Impact of honeybee and native gut microbiota on Drosophila social behavior

Diplôme Master Impact of honeybee and native gut microbiota on Drosophila social behavior eng 2026-05-07 author Tajada Lostao Paula 980716 director Liberti Joanito 0000-0002-4158-2591 429670 Département de génétique et évolution (Genev) (BIANI) 50 In a few model organisms, the gut microbiota has been shown to influence social behavior via the gut-brain-axis, but such research has mainly focused on individuals rather than groups. Recent work in honeybees suggests that gut microbial communities may also affect colony-level dynamics. However, the mechanisms underlying these effects remain poorly understood, and models to study group-level behaviors are scarce. Drosophila melanogaster is a promising option owing to available genetic tools and previous work on microbiota-dependent neural and behavioral effects. Although flies lack the complex social structure of eusocial insects, their social behaviors can be tracked via advanced computational ethology approaches, and the ensuing microbial influences probed through gnotobiotic manipulations. In this study, we tested whether native and non-native (honeybee-associated) gut microbial communities influence social behavior in D. melanogaster. Germ-free flies were inoculated with either a 5-strain native microbiota or a 12-strain bacterial community transplanted from the honeybee, and video recorded the following day. Videos were analyzed with SLEAP, a pose estimation tool that tracks individual body parts over time, enabling high-resolution behavioral quantification. From the position data, we extracted key behavioral metrics to assess microbial effects on group behavior and activity. Fly guts were then dissected, and DNA was extracted for 16S rRNA gene amplicon sequencing to characterize bacterial composition and determine whether the inoculated microbes were present in the gut. Gut bacterial communities segregated by inoculation treatment, however not all inoculated strains were detected in the fly gut at the end of experiment. Among honeybee microbes, only Bifidobacterium was found in high relative abundance across samples, while native communities were dominated by Leuconostoc and Acetobacter. Despite these consistent microbial signatures, no significant effects of microbial treatments on fly social behavior or general activity were detected. This study highlights the potential of D. melanogaster as a tractabletransplantation system for exploring how gut microbes influence group behavior, and underscores that variation in microbiome assembly may influence or mask the emergence of microbiome-dependent effects on collective behavior. Dewey 590 Master in Biology, orientation of Molecular Biosciences, Genetics and Evolution 44 Département de génétique et évolution 162 false 1438 Groupe Liberti 7e704059-8c5a-4683-a832-c79601dc9649 Master thesis Restricted MasterThesis_PaulaTajada_28042026.pdf 2382553 application/pdf b56cce36613ddfd8ae6d819af8e33d2d286bddeb6c65746a8bfc247d7f3b5195 restrictedAccess Faculté des sciences / Section de biologie / Département de génétique et évolution

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