Till evolution do us part: The diversity of symbiotic associations across populations ofPhilaenusspittlebugs

Abstract

AbstractSymbiotic bacteria have played crucial roles in the evolution of sap-feeding insects and can strongly affect host function. However, their diversity and distribution within species are not well understood; we don’t know to what extent environmental factors or associations with other species may affect microbial community profiles. Here, we sequenced host and bacterial marker gene amplicons to survey the bacterial community composition across multiple populations ofPhilaenusspittlebugs.Host mitochondrial sequence data confirmed morphology-based identification of 6 species and revealed two divergent clades ofPhilaenus spumarius. All of them hosted the primary symbiontSulciathat was almost always accompanied bySodalis. Interestingly, populations and individuals often differed in the presence ofSodalissequence variants, suggestive of intra-genome 16S rRNA variant polymorphism combined with rapid genome evolution and/or recent additional infections or replacements of the co-primary symbiont. The prevalence of facultative endosymbionts, includingWolbachia, Rickettsia, andSpiroplasma, varied among populations.Notably, COI amplicon data also showed that nearly a quarter ofP. spumariuswere infected by parasitoid flies (Verralia aucta). One of theWolbachiaOTUs was exclusively present inVerralia-parasitized specimens, suggestive of parasitoids as their source and highlighting the utility of host gene amplicon sequencing in microbiome studies.