Nest architecture influences the survival of termites with different nesting strategies following pathogen exposure

Homeostatic nests are a ubiquitous characteristic of social insects, including termites. While some distinctive nest design features may allow for species identification, particular nest types are generally associated with phylogeny and life history strategy. Previous studies have analyzed the nest architectures of various social insects, and identified specific behaviors to defend the nest from predators, pathogens, and parasites. However, the influence of nest structure on termite survival against parasites or pathogens has not been empirically examined, despite the abundance of potential pathogens within social insect habitats. To test the effect of nest architecture on termite survival, five types of corrugated cardboard nest structures were constructed based on naturally occurring designs. Replicate groups of individuals from three species with different natural nesting strategies (Zootermopsis angusticollis, one-piece nest; Reticulitermes flavipes, intermediate nest; and Nasutitermes corniger, separate, arboreal nest) were exposed to either a control solution or conidia suspension of the generalist entomopathogen Metarhizium anisopliae. After 20 days, nest architecture was found to be a significant, independent predictor of survival in all three species. The nest that fostered the highest survival rate varied among species, indicating that termite survival relies in part upon the particular nest structure to which a species is adapted. This further supports the adaptive role that nests have had on social immunity and termite evolution.