Culture independant microbial community analysis of economically important psyllid pests

The potato psyllid, Bactericera cockerelli, is an emerging agricultural pest of solanaceous crops such as potato, tomato, and peppers. Resident populations of potato psyllid occur in the southern US, Mexico, Central America, and New Zealand. Annually, the potato psyllid range expands north from Texas and California through the central US and Pacific Northwest into Canada following optimal breeding temperatures. The potato psyllid is the vector of Candidatus Liberibacter solanicearum, the causal agent of Zebra Chip of potato. To better understand factors affecting the transmission of Candidatus Liberibacter solanicearum, the bacterial symbiont communities of individual potato psyllids were assessed using 16s 454 pyrosequencing. The psyllids analyzed were collected from 2008-2011 from the central and western United States, Central America, and New Zealand, with carrot psyllids (Trioza apicalis) included as an outlier. Pyrosequencing results were used to quantify Liberibacter infection, identify differences in symbionts between populations, and to determine if bacterial symbiont communities can be used as an identifying trait of a population. 16s sequences were analyzed using the Qiime 1.5 suite (qiime.org) with sequences being identified using the RDP database (http://rdp.cme.msu.edu). Clustering analysis separated the psyllids based on their bacterial symbionts into groups that reflected their location, though disproportionately high concentrations of certain bacteria skewed some results. Pyrosequencing was able to detect Liberibacter in lower concentrations than traditional or quantitative PCR methods, providing a clearer picture of the severity of the Candidatus Liberibacter solanicaerum outbreak.