Means (± SE) of the bacterial/host gene copy ratio and statistical testsa.

aValues correspond to the mean number of symbiont gene copies ± SE (16S rDNA for Portiera, dnaK for Hamiltonella and gltA for Rickettsia) divided by the number of nuclear gene copies (actin gene). Kruskal-Wallis and Mann-Whitney nonparametric tests were performed with a probability level of significance of 0.05. Means marked with the same letter are not significantly different (Mann-Whitney test). For Kruskal-Wallis tests, p-values are indicated. Bold typeface indicates significant effects. n -number of individuals used for the quantifications.