Variation and diversification of the microbiome of Schlechtendalia chinensis on two alternate host plants.

Schlechtendalia chinensis, a gall-inducing aphid, has two host plants in its life cycle. Its wintering host is a moss (typically Plagiomnium maximoviczii) and its main host is Rhus chinensis (Sumac), on which it forms galls during the summer. This study investigated bacteria associated with S. chinensis living on the two different host plants by sequencing 16S rRNAs. A total of 183 Operational Taxonomic Units (OTUs) from 50 genera were identified from aphids living on moss, whereas 182 OTUs from 49 genera were found from aphids living in Sumac galls. The most abundant bacterial genus among identified OTUs from aphids feeding on both hosts was Buchnera. Despite similar numbers of OTUs, the composition of bacterial taxa showed significant differences between aphids living on moss and those living on R. chinensis. Specifically, there were 12 OTUs from 5 genera (family) unique to aphids living on moss, and 11 OTUs from 4 genera (family) unique to aphids feeding in galls on R. chinensis. Principal Coordinate Analysis (PCoA) also revealed that bacteria from moss-residing aphids clustered differently from aphids collected from galls. Our results provide a foundation for future analyses on the roles of symbiotic bacteria in plant-aphid interactions in general, and how gall-specific symbionts differ in this respect.