title: Function of Sitka spruce stone cells as a physical defence against white pine weevil.
abstract: Stone cells are a physical defence of conifers against stem feeding insects such as weevils and bark beetles. In Sitka spruce, abundance of stone cells in the cortex of apical shoot tips is associated with resistance to white pine weevil. However, the mode of action by which stone cells interfere with growth and development of weevil larvae is unknown. We developed a bioassay system for testing potential effects of stone cells, which were isolated from resistant trees, on weevil larvae. Bioassays using artificial diet and controlled amounts of stone cells focused on physical defence. We evaluated the effects of stone cells on establishment of neonate larvae, mandible wear and changes in relative growth rates of third instar larvae. Establishment of neonates and relative growth rates of third instars were significantly reduced by stone cells. Stone cells appeared to be indigestible by weevil larvae. Our results suggest that stone cells affect weevil establishment and development by forming a physical feeding barrier against neonate larvae at the site of oviposition, and by reducing access to nutrients in the cortex of resistant trees, which contain an abundance of stone cells in place of a more nutrient rich tissue in susceptible trees.
authors.affiliation: Michael Smith Laboratories, University of British Columbia, 301-2185 East Mall, Vancouver, British Columbia, Canada, V6T 1Z4.
authors.forename: Justin G A
authors.initials: JG
authors.lastname: Whitehill
authors.affiliation: Michael Smith Laboratories, University of British Columbia, 301-2185 East Mall, Vancouver, British Columbia, Canada, V6T 1Z4.
authors.forename: Hannah
authors.initials: H
authors.lastname: Henderson
authors.affiliation: British Columbia Ministry of Forests, Lands and Natural Resource Operations, Tree Improvement Branch, Kalamalka Forestry Centre, 3401 Reservoir Road, Vernon, British Columbia, Canada, V1B 2C7.
authors.forename: Ward
authors.initials: W
authors.lastname: Strong
authors.affiliation: British Columbia Ministry of Forests, Lands and Natural Resource Operations, Tree Improvement Branch, Kalamalka Forestry Centre, 3401 Reservoir Road, Vernon, British Columbia, Canada, V1B 2C7.
authors.forename: Barry
authors.initials: B
authors.lastname: Jaquish
authors.affiliation: Michael Smith Laboratories, University of British Columbia, 301-2185 East Mall, Vancouver, British Columbia, Canada, V6T 1Z4. bohlmann@msl.ubc.ca.
authors.forename: Jörg
authors.initials: J
authors.lastname: Bohlmann
mesh_terms: D000818:Animals; D005247:Feeding Behavior; D054884:Host-Pathogen Interactions; D007814:Larva / Q000254:growth & development / Q000502:physiology; D028222:Picea / Q000166:cytology / Q000502:physiology*; D013312:Stress, Physiological; D048889:Weevils / Q000502:physiology*
keywords: conifer defence; plant insect interaction; plant resistance; sclereid