Lady beetle eggs hatching

[rjlittlefield]

"Lady Beetle Eggs Hatching -- 10 Hours in 2 Minutes"



This is just as the title suggests -- a time lapse of 10 hours, displayed in 2 minutes, as 30 fps with one frame shot every 10 seconds. There are 9 eggs at the beginning. 7 will hatch, one is sterile and is eaten by the hatchlings, and the last one would have hatched but was too slow and also gets eaten.

The video clearly shows use of what I described on YouTube as the "posterior suction gripper". That organ is impossible to overlook in real life because of its frequent use, but it was remarkably hard for me to find documented on the internet. Finally at https://extensionpubs.unl.edu/publicati ... 0-2007.pdf I found the brief note that

Lady beetle larvae have an anal organ resembling a suction cup, which they use to grip vegetation as they move about.

More helpfully, at https://www.zin.ru/animalia/coleoptera/ ... nks56b.pdf ("OBSERVATIONS ON THE BEHAVIOUR AND MORTALITY IN COCCINELLIDAE BEFORE DISPERSAI, FROM THE EGG SHELLS" by C. J. BANKS, Ph.D., F.R.E.S.PROC. R. ENT. SOC. LOND. (A) 31. PTS. 4-6. (JUNE, 1956)), I found the comment that

the evaginated rectum acts as a sucking disc which is used in locomotion (Gage, 1920)

Never underestimate the ability of Mother Nature to make basic anatomy serve multiple functions!

Here are a couple of stills from the sequence. The first just shows a larva emerging from its eggshell, and the second shows a mass of larvae several hours later, moving around with the aid of their sucking discs. They have no hesitation about attaching those to each other, sometimes even on the largest of spines where I suppose they act more like grippers than suckers.





Here is a high mag stereo (crossed eye) of a preserved specimen, showing the sucker in more detail.



All this stuff has been studied before, of course. The reference to Gage, 1920, expands as "GAGE, J. H., 1920, The larvae of the Coccinellidae. Illinois biol. Monogr. 6 : 1-294", which I take to mean 294 pages. I have not found a good copy of that, but I have ordered a copy of "A Natural History of Ladybird Beetles", https://www.amazon.com/dp/1107116074 . I expect that to have plenty of information to keep me amused for even more days than it took to shoot and process these photos.

Photos were mostly with Canon MP-E at 2X on Canon R7 camera (APS-C format), then slightly cropped for conversion to video. The high mag stereo is with Mitutoyo 20X NA 0.42 on Raynox DCR-150, so about 21X on sensor, again somewhat cropped for display here. All still images sharpened with Topaz AI. Specimen dehydrated in ethanol then acetone, then air dried. That worked great on the first specimen I tried, and failed miserably on all the others by extreme collapse while air drying. In all cases I skipped my customary boiling water bath, which I suspect was the cause of the failures.

--Rik

[Beatsy]

Super-interesting post Rik. The time-lapse is great.

Nothing like waking up to an anal organ close-up, in stereo. Only on PMN!

[CrispyBee]

Wow! Awesome timelapse!!

And thank you for the info about the suction-cup, I've always thought they simply uhm... how should I put it... stuck their butt to twigs, didn't occur to me that it's a special 'sucker'!

[rjlittlefield]

Thanks for the feedback, guys!

This is the first long time-lapse that I've ever thought was worth publishing. All told, it was a matter of 3 days, over 26,000 frames, and 79 GB of photos, of which I used roughly the last 4320 frames and 12.6 GB. All the rest was just time spent waiting for something interesting to happen.

As I write this, I'm bothered that the numbers don't quite work out. I had Photoshop load the image sequence at 30 fps, cropped it to a good starting point, and ended up with 120 seconds of video, from which I inferred 3600 frames = 10 hours. But in the original source images, 3600 frames back from the end does not correspond to the start of the video. It takes around 4320 frames = 12 hours to do that. The difference seems far too big to be any sort of rounding error, but at this moment I have no idea what caused it. I expect I'll investigate later.

For now, I'd also like to document the setup for the high mag stereo:





As shown in the pictures, the specimen is glued to the end of an insect pin, which is held in a small balsa cage that will remain with the specimen when I put it in a storage box with label attached. In combination with the fine rotary controls of my positioning stack, this worked very nicely to shoot lateral, ventral, and oblique views of the specimen without ever releasing the pin from the grip of the cage. It's always risky to manipulate small dry mounted specimens, but this approach has felt a lot less risky than usual.

--Rik

[Macrero]

Very nice and interesting.

[CrispyBee]

As shown in the pictures, the specimen is glued to the end of an insect pin, which is held in a small balsa cage that will remain with the specimen when I put it in a storage box with label attached. In combination with the fine rotary controls of my positioning stack, this worked very nicely to shoot lateral, ventral, and oblique views of the specimen without ever releasing the pin from the grip of the cage. It's always risky to manipulate small dry mounted specimens, but this approach has felt a lot less risky than usual.

--Rik

Even though that's not the main focus of your thread I find that way of "cataloging" and storing specimens very interesting as well! Did you make a similar arrangement for your ants?

[fleegix]

Fantastic, thanks for sharing. Would you consider timelapsed focus stacks to be an interesting/viable potential next step?

[rjlittlefield]

Did you make a similar arrangement for your ants?

I did not, but I wish I had and I surely will next time.

What I have usually done in the past is some variation of classical entomological pinning. The pin might go directly through the specimen, or perhaps a minuten pin through the specimen and then the minuten mounted in a small block of foam or balsa, or maybe the specimen glued to a small triangle of paper and then the triangle pinned. A paper label goes on the same pin, and the combination gets pinned into the bottom of a box. All of these work fine for specimens to be viewed at most under a dissecting scope, but the mounting pins often prevent access by objectives with short working distances.

In the case of this beetle larva, I expected that I would want to image the sucker from several different angles, I wanted to do the positioning under a stereo scope before moving the specimen to my high mag vertical setup, then move it to a box for storage, and I wanted to do all that without having to grip anything with forceps. At some point a vision rather like the pictured cage occurred to me, and since I happened to have balsa and superglue at hand, that's what got used.

So far it looks pretty good. But I will be interested to see how the scheme fails, which most of them eventually do in one way or another.

(As I write this, I am remembering a science documentary that involved in part moving dried and gold-plated specimens from a storage box into an SEM and back. The results were properly impressive, with appropriate music and narration, and everything was just perfect ... until in the last split second before cutting to a different scene, the forceps clicked on the pin and the camera showed a bit of gold specimen bouncing across the bottom of the storage box. I assume that either the editors did not notice or they had an unusually well honed sense of honesty in showing how the process actually works.)

Fantastic, thanks for sharing. Would you consider timelapsed focus stacks to be an interesting/viable potential next step?

For me, that's a definite "maybe but probably not". Certainly there are subjects where time lapse focus stacks are completely appropriate. Examples include plants growing and garbage rotting -- especially if the garbage rotting also involves slime molds fruiting. At viewtopic.php?p=279826#p279826 , I wrote that

At their best the final time lapses can be stunning, see for example https://www.youtube.com/watch?v=YFpdDyzbdXc by the member known here as "starshade" (some discussion at http://www.photomacrography.net/forum/v ... hp?t=23205 ). Separately, the recent Disney / National Geographic series "Welcome To Earth" has a couple of sequences of time-lapse slime mold, growing their reproductive structures, made using Zerene Stacker. I helped the photographers get started, and if it's any comfort, I can assure you that they had to deal with the same sort of issues that you're wrestling with. In the end, of course their stuff looks great or it would not have gotten into the final release: Episode 3, "Mind of the Swarm", 29:25 - 32:05, especially 30:56-31:52.

However, my personal interests tend toward things like these eggs hatching, where the subjects do little or nothing for a long time, then suddenly switch to a different mode where focus stacking is essentially impossible. So, I'm happy to watch while other people do the time lapse focus stacked stuff, but probably I won't be doing any myself unless I want to create a driver/testcase to push tech development.

--Rik

[fleegix]

Fantastic, thanks for sharing. Would you consider timelapsed focus stacks to be an interesting/viable potential next step?

For me, that's a definite "maybe but probably not". Certainly there are subjects where time lapse focus stacks are completely appropriate. Examples include plants growing and garbage rotting -- especially if the garbage rotting also involves slime molds fruiting. At viewtopic.php?p=279826#p279826 , I wrote that

At their best the final time lapses can be stunning, see for example https://www.youtube.com/watch?v=YFpdDyzbdXc by the member known here as "starshade" (some discussion at http://www.photomacrography.net/forum/v ... hp?t=23205 ). Separately, the recent Disney / National Geographic series "Welcome To Earth" has a couple of sequences of time-lapse slime mold, growing their reproductive structures, made using Zerene Stacker. I helped the photographers get started, and if it's any comfort, I can assure you that they had to deal with the same sort of issues that you're wrestling with. In the end, of course their stuff looks great or it would not have gotten into the final release: Episode 3, "Mind of the Swarm", 29:25 - 32:05, especially 30:56-31:52.

However, my personal interests tend toward things like these eggs hatching, where the subjects do little or nothing for a long time, then suddenly switch to a different mode where focus stacking is essentially impossible. So, I'm happy to watch while other people do the time lapse focus stacked stuff, but probably I won't be doing any myself unless I want to create a driver/testcase to push tech development.

--Rik

Makes sense, thanks for your reply and the link to the other thread on this.

[Guppy]

Hi Rik

A very good and informative video.
I was not aware of cannibalism in Lady Beetle larvae.

Kurt

[WojTek]

Hello Rik,
Very interesting story, fantastic video and great photos.
I also like your setup and especially the difusser.
Best, ADi

[MarkSturtevant]

Very well done! Rear appendages on beetle larvae are called urogomphi, and maybe that is what these rear suckers are. More familiar examples are found in larvae of bark beetles and other beetle larvae: https://bugguide.net/node/view/628061/bgimage. They can look like pincers or like segmented cerci, but perhaps they can be suction organs?

[rjlittlefield]

I recently showed this material to several people in offline presentations, and every time I showed the pictures I heard some variation of

"Oh look, how cute -- you can see their little eyes developing inside the eggs!"

Well, no, not really.

But to be fair, that's the same thing that I thought at first. I did not really get clued in until I received my copy of "A Natural History of Ladybird Beetles" (M. E. N. Majerus, 2017).

It was there, on page 56, where I read that

The first task for the fully developed embryo is to force its way out through the eggshell. This is achieved by the use of egg-bursters, which are specialized cuticular structures on the egg or thorax of the embryo. The egg-bursters make the initial break in the egg chorion, and then the larva uses blood pressure to enlarge the break. Egg-bursters seem to have no other function than aiding the young larva's escape from its eggshell, for they are lost on the first larval skin-shed, or ecdysis.

I took a closer look at the image sequence, and sure enough:



So, the things that look like eyes are actually egg-bursters. Video focusing on this action is at https://youtu.be/nLdSEjuGj1c .

Now I'm wondering exactly how my favorite moths and butterflies get out of their eggs. A question for another day!

--Rik

[rjlittlefield]

Rear appendages on beetle larvae are called urogomphi, and maybe that is what these rear suckers are.

My impression is that the term urogomphi refers to things that grow on the outside of larvae, sort of like prolegs in lepidoptera except dorsal instead of ventral.

R.F.Chapman, in "The Insects", writes that

Some larval Coleoptera have a pair of processes called urogomphi, which are outgrowths of the tergum of segment 9 (Fig. 11.8c). They may be short spines or multi-articulate filaments and they may be rigid with the tergum or arise from the membrane behind it so that they are mobile. Jeannel (1949) regards them as homologous with cerci, but see Crowson (1960).

Chapman's Figure 11.8c clearly shows a urogomphus projecting dorsally, consistent with being an outgrowth of a tergum.

But the lady beetle's "posterior suction gripper", as I've called it for delicacy, does not fit any part of that description.

Instead, when not deployed the sucker/gripper totally disappears back into the end of the abdomen. This cannot be seen clearly in the video, partly for lack of focus and partly because the hatchlings had it deployed most of the time while jostling with each other. But in dead specimens the effect was quite obvious.

So, I think the phrasing that "the evaginated rectum acts as a sucking disc" (by Banks, referencing Gage) is an excellent description of what I saw. The sucker/gripper appears very much to be an alternate use of the normally internal digestive tract anatomy, as opposed to something different and external.

I was eager to see what "A Natural History of Ladybird Beetles" would have to say on the topic. But so far, all that I've been able to find is the comment on page 38 that

The abdomen has ten segments, the last segment bearing a sucking organ, the anal cremaster, which can attach to the substrate.

Further detail is given that the cremaster is used to anchor the old skin during molting. I find nothing about its routine use in locomotion or for anchoring while feeding, and nothing more about the anatomical origin of the structure. I have also searched for, but failed to find on the internet, any other use of the term "cremaster" (in insects) that does not involve anchoring a pupa.

Considering myself as an unusually flexible LLM, I have to conclude that this is a place where mere words are not very helpful -- I have to think about what the thing really is and does in the physical world.

--Rik