relaxing Chrisididae stored in ethanol

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relaxing Chrisididae stored in ethanol

Postby Maarten J » 01 Mar 2012 15:24

Hello,

I'm new to this forum and although a little bit related to Cosmins topic about preparation here my question.
Over several years now I collected Chrysididae in Belgium, mainly the Flemish part. As collecting methods I used colored pan-traps, malaise-traps and collecting by hand-held net. Specimens collected by hand-held net where killed with ethyl-acetate vapor and where pinned shortly after.
My question is especially related to the specimens collected in pan-traps and malaise traps who were stored in ethanol. For identification I want to pin or glue them on labels. My problem is that I can't find a method to relax these specimens enough to readjust their wings, jaws and extract the female ovipositor. So far I've tried 4 methods: 1) put them in water for 24-36 hours; 2) left them in a humidificator for 24-36 hours; 3) put them in the freezer for some days and 4) left them in Cellosolve (2-ethoxyethanol) for 24-48 hours and followed by 1-2 hours in Histo-Clear II.
In all cases the specimens wings, jaws and female ovipositor where not relaxed enough to readjust them and glue the specimen nicely arranged on a transparent label.

Can anyone give me some advice on relaxing Chrysididae previously stored in ethanol?
Do most of you glue or pin Chrisididae? On this website I read that glue them on transparent labels is favoured.

Many thanks!

Maarten
(Belgium)
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Re: relaxing Chrisididae stored in ethanol

Postby Euchroeus » 10 Mar 2012 12:12

Dear Maarten :welcome:

I'm sorry, but I found your message only few minutes ago.

Personally I don't have any suggestion.
By the way, I'm not interested in material collected in Malaise traps, beacuse it's really impossible to prepare it. So I always refuse specimens collected with this kind of trap.
Often the cuticula is too much dehydrated and the dehydration cause many problems. The dehydrated cuticula can modify the anal margin and the relative position of the anal teeth, which is very important in some species groups (i.e. ignita group). Moreover, it's basically impossible to extract the dehydrated male genitalia, because you'll always break them.

In case of specimens collected with yellow pan traps is usually easier. I prepare them with pins, exactly as Coleoptera.

Cheers
Paolo
Paolo Rosa - www.chrysis.net
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Re: relaxing Chrisididae stored in ethanol

Postby Alex » 12 Mar 2012 05:08

Hi Maarten,

I dont know if this will work or not, but you could give it a try if you want:
Add your dessicated specimen to a syringe 1/3 filled with water (no air bubbles), put your thumb over the nib that is used to attach needles (ofcourse, no needle should be attached!) and by pulling the plunger create a vacuum in the barrel. Shake the syringe to remove the bubbles from the specimen, let go of the plunger, push out the air and redo the vacuum step like that a couple of times.
This draws out the air in the specimen and replaces it with water very quickly, and is escpecially good at rehydrating soft tissues. Muscles might still be a problem though, and if you have un-cooperative specimens I would give the same advice as Paolo, ie place the hydrated specimen on styrofoam (or similar) and use needles to position it, then leave it to dry. Mandlibles can be forced open with carefull use of two hooked needles, but it is a lot of work.
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Re: relaxing Chrisididae stored in ethanol

Postby Maarten J » 12 Mar 2012 22:20

Many thanks for the replies!
Today I was in the field with someone who is specialized in DNA-extraction. I asked him the same question and he told me that the alcohol is not only dehydrating the specimen but also changes the proteins in a way that it's not reversible. Because of this muscles and other tissue becomes rigid, according to him it's not possible to rehydrate and soften it again.

Best wishes,
Maarten
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Re: relaxing Chrisididae stored in ethanol

Postby cosmln » 15 Mar 2012 21:34

I think the only way in this case will be to destroy somehow the muscle... i think that one way will be a controlled decomposition... the soft tissue to break and to remain more or less only with hard tissue.

but don't know how to do this :(

all my best,
Cosmin
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