Global infection of a highly derived Wolbachia lineage in Pentalonia aphids

Wolbachia (α-Proteobacteria) is an obligate intracellular symbiont known to infect more than 65% of insect species. However, only a handful of studies have documented Wolbachia infection within aphids (Hemiptera: Aphididae). In this study, we examined the prevalence and evolution of Wolbachia in aphids of the genus Pentalonia. A total of 260 colonies of Pentalonia nigronervosa and P. caladii aphids were collected on various host plants across the Hawaiian Islands, Guam, India, and Australia. Diagnostic PCRs were performed using Wolbachia specific primers to determine the infection frequencies across the aphid colonies. Genomic sequences including 16S rRNA, the Multilocus Sequence Typing (MLST) genes, and those from the Wolbachia bacteriophage WO were used to characterize the diversity and evolution of the Wolbachia strains. Infection rates among the field-collected colonies of P. nigronevosa and P. caladii in the Hawaiian Islands were similar and averaged at 83% and 82%, respectively. However, there was no association between Wolbachia infection in aphids and host plant use. Wolbachia was also detected in P. nigronevosa samples from Australia, India, and Guam, demonstrating generalized infections. Bacteriophage, 16S rRNA MLST sequences revealed that a highly diverged strain of Wolbachia (wPe) globally colonize Pentalonia aphids. The large divergence with the extant lineages that colonize other arthropods, suggests that wPe may be part of a novel supergroup recently identified in other aphid species.