|■Tokyo National Research
Institute for Cultural Properties
||■Center for Conservation
|■Department of Art Research,
Archives and Information Systems
||■Japan Center for
International Cooperation in Conservation
|■Department of Intangible
DNA base sequence analysis
The Biological Science Section of the Center for Conservation Science has been promoting basic research on a new technology useful for detecting cultural property pests or pest identification methods that use DNA analysis. In order to specify the type of a cultural property pest, we generally identify the species by comparing the characteristics of the external morphology of the pest with information described in pictorial books and specialized guides. The similar external morphology of some pests will make type specification difficult and require specialized knowledge, including dissection and comparison of body details. In addition, we frequently experience a situation that allows us to obtain only limited parts of their bodies. Therefore, we have been analyzing some specific regions of DNA of cultural property pests, creating a unique database of base sequence information specialized for cultural property pests, and attempting to apply the “DNA barcoding” method to conduct type specification by using DNA obtained from unidentified samples.
We conducted a field survey from August 6th to 7th, 2020, in the historical wooden structures in Nikko, Tochigi Prefecture, in an attempt to capture several species of Anobiidae not registered in the database. With no effective traps available to capture target Anobiidae during the field survey, we conducted persistent research, checking every detail of the damaged wooden structures, which resulted in the capture of several species of Anobiidae.
To date, we have determined the DNA base sequences of about 40 major cultural property pests, including the individuals obtained from this field survey, and are now proceeding with the creation of the database. Included in it are many types unregistered in the public database. We can safely say that it is a matter of great importance to build a database specializing in cultural property pests.
Hereafter, we plan to develop technology to identify the pests from their body parts such as legs and wings, extract DNA from molting shells and manure left in damaged parts, and identify the “criminal” that has harmed cultural properties.
Research on the folklore pertaining to wall painting iconography
Investigation to evaluate the state of wall paintings damaged by pests
Tokyo National Research Institute for Cultural Properties is providing technical support and human resource training to restore wall paintings and the exterior walls of brick temples at the Bagan Archaeological Site in Myanmar. The decision to register Bagan as a world cultural heritage site was made at the 43rd session of the World Heritage Committee in 2019. In response to this decision, the “Bagan International Coordinating Committee (BICC)” was set up to work on improving the conservation system. The Committee is making arrangements for holding an international conference annually for information sharing and mutual adjustment so as to better utilize the initiatives taken in each support-providing country.
To collect information on such changes in local situations, we visited the Ministry of Religious Affairs and Culture of Myanmar (Naypyidaw) and the Bagan branch of the Department of Archaeology and National Museums from January 15th through 31st, 2020, and exchanged opinions on the direction of the future cooperative project. Responding to expectations of further technical assistance to local experts, we agreed to continue with our support activities.
In addition, research on the folklore pertaining to wall painting iconography was conducted following the previous one in July 2019. On-site investigation was also carried out to evaluate the state of wall paintings damaged by pests and to discuss countermeasures. With respect to the iconographic research, we gathered information showing the relation between the acceptance of Buddhism and an indigenous belief specific to Myanmar from local intellectuals. Also, to find the influence of the indigenous belief on wall paintings, we collected detailed examples primarily from Bagan. We now plan to expand the scope of this research beyond Bagan. Furthermore, the investigation of wall paintings damaged by pests revealed their destruction by termites and potter wasps. Therefore, we plan to conduct detailed research to establish countermeasures suitable to the local environment.
The Institute will continue providing technical support and undertaking research activities based on the opinions of local experts for comprehensive conservation of cultural properties at the Bagan Archaeological Site.
A scene from the workshop
The 2nd workshop for specialists on the new insecticidal treatment for historical wooden buildings, known as “humidity-controlled warm-air treatment,” was held on May 9th, 2019.
Pest-borne damage to historical wooden buildings risks not only the loss of important wooden materials but also building safety, as the wooden materials can become hollow, thus weakening the strength of the lumber construction material and the building itself. In response to severe pest-borne damage, the Rinno-Ji Temple at Nikko has undergone closure and repair. Fumigation with sulfuryl fluoride gas, which is known to have almost no effect on cultural properties, was performed to eradicate all noxious pests in the building. However, there are huge health and safety risks associated with the use of mass fumigation with poisonous chemical substances, and such treatment can also dissuade neighboring institutions from opening to the public.
To address this issue, humidity-controlled warm-air treatment was developed as a new insecticidal treatment. This method eliminates pests by increasing the temperature to 60 degrees Celsius while regulating the humidity without altering the water content of the wood, thus minimizing any damage to the wooden content. Two successful domestic cases have been reported with no significant damage found in buildings containing Urushi (Japanese lacquer) decorations. Subsequent examination of these cases indicates that the technology used in this new treatment is nearly ideal. Nevertheless, concerns have been raised regarding the number of technicians required and the cost involved, which must be addressed before formally establishing humidity-controlled warm-air treatment as a valid insecticidal treatment. Also, since this a newly developed treatment, its long-term performance is difficult to evaluate; there may be as yet unknown effects inherent in the use of this treatment.
Several issues must be resolved before humidity-controlled warm-air treatment can be considered to be an established insecticidal treatment method. We look forward to working over the long-term in cooperation with related organizations.
A scene from the workshop
A field survey on the damage situation of a historic building
Structures of historical buildings in Iran are mainly made of bricks or clay walls. However, wood is also used for making its roof frame, beams, window frames and so on. Damage of termites is found extensively in the central to southeastern parts of Iran, including Isfahan according to a preliminary survey conducted last fiscal year, and it is the major issue of the conservation of historical buildings in these regions. Termites are notorious as an insect pest for wooden materials. Their damage used to be widely found in Japan as well, but preventive measures have been gradually established to date. In order to support for establishing appropriate measures for conserving wooden built heritage and historical objects in Iran by sharing such knowledge, Tokyo National Research Institute for Cultural Properties (TNRICP) and Iranian Cultural Heritage, Handicrafts and Tourism Organization (ICHHTO) co-organized a workshop on insect damage to wooden cultural properties in Isfahan from April 17th through 19th, 2017.
From Japan, Mr. Masahiko TOMODA and Mr. Hiroki YAMADA of the Japan Center for International Cooperation in Conservation of TNRICP, Mr. Yukio KOMINE of the Center for Conservation Science of TNRICP and Mr. Kazushi KAWAGOE, Senior Researcher of Institute for Environmental Culture, participated in the workshop. From Iran, more than 20 experts got together from various parts of the nation, including Yazd, Tehran and Gilan, as well as Isfahan. On Day 1 and Day 3, presentations were given from both sides on materials and structures of historical buildings in both countries, and actual cases and monitoring surveys of insect pest damage to them. On Day 2, to discuss specific measures and others, all participants visited historical buildings to conduct a survey to identify termite damage and a test to install IGRs (Insect Growth Regulators) that does not affect the environment badly.
We heard that after the workshop, ICHHTO began preparation for establishing a new laboratory engaged in research on the prevention of termites in Isfahan. We believe that this workshop was able to contribute to conserving Iran’s valuable cultural heritage in any way.
installation of FIT
The Center for Conservation Science has been moving forward the basic research on “hot-air processing” as one of the new ways of exterminating insect pests in historical wooden architecture. It heats a structure while maintaining a steady moisture content so that wood or coloration sustains no damage, thereby exterminating insect pests that perforate members inside the building, such as columns and beams, or cause feeding damage to them.
In research such as this, it is ideal to use insect pests that actually cause damage when evaluating insecticidal effects. However, it becomes necessary to identify ways of collecting living insect pests efficiently or to establish an artificial rearing method to ensure their steady availability. To that end, we here discuss ways of capturing them.
In the case of ordinary sticky traps for capturing flying insects, because an adhesive substance adheres to the insect pests captured, it is difficult to catch them alive. We therefore looked into how they are captured by applying a method called a Flight Interception Trap (FIT). The FIT utilizes the characteristic that a flying insect shrinks its wings or legs and falls when hitting an obstacle and thus is made up of a transparent collision plate and a trapping container installed underneath.
When we conducted a survey on insect pests captured by using a FIT at a temple on Mt. Nikko this fiscal year, we succeeded in capturing the intended insect pests (mainly deathwatch beetles) alive. Being able to capture them alive can not only provide clues to elucidating their biology or life history but also lead to artificial rearing.
We believe that it is important to accumulate the results of such basic research activities as the foundation underpinning the development of new ways to exterminate insect pests in historical wooden architecture.