title: Identification and phenology of Hyalesthes obsoletus (Hemiptera: Auchenorrhyncha: Cixiidae) nymphal instars.
abstract: Urtica dioica and Convolvulus arvensis are the main host plants of Hyalesthes obsoletus and play an important role in the epidemiology of Bois noir of grapevines. The earliest survey, which was carried out to compare the phenology of nymphal instars on U. dioica and C. arvensis, had highlighted some problems in the identification of the instars. Therefore, the correct identification of nymphs to species and instar level became a preliminary aim of this research. Adults and nymphs attributable to H. obsoletus were collected during 2008-2010 in three flatland vineyard habitats of northern Italy on U. dioica, C. arvensis and Artemisia verlotorum. Nymphs and morphologically identified adults of H. obsoletus were submitted to molecular identification. Morphometric and morphological studies were carried out on nymphs collected in the field or obtained in laboratory rearings. Molecular methods not only confirmed the identity of adults, but also allowed the assignment of the nymphs to this species. Morphometric and morphological characteristics (e.g. body and head-thoracic lengths, number of thoracic pits) showed the existence of five nymphal instars. Morphometric differences between newly hatched and older first-instar nymphs were observed. A key to distinguish the five instars was proposed. Evident differences between H. obsoletus nymphs studied here and elsewhere were identified. According to differences in adult-flight period, an earlier phenology of nymphs on C. arvensis than on U. dioica was observed. In particular, the typical overwintering instar was the second on U. dioica and the third on C. arvensis.
authors.affiliation: Department of Agricultural and Environmental Sciences, University of Udine, Via delle Scienze 206, 33100 Udine, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Cargnus
authors.affiliation: Department of Agricultural and Environmental Sciences, University of Udine, Via delle Scienze 206, 33100 Udine, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Pavan
authors.affiliation: Department of Environmental Agronomy and Crop Sciences, University of Padua, Viale dell'Università 16, 35020 Legnaro (PD), Italy.
authors.forename: N
authors.initials: N
authors.lastname: Mori
authors.affiliation: Department of Agricultural and Environmental Sciences, University of Udine, Via delle Scienze 206, 33100 Udine, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Martini
mesh_terms: D000818:Animals; D019306:Artemisia / Q000502:physiology; D031254:Convolvulus / Q000502:physiology; D003576:Electron Transport Complex IV / Q000235:genetics; D005260:Female; D006430:Hemiptera / Q000033:anatomy & histology* / Q000145:classification* / Q000235:genetics / Q000502:physiology; D060434:Herbivory; D007300:Insect Control; D019476:Insect Proteins / Q000235:genetics; D007558:Italy; D008297:Male; D024101:Mitochondrial Proteins / Q000235:genetics / Q000502:physiology; D009758:Nymph / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics / Q000502:physiology; D016133:Polymerase Chain Reaction; D026982:Urtica dioica / Q000502:physiology
chemical_list: D019476:Insect Proteins; D024101:Mitochondrial Proteins; D003576:Electron Transport Complex IV