How many sperm are used to fertilise each egg?

[Motobiman]

We had a question at our teaching apiary last week that has caused some discussion and thrown up several others and during reading I have not been able to answer it.

Maybe our forum experts can help?

When the queen lays an egg and it is fertilised.

How many sperm does she utilise to fertilise each egg, is it possible for one males sperm to clump together in her spermatheca thus causing 'batching' of eggs from one sire and does the relative 'strength' or 'vigour' of an individuals sperm mean one sire is more successful than others, thus causing prevalence of his offspring in the colony?

 

[MartinL]

Never really considered it,

I expect 1?



But no doubt, some will say not!

Should have listened more closely when being told about the birds & bees instead of giggling at the back of the class.

 

[Motobiman]

Never really considered it,

I expect 1?



But no doubt, some will say not!

Most papers suggest 'a few' and one (grateful link received elsewhere on here) says between 3 and ten.

So the 'batching' and possible dominance of one male question remains.

 

[B+.]

Most papers suggest 'a few' and one

Only 1 spermatozoa will fuse with the egg nucleus.

 

[Truble]

I recall reading that a few sperm are released with no exact number given. It would be difficult for a queen to release an exact number of sperm, say 2 or 3 every time she fertilizes and egg. Only one successful sperm out of those released making the fertilization.

 

[Erichalfbee]

Only 1 spermatozoa will fuse with the egg nucleus.

the egg wall becomes impermeable to further penetration once one sperm breaks through and loses its tail

 

[nantmoel]

the egg wall becomes impermeable to further penetration once one sperm breaks through and loses its tail

 

[Motobiman]

Only 1 spermatozoa will fuse with the egg nucleus.

Yes I know how the single sperm fertilisation process works and she on,y releases between 3 and 10 sperm at a time unlike millions in the mammalian process.

Hence the question, is there competition between sperm to fertilise the egg, like in mammals indicating that more active or healthier sperm are more likely to win, or is it purely chance in bees?

 

[For want of a better word]

ONE

Darwin's survival of the fittest even counts for insects!

However Chimera-ism can occur when the egg divides that has lead to ( pre DNA days) some believing that more than one sperm can be involved in fertilisation ( not helped by the "Kut and Paste brigade so prevalent in beekeeping books)

Yeghes da

 

[Truble]

the egg wall becomes impermeable to further penetration once one sperm breaks through and loses its tail

According to Koeniger's chapter in "Bee breeding and genetics" between 1-10 sperm penetrate through the egg wall via the micropyle, but only one of these is destined to fuse with the egg cell pro-nucleus, the failed sperm then degenerate within the cytoplasm of the egg...assuming all goes well. There are various things that can go wrong, if 2 sperm unite and the pronucleus remains unfertilized you get a gynandromorph in which diploid female tissue originates from 2 fathers without any contribution from the mother. Sometimes the sperm fail to degenerate and you get male tissue formed in a female bee.

 

[REDWOOD]

The competition in honey bees are the drones,

 

[Erichalfbee]

According to Koeniger's chapter in "Bee breeding and genetics" between 1-10 sperm penetrate through the egg wall via the micropyle, but only one of these is destined to fuse with the egg cell pro-nucleus, the failed sperm then degenerate within the cytoplasm of the egg...assuming all goes well. There are various things that can go wrong, if 2 sperm unite and the pronucleus remains unfertilized you get a gynandromorph in which diploid female tissue originates from 2 fathers without any contribution from the mother. Sometimes the sperm fail to degenerate and you get male tissue formed in a female bee.

Thank you Truble.
I must admit I was extrapolating my Biology knowledge gleaned many years ago. Thank you for correcting me

PS genetics was never my strong point (save counting coloured eyes in fruit flies) .....too much maths in it

 

[Motobiman]

Thanks for that Truble.

And the last part of the question, do eggs get laid in patriarchal 'batches' and if they do, is it due to 'clumping' of sperm in the queen or some other mechanism?

I ask because other research I read suggests there are often varying percentages of patriarchal origin in a colony, up to 32 percent in some cases, so something is going on there unless it's only linked to the number of individuals the queen mates with and/or the relevant virility of the sperm.

 

[Truble]

I'm not clever enough to know the answer to your question I'm afraid. From what little I've read it appears to be a grey area and most books skirt over the issue which suggests that the real answer is not known. From the genetic books it appears that some scientists think sperm is randomly selected, but there are findings (as you suggest yourself) that indicate some patrilines are over-represented, when compared to the ratio of sperms stored. But the reason for this is currently unknown, by me at least (which doesn't mean a lot!). Clumping may certainly be a possibility. If you find any answers please post as I'd be interested in reading them. The only paper I can find that is accessible (link here) suggest random usage of sperm. They also found that sequentially laid eggs were not fertilized by sperm of the same father with a higher probability than predicted by the ratios of patrilines. Which goes some way to answering your original question.
As they don't know how the queen keeps the sperm fresh and alive in the spermatheca for such an extended period it appears there is still lots to find out.

 

[midnight sun]

the egg wall becomes impermeable to further penetration once one sperm breaks through and loses its tail

Please don't use words like 'penetration' on this forum Erica. You forget that there are a few old men who read these posts and it is still Summer! The consequences could be catastophic!

 

[Erichalfbee]

Please don't use words like 'penetration' on this forum Erica. You forget that there are a few old men who read these posts and it is still Summer! The consequences could be catastophic!

I don't know what you mean

 

[Motobiman]

Thanks Truble, more reading of that paper.

It's mentioned on page 9.

My understanidng is:

The ejaculate moves towards the spermatheca (along a tubular structure) so clearly as it fills the possibility of mixing reduces and when it's full the remaining ejaculate is jettisoned.

So (presumably) later matings may not be represented in the progeny at all.

Further as the fluid is withdrawn during egg laying from one point and the volume of fluid involved is the same and replaced by natural bodily processes the concentration of sperm reduces and mixing continues so the incidence of patriline bunching reduces too.

Simple.

 

[bontbee]

Have a look at Koeniger, Koeniger (with Elllis and Connor)'s little book, "Mating Biology of the Honey bee", An excellent read which explains many aspects of this subject.

 

[B+.]

So (presumably) later matings may not be represented in the progeny at all.

I think this is very unlikely. Sperm are thoroughly mixed in the queens spermatheca so the possibility of a mating not being represented in the progeny at all is effectively zero.

 

[Motobiman]

I think this is very unlikely. Sperm are thoroughly mixed in the queens spermatheca so the possibility of a mating not being represented in the progeny at all is effectively zero.

That's not how I read the paper referenced above because very little of the sperm deposited during mating actually reaches the spermatheca.

Secondly the paper makes the point that when the spermatheca is full then little mixing occurs and it's only later as the concentration of sperm reduces does more thorough mixing take place.

This seems obvious with the way fluids behave in a 'closed' space.

And thirdly the results show a marked reduction in paterline progeny percentages as time passes so effectively it should drop to zero at some point for the drones depositing lesser or later sperm during the mating.

Most sperm of course is ejected before it passes into the spermatheca so if the ejection is out of the same orifice as it was deposited it follows that 'last in first out' favours the earlier matings.

Wouldn't it?