attempting to preserve/ freeze dry Monarch caterpillar

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zzffnn
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Post by zzffnn »

Mark's ideas make good sense, chemically and biologically. And they can probably be applied to other insects too.

I talked an entomology professor (who specialized in moth caterpillars) a few days ago and asked him for a foolproof, easy-to-get/use field preservatives for caterpillars. He said just immerse directly in vinegar, when I am in the field, then mail the caterpillars to him. He was too busy to type long enough to explain it though.

But I think firstly removing gut content, then immerse in KAAD (which contains glacial acetic acid = highly concentrated "vinegar") would work better, assuming you don't need the gut contents and would rather keep original colors.

This is slightly off topic, but I would like to ask Mark:

70%-80% alcohol can denature proteins too, though likely much slower than boiling water. Do you know if protein denaturation is the major factor for losing colors in caterpillars?

I did notice that alcohol removes the green color of lacewings VERY quickly, within a few hours.
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Len Willan
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Post by Len Willan »

The Current Entomological Reference for collection management is
Methods for Collecting, Preserving and Studying Insects and Other Terrestrial Arthropods
MS Upton EL Mantle
Book • January 2010?with?5,494 Reads
PDF Available here
Note Chapter 3 Preservation and Storage
https://www.researchgate.net/publicatio ... Arthropods

zzffnn
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Post by zzffnn »

Len Willan wrote:The Current Entomological Reference for collection management is
Methods for Collecting, Preserving and Studying Insects and Other Terrestrial Arthropods
MS Upton EL Mantle
Book • January 2010?with?5,494 Reads
PDF Available here
Note Chapter 3 Preservation and Storage
https://www.researchgate.net/publicatio ... Arthropods
Thank you very much! This pdf is amazing and very helpful.

So acetic acid inactives enzymes that changes color. Fixing agent (see page 34 of the pdf) generally contains some acetic acid and alcohol (which denatures proteins too).

I will use a formulation with acetic acid, alcohol, distilled water and glycerol, without other harmful reagents, as my general purpose hobbyist fixative.

ctron,
That pdf mentions catepillar preservation quite many times. You may find it very helpful to you as well.
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MarkSturtevant
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Post by MarkSturtevant »

Good point about the alcohol. There are different pigments, and some are in the cuticle and others will be in cells under the cuticle. For many insects, the colors we see when they are alive include colors in their epidermis but also in deeper tissues sometimes. The blood can provide a color (especially green). A lot of the colors are combinations, really, where one source of color is superimposed on a different source of color, and we see their combined colors.
Some colors can be denatured and changed or extracted with alcohol. So you could try the acetic acid bath to see how it works, and you could maybe try the KAAD to see how it works. I don't know which will be best in this situation.
Evisceration of a cat by 'rolling' it out is best when its soft, and the tissues are not made stiffer by fixing in KAAD or acetic acid. I think (am not sure) that you could do all tests with reagents after the cat has been rolled out. In the case of a monarch larva, I would expect the colors are all in the cuticle and maybe epidermis. So you can roll one out without losing colors. If you feel you need to eviscerate after its been fixed in a reagent, you can still eviscerate by cutting it open along the ventral side and removing the insides. The traditional way of dealing with that situation is to then stuff the body with some kind of batting and drying it out. People generally close the pelt around the batting and hold it there by bracing it with insect pins as it dries out. I suspect that this will come out not looking that great with a caterpillar, but I have never tried that with one of these so I don't know from experience.
Mark Sturtevant
Dept. of Still Waters

grgh
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Post by grgh »

Place any critter in white vinegar from 1 to 2 hours, then transfer into alcohol or 70% isopropanol.
Even on lacewings the vinegar will preserve the colour.
you will need to leave in alcohol up to three weeks. then let air dry.
always worked on cabbage white caterpillars and small moths.

I have found that this does not work on wings that are already developed should i use polarisation? that i cannot understand.
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zzffnn
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Post by zzffnn »

grgh wrote:Place any critter in white vinegar from 1 to 2 hours, then transfer into alcohol or 70% isopropanol.
Even on lacewings the vinegar will preserve the colour.
you will need to leave in alcohol up to three weeks. then let air dry.
always worked on cabbage white caterpillars and small moths.
That is what I do with most I sects, except for lacewings. For the 6 lacewings I tried that on, 70% isopropanol still removed some colors, after about 6 hours soak (which was preceded 2 hrs soak in 5% white vinegar). So for my lacewings, I do 2 hrs vinegar followed by 2 hrs of isopropanol and air drying.
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