2019 Vector Role of Cixiids and Other Planthopper Species, Phytoplasmas: Plant Pathogenic Bacteria – II

Abstract

Cixiid planthoppers are primary vectors of several phytoplasma associated diseases on economically important crops as well as on herbaceous plants that act as pathogen reservoirs. The main phytoplasma transmitted by the cixiid species is ‘Candidatus Phytoplasma solani’, also known under the trivial name of “stolbur” phytoplasma. The principal vector of ‘Ca. P. solani’ is Hyalesthes obsoletus, while three additional cixiid vectors are assumed to have minor or middle role in transmission, or have local importance: Reptalus panzeri, R. quinquecostatus and Pentastiridius leporinus. “Bois noir” disease of grapevine is the most studied and widespread ‘Ca. P. solani’-associated disease transmitted by H. obsoletus. Studies on spread and epidemiology of this disease resulted in identification of several epidemiological cycles in the different parts of Europe. Each cycle is associated with specific plant-hosts of the vector population: Urtica dioica, Convolvulus arvensis, Vitex agnus-castus and Crepis foetida. However, in France H. obsoletus is associated with cultivated plant-hosts, Lavandula spp. and Salvia sclarea, acting as pathogen reservoirs. R. panzeri is a vector of ‘Ca. P. solani’ involved in its transmission to grapevine, maize and potato. However, its epidemiological role is up-to-date determined only in south-eastern Europe, i.e., the Balkan region; presumably due to limited geographical distribution of this cixiid species and its feeding preferences being different in central Europe. R. quinquecostatus is a vector of ‘Ca. P. solani’; but, without clear defined epidemiological role in any of the ‘Ca. P. solani’-associated diseases. P. leporinus is a major vector of ‘Ca. P. solani’ to sugar beet in France, involved in a specific epidemiological cycle dependent upon annual crop rotation including winter cereals. Role of Dictyophara europaea and planthopper putative vectors of diverse genera harboring phylogenetically diverse phytoplasma groups are also described.