02394nas a2200193   4500008004100000020001400041245014600055210006900201260000800270300001400278490000700292520163900299653002801938100003501966700002302001700001902024700002202043856013502065       2011                        eng d  a0921-297300aIncoming! Association of landscape features with dispersing mountain pine beetle populations during a range expansion event in western Canada0 aIncoming Association of landscape features with dispersing mount  cOct  a1097-11100 v263 aMountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae, Scolytinae), is a forest insect that undergoes intermittent population eruptions, causing landscape-level mortality to mature pines. Currently, an outbreak covers over 16.3 million ha of British Columbia and Alberta in western Canada. Recent incursion into the jack pine (Pinus banksiana Lamb.) of northwestern Alberta threatens further range expansion through the boreal forest to central and eastern Canada. The spread from British Columbia into northwestern Alberta has been facilitated by above-canopy dispersal of the insect by meso-scale atmospheric currents. At these scales, dispersing D. ponderosae may behave like inert particles, causing terrain-induced tropospheric convective and advective currents to influence population dispersal and establishment. We use spatial point process regression models to examine the association of meso-scale variables, including landscape features and their orientations, habitat suitability, elevation and treatment efforts, with occurrence of D. ponderosae infestations in 2004, 2005, and 2006. Infestations of D. ponderosae primarily established in canyons and valleys, before moving into more open-sloped areas. Southwestern slopes of midslope ridges and small hills, southwest facing open slopes, and valleys that run in a northeast-southwest cardinal direction were positively associated with higher intensities of infestation. This study provides insight into the influences of complex terrain on landscape disturbance by a forest insect, and can be used to prioritize areas for potential management.10aDendroctonus ponderosae1 ade la Giroday, Honey-Marie, C.1 aCarroll, Allan, L.1 aLindgren, B.S.1 aAukema, Brian, H.  uhttps://weevil.myspecies.info/incoming-association-landscape-features-dispersing-mountain-pine-beetle-populations-during-range-exp02390nas a2200205   4500008004100000020001400041245013400055210006900189260000800258300001400266490000700280520162500287653002801912100002101940700002201961700002001983700002302003700002302026856013502049       2011                        eng d  a0045-506700aEfficacy of tree defense physiology varies with bark beetle population density: a basis for positive feedback in eruptive species0 aEfficacy of tree defense physiology varies with bark beetle popu  cJun  a1174-11880 v413 aWe evaluated the ability of constitutive and inducible defenses to protect trees and restrict herbivore reproduction across the endemic, incipient (i.e., transitory), and eruptive phases of a native bark beetle species. Host defenses were major constraints when mountain pine beetle (Dendroctonus ponderosae Hopkins) populations were low, but inconsequential after stand-level densities surpassed a critical threshold. We annually examined all lodgepole pines (Pinus contorta Douglas var. latifolia) in six 12-18 ha stands for 3-6 years for beetle attack and establishment as beetle densities progressed through various population phases. We also assayed a suite of tree physiological and chemical attributes and related them to subsequent attacks during that year. Rapidly inducible defenses appeared more important than constitutive defenses, and total monoterpenes were more important than particular constituents. Trees that exude more resin and accumulate higher monoterpene concentrations in response to simulated attack largely escaped natural attacks when populations were low. In stands where beetles had reached incipient densities, these defenses were ineffective. Larger diameter trees had more pronounced defenses than smaller diameter trees. As populations increased, beetles selected increasingly larger, more resource-rich trees, despite their better defenses. When populations were too low for cooperative attack, beetles exploited trees weakened by lower-stem insects. Behavioral plasticity allows beetles to persist at endemic levels until conditions shift, after which positive feedbacks predominate.10aDendroctonus ponderosae1 aBoone, Celia, K.1 aAukema, Brian, H.1 aBohlmann, Joerg1 aCarroll, Allan, L.1 aRaffa, Kenneth, F.  uhttps://weevil.myspecies.info/efficacy-tree-defense-physiology-varies-bark-beetle-population-density-basis-positive-feedback-erupt