[Taxacom] Palcohol?

[John Noyes]

Hi Ken and others,

Glycerol should be avoided at all costs for small things with broader or softer wings (such as parasitic wasps <2mm). It makes the wings very soft and floppy (as does acetic acid in AGA) so that it is difficult or impossible to dry them flat even if they are Critical Point Dried.

It seems that ethanol stronger than 70% (even 95%) is OK for smaller, winged insects especially if they are Critical Point Dried. It used to be thought that stronger alcohols made these insects brittle, but that was because of the addition of methyl alcohol to the alcohol or perhaps because the insects were stored for a prolonged period at higher temperatures or in daylight. Apart from making the smaller insects brittle, IMS (with methyl alcohol) will tend to make the insects lose their wings readily if the wings are moved at all during mounting. It is also said to destroy DNA. In my view IMS and isopropyl alcohol should be avoided, at all costs, when preserving smaller (<2mm), winged insects.

John

John Noyes
Scientific Associate
Department of Life Sciences
Natural History Museum
Cromwell Road
South Kensington
London SW7 5BD 
UK
jsn at nhm.ac.uk
Tel.: +44 (0) 207 942 5594
Fax.: +44 (0) 207 942 5229

Universal Chalcidoidea Database (everything you wanted to know about chalcidoids and more):
www.nhm.ac.uk/chalcidoids?

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Ken Kinman
Sent: 23 April 2014 03:24
To: taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] Palcohol?

Hi all,
      I've never stored insects in alcohol, but I've read that both ethanol and isopropanol can make them brittle (some say ethanol is worse, others say isopropanol is worse).  But there does seem to be agreement that concentrations above 70% of either of them can definitely make them brittle.  Anyway, I am wondering if the addition of glycerol helps mitigate that problem.  A few of my spider specimens were saved from dehydration when the alcohol evaporated over the years, but the glycerol kept them moist.                             -----------------Ken                   P.S.  I couldn't find anything about DNA being trashed by isopropanol.  It is often used to extract DNA, so does it only trash the DNA over a long time period?  Most of my spiders were collected in the 1970s.  

------------------------------------------------------------------------------------------------------------

> On 22.04.2014 13:15, John Noyes wrote:
> > Apart from trashing DNA, it also trashes many types of smaller 
> > insects by making them so stiff that the become difficult/impossible 
> > to card-mount or put on slides. The same also goes for IMS.
> >
> > John
> >
> > John Noyes
> > Scientific Associate
> > Department of Life Sciences
> > Natural History Museum
> > Cromwell Road
> > South Kensington
> > London SW7 5BD
> > UK
> > jsn at nhm.ac.uk
> > Tel.: +44 (0) 207 942 5594
> > Fax.: +44 (0) 207 942 5229
> >
> > Universal Chalcidoidea Database (everything you wanted to know about 
> > chalcidoids and more):
> > www.nhm.ac.uk/chalcidoids
> >
> >
> > -----Original Message-----
> > From: taxacom-bounces at mailman.nhm.ku.edu
> > [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Daniel 
> > Janzen
> > Sent: 22 April 2014 22:38
> > To: Neal Evenhuis
> > Cc: taxacom at mailman.nhm.ku.edu
> > Subject: Re: [Taxacom] Palcohol?
> >
> > It is my understanding that isopropyl alcohol trashes DNA or 
> > otherwise makes it very difficult to extract.  Think on that for 
> > pickling museum specimens.  I know of no circumstance where you can 
> > get (or ship) isopropyl but not get (or ship) 80-95% ethanol.
> >
> > Just a thought.   Dan Janzen
> >

 		 	   		  
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