Forum Entomologi Italiani

No Giacomo, non in alcool, che rende le larve scure e "floscie".
Per le larve si deve usare una miscela chiamata Pampel (Pampel's fluid).
Ne trovi la descrizione qui http://www.fao.org/docrep/003/t0146e/T0146E02.htm

The best general-purpose preservative is Pampel's Fluid. This is prepared by mixing the following ingredients together (in parts by volume to give the quantity required) in the order shown: 30 parts water (preferably distilled); 15 parts 95% ethyl alcohol; 6 parts 40%(w/v) formaldehyde; and 4 parts glacial acetic acid. (Never start with the acid: always add it slowly after mixing the other ingredients.) If possible, let the mixture stand for a few days before use: the unpleasant smells of the acid and aldehyde will then have disappeared. If glacial acetic acid is not available, or is considered too dangerous to transport or stock, replace the water and concentrated acid in the above list with either 7.5 parts water and 26.5 parts 15% acetic acid solution. or 14 parts water and 20 parts 20% acetic acid solution. If industrial acetic acid is not available. A similar (but weaker) preservative can be made by mixing: 35 parts strong vinegar (preferably white); 15 parts absolute (> 99.5%) ethyl alcohol; and 2.5 parts 40%(w/v) formaldehyde.

Ma lo trovi anche nel lavoro di Svacha che ho citato in precedenza, presente nella libreria del forum.

A few words need to be said about preservation and storage. Cerambycid larvae with their
generally soft unsclerotized body require special treatment. The procedure usual in other insects
(although even there not very suitable), i.e. to merely put the larvae in 70 — 80 % ethanol, is
entirely insufficient. Larvae thus preserved mostly lose their natural colour (darken), and become
often so contracted that many characters are very difficult to study. Legs, antennae and palps
often break off, and dissection is almost impossible, since all parts of the body become hard
and fragile.
I mostly use (even during field works) the following procedure: The larvae are killed by immers-
ion for about 2—20 seconds (according to size) into hot water (about 80 — 90 °C, boiling water
just put off from the fire), then perforated once or twice in lateral intersegmental zones to prevent
osmotic deformation (the instrument for making the incision must be provided with a very sharp
and slender point) and put in the so-called Pampel's Fluid (IMMS, 1939, cited after DUFFY, 1953):

glacial acetic acid 4 parts
distilled water 30 parts
formaldehyde 6 parts
ethyl alcohol (95 per cent) 15 parts

DUFFY (1. c.) has not mentioned the concentration of the formaldehyde, consequently it should
be supposed to be of 100 %, I use 40 % aqueous solution in the same proportion (6 parts) with
good results.
Some specimens (particularly those shortly after moulting) may collapse when picked out
from the hot water - then they must be allowed to grow cold slowly in the water.
It is advantageous to slightly narcotize the larvae before immersion in the hot water, using
the same chemicals as for killing the adult beetles (e.g. ethyl acetate), as the larvae will not twist,
contract thoracic sternum or retract the mouthparts. However, care should be taken to narcotize
the larvae only till they cease to move, not longer - their body turgor should be preserved, other-
wise some protuberant body structures may collapse and become folded.
To save time and labour, specimens may be simply immersed in the Pampers Fluid, but the
results are not so good, although much better than when using ethanol alone.
I prefer to keep specimens permanently in the Pampel's Fluid, as spirit may cause some un-
wanted changes even in the already fixed larvae.
Contrary to ordinary use, I keep my larvae in glass tubes with plastic stoppers, not in tubes
plugged with cottonwool and placed in a jar filled with the preserving medium. It is much more
pleasant to work with such material as one can avoid continuous contamination of hands with
the fluid used; in fact the latter alternative cannot be at all used if one wants to keep the larvae
permanently in fluids like the Pampel's destructive to human epitheliums (for this reason the
larvae preserved in the Pampel's Fluid must be of course examined in a dish with spirit - the
evaporations of the Pampel must not be inhaled or get in the eyes). During prolonged storage,
however, even the stoppered tubes should be kept in some air-tight containers.

E' molto più comodo, come normalmente faccio io, far preparare il liquido in farmacia.

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Gianfranco Sama

"Benedetto colui che ti aiuta a correggere i tuoi errori invece di scagliarteli contro"
___________________________________
Gershom Sholem

Grazie della ricetta (e del consiglio di farmela fare dal farmacista!)

Per ora io mi trovo bene (Gianfrnco non strapparti i capelli dalla disperazione! ) con un solvente per lo smalto per le unghie...
E' composto da butanone, acqua e alcol isopropilico...
Costa una cavolata: 50cent/1euro.

Ci tengo diverse larve (non solo cerambici, ma anche Cetonidae, Lucanidae e un Buprestidae), tra cui una grossa di Prionus.
Per ora sono alcuni mesi che vi stanno a mollo, e, fatta eccezione per un Aegomorphus clavipes, le altre sono tutte gialle e rigide...
Mi porto il Prionus a Modena così mi dici se va bene uguale.

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Giacomo

Gialle ?, dovrebbero essere biancastre !

_________________
Gianfranco Sama

"Benedetto colui che ti aiuta a correggere i tuoi errori invece di scagliarteli contro"
___________________________________
Gershom Sholem

Giallastre... erano tutte prossime alla metamorfosi.

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Giacomo