title: Host-Parasite Interactions from the Inside: Plant Reproductive Ontogeny Drives Specialization in Parasitic Insects.
abstract: Host plant interactions are likely key drivers of evolutionary processes involved in the diversification of phytophagous insects. Granivory has received substantial attention for its crucial role in shaping the interaction between plants and their seed parasites, but fine-scale mechanisms explaining the role of host plant reproductive biology on specialization of seed parasites remain poorly described. In a comparative approach using plant histological techniques, we tested the hypotheses that different seed parasite species synchronize their life cycles to specific stages in seed development, and that the stage they target depends on major differences in seed development programs. In a pinaceous system, seed storage products are initiated before ovule fertilization and the wasps target the ovule's nucellus during megagametogenesis, a stage at which larvae may benefit from the by-products derived from both secreting cells and dying nucellar cells. In a cupressaceous system, oviposition activity peaks later, during embryogenesis, and the wasps target the ovule's megagametophyte where larvae may benefit from cell disintegration during embryogenesis. Our cytohistological approach shows for the first time how, despite divergent oviposition targets, different parasite species share a common strategy that consists of first competing for nutrients with developing plant structures, and then consuming these developed structures to complete their development. Our results support the prediction that seed developmental program is an axis for specialization in seed parasites, and that it could be an important parameter in models of their ecological and taxonomic divergence. This study provides the basis for further investigating the possibility of the link between plant ontogeny and pre-dispersal seed parasitism.
authors.affiliation: INRA, UR 629 Ecologie des forêts méditerranéennes, F-84914, Avignon, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Boivin
authors.affiliation: INRA, UR 629 Ecologie des forêts méditerranéennes, F-84914, Avignon, France.
authors.forename: Cindy
authors.initials: C
authors.lastname: Gidoin
authors.affiliation: University of Victoria, Department of Biology, Centre for Forest Biology, Victoria, BC, V8W 3N5, Canada.
authors.forename: Patrick
authors.initials: P
authors.lastname: von Aderkas
authors.affiliation: INRA, UR 629 Ecologie des forêts méditerranéennes, F-84914, Avignon, France.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Safrana
authors.affiliation: INRA, UR 629 Ecologie des forêts méditerranéennes, F-84914, Avignon, France; Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, Sault Ste Marie, ON, P6A 2E5, Canada.
authors.forename: Jean-Noël
authors.initials: JN
authors.lastname: Candau
authors.affiliation: INRA, UR 629 Ecologie des forêts méditerranéennes, F-84914, Avignon, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Chalon
authors.affiliation: INRA, UR 629 Ecologie des forêts méditerranéennes, F-84914, Avignon, France.
authors.forename: Marion
authors.initials: M
authors.lastname: Sondo
authors.affiliation: Univ Avignon, EA 4279, BP 21239, F-84916, Avignon, Cedex 9, France.
authors.forename: Mohamed
authors.initials: M
authors.lastname: El Maâtaoui
mesh_terms: D000818:Animals; D005075:Biological Evolution; D006790:Host-Parasite Interactions; D008018:Life Cycle Stages / Q000502:physiology*; D010058:Oviposition / Q000502:physiology; D012639:Seeds / Q000469:parasitology*; D013559:Symbiosis; D064028:Tracheophyta / Q000469:parasitology*; D014863:Wasps