title: Predator exposure-induced immunosuppression: trade-off, immune redistribution or immune reconfiguration?
abstract: Although predator exposure increases the risk of wound infections, it typically induces immunosuppression. A number of non-mutually exclusive hypotheses have been put forward to explain this immunosuppression, including: trade-offs between the immune system and other systems required for anti-predator behaviour, redistribution of immune resources towards mechanisms needed to defend against wound infections, and reconfiguration of the immune system to optimize defence under the physiological state of fight-or-flight readiness. We tested the ability of each hypothesis to explain the effects of chronic predator stress on the immune system of the caterpillarManduca sextaPredator exposure induced defensive behaviours, reduced mass gain, increased development time and increased the concentration of the stress neurohormone octopamine. It had no significant effect on haemocyte number, melanization rate, phenoloxidase activity, lysozyme-like activity or nodule production. Predator stress reduced haemolymph glutathione concentrations. It also increased constitutive expression of the antimicrobial peptideattacin-1but reducedattacin-1expression in response to an immune challenge. These results best fit the immune reconfiguration hypothesis, although the other hypotheses are also consistent with some results. Interpreting stress-related changes in immune function may require an examination at the level of the whole organism.
authors.affiliation: Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada B3H 4R2 sadamo@dal.ca.
authors.forename: Shelley A
authors.identifier: 0000-0002-5973-571X
authors.initials: SA
authors.lastname: Adamo
authors.affiliation: Department of Biology, Acadia University, Wolfville, NS, Canada B4P 2R6.
authors.forename: Russell H
authors.initials: RH
authors.lastname: Easy
authors.affiliation: Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada B3H 4R2.
authors.forename: Ilya
authors.initials: I
authors.lastname: Kovalko
authors.affiliation: Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada B3H 4R2.
authors.forename: Jenna
authors.initials: J
authors.lastname: MacDonald
authors.affiliation: Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada B3H 4R2.
authors.forename: Ashleigh
authors.initials: A
authors.lastname: McKeen
authors.affiliation: Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada B3H 4R2.
authors.forename: Taylor
authors.initials: T
authors.lastname: Swanburg
authors.forename: Kurtis F
authors.initials: KF
authors.lastname: Turnbull
authors.affiliation: Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada B3H 4R2.
authors.forename: Catherine
authors.initials: C
authors.lastname: Reeve
mesh_terms: D000818:Animals; D004924:Escape Reaction; D005786:Gene Expression Regulation; D005978:Glutathione / Q000032:analysis / Q000276:immunology; D006434:Hemocytes / Q000166:cytology / Q000276:immunology; D006458:Hemolymph / Q000276:immunology; D007108:Immune Tolerance; D019476:Insect Proteins / Q000032:analysis / Q000276:immunology; D018402:Manduca / Q000166:cytology / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D009655:Octopamine / Q000032:analysis / Q000276:immunology; D011235:Predatory Behavior; D013312:Stress, Physiological
chemical_list: D019476:Insect Proteins; C039711:attacin antibacterial protein, insect; D009655:Octopamine; D005978:Glutathione
keywords: Attacin; Chronic stress; Ecoimmunology; Glutathione; Octopamine; Phenoloxidase; Predation; Stress hormones