title: A hemiterpene glucoside as a probing deterrent of the bean aphid, Megoura crassicauda, from a non-host vetch, Vicia hirsuta.
abstract: The bean aphid, Megoura crassicauda Mordvilko, feeds selectively on plants belonging to the genus Vicia (Fabaceae). However, it never infests the tiny vetch, V. hirsuta (L.) Gray. The aphid appeared to discriminate between host and non-host plants by tasting specific chemicals during penetration of its stylet into the plant tissues. The aphid, after being stimulated by specific probing stimulants, deposited characteristic proteinous stylet sheaths through a parafilm membrane, which has one side in contact with an extract solution of Vicia angustifolia. However, an addition of a V. hirsuta extract to the medium strongly inhibited the salivary sheath formation. A specific probing deterrent was isolated from a V. hirsuta extract by monitoring the inhibitory effect, and identified as (E)-2-methyl-2-butene-1,4-diol 4-O-beta-d-glucopyranoside. A mixture of the glycoside and the stimulatory V. angustifolia fraction in the same equivalency found in plants significantly decreased the probing activity in M. crassicauda. Since the stylet insertion process is a crucial step for the aphid's settlement on a plant, the glycoside seems to act as an effective chemical barrier for V. hirsuta.
authors.affiliation: Laboratory of Chemical Ecology, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Ohta
authors.forename: Naoki
authors.initials: N
authors.lastname: Mori
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Kuwahara
authors.forename: Ritsuo
authors.initials: R
authors.lastname: Nishida
mesh_terms: D000818:Animals; D001042:Aphids / Q000187:drug effects* / Q000502:physiology*; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology; D005518:Food Preferences / Q000187:drug effects; D005960:Glucosides / Q000737:chemistry / Q000494:pharmacology*; D006790:Host-Parasite Interactions; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry; D013729:Terpenes / Q000737:chemistry / Q000494:pharmacology*; D031306:Vicia / Q000737:chemistry* / Q000469:parasitology*
chemical_list: D005960:Glucosides; D010936:Plant Extracts; D013729:Terpenes