Crepis foetida L.: New host plant of cixiid planthopper Hyalesthes obsoletus Signoret 1865 (Hemiptera: Cixiidae), vector of stolbur phytoplasma

Abstract

Epidemiology of plant diseases caused by phytoplasmas depends on vector's biology and its preference to the host plant. Grapevine yellows (GY) caused by stolbur phytoplasma (16SrXII-A subgroup, 'Candidatus Phytoplasma solani'), during last 15 years became one of the economically most important diseases of the grapevine in Europe. The cixiid plant­hopper Hyalesthes obsoletus Signoret (Hemiptera: Cixiidae) is a principle vector of stolbur phytoplasma and has the main influence on the incidence of the disease and yield loses in the vineyards. Epidemiological cycle of the Bois Noir (BN) is determined by the host plant of the H. obsoletus which is primal source of the disease in the vineyard and it affects presence of the pathogen in the insect's population. Presence of stolbur phytoplasma and symptoms of the BN disease is registered in all wine growing regions in Serbia. This research was focused toward determining host plants of the H. obsoletus and its ge­netic characteristics in order to determine epidemiological characteristics of BN in Serbia. Based on this field research, along with populations associated with previously known host plants nettle (Urtica dioica) and bindweed (Convolvulus arvensis), new host plant association with Crepis foetida L (Asteraceae) was registered on several localities in east and south Serbia. Genetic structure of H. obsoletus populations associated with specific host plants is analyzed in order to obtain precise information about epidemiological cycle of stolbur phyto­plasma in agroecosystems in Serbia. According to results of the three analyzed mtDNA regions, genetic differentiation is present between H. obsoletus populations associated with C. arvensis and U. dioica on the one and C. foetida on the other side. Domination of one of these two genotypes in nature and distribution of the host plants provides the basis for further research of the potential vector ability and characterization of the stolbur phytoplasma which is being transmitted by H. obsoletus and epidemiological cycles related to the new host plant in Serbia.