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 Checking for pests Good housekeping Good housekeping Good environment without extremes of temperature or humidity Good environment without extremes of temperature or humidity Quarantine procedures to prevent introduction of live pests Quarantine procedures to prevent introduction of live pests Safe and effective control treatments for objects Safe and effective control treatments for objects

Options for control treatments Low temperature Low temperature Anoxia Anoxia Carbon dioxide Carbon dioxide High temperature High temperature

Low temperature -20°C for 2 weeks -20°C for 2 weeks -3o°C for 3-5 days -3o°C for 3-5 days Effective but objects MUST be bagged to prevent moisture changes Effective but objects MUST be bagged to prevent moisture changes

Carbon dioxide Effective, but exposure can take 3 weeks or more Effective, but exposure can take 3 weeks or more Issues with registration in some countries Issues with registration in some countries

Anoxia Can be effective, but exposure can take 3 – 5 weeks Can be effective, but exposure can take 3 – 5 weeks Difficult to maintain 0.3% oxygen for a long period Difficult to maintain 0.3% oxygen for a long period Not effective for some wood borers Not effective for some wood borers

Heat treatment Historical use of heat to kill insects Heating food on sheets in tropics Heating food on sheets in tropics Heating buildings to kill food pests Heating buildings to kill food pests Heating insect drawers to kill carpet beetles Heating insect drawers to kill carpet beetles

How high a temperature do you need to kill insects?  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 Drying out of objects Drying out of objects Splitting, shrinkage and cracking Splitting, shrinkage and cracking

What happens if you control the humidity to a set level? There is no transfer of moisture from the object to the environment There is no transfer of moisture from the object to the environment No shrinkage, cracking or distortion No shrinkage, cracking or distortion

Development of the ThermoLignum Chamber Computer controlled heat/ chamber with RH control developed in Germany Computer controlled heat/ chamber with RH control developed in Germany UK chamber in operation since 1994 UK chamber in operation since 1994 Chambers also in Austria, Norway Switzerland and Belgium Chambers also in Austria, Norway Switzerland and Belgium

Operating system The key is to introduce moisture in the heating cycle The key is to introduce moisture in the heating cycle Remove moisture in the cooling cycle Remove moisture in the cooling cycle

Practical treatments Objects treated for major UK museums include:- Books Books Archives Archives Textiles Textiles Leather Leather Upholstery Upholstery Wooden objects Wooden objects Contemporary Art Contemporary Art

Trials at the Natural History Museum London Mammals Mammals Birds Birds Crustacea Crustacea Insects Insects Vascular plants Vascular plants Bryophytes Bryophytes Lichens Lichens Fish Fish

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? Some concerns that 52°C may affect subsequent DNA extraction from specimens 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 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 Kigawa et al 2003 Tested the effects of a range of treatments on DNA of fungi and chicken meat 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

Practical treatments of natural history collections in the UK Scarborough, England

Practical treatments of natural history collections in the UK Kew Herbarium

Key benefits in practice Speed of treatment - 24 hour cycle Speed of treatment - 24 hour cycle No need to bag objects – particularly costly with large scale freezing programmes 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 Energy consumption - Need for detailed cost breakdown of -30C for 3-4 days and +52C for a few hours

Heat treatments in the future? Ensure that there is clear understanding of the difference between heat treatments with and without controlled humidity 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 Demonstrate the low risks to collections from controlled humidity heat treatments Wider acceptance in the light of advantages of labour input and energy budget Wider acceptance in the light of advantages of labour input and energy budget