Insetti vettori dello “stolbur” del pomodoro in Emilia-Romagna

[Autom. eng. transl.] During the late spring-summer 2010, a series of monitoring activities were carried out in the field of Auchenorrinchi Emitters present in some industrial tomato plots in the provinces of Piacenza and Parma. These activities were completed with laboratory analyzes aimed at determining the presence, in the captured insects, of the phytoplasma responsible for the hypertrophic tomato virescence. At the same time, tomato plants with symptoms attributable to the "stolbur" and various weeds present in the same environments were also analyzed using the same methods. The insects were collected by performing, at regular intervals, mowing with an entomological screen, or with yellow chromotactic traps. Several hundred leafhoppers have been captured through mowing and several thousand with traps. Of the 76 specimens, the biomolecular assays were carried out aimed at identifying any phytoplasmas and their characterization to confirm their belonging to the taxonomic group of the "stolbur" (XIIA group) and to the related subtypes "tuf" ("VK" strains), according to Langen & Maixner (2004). In 13% of the analyzed specimens DNA of phytoplasmas of the XIIA group was found and always only of the "tuf b" type (strain "VKII"). The positive specimens all belonged to the species Hyalesthes obsoletus Signoret and had all been collected on Convolvulus arvensis L. or on tomato. In turn, C. arvensis and tomato were found to be infected with "stolbur" and always of the "tuf b" type ("VKII" strain) while the "VKI" strain (type "tuf a") was found on nettle. Therefore, a direct involvement of H. obsoletus in the transmission of the stolbur phytoplasma from the convolvulus to the tomato seems very probable, while, according to the data collected, to date no other vectors seem to be involved in the transmission of this pathogen in the provinces of Piacenza and Parma.