Risk assessment of ‘Candidatus Liberibacter solanacearum’ transmission by the psyllids Bactericera trigonica and B. tremblayi from Apiaceae crops to potato

Abstract

Candidatus Liberibacter solanacearum (Lso) is bacterium transmitted by psyllids to Solanaceae and Apiaceae plants. So far, Lso is found in Europe affecting Apiaceae. In the Mediterranean region, Bactericera trigonica is the only known vector of Lso, but the leek-onion psyllid Bactericera tremblayi is another widespread psyllid and potential vector of Lso. Commonly, carrot, leek and potato are cultivated in the same zones and it is uncertain if these psyllid species are able to transmit Lso to potato plants. Here, we assessed the transmission of Lso by B. trigonica and B. tremblayi to potato plants. B. trigonica showed preference to ingest from the phloem, settle and oviposit on carrot and celery but not on potato. This was correlated with high Lso transmission rates to both carrot (80%) and celery (70%) but very low to potato (≤3%). B. tremblayi preferred leek over carrot and potato, the latter being the less preferred host. B. tremblayi readily ingested from the phloem of infected carrots but failed to transmit Lso from carrot to carrot. Our study shows that the risk of Lso transmission from Apiaceae to potato by B. trigonica is very low, and that B. tremblayi is not a likely vector of Lso.

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

“…Remarkably, Sandanayaka et al (2014) working with B. cockerelli and Antolínez et al (2017b) with B. trigonica observed also a low percentage of tomato and potato plants positive for CaLso in transmission assays, respectively, despite no phloem activities were recorded for those psyllids in eight hours' EPG studies, suggesting that few individual of the psyllids might reach the phloem of the host plants on longer observation periods.…”

“…However, other Bactericera species has been recorded, that might act as more effective vectors within potato (Teresani et al, 2015). Although this option should be discarded for B. tremblayi in view of recent findings by Antolínez et al (2017b), there is still a need to study the role of B. nigricornis among other potential vectors naturally present in the crop.…”

“…The transmission of CaLso, which causes vegetative disorders in Apiaceae in Spain, has been associated with B. trigonica, the predominant psyllid species on carrot and celery (Alfaro-Fernández et al, 2012;Teresani et al, 2015). In addition, several studies have recently been published about sex-specific probing behaviour and the characterization of the EPG of B. trigonica on carrots (Antolínez et al, 2017a,c), and a risk of bacterial transmission from Apiaceae to potato by this psyllid and B. tremblayi (Antolínez et al, 2017b). However, it is advisable to have more outcomes for the transmission of this bacterium and particularly after the first outbreak in Spain of zebra chip (http://www.…”

“…The EPG waveforms of psyllids are reported for D. citri (Bonani et al, 2010;Cen et al, 2012b), B. cockerelli (Butler et al, 2012;Pearson et al, 2014;Sandanayaka et al, 2014;Mustafa et al, 2015), C. pyri L. (Civolani et al, 2011) and Psylla pyricola Förster (Ullman & McLean, 1988). Comparison by EPGs waveforms of the probing behaviours of males and females of B. trigonica in carrot has been recently reported (Antolínez et al, 2017a) and the characterization of the electrical penetration graphs (Antolínez et al, 2017b).…”

“…CaLso is transmitted by Bactericera cockerelli Sulc in potato and tomato (Secor et al, 2009) and by Trioza apicalis Förster in carrot in northern Europe (Nissinen et al, 2014). Bactericera trigonica Hodkinson is associated with vegetative disorders of carrot and celery in Spain (Alfaro-Fernández et al, 2012;Teresani et al, 2014), and Antolínez et al (2017aAntolínez et al ( , 2017b described the feeding behaviour of B. trigonica on carrot plants and reported that the transmission of CaLso was not affected by the vector gender. Moreover, Munyaneza et al (2016) assessed the ability of the potato psyllid B. cockerelli to transmit CaLso from potato to carrot, and Antolínez et al (2017b) the risk of transmission of CaLso from Apiaceae to potato by B. trigonica.…”