Double infection of Candidatus phytoplasma asteris and Candidatus phytoplasma vitis in the vector Euscelidius variegatus Kirschbaum.

Competition between Chrysanthemum yellows (CYP) and Flavescence dorée (FD70) phytoplasmas was studied. In the experi-ments the vector Euscelidius variegatus was allowed to acquire both phytoplasmas by feeding first on CYP and then on FD70 in-fected plants and viceversa. Titre of both phytoplasmas was quantified over time in the same insects. Transmission experiments to broad bean, host-plant of both phytoplasmas, were carried out from 14 days after the start of the acquisition until death of leaf-hoppers. Quantitative Real Time PCR assays demonstrated that FD70 multiplies at a higher rate in E. variegatus compared to CYP. Both phytoplasmas reached similar titres in single- and double-infected insects. CYP titre increases faster when the vector already acquired FD70. In spite of its lower multiplication in the insect body, CYP is much more efficiently transmitted than FD70 by double-infected insects.