Interspecific competition and territory defence mechanism of Coptotermes formosanus and C. gestroi (Isoptera: Rhinotermitidae)

The Formosan subterranean termite, Coptotermes formosanus Shiraki and the Asian subterranean termite, C. gestroi (Wasmann) are most widely distributed species of Coptotermes and have sympatric zone in subtropics. Coptotermes formosanus colonized the overlapped areas earlier than C. gestroi did. Results of the no-choice bioassay and the foraging arena bioassay showed C. gestroi was more aggressive than C. formosanus. The result of foraging arena bioassay supported the long-held assumption that interspecific competition is an important regulatory factor to maintain termite colonial territories. Tunnel interception of the two species resulted in minor fight and then both species buried the connected tunnel at multiple locations shortly, which prevented fierce combats with heavy loose. Termite cadaver resulting from agonistic behavior is a stimulus for tunnel clogging and a deterrent for reopening the clogs. We speculate the neighboring territories of subterranean termites are maintained in a dynamic equilibrium. The tunnel interception would offer information of conditions of neighboring colonies. If both neighboring colonies are active, the minor fights resulting from tunnel interception would delineate the colonial boarder. If one colony is dead, the active colony could invade the vacated territory quickly through the existing tunnel system.