Metagenomic analysis reveals changes of the Drosophila suzukii (Matsamura) microbiota in the newly colonised regions

The spotted wing drosophila, Drosophila suzukii (Matsumura) (Diptera, Drosophilidae) is a highly polyphagous pest of a wide variety of wild or cultivated berry and stone fruit. Originating from Southeast Asia it has recently invaded a wide range of regions in Europe and North-America. It is well known that insect microbiotas may significantly influence several aspects of the host biology and play an important role in invasive species introduction into new areas. However, in spite of the great economic importance of D. suzukii, a limited attention has been given so far to its microbiota. In this study, we present the first in-depth characterization ofgut bacterial diversity from field (native and invasive range) and lab-reared populations of this insect. The gut bacterial communities of field insects were dominated, regardless of their origin, by two families of the phylum Proteobacteria: Acetobacteraceae and Enterobacteriaceae, while Firmicutes, mainly represented by the family Staphylococcaceae, prevailed in lab-reared population. Locality was the most significant factor in shaping the microbiota of wild flies. Moreover, a negative correlation between diversity and abundance of Enterobacteriaceae and the time elapsed since the establishment of D. suzukii in a new region was observed. Altogether our results indicate that habitat, food resources as well as the colonization phase of a new region contribute to shape the bacterial communities of the invasive species which, in turn, by evolving more quickly, could influence host adaptation in a new environment