We aim at describing and comparing gut microbial assemblages across closely related fruit flies with diverse feeding strategies. As such the project focuses on representatives of the main fruit fly pest genera found in Europe and Africa: Ceratitis and Bactrocera (including Zeugodacus), by comparing the gut microbiomes of target species with different feeding strategies (from polyphagous, to monophagous), and by quantifying the effects of host plant choice, interpopulation variability and rearing history. This will provide the necessary baseline data for innovative research on relationships between insect endosymbionts, host range spectrum, and metabolic processes.