[Nhcoll-l] Freezer recommendation

[Simon Moore]

Thanks from me too concerning this information as I am often asked about the Best Way to use freezers in IPM.  The problem is that there are many variations on that theme: timing at -20deg. Is one of the main issues.  Presently, I advise 3 weeks at -20 then a 24 hour thaw to let eggs hatch, followed by another 3 weeks at -20.. This does seem to work well but the time taken to freeze a big collection takes rather long. I have also heard that 3 hours is the minimum time to kill larvae, pupae and imagoes.  
So, is there an agreed Best Practice method for this timing-wise?

With all good wishes, Simon

Simon Moore MIScT, RSci, FLS, ACR
Conservator of Natural Sciences and Cutlery Historian.

www.natural-history-conservation.com


> On 12 Aug 2024, at 08:28, Gali Beiner <gali.beiner at mail.huji.ac.il> wrote:
> 
> Dear all, and notably Chris, John, Beth, Dirk, George (and others who answered personally) - 
> 
> Thank you all for your helpful responses! I do agree that minus 80C is overkill for pest control purposes, so our main aim will be to find the best solution for our curators in terms of preserving tissue/DNA samples without being interfered, or at least not often interfered, by pest control requirements. 
> 
> One of the great functions of this List is to help the conservator to inform other staff of the best current practices in the field. Thank you all for helping me create good recommendations for our curators and collection managers! 
> 
> Gali 
> 
> On Sun, Aug 11, 2024 at 2:58 PM Gali Beiner <gali.beiner at mail.huji.ac.il> wrote:
> 
> Dear All, 
> 
> I'd like to ask for opinions regarding the choice of a freezer for our herbarium. The herbarium already has a -40C freezer for pest control purposes, but the combination of large quantities of incoming material for freezing with questions regarding additional possible uses for the freezer raised the question whether a new, additional freezer should be a -40C freezer or a -80C freezer. 
> 
> Generally speaking, pest control does not usually require temperatures as low as -80C, but DNA preservation (samples, tissues from non-herbal collections) does. Would you consider keeping a -80C freezer to serve both purposes as need arises? I'm curious to hear whether other herbaria use -80C freezers or choose higher temperatures. There is of course the question of cost vs actual requirements, and the main requirement right now is for pest control prior to entry into the herbarium. 
> 
> A penny for your thoughts, 
> 
> Gali
> -- 
> Gali Beiner (ACR)
> Conservator, Palaeontology Lab
> National Natural History Collections
> The Hebrew University of Jerusalem 
> Berman Building, Edmond J. Safra campus, Givat Ram
> Jerusalem 91904, Israel
> Fax. 972-2-6585785
> gali.beiner at mail.huji.ac.il
> https://nnhc.huji.ac.il/?lang=en
> 
> 
> -- 
> Gali Beiner (ACR)
> Conservator, Palaeontology Lab
> National Natural History Collections
> The Hebrew University of Jerusalem 
> Berman Building, Edmond J. Safra campus, Givat Ram
> Jerusalem 91904, Israel
> Fax. 972-2-6585785
> gali.beiner at mail.huji.ac.il
> https://nnhc.huji.ac.il/?lang=en
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