Candidatus Liberibacter solanacearum (CaLsol) is an α-proteobacterium that infects several solanaceous and apiaceous crops. It is vectored by three species of psyllid – Bactericera cockerelli in the Americas and New Zealand; Bactericera trigonica in Europe and the Mediterranean, and Trioza apicalis in Northern Europe. CaLsol is the causal agent of zebra chip disease in potato that has led to huge economic losses in America and New Zealand. The European haplotypes are primarily associated with apiaceous crops, largely in carrot, although recent evidence suggests they can infect potato, albeit at low levels. There are approx. 3800 species of psyllid worldwide. Many psyllid species, including vectors, lack taxonomically useful characteristics and can be easily misidentified. With only three known vectors, their accurate identification is crucial to monitor known/potential vectors and gain an understanding of psyllid biology and ecology, building on our understanding of epidemiology and improving pest risk analyses. Information on the distribution of several important species remains incomplete, especially for Scotland - the second biggest producer of seed potatoes in Europe. We reviewed and surveyed psyllid populations using a network of 12.2m suction traps in England, Scotland and Sweden (Rothamsted Insect Survey and EXAMINE networks). We found new species for all three countries, with several species displaying a summer and autumn population peak. The main vector in Sweden and England – T. apicalis, was caught in both countries, highlighting the networks potential as a monitoring/surveillance system for vectors. Species identification was carried out using classical taxonomy, in combination with molecular tools including non-destructive DNA extraction and DNA sequencing. Species-specific real-time PCR assays have been designed for two known, and one potential, vector to facilitate the rapid identification of species. Bulk DNA samples from suction trap catches are currently being used to test the assay sensitivity.

Project number: POnTE-635646