title: Immune defence strategies of generalist and specialist insect herbivores.
abstract: Ecological immunology examines the adaptive responses of animals to pathogens in relation to other environmental factors and explores the consequences of trade-offs between investment in immune function and other life-history traits. Among species of herbivorous insects, diet breadth may vary greatly, with generalists consuming a wide variety of plant families and specialists restricted to a few species. Generalists may thus be exposed to a wider range of pathogens exerting stronger selection on the innate immune system. To examine whether this produces an increase in the robustness of the immune response, we compared larvae of the generalist herbivore Heliothis virescens and the specialist Heliothis subflexa challenged by entomopathogenic and non-pathogenic bacteria. Heliothis virescens larvae showed lower mortality, a lower number of recoverable bacteria, lower proliferation of haemocytes and higher phagocytic activity. These results indicate a higher tolerance to entomopathogenic bacteria by the generalist, which is associated with a more efficient cell-mediated immune response by mechanisms that differ between these closely related species. Our findings provide novel insights into the consequences of diet breadth and related environmental factors, which may be significant in further studies to understand the ecological forces and investment trade-offs that shape the evolution of innate immunity.
authors.affiliation: Department of Entomology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Strasse 8, Jena 07745, Germany abarthel@ice.mpg.de.
authors.forename: Andrea
authors.initials: A
authors.lastname: Barthel
authors.affiliation: Department of Infection Biology, Hans Knöll Institute, Beutenbergstrasse 11, Jena 07745, Germany.
authors.forename: Isabell
authors.initials: I
authors.lastname: Kopka
authors.affiliation: Department of Entomology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Strasse 8, Jena 07745, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Vogel
authors.affiliation: Department of Infection Biology, Hans Knöll Institute, Beutenbergstrasse 11, Jena 07745, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Zipfel
authors.affiliation: Department of Entomology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Strasse 8, Jena 07745, Germany.
authors.forename: David G
authors.initials: DG
authors.lastname: Heckel
authors.affiliation: Department of Entomology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Strasse 8, Jena 07745, Germany IBED, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors.forename: Astrid T
authors.initials: AT
authors.lastname: Groot
mesh_terms: D000818:Animals; D001412:Bacillus subtilis / Q000502:physiology*; D001413:Bacillus thuringiensis / Q000502:physiology*; D004032:Diet; D007814:Larva / Q000276:immunology / Q000382:microbiology / Q000502:physiology; D009036:Moths / Q000254:growth & development / Q000276:immunology / Q000382:microbiology / Q000502:physiology*; D012705:Serratia / Q000502:physiology*; D013045:Species Specificity
keywords: diet breadth; ecological immunology; entomopathogenic bacteria; haemocytes