Social symbionts or ‘‘inquilines’’ are arthropods—mites, isopods, springtails, crickets, flies, beetles, et cetera—that live in the nest of their ant hosts and have a symbiotic relationship with them. This relationship can be parasitic, commensalistic, or mutualistic. Relationships between ants and their diverse inquiline arthropod species are influenced by a range of ecological and life history characteristics. Inquilines live in a stable microclimate, have access to abundant food, and are protected from predators and most microbial pathogens through a ‘‘social immunity’’, which results in reduced virulence.
Ants are host to a diversity of symbiotic microorganisms. Given the presence of inquilines in the ant nest “microhabitat”, it is possible that the arthropods cohabiting in the nest acquire some of these microorganisms through host shifting. An example is Rickia wasmannii (Laboulbeniales), a fungal ectoparasite that is exclusively associated with Myrmica ants. Surveying ant nests in Hungary revealed fruiting bodies of Rickia on inquiline mites (Acaridae) and an inquiline fly larva (Diptera). These findings prove that R. wasmannii is capable of infecting phylogenetically unrelated “alternative” host species that co-occur in the ant nest “microhabitat”. However, no research has focused on the study of symbiotic associates of ant inquilines and most of our knowledge in this field is the result of fortuitous observational data. We have no idea about infection prevalences, seasonal patterns in infection, or (the extent of) host associations.
In this project, Myrmica ant nests will be sampled in Moelingen (Belgium) and Wijlre-Eys (The Netherlands). Ants and their inquilines will be sampled directly in their nests and screened in the laboratory for the presence of the ectoparasitic fungus Rickia wasmannii and other ectosymbiotic ant-associates. Nest variables and spatial organization of the sampled nests will be mapped to assess ecological and spatial drivers promoting Rickia infection of the ant microcosms. Ant–Rickia and inquiline–Rickia associations will be described based on morphology and DNA-based analyses, to confirm identity. Transmission of Rickia to its usual ant hosts and different inquilines found within Myrmica nests will be comparatively assessed in laboratory bioassays. Finally, there is the possibility to further explore the effect of Rickia infection on the fitness and behavior of both the ants and inquilines using survival tests and behavioral tracking experiments. The student will become familiar with the concept of integrative taxonomy in mycology, molecular research (DNA isolation, PCR amplification, Sanger sequencing, molecular phylogeny), and standard techniques in behavioral and spatial ecology. This project is a collaboration between the Research Group Mycology and the Terrestrial Ecology Unit, Department of Biology, Ghent University.
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