Using primary endosymbionts as a tool for constructing potato psyllid (Bactericera cockerelli) phylogenies

Potato psyllids (Bactericera cockerelli) feed on the phloem of several solanaceous plants and are capable vectors of a phytopathogen that affects agriculturally significant crops. Within psyllids are many prokaryotic endosymbionts that are vertically transmitted to subsequent generations. In this study, evolutionary and coevolutionary  phylogenies of the potato psyllid were examined using a comparative analysis of host and primary endosymbiont phylogenetic trees.  The primary endosymbiont of potato psyllids, Candidatus Carsonella ruddii (CCr), is located inside specialized host cells called bacteriocytes and is essential to the survival of its host. CCr produce necessary amino acids missing from the potato psyllid’s diet. Individual potato psyllids collected between 2009 and 2011 were selected based on collection location and date. From these psyllids, DNA fragments of several ribosomal protein components (S7e, S8, L18e and L27Ae) and ribosomal genes from CCr were amplified. Each amplified DNA product was then purified by ethanol precipitation and sequenced using the Sanger method. The resulting sequences were used to build the comparative phylogenies of the psyllid host and primary endosymbiont.