Synopsis: Latest analysis on the maternal impact in honey bees suggests queen rearing utilizing employee larvae could produce undersized and underperforming queens.

Introduction

Nearly all of books and articles I’ve learn on queen rearing emphasise that larger queens are higher queens. The rationale is easy. Larger queens are higher as a result of their bigger abdomens include extra ovarioles and bigger spermatheca. With out getting too anatomically technical, these are the reproductive organs for producing eggs and storing sperm. Massive queens ought to due to this fact have the ability to lay extra eggs for longer; larger fecundity, as scientists name it.

Extra eggs – all different issues being equal – imply bigger, stronger, colonies, which implies extra honey … or extra nucs, or propolis or pollination or no matter you retain bees for.

There’s good assist – each anecdotal and scientific – for the advantages of bigger queens, courting again many years .

Huge yellow queen

Due to this, directions on queen rearing often stress the significance of feeding your cell elevating colonies properly, even supplementing them with syrup and pollen if wanted. This advantages larval growth, so growing the scale of the ensuing queen.

Nevertheless, very current research counsel that the origin of the beginning materials – the larva – used for cell elevating has a basic affect on the completed queen.

These research display, for the primary time, a maternal impact in honey bees.

The outcomes indicate that the strategies used to rear virtually all queens (by commercials and amateurs) will end in undersized, poorer high quality, queens than may be achieved.

Lastly, I believe there are implications from these research that may encourage extra freshmen to begin queen rearing.

That is the primary of a 3 half sequence on queen rearing. Elements two and three will comply with in the end (although maybe not instantly).

At this time I’ll cowl the science. Sooner or later, I’ll talk about the sensible beekeeping … keep tuned.

‘Typical’ strategies used to rear queens

After all, beginning any description of a beekeeping methodology with the phrase typical means I’ll be swamped by a tsunami of feedback like “I’ve by no means achieved it that approach”.

Bear with me, this bit simply units the scene …

I outline ‘lively’ queen rearing as any methodology that doesn’t depend on the pure manufacturing of swarm cells.

In these ‘lively’ strategies, a colony is made receptive to producing new queens, for instance by eradicating the unique queen. Underneath the ‘emergency response’ this induces, the colony begins to rear new queens if they’ve – or are supplied with – appropriate beginning materials.

By desire, a colony rears new queens from 3 day outdated eggs, however they will additionally use very younger larvae.

Beekeepers exploit this response by introducing chosen younger larvae (from a ‘good’ colony), typically introduced vertically in wax or plastic cups.

These larvae are fed copious quantities of royal jelly, develop quickly and emerge as virgin queens.

I hope that’s a generic sufficient description that almost all readers each recognise and may settle for.

Earlier than shifting on, I wish to stress one crucial level … when queen rearing utilizing the emergency response, the larvae chosen to be reared as new queens are employee larvae.

Grafting …

For business or many beginner queen rearing approaches, these younger employee larvae are grafted from a donor colony.

Grafting includes the handbook switch of a younger larva from a employee cell to a vertically-orientated cell within the cell elevating colony. This vertical orientation triggers the copious feeding with royal jelly, and this wealthy food regimen induces the adjustments in methylation and gene expression that convert what would have developed right into a employee bee into a brand new queen.

A whole bunch of 1000’s of queens are produced like this yearly.

Maternal results

A maternal impact is the causal affect of the mom on the phenotype of the offspring.

The phenotype is the looks or efficiency of a person. The OED defines it as:

The sum complete of the observable traits of a person.

Clearly, there’s a genetic relationship between the queen and the egg she lays. Nevertheless, this isn’t a maternal impact.

The latter is extra particularly taken to imply a larger funding by the mom (queen within the case of honey bees) in sure younger which can be being reared.

For instance:

• in some geese and fish, the feminine makes a larger funding in egg manufacturing (i.e. laying bigger eggs) if the perceived high quality of the mate is greater
• the ant Pheidole pallidula produces bigger eggs through the a part of the season through which sexual generations are produced

In these well-documented examples, the mom produces higher ‘high quality’ eggs solely beneath sure circumstances. This will likely enhance the long-term possibilities for the survival of the progeny.

Till a couple of years in the past, there had been virtually no evaluation of the maternal impact in honey bees. Queen growth was thought of to be solely because of the environmental situations skilled by the larva. That is exploited after we rear queens from grafted employee larvae.

Nevertheless, between 2019 and 2023 three associated research had been printed demonstrating that queens lay bigger eggs destined to turn into queens, and that the ensuing new queens are bigger and extra productive.

I’m primarily going to deal with research by Wei et al., (2019) and Yu et al., (2023) as these include outcomes which can be simpler to explain and most accessible with out the necessity for a doctorate in molecular genetics.

A testable speculation

Like all good experiments, the preliminary query posed was comparatively simple:

Do queens produce bigger eggs when laying in queen cells?

Which, after all, instantly prompts the plain follow-up query …

Do bigger eggs generate bigger (or higher) queens?

To check this speculation, it was essential to induce a queen (or a number of, as there are lots of repeats on this examine) to put eggs in each employee and queen cells, to characterise the eggs laid, after which to rear them into new queens beneath standardised situations.

The distinction between queen cells and employee cells is primarily dimension . Employee cells are narrower than queen cells.

The authors used a modified system first described within the American Bee Journal (Pan et al., 2013). That is broadly just like the Nicot Cupkit system acquainted to many beekeepers.

Nicot Cupkit queen rearing system

A sheet of plastic basis was engineered to include detachable cell cups on quick spigots. The cups had been both small or massive diameter – representing employee or queen cells. The quick spigot aided dealing with the egg-containing cell cup with out touching the egg.

After the queen had laid within the cell cups they may very well be faraway from the encompassing comb and introduced, vertically, on a cell bar body in a colony set as much as rear queens.

Cell bar body with vertically oriented plastic Nicot queen cups

Employee and queen cell cups had been 4.9 mm or 9.7 mm in inside diameter respectively. The ABJ article solely describes one dimension. You’ll must learn it and the strategies part of Wei et al., (2019) for full particulars.

Bear in mind

As is common … there are many repeats within the examine. Totally different queens, completely different colonies and so on. Outcomes are both statistically vital, that means very unlikely they’re as a result of probability, or not statistically vital. The latter does not imply that they’re as a result of probability, however that they may be.

For brevity, I’m going to deal with the statistically vital outcomes and never offer you all of the gory particulars about numbers of repeats, commonplace deviation or the statistics. If the outcomes aren’t vital however are attention-grabbing, I’ll make that clear.

Pour your self a stiff drink (or two) and skim the paper(s) your self; they’re all Open Entry and freely out there.

You received’t remorse it .

Queens lay bigger eggs in queen cells

Eggs change in dimension throughout growth. Subsequently, the authors standardised each the period of egg laying and the timing of egg sizing. Queens had been caged on frames containing queen cell cups for six hours after which transferred for an extra 6 hours to a body containing employee cell cups. The load of eggs was decided as quickly because the queen was eliminated, i.e. they had been not more than 6 hours outdated.

Eggs laid in queen cells are heavier (from Wei et al., 2019)

Eggs laid in queen cell cups (QE = queen eggs) had been 13.26% heavier, 2.43% longer and 4.13% thicker than eggs laid in employee cell cups (WE = employee eggs).

For the rest of the examine, Wei et al., (2013) in contrast queens reared from these QE or WE. I’ll time period these QE- or WE-queens.

Nevertheless, for comparability, they moreover incubated a number of the WE within the authentic colony till they had been 2 day outdated larvae (designated 2L) earlier than transferring them to the queen rearing colony. These are older than could be used for queen rearing, and could be anticipated to provide substandard queens (I’ll name these 2L-queens) … bear that in thoughts as I talk about the outcomes.

Bigger eggs produce heavier queens

Queen and employee eggs (QE and WE) and 2L larvae had been reared in the identical queenless cell elevating colonies, the ensuing queen cells had been caged after capping and the queens that subsequently emerged had been collected and weighed.

Queens reared from eggs laid in queen cells are heavier (from Wei et al., 2019). Notice, darkish containers are 2L-queens

Within the 5 cell elevating colonies used (solely 3 proven above), QE-queens had been the heaviest, and had been considerably heavier than WE-queens in 3/5 colonies. The distinction in weight between the QE- and WE-queens was ~10%.

2L-queens had been typically the lightest general, although they weren’t all the time considerably lighter than WE-queens.

Heavier queens have extra ovarioles

Ovarioles are vital … we’ve identified because the early 70’s that queens with extra ovarioles are extra fecund.

QE-queens had 13% extra ovarioles than 2L-queens, a big distinction. Nevertheless, QE- and WE-queens didn’t have considerably completely different numbers of ovarioles within the first examine.

I’ve not bothered displaying one more graph for instance this end result.

In a current follow-up examine by the identical authors (Yu et al., 2023) they analysed the reproductive means of those queens. On this examine, they additionally re-quantified ovariole quantity and the load of the thorax of the queens.

Why thorax weight? Thorax weight is vital because it displays the scale and power of the flight muscular tissues in addition to being indicative of the general dimension of the queen. The queen could not fly a lot – a couple of orientation and mating flights, and when swarming – however when she does it is crucial that she flies strongly.

Ovariole quantity (A) and thorax weight (B) of queens (from Yu et al., 2023)

Like the load general (see above), the thorax weight of QE-queens was considerably larger than WE- or 2L-queens (which had been additionally considerably completely different). As well as, on this newer examine, the ovariole quantity in QE-queens was considerably larger than WE- or 2L-queens when analysed.

Why was there a distinction within the newer examine? I don’t know, and the authors don’t remark …

Reproductive high quality of reared queens

You possibly can measure reproductive high quality of queens in two basic methods; the variety of eggs laid and the colony progress potential, measured by way of capped employee cells.

QE-queens laid considerably extra eggs than 2L-queens, however the different comparisons (QE vs. WE or WE vs. 2L) weren’t considerably completely different. For curiosity, I dug into the numbers and regarded on the queen laying charges which had been ~250-450 in 6 hours, so ~55 per hour or ~1 per minute … on a regular basis. What a life!

At 12 days the authors measured capped employee cells the place the outcomes had been related in rating and significance to the egg laying outcomes i.e. QE >> 2L, however no vital distinction between the opposite two comparisons. Nevertheless, at this stage the rating was a bit extra apparent … QE > WE >2L, with common numbers of capped cells at 12 days being ~6,500, ~5,500 and ~4,000 respectively

The ultimate distinction they quantified within the reproductive capability of reared queens was somewhat odd (a minimum of, it appeared that technique to me). Eggs laid by QE-queens had been considerably longer than these laid by WE- or 2L-queens, however had been an analogous weight and thickness.

I’m unsure what this implies.

A fast abstract …

Though there’s a little bit of variation, the take dwelling message thus far is that queens reared from eggs laid in queen cells (QE-queens) had been:

• heavier, with a bigger thorax
• had extra ovarioles
• laid extra eggs, and
• produced extra brood

These are all options you’ll in all probability wish to see in your queens.

How do progeny queens or employees reared from QE-queens carry out? Are they higher than progeny from WE- and 2L-queens?

Arguably, that is much more vital than fecundity per se.

Dimension and productive capability of employee progeny

The dimension of employees that developed from eggs laid by the three queen sorts was decided. Employee progeny from QE-queens had been considerably heavier than from WE- or 2L-queens, and so they had longer and wider wings.

Productive capability is a time period that covers a variety of employee exercise; water, nectar or pollen assortment, honey saved, larvae fed, corpses eliminated, cells cleaned and so on.

Simply concerning the best of those to quantify is pollen assortment. You rear brood from QE-, WE- or 2L-queens, label a number of hundred newly-emerged employees after which – as soon as they’ve matured into foragers – you seize returning marked pollen-carrying bees and weigh the contents of their pollen baskets .

Employees from QE-queens collected extra pollen than employees from 2L-queens, although not considerably greater than employees from WE-queens.

Why are employees from QE-queens larger?

One risk is that they’re extra ‘engaging’ to nurse bees, so get extra consideration and are fed extra, or extra typically, or each.

While this may be measured (it’s worthwhile to use an statement hive, barcoded employees and a ‘shedload’ of picture evaluation) another technique is to switch sooner or later outdated larvae into queen cells after which quantify the quantity of royal jelly that accumulates within the cells over a 48 hour interval. Extra ‘engaging’ larvae will likely be fed bigger quantities of royal jelly.

Larvae from QE-queens gathered considerably extra royal jelly than larvae from WE- or 2L-queens.

And, by logical extension, if eggs laid by QE-queens acquired higher feeding you’ll count on queens reared from these well-fed larvae would turn into larger queens … and so they do.

Queen dimension

To keep away from confounding this a part of the evaluation with the – now identified – variations in queen dimension from eggs laid in queen cells, employee cells or from 2 day outdated larvae, the authors used commonplace queen rearing methods – grafting 2 day outdated employee larvae derived from QE-, WE- or 2L-queens – from commonplace employee cells into queen cups.

Queens reared from employee larvae laid by QE-queens had been considerably bigger – outlined by thorax size and width – than queens from equally aged larvae from both WE- or 2L-queens. Disappointingly, they didn’t quantify different helpful parameters corresponding to weight or ovariole numbers .

OK, so the place are we?

That’s loads to consider.

Like many experiments, the outcomes aren’t completely ‘minimize and dried’ … there are a couple of bizarre discrepancies, and one or two experiments ought to have been repeated to get extra statistically sturdy knowledge. The strategies and outcomes on royal jelly quantification are contradictory and really poorly described; I’ve achieved my finest to interpret what was achieved.

I’ve omitted solely dialogue of the differential gene expression within the authentic Wei et al., (2019) paper and the extra intensive evaluation of gene methylation reported within the associated He et al., (2021) examine. Suffice to say, when QE-queens had been in contrast with WE- or 2L-queens there have been vital variations in:

“… mTOR, MAPK, Wnt, Notch, Hedgehog, FoxO, and Hippo signalling pathways which can be concerned in regulating caste differentiation, replica and longevity.”

Which, the cognoscenti  will admire, is precisely what you’ll count on, and which explains most of the phenotypic variations within the ensuing queens.

And, even in case you’re not a member of the cognoscenti, I hope you’ll be able to benefit from the names of genetic management pathways like Hippo and Hedgehog.

What are the conclusions and implications of this examine?

Conclusions

The primary and most vital take dwelling message is that queens reared from eggs laid in queen cells are often larger and higher than these reared from employee cell-derived eggs. Moreover, they’re all the time larger and higher than from queens reared from two day outdated employee larvae.

We’ve lengthy identified that ‘outdated’ larvae are a poor beginning materials for top of the range queens, however the advantages – by way of fecundity and presumably different traits not (but) measured – of eggs laid in queen cells over these laid in employee cells is new.

This can be a maternal impact and – amazingly contemplating the variety of research on their replica – it’s the primary clear proof that it happens in honey bees. Apparently research from 50 years in the past steered that there was a relationship between egg and queen dimension, however the 2019 paper by Wei and colleagues confirms it.

This maternal impact is not restricted to progeny queens. Employees that develop from eggs laid in employee cells by QE-derived queens are additionally higher high quality, a minimum of based mostly upon the restricted evaluation performed.

This maternal impact seemingly advantages the complete colony.

Extensive, wider, widest

Queens can decide the distinction in dimension between employee and drone cells utilizing their forelegs. They use this to selectively lay unfertilised eggs in drone comb. Maybe an analogous mechanism operates to establish queen cells?

However understanding the scale of the cell is barely half the story … can queens additionally measure massive or small eggs earlier than oviposition, selectively laying massive eggs in queen cells?

Alternatively, and probably extra realistically, maybe queens pause earlier than egg laying after they discover a queen cell? It’s identified that delayed oviposition leads to larger eggs with extra yolk protein.

Implications for queen rearing.

Grafting-based queen rearing strategies – which account for nearly all commercially reared queens – use chosen day-old employee larvae. As proven above, these seemingly produce inferior queens to these reared from eggs laid in queen cells … inferior as outlined by dimension, ovariole quantity and within the high quality of eggs and brood they produce.

Repeated rounds of grafting-based queen rearing could be anticipated to have a cumulative and long-term deleterious impact on the standard of the queens, and the colonies that they head.

How do you suppose the final queen you bought was reared?

And what was her mom reared from?

And her grandmother?

What about her great-grandmother?

Sure, virtually definitely, from grafted day-old employee larvae.

Implications for freshmen

Grafting, or the perceived want to graft, is without doubt one of the main disincentives stopping freshmen trying to rear their very own queens.

Nevertheless, if higher queens actually are produced from eggs laid in queen cells, it means that alternate strategies ought to be used that don’t contain grafting.

This could encourage a number of the grafting-averse beekeepers to begin rearing queens.

That, and the strategies concerned, would be the topic of one other put up on this subject.

Notes

Since I’ve already drafted components of the 2 follow-up posts to this text (and don’t have any intention of both writing one thing completely different or regurgitating them of their unfinished state as responses to feedback!) please deal with the primary conclusions of those research in any feedback, relatively than the potential implications, notably for freshmen. The identification of a maternal impact is vital for our understanding of honey bee reproductive behaviour.

References

He, X.J., Wei, H., Jiang, W.J., Liu, Y.B., Wu, X.B., and Zeng, Z. (2021) Honeybee (Apis mellifera) Maternal Impact Causes Alternation of DNA Methylation Regulating Queen Improvement. Sociobiology 68: e5935 https://doi.org/10.13102/sociobiology.v68i1.5935.

Pan, Q-Z, Wu, X-B, Guan, C. and Zeng, Z-J (2013) A brand new methodology of queen rearing with out grafting larvae ABJ 153(12):1279.

Wei, H., He, X.J., Liao, C.H., Wu, X.B., Jiang, W.J., Zhang, B., et al. (2019) A Maternal Impact on Queen Manufacturing in Honeybees. Present Biology 29: 2208-2213.e3 https://doi.org/10.1016/j.cub.2019.05.059.

Yu, L., He, X., Shi, X., Yan, W., and Wu, X. (2023) Honey bee maternal results enhance employee efficiency and reproductive means in offspring. Entrance Cell Dev Biol 11: 1156923 https://doi.org/10.3389/fcell.2023.1156923.