Termite-Termite Interactions: Workers as an Agonistic Caste

Termite soldiers are a defensive caste. Their heavily sclerotized head capsules can be equipped with hard mandibles capable of crushing, pinching, piercing, or slashing predators. Soldier castes of many phylogenetically advanced species have well-developed frontal glands and are capable of exuding or spraying chemical secretions. Such chemical armaments are toxic, irritable, or oily fluids which can impair physiological, sensory and/or mechanical faculties of the recipient (Prestwich, 1979). Termite soldiers are thus formidable opponents for ants and vertebrate predators. Soldiers are fed by workers and their behavior within the colony is generally limited to signaling alarm, participating in defense, and organizing foraging expeditions (Stuart, 1969; Traniello, 198 l). Despite their specialization, however, soldiers are not the only defensive caste in a termite colony: worker termites of some species (from four families) are known to be able fighters in termite-termite aggressive interactions [Kalotermitidae (Grassi and Sandias, 18961897; Dropkin, 1946); Hodotermitidae (Nel, 1968); Rhinotermitidae (Pickens, 1934; Cl6ment, 1978); Termitidae (Dudley and Beaumont, 1889a,b; Andrews 1911)]. This paper explores intra- and interspecific agonistic encounters among termites, and focuses on the roles of workers and soldiers in such conflicts. The report is presented in two sections, corresponding to two sets of experiments on this topic. Section A describes a field manipulation inducing intraspecific encounters among colonies of Nasutitermes corniger in Costa Rica. Section B presents data on laboratory experiments examining intra- and interspecific interactions among four species of Panamanian termites.