Using the Thermo lignum heat process for treatment of natural history specimens
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Using the Thermo lignum heat process for treatment of natural history specimens - Research and practical experience. David Pinniger. Integrated pest management is essential to prevent insect damage to collections. Main components of IPM. Checking for pests Good housekeping

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David pinniger
Using the Thermo lignum heat process for treatment of natural history specimens-Research and practical experience

David Pinniger



Main components of ipm
Main components of IPM damage to collections

  • Checking for pests

  • Good housekeping

  • Good environment without extremes of temperature or humidity

  • Quarantine procedures to prevent introduction of live pests

  • Safe and effective control treatments for objects


Options for control treatments
Options for control treatments damage to collections

  • Low temperature

  • Anoxia

  • Carbon dioxide

  • High temperature


Low temperature
Low temperature damage to collections

  • -20°C for 2 weeks

  • -3o°C for 3-5 days

  • Effective but objects MUST be bagged to prevent moisture changes


Carbon dioxide
Carbon dioxide damage to collections

  • Effective, but exposure can take 3 weeks or more

  • Issues with registration in some countries


Anoxia
Anoxia damage to collections

  • Can be effective, but exposure can take 3 – 5 weeks

  • Difficult to maintain 0.3% oxygen for a long period

  • Not effective for some wood borers


Heat treatment historical use of heat to kill insects
Heat treatment damage to collectionsHistorical use of heat to kill insects

  • Heating food on sheets in tropics

  • Heating buildings to kill food pests

  • Heating insect drawers to kill carpet beetles


How high a temperature do you need to kill insects
How high a temperature do you need to kill insects? damage to collections

  • 52°C for most museum pests

  • 55°C g for some woodborers such as Hylotrupes

    1 to 2 hours exposure will kill

    insect eggs, larvae, pupae and adults


The main issues using heat with uncontrolled humidity
The main issues using heat with uncontrolled humidity damage to collections

  • Drying out of objects

  • Splitting, shrinkage and cracking


What happens if you control the humidity to a set level
What happens if you control the humidity to a set level? damage to collections

  • There is no transfer of moisture from the object to the environment

  • No shrinkage, cracking or distortion


Development of the thermolignum chamber
Development of the ThermoLignum Chamber damage to collections

  • Computer controlled heat/ chamber with RH control developed in Germany

  • UK chamber in operation since 1994

  • Chambers also in Austria, Norway Switzerland and Belgium


Operating system
Operating system damage to collections

  • The key is to introduce moisture in the heating cycle

  • Remove moisture in the cooling cycle


Practical treatments
Practical treatments damage to collections

Objects treated for major UK museums include:-

  • Books

  • Archives

  • Textiles

  • Leather

  • Upholstery

  • Wooden objects

  • Contemporary Art


Trials at the natural history museum london
Trials at the Natural History Museum London damage to collections

  • Mammals

  • Birds

  • Crustacea

  • Insects

  • Vascular plants

  • Bryophytes

  • Lichens

  • Fish


Further trials to measure relative humidity inside insect drawers
Further trials to measure relative humidity inside insect drawers

  • Generally very stable and consistent conditions in closed insect drawers

  • Key issues

    Spacing of drawers

    to ensure sufficient

    air circulation space

    [See Ackery et al 2005 for details]


What is the effect of heat treatment on dna
What is the effect of heat treatment on DNA? drawers

  • Some concerns that 52°C may affect subsequent DNA extraction from specimens

  • Trials of fresh and aged insect material at the NHM London showed no effect on DNA extraction

    [See Ackery et al 2004 for details]


Other research
Other research drawers

Kigawa et al2003

  • Tested the effects of a range of treatments on DNA of fungi and chicken meat

    Heat, freezing and anoxic treatments had no measurable effects on DNA




Key benefits in practice
Key benefits in practice UK

  • Speed of treatment - 24 hour cycle

  • No need to bag objects – particularly costly with large scale freezing programmes

  • Energy consumption - Need for detailed cost breakdown of -30C for 3-4 days and +52C for a few hours


Heat treatments in the future
Heat treatments in the future? UK

  • Ensure that there is clear understanding of the difference between heat treatments with and without controlled humidity

  • Demonstrate the low risks to collections from controlled humidity heat treatments

  • Wider acceptance in the light of advantages of labour input and energy budget