Using Quantitative Real Time PCR Melt Curve Analysis of Partial CO1 Sequence for Rapid Biotype Differentiation of Bactericera cockerelli (Hemiptera: Triozidae)

The potato psyllid, Bactericera cockerelli (Sulc), is a native of North America and occurs from Central America to Canada. A newly emerging plant pathogen, Candidatus Liberibacter solanacearum, associated with potato psyllids in North America and New Zealand, has become a major concern in many solanaceous crops worldwide. In potato, Solanum tuberosum L., the resulting disease is called zebra chip, but similar foliar and vascular symptoms have been reported in tomato, Solanum lycopersicum L., and peppers, Capsicum annuum L. To date, it is known that potato psyllids transmit Candidatus Liberibacter solanacearum, and they are the primary mode of pathogen spread in potato, tomato, and pepper agroecosystems in North America and New Zealand. Potato psyllids have a rather wide range of hosts, including wild plants, from which the psyllids may spread to crop plants. Within the insect species, B. cockerel, two biotypes are reported to exist. This differentiation was originally associated with hardiness to cold temperatures and can be monitored through genotypic variations in the cytochrome oxidase 1 (CO1) gene. In this study, two potato psyllid biotypes from four locations were delineated by melt temperature analysis following Sybr Green quantitative real-time PCR. In North Dakota, a northern extreme for the central range of potato psyllids, 100% of samples were "Central Biotype"; whereas, both biotypes (Central and Western) were found in Colorado where the two biotypes seem to overlap.