EVALUATION AND INSECT CONTROL

Abstract

The Museum of the Banco Central del Ecuador in Quito has various collections, ranging from archaeological objects to modern art. The collections are generally sound because the environmental conditions in storage and exhibition areas are stable, maintaining suitable levels of temperature and relative humidity with small variations. An evaluation has been carried out on sculptures, wooden objects and graphic art, analyzing insect infestation and microorganism activity and identifying three levels of deterioration. The level of damage in sculptures and wooden artifacts was high for 8.1% of the objects in the collection, moderate for 12.5% and low for 38.2%. The presence of fungi in graphic art was moderate for 7.1 % of the collection and low for 11.0%, showing an opposite tendency. Objects made of cedarwood or those completely covered with polychromy, by artists like Caspicara, Velez or Sangurima, did not show any damage by insects. This may be due to the mixture of oil and proteinaceous medium that these artists applied on their sculptures to obtain very hard layers, thus avoiding insect attack. The city of Quito is located on an ecological plateau 2,880 meters above sea level, modified by its closeness to the Equator. Weather conditions are not extreme. There are two seasons: winter, with temperatures not lower than 7°C and precipitation between 79 and 175mm, and summer, with average temperatures of 22°C and precipitation between 20 and 112mm. The flora and fauna are not as exotic as in a tropical climate. In the museum artifacts we found Xestobium sp. (Coleoptera, Anobidae), identified by Dr Giovanni Onore, entomologist at the Pontificia Universidad Cat6lica del Ecuador. The same species has been found in other places in Quito, such as the Convent of San Francisco and the Jesuit Church. The insect measures 4.98 x 2.21mm and produces cavities up to 3.09mm in diameter. The use of chemical fumigants has been widespread in Ecuador and the application of phosphine was very common. This caused damage to artifacts which included metallic elements, besides being harmful to humans and causing environmental contamination. Gold, silver and metallic paint, materials susceptible to change, can be found in 66.2% of the sculptures and wooden objects in the museum; therefore another method with less risk had to be chosen. First we tested gamma radiation at the Escuela Politecnica Nacional, which has a radiation source and the infrastructure required. On a few occasions this process had to be used because gilded objects needed emergency treatment. However, a literature survey (1-6], and technical assistance from Spain through a course on this topic in Quito, helped us to apply inert gases to the eradication of insect pests. This procedure is now being applied using argon or nitrogen, barrier-film bags and Ageless oxygen scavenger, controlling the relative humidity by bubbling the gas through water and with solutions of magnesium chloride inside the bags; the equipment includes a relative humidity sensor and a remote sensor to monitor oxygen. Author's address: Restoration Department, Museo del Banco Central del Ecuador, Av. 10 de Agosto y Briceno, Quito, Ecuador.