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A rare anobiid species in Japan, Priobium cylindricum, was found by chance in the restoration work of the Sambutsu-do of Rinnohji temple in 2008.Severe damage was found in some structural wooden pieces of the temple. The damage was very severe in hard (heart)wood, showing a powdery state and many holes of various sizes. Such severe damage of heart wood is commonly observed in timbers infested by termites, which are known to digest cellulose and hemicellulose effectively with enzymes such as cellulases. From observations of significant damage of heart wood of woodenhistoric buildings by Priobium cylindricum,we suspected that the anobiid might also utilize enzymes to damage cellulose of wood.Larvae of Priobium cylindricum were collected from infested wooden parts of the Sambutsu-do, and enzymatic activity of crude extract of the insect larvae was measured in comparison with that of a termite species, Hodotermopsis sjostedti, and other common insect species that affect cultural objects,such as Lasioderma serricorne, Attagenus japonicas and Anthrenus verbasci. As a result, crude extracts of the active larvae of Priobium cylindricum showed enzymatic activity of CMCase,xylanase and cellobiosidase.Comparative activity values of CMCase and xylanase were lower than those of a termite of Hodotermopsis sjostedti, but that of cellobiosidase which represents cellulase activity of crystalline cellulose was almost the same as that of Hodotermopsis sjostedti. However,larvae of Priobium cylindricum just before pupation did not show significant activity of such enzymes. This suggests that at least the active larvae of Priobium cylindricum that are infesting wood have detectable enzymatic activity. Larvae and adults of Lasioderma serricorne, larvae of Attagenus japonicas and adults of Anthrenus verbasci did not show significant cellulase activity. Crystalline cellulose content of the powdery parts infested by Priobium cylindricum was measured and compared with the healthy parts of the same timber.The result showed a decrease of crystalline cellulose content in the infested powdery parts, and this seemed to be consistent with the detection of cellulase activities from the active larvae of Priobium cylindricum.

Damage by wood borer insects is often observed with wooden objects or wooden historic buildings. X-ray CT (computer tomography) is a non-destructive method used to look into inside conditions of cultural objects. We tried to observe the change over time of damaged objects using X-ray CT and to detect the activity of some insects. By measuring damaged objects repeatedly, it was found that the activity of some insects was detectable as changes in their position inside the objects. Usually, it is not easy to appraise the effect of pest controlling treatment on wood borerinsects in actual damaged wooden pieces. Thus, we tried an application of X-ray CT to learn the effect of treatment in these cases. We divided a wooden block which was infected by Priobium cylindricum into two pieces. Only one piece was treated with approximately 60% CO2 for two weeks to eradicate insects. Then the activity of insects in both wooden pieces was observed over time by X-ray CT. Changes in the position of insect larvae were clearly shown in the non-treated wooden piece. On the other hand, no change was observed in the treated wooden piece. It was possible to estimate the effect of treatment of insect eradication by comparing the activities of insects over time by X-ray CT.

Much is not known about the ecological characteristics of wood-boring anobiids that infest wooden cultural properties in Japan except for those of a very frequently seen species, Nicobium hirtum. A very rare anobiid species in Japan, Priobium cylindricum, was found by chance in the restoration work of the Sambutsu-do of Rinnohji temple in 2008. Severe damage was found in some structural wooden pieces of the temple. The damage seemed to have rare characteristics: very severe damage in hard (heart) wood, parts extensively damaged to a powdery state and many holes of various sizes. However, damage was not clear by observation from the outside of the structure, especially when seen from the red painted layer of urushi. To know the approximate number of insects in the structure, surveys with an extensive large number of adhesive tapes (fly catcher ribbons) were used to see adult insect emergence in the warm season, from June to August. As a result, a large number of adult insects of Priobium cylindricum was trapped with the adhesive ribbon in the loft and basement spaces of Sambutsudo. On the other hand, there was no sign of emergence of the insect in the loft of the adjacent structure, Goho- endo. At another structure, Daiyu-in Nitenmon, Priobium cylindricum was not found by the same method. But other anobiids, Trichodesma japonicum and Sculptotheca hilleri, were trapped by adhesive ribbons in the loft. There were signs of infestation in the logs in the loft space, and dead insects of these species were also found on the floor. A live adult insect, a live larvae and droppings of Trichodesma japonicum were found from one of the damaged wooden pieces. From these observations it is highly possible that this anobiid has been involved in the same kind of damage to wooden logs and panels in the loft. The survey measure adopted here was very effective in catching the insects which may be involved in the present damage. Countermeasures must be proposed based on the results of such surveys.