Conserved gut microbiota in a herbivorous beetle mediates the degradation of host plant defenses

The gut microbiome of insects is known to play essential roles in host's fitness through a variety of functions including nutritional supplementation of diets, influencing development, and mediating parasite and pathogen resistance. In this thesis, we have explored the role that gut microbes may play in the degradation of plant secondary metabolites that are toxic to insects, focusing primarily on the pine weevil (Hylobius abietis) and terpenoids. Characterization of the gut bacterial community of the pine weevil revealed a relatively stable microbiota at higher taxonomical levels (e.g. family and genus) across different locations in Europe, especially within the Enterobacteriaceae family. Despite showing some variation between locations, the pine weevil harbors a "core microbiota" composed of close relatives of Rahnella sp, Erwinia sp and Serratia sp.