| Title: | Drought-Mediated Changes in Tree Physiological Processes Weaken Tree Defenses to Bark Beetle Attack |
| Author(s): | Kolb T; Keefover-Ring K; Burr SJ; Hofstetter R; Gaylord M; Raffa KF; |
| Address: | "School of Forestry, Northern Arizona University, Flagstaff, AZ, 86001, USA. tom.kolb@nau.edu. Departments of Botany and Geography, University of Wisconsin-Madison, Madison, WI, 53706, USA. Forest Health Protection, USDA Forest Service, Fairbanks, AL, 99701, USA. School of Forestry, Northern Arizona University, Flagstaff, AZ, 86001, USA. Forest Health Protection, USDA Forest Service, Flagstaff, AZ, 86011, USA. Department of Entomology, University of Wisconsin-Madison, Madison, WI, 53706, USA" |
| DOI: | 10.1007/s10886-019-01105-0 |
| ISSN/ISBN: | 1573-1561 (Electronic) 0098-0331 (Linking) |
| Abstract: | "Interactions between water stress and induced defenses and their role in tree mortality due to bark beetles are poorly understood. We performed a factorial experiment on 48 mature ponderosa pines (Pinus ponderosa) in northern Arizona over three years that manipulated a) tree water stress by cutting roots and removing snow; b) bark beetle attacks by using pheromone lures; and c) phloem exposure to biota vectored by bark beetles by inoculating with dead beetles. Tree responses included resin flow from stem wounds, phloem composition of mono- and sesqui-terpenes, xylem water potential, leaf gas exchange, and survival. Phloem contained 21 mono- and sesqui-terpenes, which were dominated by (+)-alpha-pinene, (-)-limonene, and delta-3-carene. Bark beetle attacks (mostly Dendroctonus brevicomis) and biota carried by beetles induced a general increase in concentration of phloem mono- and sesqui-terpenes, whereas water stress did not. Bark beetle attacks induced an increase in resin flow for unstressed trees but not water-stressed trees. Mortality was highest for beetle-attacked water-stressed trees. Death of beetle-attacked trees was preceded by low resin flow, symptoms of water stress (low xylem water potential, leaf gas exchange), and an ephemeral increase in concentrations of mono- and sesqui-terpenes compared to surviving trees. These results show a) that ponderosa pine can undergo induction of both resin flow and phloem terpenes in response to bark beetle attack, and that the former is more constrained by water stress; b) experimental evidence that water stress predisposes ponderosa pines to mortality from bark beetles" |
| Keywords: | "Animals Chromatography, Gas Coleoptera/*physiology *Droughts Host-Parasite Interactions/*drug effects Pinus ponderosa/*chemistry/metabolism Plant Bark/chemistry/metabolism Resins, Plant/chemistry/metabolism Seasons Terpenes/analysis/chemistry/*pharmacolog;" |
| Notes: | "MedlineKolb, Thomas Keefover-Ring, Ken Burr, Stephen J Hofstetter, Richard Gaylord, Monica Raffa, Kenneth F eng no. 230732/National Institute of Food and Agriculture McIntire-Stennis Program (US)/ 2019/09/08 J Chem Ecol. 2019 Oct; 45(10):888-900. doi: 10.1007/s10886-019-01105-0. Epub 2019 Sep 7" |
