Wolbachia are a cytoplasmic sex ratio distorters that infect reproductive tissues of the host and manipulate their reproduction. These endosymbiont bacteria play an important part in the structure and dynamic of their host populations and species evolution. Wolbachia are a maternal ly transmitted bacterium but infection may also resulted from horizontal transfer between species. We studied Wolbachia infection in a cereal food web (aphid, parasitoid and predator species. The Wolbachia prevalence was analysed in relation with ecological traits of the host species and in evolutionary view (wsp gene phylogeny, transmission).