Diurnal and seasonal activity patterns for the western drywood termite, Incisitermes minor, in naturally infested wood

Activity of colonies of the western drywood termite, Incisitermes minor, was measured by acoustic emission (AE) in five loquat (Eriobotrya japonica) logs. All logs came from the same tree and were similar in length and age. The AE activity was monitored for one year under ambient conditions in a small wooden structure maintained at the University of California Richmond Field Station. All AE, temperature, and humidity data were automatically collected and entered into a database for analyses. Termites in all five logs displayed a similar diurnal cycle of activity, peaking in the late afternoon. AE activity was greater during the warmer summer months compared to the cooler winter months. Daily and seasonal fluctuations in temperature were significantly associated with activity, whereas humidity did not appear to affect activity. Possible mechanisms that drive the circadian rhythm and the possible implications for inspections and post-treatment analysis will be discussed.