With just a few exceptions, we've realized excellent success with a single freeze/thaw cycle that attains -20C at the core for at least several days. The eggs of the odd beetle (Thylodrias contractus) have proven somewhat resistant to that single freeze/thaw routine. Where those have become apparent, we have had more success with two freeze/thaw cycles, with a few weeks at ambient temperature between. We believe that the interval between cycles allows the embryos to complete development and for the larvae to hatch. The larvae may be less tolerant of freeze damage. This is twice the work, and adds cost, but it seems justified.
Richard J. Pollack, PhD HARVARD UNIVERSITY Environmental Health and Safety (EH&S) Senior Environmental Public Health Officer 46 Blackstone St. Cambridge, MA 02139 Office: 617-495-2995 Cell: 617-447-0763 www.ehs.harvard.edu [email protected]<mailto:[email protected]> ________________________________ From: [email protected] <[email protected]> on behalf of Adrian Doyle <[email protected]> Sent: Friday, May 3, 2019 8:52 AM To: [email protected] Subject: RE: [pestlist] Freeze once or freeze twice? Dear all Double freezing shouldn’t be necessary so long as the core temperature of the object is at the correct temperature for the correct time Adie Mr Adrian (Adie) Doyle Integrated Pest Management Manager British Museum Property & Facilities Management Great Russell Street, London WC1B 3DG Tel: 020 7323 8207 Mobile 07813 363292 Also available by Radio Email: [email protected] The British Museum Great Russell Street, London WC1B 3DG britishmuseum.org<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.britishmuseum.org_&d=DwMFaQ&c=WO-RGvefibhHBZq3fL85hQ&r=GO7C3XN3WgFy2IP-bFBbnUs_CYntqj57Dprtl40-_KE&m=KRZ96gVQb0TQidSnHlvfv-rIEdUMfutjX4Fnk4u3UZ0&s=36vxZSWgKitptU6TkRXKP_dW_rS2PTl4_ObQXh0w8m0&e=> The security classification for this message is OFFICIAL From: [email protected] [mailto:[email protected]] On Behalf Of Sharon Penton Sent: 03 May 2019 13:51 To: [email protected] Subject: [pestlist] Freeze once or freeze twice? Good morning all, Some of my colleagues are adamant about freezing collection twice when dealing with pest. They freeze a first time then let everything get back to room temperature for a day or so then freeze again. Is this common practice? I've always thought if we can achieve a reliable -30 that should take care of all adults larvae and eggs? Would someone mind weighing in? Thanks! Sharon -- You received this message because you are subscribed to the Google Groups "Museumpests" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]<mailto:[email protected]>. To post to this group, send email to [email protected]<mailto:[email protected]>. 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