Japanese

2002

To evaluate termite activity in monitoring stations non-destructively, metabolic gas from termites and acoustic emission from feeding activity of termites were measured. Ten stations with small wood stakes of Japanese red pine (Pinus densiflora) were buried around a house attacked by Coptotermes formosanus Shiraki. The air in the station was collected by sucking through a drilled hole of the station lid and analyzed using two types of ceramic gas sensors (odour- and hydrogen-selective sensors). Acoustic emissions (AEs) were detected by a PZT sensor attached on the cross section of one of the small stakes in the station. The concentrations of two components of the gas, odour and hydrogen, and AE event rate per 2 minutes were measured periodically. The infestation activity was also evaluated by visual inspection. In the early stage of the experiment, from the first to the third measurements, neither AEs nor significant concentration level of the gas components were detected, and no termites was observed in all the stations. After then termites were observed in the stations, and higher gas concentration of odour and hydrogen and larger numbers of AE events were detected. These findings suggest that termite attack in the monitoring station can be evaluated by using two types of the gas sensors and AE sensor.

Fig. 1. Test house and setup of the monitoring stations.
Fig. 2. Measurement of gases using the odor- or Hydrogen-selective sensor.
Fig. 3. AE monitoring in the monitoring station.
Table 1. Identifying values of odor-selective sensor in the monitoring stations.
The values described red show the peak identifying values in the monitoring station where termite attacks to wood stakes were observed, and the red line shows the boundary that the swarming of termite occurred.
Table 2. Identifying values of H2-selective sensor in the monitoring stations.
The values described red show the peak identifying values in the monitoring station where termite attacks to wood stakes were observed, and the red line shows the boundary that the swarming of termite occurred.
Table 3. AE event rates for 2minutes in the monitoring stations
The values described red show the AE event rates in the monitoring station where termite attacks to wood stakes were observed, and the red line shows the boundary that the swarming of termite occurred.
Table 4. Identifying values of odor- and H2-selective sensor and AE event in the monitoring stations after using termiticide.
The values described red show the peak identifying values and the AE event rates in the monitoring station where termite attacks to wood stakes were observed.
Table 5. Identifying values of odor- and H2-selective sensor in the centre of the nest.
The orange or blue line shows the boundary of swarming or before and after inserting termiticide to the three stations, respectively.

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