Stop the Rot

Ancient artworks are as popular with beetles, bacteria and fungi as they are with us. But new techniques are helping to win the battle to save our cultural heritage. Emma Young reports

The scene of the crime is an art gallery in Caracas, Venezuela. The victim lies on her back, riddled with holes. This is no one-off: all the evidence points to a group of suspects who have orchestrated a series of vicious attacks worldwide. Special agents have been tracking them for years.

The scene of the crime is an art gallery in Caracas, Venezuela. The victim lies on her back, riddled with holes. This is no one-off: all the evidence points to a group of suspects who have orchestrated a series of vicious attacks worldwide. Special agents have been tracking them for years.

What sets this whodunit apart is that the victim isn't a person; it is an 18th-century wooden statue of the Virgin Mary, the Immaculada. And it's in danger of being turned to sawdust by beetles. The statue is part of the estimated one-third of Venezuela's artefacts that have become a feast for bugs.

Heat and humidity make tropical countries ideal breeding grounds for these pests, but the problem is not confined to equatorial regions. Across the globe, insects, bacteria and fungi are ripping into Old Masters, statues, paintings and historical documents.

Now, a new breed of art conservator is fighting back. Using the skills of a detective and a biologist, they are revealing the precise identities of the perpetrators and dreaming up ingenious ways to foil them - one of which is to be tested on the Immaculada.

People have tried for centuries to protect artworks, but methods of pest control brought their own problems. Fumigants can harm humans, and some treatments damage the environment: methyl bromide, for example, depletes the ozone layer. And some damage the works themselves. "There's a history of chemicals that have been found to cause damage," says the cell biologist Robert Koestler, the director of the Smithsonian Center for Materials Research in Maryland. Koestler and others realised that they needed to target their treatments more effectively. And first, they had to hone their skills in identifying the suspects.

Take fungal attacks. "The black stain left by some fungi is particularly difficult to get rid of," Koestler says. Enzymes can be used to remove the melanin deposits, but because melanin is basically lignin, removing it destroys the lignin in the paper. That can cause the paper to disintegrate. Knowing which fungus is to blame could help, because different strains might target the fungal melanin and ignore the lignin in the paper.

Before moving to the Smithsonian, Koestler was a conservator at the Metropolitan Museum of Art in New York. His team there included the microbiologist Maria Pia Di Bonaventura, who in 2000 began working on a project to identify the strains of fungi that were staining drawings by the 19th-century American artist Louis Comfort Tiffany.

Di Bonaventura, now at the American Museum of Natural History in New York, isolated fungal DNA from the drawings, sequenced it and compared the sequences with those in the US National Institutes of Health GenBank database. This revealed that species of Chaetomium were in the frame for grey and black stains, while brown stains were produced by species of Cladosporium. Knowing this means that treatment can be focused on the stain's removal, Di Bonaventura says.

Using DNA sequencing to identify infestations has huge potential. In another study, Christopher McNamara of Harvard University and his team used sequencing to find out what was eating stone blocks and carvings in Mayan ruins in Mexico. Studies revealed microbes on the surface of the stone, but last year, McNamara said DNA sequencing had uncovered a different community of organisms within, which were breaking down the limestone as they grew.

But it's still not clear how to kill them. "Any attempt will encounter serious difficulties in delivering the treatment to the target," McNamara says. But at least he has a clearer idea of what he's dealing with.

At UNU-Biolac, a UN university in Caracas, director José Ramirez and his colleagues have used the technique on faecal remains. "DNA typing is easy to perform and cheap," Ramirez says. Faecal "mugshots" like these can help in cases of mistaken identity.

Cigarette beetles and odd beetles, which are common pests, are omnivorous, which can make them museum-wreckers. "To a non-specialist, the two look similar," says Ruth Norton, the chief conservator at the Field Museum in Chicago. But the odd beetle is far more pernicious. "It can have a very extended lifespan and survive food scarcity," Norton says. Simple DNA analysis could allow curators to distinguish between odd beetles and cigarette beetles. If they find odd beetles at work, they'll know they need a comprehensive, long-term control strategy.

Most curators still use chemicals to keep pests in check, but being able to identify the organisms precisely is helping in the development of non-toxic alternatives. Koestler is exploring the possibility of suffocation. His preferred method is to seal an infested artwork in a plastic bag, then pump argon in and oxygen out. He and other researchers have been investigating the breathing and death rates of a wide range of insect pests.

Nieves Valentin of the Getty Conservation Institute in Los Angeles has found that at 40 per cent relative humidity and 20C, in an atmosphere where oxygen has been reduced to less than 300 parts per million and replaced with argon, the old house borer beetle takes at least 14 days to die, while the black carpet beetle perishes in just three. "Using this technique, anything that requires oxygen to stay alive will succumb," Koestler says.

Other researchers are experimenting with different gases and containers. At the Australian Museum in Sydney, Vinod Daniel uses nitrogen instead of argon. "Low oxygen in the chamber is the safest pest-killing technique," he says. But the method is expensive, especially in humid countries where the higher water content in the atmosphere allows pests to survive for longer without oxygen.

Another approach Daniel and colleagues are investigating is to "cook" the pests. They found that to kill all the usual suspects, an artefact must be heated to 52C and kept at that temperature for about six hours. This can be achieved simply by placing the infested object in a black plastic bag, inside a clear plastic bag, and leaving it in the sun.

This low-tech approach is ideal for use in developing countries. But heat treatment has a drawback: the expansion and contraction caused by changes in temperature and humidity can damage the artefact.

Then, you need to keep the bugs at bay once an item has been treated. "Some methods may work temporarily, but the chances of reinfestation are much higher in the tropics," Ramirez says. "And many countries in the tropics do not have the means for artificial climate control." This has left some conservators looking for alternative, non-toxic methods. One solution is biological control.

The approach was hotly debated in November at a symposium hosted by UNU-Biolac and attended by more than 100 delegates from Latin America, Europe and the United States. "Fighting biological agents with other biological entities, like bacteria, fungi, other insects and animals, could be interesting as a 'clean' control method," says Benoît de Tapol from the National Art Museum of Catalonia in Barcelona, who was among those who attended the meeting.

José Ramirez's trial on the Immaculada will involve inoculating the sculpture with Bacillus thuringiensis, a bacterium that produces a toxin. He hopes this will not only kill the beetles, but form spores that stay in the statue, vaccinating it against further attack.

This is an edited version of an article that first appeared in 'New Scientist'

Start your day with The Independent, sign up for daily news emails
ebooks
ebooksA special investigation by Andy McSmith
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Ashdown Group: Senior Accounts Assistant - Accounts Payable - St. Albans

£26000 - £28000 per annum + benefits : Ashdown Group: Senior Accounts Assistan...

Ashdown Group: Treasury Assistant - Accounts Assistant - London, Old Street

£24000 - £26000 per annum + benefits : Ashdown Group: A highly successful, glo...

Recruitment Genius: Installation and Service / Security Engineer

£22000 - £40000 per annum: Recruitment Genius: This company is part of a Group...

Recruitment Genius: Service Charge Accounts Assistant

£16000 - £18000 per annum: Recruitment Genius: Are you a a young, dynamic pers...

Day In a Page

General Election 2015: Chuka Umunna on the benefits of immigration, humility – and his leader Ed Miliband

Chuka Umunna: A virus of racism runs through Ukip

The shadow business secretary on the benefits of immigration, humility – and his leader Ed Miliband
Yemen crisis: This exotic war will soon become Europe's problem

Yemen's exotic war will soon affect Europe

Terrorism and boatloads of desperate migrants will be the outcome of the Saudi air campaign, says Patrick Cockburn
Marginal Streets project aims to document voters in the run-up to the General Election

Marginal Streets project documents voters

Independent photographers Joseph Fox and Orlando Gili are uploading two portraits of constituents to their website for each day of the campaign
Game of Thrones: Visit the real-life kingdom of Westeros to see where violent history ends and telly tourism begins

The real-life kingdom of Westeros

Is there something a little uncomfortable about Game of Thrones shooting in Northern Ireland?
How to survive a social-media mauling, by the tough women of Twitter

How to survive a Twitter mauling

Mary Beard, Caroline Criado-Perez, Louise Mensch, Bunny La Roche and Courtney Barrasford reveal how to trounce the trolls
Gallipoli centenary: At dawn, the young remember the young who perished in one of the First World War's bloodiest battles

At dawn, the young remember the young

A century ago, soldiers of the Empire – many no more than boys – spilt on to Gallipoli’s beaches. On this 100th Anzac Day, there are personal, poetic tributes to their sacrifice
Dissent is slowly building against the billions spent on presidential campaigns – even among politicians themselves

Follow the money as never before

Dissent is slowly building against the billions spent on presidential campaigns – even among politicians themselves, reports Rupert Cornwell
Samuel West interview: The actor and director on austerity, unionisation, and not mentioning his famous parents

Samuel West interview

The actor and director on austerity, unionisation, and not mentioning his famous parents
General Election 2015: Imagine if the leading political parties were fashion labels

Imagine if the leading political parties were fashion labels

Fashion editor, Alexander Fury, on what the leaders' appearances tell us about them
Phumzile Mlambo-Ngcuka: Home can be the unsafest place for women

Phumzile Mlambo-Ngcuka: Home can be the unsafest place for women

The architect of the HeForShe movement and head of UN Women on the world's failure to combat domestic violence
Public relations as 'art'? Surely not

Confessions of a former PR man

The 'art' of public relations is being celebrated by the V&A museum, triggering some happy memories for DJ Taylor
Bill Granger recipes: Our chef succumbs to his sugar cravings with super-luxurious sweet treats

Bill Granger's luxurious sweet treats

Our chef loves to stop for 30 minutes to catch up on the day's gossip, while nibbling on something sweet
London Marathon 2015: Paula Radcliffe and the mother of all goodbyes

The mother of all goodbyes

Paula Radcliffe's farewell to the London Marathon will be a family affair
Everton vs Manchester United: Steven Naismith demands 'better' if Toffees are to upset the odds against United

Steven Naismith: 'We know we must do better'

The Everton forward explains the reasons behind club's decline this season
Arsenal vs Chelsea: Praise to Arsene Wenger for having the courage of his convictions

Michael Calvin's Last Word

Praise to Wenger for having the courage of his convictions