Zootermopsis

Abstract: Termites of the genus Zootermopsis have been used in many of the studies of cellulose digestion in the Isoptera. These termites are large, easy to handle, and abundant. The two species which have been used, nevadensis and angusticollis , are similar in habits and appearance but can be distinguished in most cases on the basis of the characteristics described by Sumner (1933). They show an overlapping distribution (Chap. 24 in Kofoid et al, 1934) and according to Kirby (1932) they contain the same species of cellulose-digesting protozoa. These are the large hypermastigote flagellates Trichonympha collaris, T. campanula , and T. spkaerica , and the smaller polymastigote, Trichomas termopsidis .

Abstract: Division of labor was studied in incipient colonies of the dampwood termite Zootermopsis angusticollisby recording repertoire size, behavior frequencies, and time budgets of larvae. Behavioral repertoire size increased with age: first- and secondinstar larvae were mainly inactive, whereas larvae of the third through seventh instars performed 64–100% of all tasks. The increase in repertoire size from the second to the third instar was abrupt; repertoire size and composition remained more or less constant for older instars. No correlation between age (instars III–VII) and tasks was identified, suggesting that colony labor is performed by a single functional caste that spans the third to the seventh instar without any age-based division of labor. Small colony size, low oviposition rate, simple nest architecture, a lack of spatial association of tasks, and the potential for attaining reproductive status appear to be associated with the lack of age-related behavioral specialization in Z. angusticollis.In effect, the absence of temporal polyethism in this species is likely a consequence of its nesting habits and physiological and developmental constraints.

Abstract: Cleveland ('23) pointed out that protozoa are found principally in those species of termites feeding upon wood, and by means of a well-planned series of experiments ('24) upon two wood-eating species, Reticulitermnes flavipes and Zootermopsis angusticollis, showed that when deprived of their protozoa the members of a colony were unable to survive more than 30 days upon a diet of wood or filter paper. If the protozoa were restored the termites lived 6 months or longer. This indicated that the relationship between the protozoa and the termite was one of symbiosis. It was proposed that this symbiosis could be explained along the following lines: The termite ingests and comminutes the wood, the protozoa digest the cellulose in it giving rise to sugar, and the latter is absorbed and utilized by the termite. The experiments of Trager ('34) demonstrating the cellulose-digesting capacity of one of the protozoa, Trichornowas termiopsidis, support this explanation of the symbiotic relationship. Several observations point toward the possibility that wood-digesting enzymes are also synthesized by the termites themselves. Holdaway ('33) has reported that Eutermes exitiosuts contains no protozoa yet is active in destroying wood. Analyses of nest material of E. exitiosis by Cohen ('33) show that the components of wood are not present in the same proportions in the pellets as in the wood,' the cellulose fraction in the pellets being materially less than in wood. It is possible that bacteria are responsible for wood digestion in E. exitiosus since they are reported to be present (Holdaway, '33). Cleveland ('28) observed marked differences in the longevity of wood-fed defaunated termites of different species and concluded that further investigations might show that some termites could live indefinitely upon wood even if their normal protozoan fauna were removed. The wood and pellets were not analyzed in these experiments and it is not known to what extent the