Behavioral Response of Formosan Subterranean Termites (Isoptera: Rhinotermitidae) to Soil with High Clay Content

Although our previous study showed that clay caused aggregation and particle transport behavior of the Formosan subterranean termite, Coptotermes formosanus, it is not known whether clay is preferred by C. formosanus as a substrate to live in and for bio-structure construction. In the present study, first a 24 h two-choice test was conducted to test the preference of termites to sand versus clay, both with 70 % water saturation. Significantly more termites aggregated on clay from 10 min after release on, and significantly longer tunnels were observed under clay blocks compared to sand. Two-choice tests with a 2-weeks duration were then conducted at three water saturation levels. Results showed that at 70 % saturation, a significantly higher percentage of termites aggregated in clay as compared to sand, and significantly more clay particles were deposited for shelter tube construction. At 30 and 50 % saturation however, no difference in termite aggregation was observed between clay and sand, and no shelter tubes were constructed. Our study shows that only clay with high moisture is preferred by C. formosanus. The water retention ability and physical properties of clay favor bio-structure construction.