Harnessing the Power of Electrical Penetration Graph Technology to Understand Psyllid-Transmitted Fastidious...

Psyllids, also called plant lice, are hemipteran insects that feed on phloem sap. In addition to the direct damage they cause to plants, they are vectors of many phloem-restricted bacterial pathogens belonging to the 'Candidatus Liberibacter' spp. and 'Candidatus Phytoplasma' spp. from the apple proliferation group (16SrX). Although 'Candidatus Liberibacter' spp. cells possess cell walls unlike those of the phytoplasmas, they both share a reduced genome and unavailability in culture. In addition, psyllids transmit both species of bacteria in a persistent, circulative, and propagative manner. Because of the similarity of these pathosystems, the electrical penetration graph (EPG) was employed to study the probing behavior of psyllids. Such studies may assist in understanding the specific interactions between the fastidious bacteria, plant hosts, and insect vectors and lead to innovative control strategies. Herein, we discuss the potential of the EPG to study and understand the tritrophic interactions that secure a successful transmission from plant to plant. In addition, the use of the EPG in evaluating psyllid control strategies including pesticides and tolerant varieties is reviewed.