Title: Incidence of “Candidatus Liberibacter solanacearum” in potato psyllids collected in the south-central United States Authors
Submitted to: American Journal of Potato Research
Publication Type: Proceedings
Publication Acceptance Date: April 1, 2010
Publication Date: N/A
Technical Abstract: In the last 10-15 years, the “zebra chip” (ZC) disease of chipping potatoes has been causing significant economic damage in the US, especially in Texas, Nebraska, Kansas, Colorado, and Wyoming. The disease also occurs in Mexico, Central America, and was recently reported in New Zealand. In about 2007, ZC was found to be associated with the potato-tomato psyllid (Bactericera cockerelli), although the exact nature of the association was unknown at that time. In 2008 an alpha-proteobacterium designated Candidatus Liberibacter psyllaurous (syn. Ca. L. solanacearum) was found to be transmitted to solanaceous hosts, including potato, by the potato psyllid. In order to gain a better understanding of the nature of the psyllid-bacterium association, beginning in January of 2009 we have been collecting psyllids weekly from sticky traps placed at numerous locations in Texas (especially the lower Rio Grande Valley), Nebraska, and Kansas. Most of the insects were tested individually by PCR for Ca. L. solanacearum, but during the peak insect period (Apr.-Aug.) some were tested in pairs. Between January and October, 2009, a total of 2,162 nucleic acid extractions were tested, representing 2,424 insects. Of these, 2.3% were positive for the bacterium. The relatively low incidence of the bacterium in the insects may reflect the relatively low amount of ZC seen in this region in 2009. Additionally, 90 potential “reservoir” host plants (Solanum elaeagnifolium, Lycium berlandieri, Cynanchum leave, and Solanum triquetrum) were tested for Ca. L. solanacearum but only one S. elaeagnifolium was positive. The insect testing is continuing weekly and results of the 2010 testing will be discussed.