title: Spruce Budworm (Lepidoptera: Tortricidae) Oral Secretions II: Chemistry.
abstract: As sessile organisms, plants have evolved different methods to defend against attacks and have adapted their defense measures to discriminate between mechanical damage and herbivory by insects. One of the ways that plant defenses are triggered is via elicitors from insect oral secretions (OS). In this study, we investigated the ability of second-instar (L2) spruce budworm [SBW; Choristoneura fumiferana (Clemens)] to alter the volatile organic compounds (VOCs) of four conifer species [Abies balsamea (L.) Mill., Picea mariana (Miller) B.S.P., Picea glauca (Moench) Voss, Picea rubens (Sargent)] and found that the emission profiles from all host trees were drastically changed after herbivory. We then investigated whether some of the main elicitors (fatty acid conjugates [FACs], β-glucosidase, and glucose oxidase) studied were present in SBW OS. FACs (glutamine and glutamic acid) based on linolenic, linoleic, oleic, and stearic acids were all observed in varying relative quantities. Hydroxylated FACs, such as volicitin, were not observed. Enzyme activity for β-glucosidase was also measured and found present in SBW OS, whereas glucose oxidase activity was not found in the SBW labial glands. These results demonstrate that SBW L2 larvae have the ability to induce VOC emissions upon herbivory and that SBW OS contain potential elicitors to induce these defensive responses. These data will be useful to further evaluate whether these elicitors can separately induce the production of specific VOCs and to investigate whether and how these emissions benefit the plant.
authors.affiliation: * These authors contributed equally to this work.
authors.forename: Gaëtan
authors.initials: G
authors.lastname: LeClair
authors.affiliation: * These authors contributed equally to this work.
authors.forename: Martin
authors.initials: M
authors.lastname: Williams
authors.forename: Peter
authors.initials: P
authors.lastname: Silk
authors.forename: Eldon
authors.initials: E
authors.lastname: Eveleigh
authors.forename: Peter
authors.initials: P
authors.lastname: Mayo
authors.forename: Matt
authors.initials: M
authors.lastname: Brophy
authors.forename: Brittany
authors.initials: B
authors.lastname: Francis
mesh_terms: D028202:Abies / Q000737:chemistry* / Q000502:physiology; D000818:Animals; D005088:Exocrine Glands / Q000201:enzymology; D005227:Fatty Acids / Q000032:analysis; D005949:Glucose Oxidase / Q000032:analysis; D060434:Herbivory; D007814:Larva / Q000737:chemistry / Q000502:physiology; D009036:Moths / Q000737:chemistry / Q000201:enzymology / Q000502:physiology*; D009055:Mouth / Q000737:chemistry / Q000378:metabolism; D028222:Picea / Q000737:chemistry* / Q000502:physiology; D055549:Volatile Organic Compounds / Q000032:analysis*; D001617:beta-Glucosidase / Q000032:analysis
chemical_list: D005227:Fatty Acids; D055549:Volatile Organic Compounds; D005949:Glucose Oxidase; D001617:beta-Glucosidase
keywords: elicitor; fatty acid conjugate; glucose oxidase; volatile organic compound; β-glucosidase