par Timmermans, Johanne 
Président du jury Mardulyn, Patrick
Promoteur Roisin, Yves
Publication Non publié, 2025-06-02
Président du jury Mardulyn, Patrick
Promoteur Roisin, Yves
Publication Non publié, 2025-06-02
Thèse de doctorat
| Résumé : | Resource differentiation plays a crucial role in enabling coexistence among social insects, particularly in termite host-inquiline systems sharing the same termitarium. This study aims at disentangling the relationship between Constrictotermes cavifrons (host) and Inquilinitermes inquilinus (inquiline), placing it in the parasitism-mutualism continuum. Moreover, because obligatory inquilines face challenges in colony establishment due to the scarcity of suitable host nests, we explore how inquilinism shapes the reproductive strategies of the dyad in light of resource availability.In the first axis, we assessed potential costs imposed on the host by the inquiline. We investigated foraging and construction behaviors of the host through video recordings, and we analyzed dietary niches of the dyad using morphological, microscopic, and isotopic analyses of individuals and nest materials. Their vital spaces were also delimited inside the termitarium by dissecting the nest. Results indicate that C. cavifrons uses soil pellets for nest construction, and does not store food. Dietary segregation is clear, with C. cavifrons consuming microepiphytes (lichens and bryophytes) and I. inquilinus feeding on mineral-organic material, likely the dark material accumulated at the base of the nest. Spatial segregation further minimizes competition, with I. inquilinus digging its galleries out of the dark organic-rich zones while C. cavifrons constructs its own, friable galleries out of clay mixed with feces and saliva.In the second axis we carried out an analysis of microsatellite markers to investigate the reproductive strategies of the dyad. Host colonies were predominantly simple families (95%) exhibiting a monogamous pattern and living in a monodomous nest, consistent with their use of widely available resources. In contrast, inquilines showed more complex structures, with 30% extended families, 5% mixed families, and frequent neotenics (25% of the nests). These patterns result from the simultaneous establishment of multiple incipient colonies within host nests, leading to competition, conflict, or merging. The use of parthenogenesis by female-female pairs was also firstly observed in the inquiline. These strategies highlight the inquiline’s reproductive adaptability to limited foundation sites.Finally, our results underscore how niche segregation and adaptative reproductive strategies mitigate conflict and enable I. inquilinus to persist as a commensal species, imposing no clear cost on the host, within the limited space of the host's nest. |
