|Fisher, Tonja -|
|Sengoda, Venkatesan -|
|Nissinen, Anne -|
|Lemmetty, Anne -|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 11, 2010
Publication Date: August 11, 2010
Repository URL: http://hdl.handle.net/10113/43949
Citation: Munyaneza, J.E., Fisher, T., Sengoda, V.G., Garczynski, S.F., Nissinen, A., Lemmetty, A. 2010. Association of 'Candidatus Liberibacter solanacearum' with the Psyllid, Trioza apicalis (Hemiptera: Triozidae) in Europe. Journal of Economic Entomology 103(4):1060-1070. Interpretive Summary: The carrot psyllid is a serious pest of carrots in northern and central Europe, where it can cause up to 100% yield loss. Mechanisms by which this insect causes damage to carrots are not yet known. Researchers at the USDA-ARS Wapato, in collaboration with scientists at MTT Agrifood Research in Finland, conducted studies to investigate whether plant pathogens may be associated with this insect. For the first time, it was discovered that carrot psyllids damage carrots by injecting into plants a new species of the bacterium Liberibacter, recently found to severely affect potatoes and several other crops in the United States and many other countries. Information from this research will help affected carrot producers in Europe and elsewhere reduce damage caused by this important plant pathogen by effectively monitoring and managing the carrot psyllid, its insect vector.
Technical Abstract: Carrot psyllid (Trioza apicalis Förster) is a serious pest of carrots (Daucus carota L.) in northern and central Europe. Carrots exhibiting symptoms of psyllid damage were observed in commercial fields in southern Finland in 2008. Symptoms in affected plants included leaf curling, yellow and purple discoloration of leaves, stunted growth of shoots and roots, and proliferation of secondary roots. Mechanisms by which carrot psyllid induces symptoms in plants are not understood and no plant pathogens have yet been associated with this insect. Given recent association of liberibacter with several crops affected by psyllids, an investigation on whether this bacterium may be associated with carrot psyllid was conducted. PCR primer pairs OA2/OI2c and LsoF/OI2c, specific for the 16S rRNA gene from “Candidatus Liberibacter solanacearum”, generated amplicons of 1,168-bp and 1,173-bp, respectively, from DNA extracted from field-collected psyllids (61 and 36.6%, respectively), laboratory-reared psyllids (70 and 33.3%, respectively), field-collected petioles from symptomatic carrots (80 and 55%, respectively), and laboratory-grown carrot tissue (100% for both primer pairs). In contrast, no PCR products were detected in DNA extracted from insect-free plants. The DNA sequences of amplicons of the genes encoding liberibacter 16S rRNA from psyllids and carrots were identical. The DNA of the 16S rRNA gene sequences determined from carrots and carrot psyllids were over 99.9% identical to analogous sequences of “Ca. L. solanacearum” amplified from several solanaceous crops and the psyllid Bactericera cockerelli (Sulc), vector of this bacterium. This is the first report of a plant pathogen associated with T. apicalis and the second psyllid species known to be associated with “Ca. L. solanacearum”.