Association of “<I>Candidatus</I> Liberibacter solanacearum” With the Psyllid, <I>Trioza apicalis</I> (Hemiptera: Triozidae) in Europe

Abstract

The psyllid Trioza apicalis Förster (Hemiptera: Triozidae) is a serious pest of carrots, Daucus carota L., in 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 T. apicalis 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 is associated with T. apicalis was conducted. Polymerase chain reaction (PCR) primer pairs OA2/OI2c and LsoF/OI2c, specific for 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 carrots (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. DNA of the 16S rRNA gene sequences determined from carrots and psyllids were 99.9% identical to analogous sequences of "Ca. L. solanacearum" amplified from several solanaceous crops and the psyllid Bactericera cockerelli (Sulc), a vector of this bacterium. This is the first report of a plant pathogen associated with T. apicalis and the second known psyllid species associated with "Ca. L. solanacearum".

Transmission of ‘Candidatus Liberibacter solanacearum’ by Bactericera trigonica Hodkinson to vegetable hosts

“…The bacterium was detected in eggs, in different nymph instars and in adults of B. cockerelli (Hansen et al, 2008) and in field-collected and laboratory-reared T. apicalis by conventional PCR (Munyaneza et al, 2010). The bacterium was also detected in B. trigonica, B. tremblayi, B. nigricornis and Bactericera sp.…”

Search for potential vectors of ‘Candidatus Liberibacter solanacearum’: population dynamics in host crops

“…Haplotype A has been found from Central to North America and New Zealand, haplotype B has been found in Mexico and the United States of America, haplotype C is present in Finland, Sweden and Norway, 2 detected in eggs, different nymph instars stages and adults of B. cockerelli (Hansen et al, 2008). The bacterium was also detected by conventional PCR in field-collected and laboratory-reared T. apicalis in southern Finland (Munyaneza et al, 2010b). Squash real-time PCR is a useful tool for the detection of nucleic acid targets in insect vectors and was successfully used to detect 'Ca.…”

“…Bactericera cockerelli Sulc is the vector of haplotypes A and B in solanaceous crops (Nelson et al, 2011). Trioza apicalis Förster was first described in carrot in Finland (Munyaneza et al, 2010b) transmitting the haplotype C (Nelson et al, 2011) and B. trigonica Hodkinson is associated with the transmission of 'Ca. L solanacearum' haplotype D in carrot and likely with haplotype E in carrot and celery in Spain (Alfaro-Fernández et al, 2012b;Nelson et al, 2012;Teresani et al, 2014).…”

Migration flight of carrot psyllid (Trioza apicalis) at various latitudes is independent of local phenology

“…Later Nissinen et al (2012) found changes in the quality of the roots by attacked plants. The possible participation of Liberibacter on this reduction was discussed by Munyaneza et al (2010). Nissinen et al (2008) performed laboratory studies on plants preferences in connection with phototaxis.…”