The occurrence of psyllids on carrot and presence of Candidatus Liberibacter solanacearum in the South-West of France

Abstract: Candidatus Liberibacter solanacearum is found in Europe affecting Apiaceae. Two psyllids are known vectors of CaLsol in Europe: Trioza apicalis and Bactericera trigonica. Whereas the biology of T. apicalis is relatively well known, this is not the case for B. trigonica. The presence of psyllids has been known for a long time in French carrot fields, but not much studied. A survey was conducted in 2016 and 2017 in carrot fields. Psyllid insects were collected in yellow traps and identified. The level of B. trigonica carrying the bacterium was also evaluated. Monitoring was set up from 2014 to 2017. Different psyllid species are present and identified; the most frequent is Bactericera trigonica. This species seems to be present in carrot fields throughout the year at different levels. We observe three main periods of flight activity in South-West France. B. trigonica can carry CaLsol around the year. The percentage of psyllids positive to CaLsol can be high, so the potential of carrot infection can be high.