Bigger eggs, better bees?

It all starts with an egg.

Whether you're making a bee or an omelette, the size of the final product is influenced by what you start with.

Essentially, the more you put in, the more you get out.

With omelettes, that's pretty obvious — think ostrich vs. quail — but is it also true for bees?

Yes, at least under certain circumstances, it is.

Regular readers will be familiar with my previous posts on the 'maternal effect' in honey bees. Studies have shown that queens lay larger eggs in oversized queen cups than they do in standard worker cells.

These larger eggs develop into larger queens … larger, that is, than queens reared from eggs laid in smaller worker cells by the same mother.

I've written half a dozen posts related to this topic, and how beekeepers might exploit it to rear bigger, better queens.

The maternal effect — a phenomenon also seen in other insects, as well as some fish and birds — is explained as the queen investing more 'resources' (i.e. laying bigger eggs) in her progeny that will go on to head a future colony.

All examples of the maternal effect, whether in bees, beluga, or budgies {{1}} are thought to be determined by the environment the mother is in when egg laying.

In the case of queen bees, it is postulated that the 'environment' is the larger diameter of the queen cell cup, which somehow induces the queen to lay larger eggs {{2}}. There may be other environmental triggers as well, but they have yet to be identified.

But how?

The obvious question arising from the demonstration of the maternal effect in honey bees is 'How does the queen change the size of egg that she lays?'

Disappointingly, I don't have an answer to that.

I think there's a general perception that the queen is 'simply' an egg-laying machine, trundling around the nest, squeezing out egg, after egg, after egg ad infinitum. Her front end having little control over what goes on at her back end.

Whilst, at a crude approximation, that is correct, it ignores an increasing body of data showing that queens can and do change the size of eggs they lay under certain conditions.

When discussing the maternal effect, and I'm asked 'How does the queen change the size of egg that she lays?', I usually waffle a bit about pauses in egg-laying, and the resulting production of larger eggs. That's also an over-simplification, but it is true and conveniently avoids telling a whole new story about other conditions in which the queen lays eggs of different sizes (which I'm doing today).

My over-simplistic answer is based upon observations showing that a queen prevented from laying — for example, by caging her — will lay larger eggs shortly after release compared with those she was laying before. I presume this is a relatively short-lived phenomenon {{3}}. It may have a rather straightforward physiological explanation … eggs retained longer in the oviduct swelling more, or something like that {{4}}.

Why are larger eggs important?

For queens, I'll refer you back to those half-dozen posts related to 'Bigger queens, better queens' and the maternal effect in honey bees.

This post is not about queens {{5}}, it's about workers … and it is about other conditions in which the queen lays larger eggs.

Whatever the caste of the progeny — or, for that matter — the species, an evolutionary biologist would justify the production of larger eggs as an investment in the next generation.

The better provisioned they are from the very start, the greater their survival, and the larger their contribution to the continued survival of the species.

But, of course, these things are a trade-off.

If the queen laid just a few dozen very large eggs, the colony would never contain enough nurse bees or foragers. It would either fail to rear sufficient new brood, or would starve because it collected too little pollen and nectar.

So, going forward, remember that 'large' and 'small' are relative terms. I'm talking about differences of perhaps 5–15%.

Remember also that egg size is related to the strain of honey bee, and may also vary between different genetic stocks of the same strain. It's not meaningful to compare the size of eggs (or queens for that matter) produced by small, dark, native bees, with big, fat, yellow, Italian bees.

We favour large queens, because they're better {{6}}, and the best are produced from large eggs {{7}}.

But remember also that bees favour large eggs when rearing queens.

Al-Khatani and Bienenfeld (2021) demonstrated that the acceptance rate of grafted larvae for queen rearing was higher if they had hatched from heavier eggs.

So, under what conditions are larger eggs produced?