| Termites construct nests that are often structurally species-specific. They exhibit a high diversity of nest structures, but their nest evolution is largely unknown. Current hypotheses for the factors that influenced nest evolution include adaptations that improved nest thermoregulation, defense against predators, and competition for limited nest sites. Studies have shown a lower prevalence of pathogens and parasites in arboreal nesting animal species compared to ground nesters. Nest building behavior is plastic and can adapt to changing environments. As termites can detect and avoid pathogens, I hypothesized that the evolution of arboreal termite nests was an adaptation to avoid infection. To test this, bacteria and fungi from nest cores, trails, and surrounding soils of the arboreal nesting Nasutitermes acajutlae were cultured. Abiotic factors such as temperature, relative humidity, and light were measured to elucidate how they influenced the interactions between termites and microbes. Fungi associated with N. acajutlae were identified to determine the potential pathogenic pressures these termites encounter in their nest as compared to the external environment. To determine the effect of nest structure on survival, termites representing the one-piece ( Zootermopsis angusticollis), intermediate (Reticulitermes flavipes) and separate (Nasutitermes corniger) type nests were exposed to the fungal entomopathogen Metarhizium anisopliae, and the termites' survival tracked over a 20-day period in five different artificial nest architectures. A protected nest environment and the benefits of socially mediated immunity within those nests have also been implicated in promoting termite eusocial evolution. In order to test whether immune protein production is socially induced in termites, the SDS-PAGE protein profiles of naive Z. angusticollis nymphs, and nestmates directly exposed to M. anisopliae were examined following social contact. The results presented in this dissertation demonstrate that arboreal termites have lower nest microbial loads and diversity compared to surrounding soils, and that the degree of social contact as influenced by nest architecture can significantly affect termite survival. This research suggests that pathogens played a role in furthering evolution and ecology of termite nesting behavior, and lays the groundwork for future studies in this area. |
