‘Candidatus Liberibacter Solanacearum’ Is Unlikely to Be Transmitted Spontaneously from Infected Carrot Plants to Citrus Plants by Trioza Erytreae

© 2020 by the authors.

Bacteria belonging to ‘Candidatus Liberibacter spp.’ are associated with various severe diseases in the five continents. The African citrus psyllid Trioza erytreae (Hemiptera: Triozidae) is an efficient vector of citrus huanglongbing-HLB disease, absent in the Mediterranean basin. This psyllid is currently present in the islands and mainland Portugal and Spain, where the prevalence of ‘Ca. Liberibacter solanacearum’ (CaLsol) associated to a carrot disease is high. Trioza erytreae normally feeds on citrus plants but has also been observed on other crops. It would be a great concern to the Mediterranean citrus industry if T. erytreae could transmit this bacterium from carrots to citrus and cause disease; therefore, the transmission of CaLsol from carrot plants to citrus plants was experimentally assessed. Although CaLsol was initially detected on receptor citrus plants in transmission assays by dodder and budding, the infection was not established. The feeding behavior by electrical penetration graphs and oviposition of T. erytreae on carrot plants versus citrus plants was evaluated. Trioza erytreae only reached the phloem in citrus plants. However, it was able to acquire CaLsol from infected carrots but unable to transmit it to citrus plants. CaLsol was detected in some carrot plants immediately after 7 and 14 days (inoculation access period), but it was not detected after one month. Trioza erytreae was unable to complete its life cycle on carrot plants. In conclusion, the efficient vector of bacteria associated to huanglongbing was unable to transmit CaLsol from carrot to citrus plants, but it acquired and transmitted the bacterium from carrot to carrot plants with low efficiency.

This research was funded by Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, INIA RTA2011-00142-C2 and INIA E-RTA2014-00008-C4. M.Q.-G.d.C. is recipient of a 2017-2020 Ph.D. grant from INIA. G.R.T. was recipient of Ph.D. grant 2010-2014 from Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Ministério da Educação, Brazil. E.B. was recipient of an INIA-CCAA 2011-2016 contract from Ministerio de Ciencia e Innovación, Spain.

Peer reviewed