Social wasps as a model to study host-microbe interactions

Social insects represent the most widespread group of organisms on the Earth. The understanding of the ecology of social insects, such as social wasps must not disregard from the study of their microbial communities. In this thesis, I have treated the microbial symbioses developed in social wasps under different points of view and in different conditions. Concerning the first task, I investigated how the gut microbial communities (bacteria and fungi) switch during the hornet ontogenetic development (from juvanile to adult life stages), and this phenomenon was studied in the invasive alien species (IAS), Vespa velutina nigrithorax, currently present in Italy. I demonstrated that the gut microbial communities of V. velutina were signficantly affected by the phenotypic variability and ontogenetic dynamics. Thus, the stage-related gut physiological changes during V. velutina development according to the stage-related diet could play a combined role in the evolution of the gut microbial communities. Regarding the second task, I performed the comparison of the gut microbial communities composition between the worker stages of the alien species V. velutina mentioned above, the native hornet Vespa crabro and their main prey Apis mellifera. The structure of the microbiota was significant associated with the insect species (V. crabro, V. velutina and A. mellifera), highlighting the presence of enriched Lactic Acid Bacteria (LAB) -related filotypes, differentially associated to the hornets and honey bees. Instead, the organization of the mycobiota appeared significantly related to the insect genus (Apis or Vespa) but not with the insect species. Thus, suggesting that the gut fungal communities of the hornets could be more affected by the environmental stimuli. Furthermore, unlike the honey bees, Saccharomycetales appeared as the comprehensive order of the entire mycobiota composition in both hornet species. Concerning the third task, I evaluated the effect of different environmental stimuli on the gut microbial composition ...