanised honey bees

Queen cells had been produced 1-2 days after de-queening. These queen cells had been prolonged from employee brood comb, however 47% of them (29/62) had been unoccupied when first elongated. On subsequent inspection, these cells contained eggs or younger larvae, and these finally developed into queens and emerged.

There are two vital conclusions from this examine:

• nearly 50% of latest queen cells in these colonies had been populated with eggs or larvae moved there by staff within the queenless colonies
• these eggs/larvae had been not as a result of laying employee exercise as they developed into queens, not drones

European honey bees

The 1983 repeat targeted on European honey bees. On this occasion, all de-queened colonies produced new queen cells inside sooner or later of queen removing.

Nonetheless, in distinction to the examine described above, solely ~5% (5/118) of those queen cells had been empty when first elongated. Though a smaller share, the importance is identical:

• the eggs or larvae that had been subsequently current in these queen cells should have been moved there by staff within the hive
• they weren’t laid by laying staff as a result of a) all cells had been occupied by larvae inside 3 days so should have been laid by the unique queen, and b) they subsequently developed into viable queens and emerged

I’m unsure why there was a distinction in brood (i.e. eggs or younger larvae) motion between the Africanised and European strains of Apis mellifera. Nonetheless, I’m in good firm …

The explanations for these completely different motion charges will not be clear (Punnett & Winston (1983) )

… so let’s not fear about it.

However what in regards to the glue?

When the queen lays an egg, she attaches it to the bottom of the cell with a glue-like secretion.

Absolutely, if the egg is moved by a employee they won’t be able to reattach it accurately to the bottom of the following cell?

Nicely, if people can do it, I’m fairly sure that bees can.

And people can.

Steve Tarber (1961) described a modified set of forceps that might be used to elevate eggs and place them in contemporary comb. About 75% of repositioned eggs would subsequently hatch in both a hive or incubator.

The ‘trick’ to the design of the forceps is outwardly the presence of ‘flared lips’ which keep away from contact with the posterior glued finish of the egg.

I’ve completely little doubt {that a} employee bee might obtain an analogous or higher degree of dexterity.

So, do bees transfer eggs throughout the colony?

Sure.

As a scientist, I can’t consider clarification – apart from employee bees transferring eggs about within the hive – for the outcomes introduced above.

Ideally, I’d additionally wish to observe bees transferring eggs. I’m not conscious I’ve ever seen this, although I’ve seen them consuming eggs.

Maybe I ought to get my prescription checked for my studying glasses in preparation for the season forward?

Can bees transfer eggs between hives?

So, if employee bees can transfer eggs inside a hive, might they transfer eggs between colonies?

Might a terminally queenless colony be ‘rescued’ by stealing eggs from a neighbouring colony?

Far fetched?

Probably, but it surely has been prompt that this happens.

An egg is smaller than a full pollen basket. I don’t know the density of both pollen or eggs, however I believe the burden isn’t very completely different. An egg would possibly mess with the aerodynamics of flight – although bear in mind bees can fly with a radio antenna protruding from the thorax – so I believe staff might transport eggs between nests.

Do they?

I doubt it.

CHCs and kin choice

To gather the egg, they’d must run the gauntlet of the guard bees within the ‘donor’ nest, after which negotiate their manner into the centre of the brood nest to pick an egg. There are plenty of bees in the way in which, and the cuticular hydrocarbons (CHCs) on the ‘thief’ from the (presumably) queenless colony would make her ‘odor’ utterly completely different.

I’m positive she’d be repulsed, or worse, fairly rapidly.

Robbing bees often succeed after they overwhelm the defences of a weakened colony. That’s a really completely different scenario from a single employee making a daring ‘smash and seize’ raid on a powerful hive.

Moreover, I can’t see this behaviour evolving for 2 causes:

• a ‘stolen’ queen could be unrelated to the robbing employee; from kin choice concept there could be little or no selective stress for the trait
• for the same cause, if the trait did evolve it will be ‘misplaced’ as quickly because the stolen queen changed all of the bees within the hive.

As all the time, Occam’s razor applies … the best clarification is often the right one.

Somewhat than predicting the evolutionarily, kleptobiotically and doubtlessly aerodynamically unlikely theft of an egg from a neighbouring colony, my guess is {that a} queen cell showing in a terminally queenless hive would comprise a drone pupa from an egg laid by a laying employee.

Sensible beekeeping

Are there any implications for beekeeping?

In all probability none.

If it occurs between employee cells then who cares? It’s simply a kind of 1000’s of hidden occasions that go on undetected or unsuspected within the colony daily.

If it includes switch of a employee egg to a queen cup, and the ensuing queen goes on to go a colony which produces 60 kg of honey subsequent season, then – once more – who cares?

However what are the implications for the maternal impact I mentioned final week? If eggs may be moved into queen cups by staff then no less than some queens might consequence from eggs chosen by staff.

In that case, there can be no ‘maternal impact’ … except the employee bees know which eggs to switch.

And I wouldn’t rule that out .

Notes

I posed the next paraphrased query within the introduction:

Can we make sure that the caged queens used within the Wei et al., (2019) examine – see the submit final week for the reference – laid the eggs within the queen cups within the modified body below the queen includer?

Regardless of re-reading the paper a number of occasions, I can’t work out whether or not the different frames within the hive might have contained eggs throughout the 6 hour interval when the queen was caged.

In the event that they did, how can we be sure that the eggs that subsequently appeared within the plastic queen cups had not been transferred there by staff? Maybe not all of them, however no less than a few of them?

This is able to essentially change the interpretation of their outcomes, and would imply that it was the employees that would discriminate between lighter and heavier eggs.

Which, after all, they will 😉 .

References

Do Bees Transfer Eggs? (1936) Bee World 17: 74–74 https://doi.org/10.1080/0005772X.1936.11093524.

Butler, C.G. (1957) The method of queen supersedure in colonies of honeybees (Apis mellifera Linn.). Ins Soc 4: 211–223 https://doi.org/10.1007/BF02222154.

Punnett, E.N., and Winston, M.L. (1983) Occasions following queen removing in colonies of european-derived honey bee races (Apis mellifera). Ins Soc 30: 376–383 https://doi.org/10.1007/BF02223969.

Taber, S., III (1961) Forceps Design for Transferring Honey Bee Eggs. Journal of Financial Entomology 54: 247–250 https://doi.org/10.1093/jee/54.2.247.

Visscher, P.Ok. (1996) Reproductive battle in honey bees: a stalemate of employee egg-laying and policing. Behav Ecol Sociobiol 39: 237–244 https://doi.org/10.1007/s002650050286.

Winston, M.L. (1979) Occasions following queen removing in colonies of Africanized honeybees in South America. Ins Soc 26: 373–381 https://doi.org/10.1007/BF02223556.

Credit

Picture of Apis mellifera capensis by Discott, CC BY-SA 4.0, by way of Wikimedia Commons.