Intraspecific interactions in a community of arboreal nesting termites (Isoptera: Termitidae)

In coconut plantations of northern New Guinea, the arboreal nesting termite community comprises three species: Nasutitermes princeps, N. novarumhebridarum, and Microcerotermes biroi. In order to assess the importance of intraspecific interactions in this community, we conducted pairwise encounters between batches of individuals in the laboratory and between entire nest populations in seminatural conditions. Three levels of agonism were defined in laboratory bioassays: anagonism, moderate agonism, and strong agonism. Anagonism was observed during all control tests with homocolonial groups and in some tests with allocolonial groups of all species. Moderate agonism included initial aggressiveness that subsequently faded out, and initially passive encounters where aggression progressively built up and led to fighting. Strong agonism corresponded to initial aggressiveness and fighting. Results obtained in laboratory bioassays were consistent with bioassays in seminatural conditions. When Nasutitermes colonies were anagonists in laboratory bioassays, their foraging trails merged without aggression in field tests. N. princeps nests that were moderately agonistic in laboratory tests fought and either continued to avoid each other or finally joined after elimination of the most aggressive individuals. The most aggressive M. biroi and N. princeps colonies fought and their foraging trails diverged afterward. Direct attacks on alien nests were witnessed in M. biroi. In all species, anagonism occurred in 21-34% of the combinations tested, between either geographically close or distant colonies. An exception was a group of 112 anagonist nests of N. princeps, which most probably constituted a supercolony. The level of agonism between Nasutitermes colonies was constant during the wet and dry season. Termite colonies excluded each other, both intra- and interspecifically, from the coconut trees, and their territories seem distributed in a mosaic pattern. Agonism between colonies may result in the elimination of the weakest colonies or in trail divergence, maintaining this mosaic. In contrast, lack of agonism between some colonies suggests the possibility of colony fusion and gene exchanges without nuptial flights.