title: Stylet penetration of Cacopsylla pyri; an electrical penetration graph (EPG) study.
abstract: Detailed information on plant penetration activities by pear psylla Cacopsylla pyri L. (Hemiptera Psyllidae) is essential to study phytoplasma transmission of "Candidatus Phytoplasma pyri" responsible of pear decline disease (PD) and to trace and evaluate resistant traits in new pear tree selections for advanced breeding programs. The electrical penetration graph technique or (full) EPG may relevantly contribute to this knowledge. C. pyri EPG waveforms were characterized on basis of amplitude, frequency, voltage level, and electrical origin. Additionally, stylet tracks and the putative location of stylet tips in the plant tissue were histologically related to EPG waveforms by light and transmission electron microscopy observations after stylectomy. More than one waveform occurred in the same tissue: PA, PB, PC1 and PC2 were all detected in the mesophyll, and PE1 and PE2 were both recorded in the phloem. Waveform PE1 was always preceded by transient waveform PD, as previously described in other psyllids. Interestingly, no brief intracellular punctures (potential drop waveforms) were observed during plant penetration, opposite of what is usually recorded in aphids and other Sternorrhyncha.
authors.affiliation: Department of Biology and Evolution, University of Ferrara, via L. Borsari 46, Ferrara, Italy. stefano.civolani@unife.it
authors.forename: Stefano
authors.initials: S
authors.lastname: Civolani
authors.forename: Marilena
authors.initials: M
authors.lastname: Leis
authors.forename: Gilberto
authors.initials: G
authors.lastname: Grandi
authors.forename: Elisa
authors.initials: E
authors.lastname: Garzo
authors.forename: Edison
authors.initials: E
authors.lastname: Pasqualini
authors.forename: Stefano
authors.initials: S
authors.lastname: Musacchi
authors.forename: Milvia
authors.initials: M
authors.lastname: Chicca
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Castaldelli
authors.forename: Remigio
authors.initials: R
authors.lastname: Rossi
authors.forename: W Freddy
authors.initials: WF
authors.lastname: Tjallingii
mesh_terms: D000818:Animals; D055724:Electrophysiological Phenomena; D005247:Feeding Behavior / Q000502:physiology*; D006430:Hemiptera / Q000502:physiology* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D009758:Nymph / Q000502:physiology; D031989:Pyrus / Q000469:parasitology*