title: Conifer stored resources and resistance to a fungus associated with the spruce bark beetle Ips typographus.
abstract: Bark beetles and associated fungi are among the greatest natural threats to conifers worldwide. Conifers have potent defenses, but resistance to beetles and fungal pathogens may be reduced if tree stored resources are consumed by fungi rather than used for tree defense. Here, we assessed the relationship between tree stored resources and resistance to Ceratocystis polonica, a phytopathogenic fungus vectored by the spruce bark beetle Ips typographus. We measured phloem and sapwood nitrogen, non-structural carbohydrates (NSC), and lipids before and after trees were attacked by I. typographus (vectoring C. polonica) or artificially inoculated with C. polonica alone. Tree resistance was assessed by measuring phloem lesions and the proportion of necrotic phloem around the tree's circumference following attack or inoculation. While initial resource concentrations were unrelated to tree resistance to C. polonica, over time, phloem NSC and sapwood lipids declined in the trees inoculated with C. polonica. Greater resource declines correlated with less resistant trees (trees with larger lesions or more necrotic phloem), suggesting that resource depletion may be caused by fungal consumption rather than tree resistance. Ips typographus may then benefit indirectly from reduced tree defenses caused by fungal resource uptake. Our research on tree stored resources represents a novel way of understanding bark beetle-fungal-conifer interactions.
authors: Division of Biological Sciences, The University of Montana, Missoula, Montana, USA. eleanorlahr@gmail.com
authors: Eleanor C
authors: EC
authors: Lahr
authors: Paal
authors: P
authors: Krokene
mesh_terms: D000818:Animals; D001517:Coleoptera / Q000382:microbiology*; D060467:Disease Resistance; D017753:Ecosystem; D005658:Fungi / Q000502:physiology*; D009336:Necrosis; D052585:Phloem / Q000382:microbiology; D028222:Picea / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*; D013559:Symbiosis; D064028:Tracheophyta / Q000382:microbiology
references: New Phytol. 2006;170(4):657-75
references: 16684230
references: Tree Physiol. 2003 Feb;23(3):191-7
references: 12566269
references: Am J Bot. 2000 Mar;87(3):302-13
references: 10718991
references: Environ Entomol. 2007 Dec;36(6):1384-96
references: 18284766
references: Microb Ecol. 2007 Jul;54(1):112-8
references: 17264992
references: Oecologia. 2006 Jun;148(3):426-36
references: 16514534
references: New Phytol. 2005 Aug;167(2):353-75
references: 15998390
references: Annu Rev Entomol. 1997;42:179-206
references: 15012312
references: Trends Ecol Evol. 2005 Aug;20(8):441-8
references: 16701415
references: J Chem Ecol. 1994 Jun;20(6):1281-328
references: 24242341
references: Science. 2008 Oct 3;322(5898):63
references: 18832638
references: Annu Rev Entomol. 2011;56:255-72
references: 20822444
references: Environ Sci Technol. 1995 Dec;29(12):2905-14
references: 22148195
references: Phytochemistry. 2010 Aug;71(11-12):1332-41
references: 20557909
references: Am J Bot. 2000 Mar;87(3):314-26
references: 10718992
references: Arch Biochem Biophys. 1999 Jun 1;366(1):75-81
references: 10334866
references: Phytopathology. 1998 Jan;88(1):39-44
references: 18944997
references: Plant Physiol. 2002 Jul;129(3):1003-18
references: 12114556
references: Mycol Res. 2004 Feb;108(Pt 2):183-8
references: 15119355
references: Tree Physiol. 2001 May;21(7):427-36
references: 11340043
references: Plant Physiol. 1999 Oct;121(2):565-70
references: 10517848