Theory: Mantids do not 'hatch' as 1st instar...

[kamakiri]

Just wanted to propose a topic for discussion that I've thought about since I was about 7.

But to be clear, I think they wiggle out of the ooth as 1st instars...but are immediately molting into 2nd instars. I don't know of any other insects that hatch and leave more than just the egg case (especially those that eat their way out). So the thread and the cast skin are 'proof' of the first molt, right?

 

[ABbuggin]

Just wanted to propose a topic for discussion that I've thought about since I was about 7.But to be clear, I think they wiggle out of the ooth as 1st instars...but are immediately molting into 2nd instars. I don't know of any other insects that hatch and leave more than just the egg case (especially those that eat their way out). So the thread and the cast skin are 'proof' of the first molt, right?

Technically your right, but for some reason "hatchlings" are still classified as first instars. I have no clue why, so it would be great if somebody else could clear that up.

 

[mrblue]

there was a good discussion on this before. i'll go look for it...

 

[Pelle]

Here are some topics about that

Click

Click

Edit: Sorry Mrblue

 

[mrblue]

haha no problem! i went off and could only find one that wasnt even the one i was thinking of, here it is:

http://mantidforum.net/forums/index.php?sh...ic=7956&hl=

the one i was thinking of was that first one you posted, thanks for finding it!

 

[Morpheus uk]

Whats just as ennoying is people using L`s lol

We have our own language so can we at least put I3 not L3?

 

[kamakiri]

Thanks for the thread links Pelle and mrblue. It looks like there's already been enough discussion about this that I didn't pick up via a google search...

But I don't really get or buy the prelarva explanation...the cast skin is not smooth or such like the interior of the ooth or individual egg casing. Well, at least not the ones I've peeled open.

 

[mrblue]

Whats just as ennoying is people using L`s lolWe have our own language so can we at least put I3 not L3?

L is short for "larval instar". I is short for "instar", and only used when referring to larval instars (not adults) so is also short for "larval instar". it has nothing to do with language, simply preference.

 

[Christian]

@Kamakiri: please read the prelarva explanation carefully, you will find the answer there. It has nothing to do with being smooth or not (the prelarval cuticle isn't smooth as it has to push the mantid out of the ooth), but whether it is a regular molt or not. It isn't a regular molt, as the mantid cuticle (the one of the L1) is already there, without being hardened and covered by the prelarval cuticle. Usual molts include the resorbtion of the old and the building of new cuticle. This is not the case in the prelarva-to-larva molt.

 

[kamakiri]

Thanks Christian for the follow-up. This is the post you refer to?

The real discussion over here was about whether the first mantid instar to be named L1 or L2. This is because mantids have an additional stadium called prelarva, that are the wormlike mantids hatching out the ooth and molting immediately. It was argued by some authors (e.g. Ehrmann), that due to this additional stadium, the prelarva has to be named L1 and thus, the young nymphs are in fact L2. This led to a considerable confusion, people selling freshly hatched larvae as L1 or L2.However, the prelarva has in fact turned out long ago to be NOT an own instar, as the prelarval cuticle is just an embryonic envelope helping the young mantid to hatch from the ooth. The first instar is already there, just covered by the embryonic cuticle, which is shed immediately after hatching. So, the little mantids which have hatched out an ooth are in fact real L1 and not L2.

Real instars differ between molts and partly resorb the old cuticle prior to shedding. A molt is a physiological process and cannot be compared to the simple cover of a prelarval cuticle. Prelarvas are found in other taxa as well and noone termed them "first instar".

I suppose I don't understand the finer point regarding the partial absorption of the cuticle.

 

[Christian]

Hi.

A molt isn't just the shedding of the skin. New skin has to be built up, parts of the old skin have to be resorbed, and finally, the remaining cuticle has to break along certain axes during the molt itself. The new skin is built up toward the end of the instar. The molt also contains physiological and morphological changes (gonads, wing pads, ear) which go further than the visible ones.

All this stuff doesn't apply to prelarvae, as the L1 underneath is already complete. This instar is already there, nothing has to be resorbed or built up.

 

[kamakiri]

...Studying some of my photos (and others) of mantises hatching, I think I understand your point a little better.

click for large size

click for large size

To me, it looks like the L1 legs are there under more of a 'sheath' instead of a 'skin'. No separate legs are in that 'sheath'. So I think that supports your point?

As for the 'remaining cuticle splitting on certain axes'...I'm a little confused since they do seem to be split in the same manner and location like a regular molt. As far as I can tell, it's essentially the same places that the subsequent molts split.

Anyway, perhaps the L1 designation should simply be given to the first instar that is able to move on its own, or exists outside of the egg case?

 

[Birdfly]

I thought this might help explain a bit better:

Mantids emerging from the ooth in what i've always refered to as a hatching cowl but Christians prelarva is a better description:

Dangling on the silk threads and using pressure to rupture the prelarval skin:

Breaking out en masse:

Nearly there, but hanging on to the prelarval skin with the cerci ? ? to harden off:

Free, 1st instar or L1, which ever you prefer:

 

[The_Asa]

Wow, nice pics :blink:

 

[idolomantis]

with that camera you can even sex them :blink:

 

[kamakiri]

Birdfly, thanks for the excellent pictures. One observation is that the hatchlings look just like any other nymph undergoing a regular molt, don't they? Especially in the shot hanging by the cerci. I'm still rather confused on the molt definition.

The next ooth I hatch I'm going to take more detailed pictures of the dry skins...