Publications

aggregation and a strong allee effect in a cooperative outbreak insect.	most species that are negatively impacted when their densities are low aggregate to minimize this effect. aggregation has the potential to change how allee effects are expressed at the population level. we studied the interplay between aggregation and allee effects in the mountain pine beetle (dendroctonus ponderosae hopkins), an irruptive bark beetle that aggregates to overcome tree defenses. by cooperating to surpass a critical number of attacks per tree, the mountain pine beetle is able to br ...	2016	27862568
spatial variability in tree regeneration after wildfire delays and dampens future bark beetle outbreaks.	climate change is altering the frequency and severity of forest disturbances such as wildfires and bark beetle outbreaks, thereby increasing the potential for sequential disturbances to interact. interactions can amplify or dampen disturbances, yet the direction and magnitude of future disturbance interactions are difficult to anticipate because underlying mechanisms remain poorly understood. we tested how variability in postfire forest development affects future susceptibility to bark beetle ou ...	2016	27821739
relative importance of climate and mountain pine beetle outbreaks on the occurrence of large wildfires in the western usa.	extensive outbreaks of bark beetles have killed trees across millions of hectares of forests and woodlands in western north america. these outbreaks have led to spirited scientific, public, and policy debates about consequential increases in fire risk, especially in the wildland-urban interface (wui), where homes and communities are at particular risk from wildfires. at the same time, large wildfires have become more frequent across this region. widespread expectations that outbreaks increase ex ...	2016	27787956
mountain pine beetle dynamics and reproductive success in post-fire lodgepole and ponderosa pine forests in northeastern utah.	fire injury can increase tree susceptibility to some bark beetles (curculionidae, scolytinae), but whether wildfires can trigger outbreaks of species such as mountain pine beetle (dendroctonus ponderosae hopkins) is not well understood. we monitored 1173 lodgepole (pinus contorta var. latifolia doug.) and 599 ponderosa (pinus ponderosa doug. ex law) pines for three years post-wildfire in the uinta mountains of northeastern utah in an area with locally endemic mountain pine beetle. we examined ho ...	2016	27783632
fortifying the forest: thinning and burning increase resistance to a bark beetle outbreak and promote forest resilience.	fire frequency in low-elevation coniferous forests in western north america has greatly declined since the late 1800s. in many areas, this has increased tree density and the proportion of shade-tolerant species, reduced resource availability, and increased forest susceptibility to forest insect pests and high-severity wildfire. in response, treatments are often implemented with the goal of increasing ecosystem resilience by increasing resistance to disturbance. we capitalized on an existing repl ...	2016	27755724
gene expression analysis of overwintering mountain pine beetle larvae suggests multiple systems involved in overwintering stress, cold hardiness, and preparation for spring development.	cold-induced mortality has historically been a key aspect of mountain pine beetle, dendroctonus ponderosae hopkins (coleoptera: curculionidae), population control, but little is known about the molecular basis for cold tolerance in this insect. we used rna-seq analysis to monitor gene expression patterns of mountain pine beetle larvae at four time points during their overwintering period-early-autumn, late-autumn, early-spring, and late-spring. changing transcript profiles over the winter indica ...	2016	27441109
change in soil fungal community structure driven by a decline in ectomycorrhizal fungi following a mountain pine beetle (dendroctonus ponderosae) outbreak.	western north american landscapes are rapidly being transformed by forest die-off caused by mountain pine beetle (dendroctonus ponderosae), with implications for plant and soil communities. the mechanisms that drive changes in soil community structure, particularly for the highly prevalent ectomycorrhizal fungi in pine forests, are complex and intertwined. critical to enhancing understanding will be disentangling the relative importance of host tree mortality from changes in soil chemistry follo ...	2017	27659418
novel forest decline triggered by multiple interactions among climate, an introduced pathogen and bark beetles.	novel forest decline is increasing due to global environmental change, yet the causal factors and their interactions remain poorly understood. using tree ring analyses, we show how climate and multiple biotic factors caused the decline of whitebark pine (pinus albicaulis) in 16 stands in the southern canadian rockies. in our study area, 72% of whitebark pines were dead and 18% had partially dead crowns. tree mortality peaked in the 1970s; however, the annual basal area increment of disturbed tre ...	2017	27901296
defense traits in the long-lived great basin bristlecone pine and resistance to the native herbivore mountain pine beetle.	mountain pine beetle (mpb, dendroctonus ponderosae) is a significant mortality agent of pinus, and climate-driven range expansion is occurring. pinus defenses in recently invaded areas, including high elevations, are predicted to be lower than in areas with longer term mpb presence. mpb was recently observed in high-elevation forests of the great basin (gb) region, north america. defense and susceptibility in two long-lived species, gb bristlecone pine (pinus longaeva) and foxtail pine (p. balfo ...	2017	27612209
toxicity of monoterpene structure, diversity and concentration to mountain pine beetles, dendroctonus ponderosae: beetle traits matter more.	a high diversity of plant defenses may be a response to herbivore diversity or may be collectively more toxic than single compounds, either of which may be important for understanding insect-plant associations. monoterpenes in conifers are particularly diverse. we tested the fumigant toxicity of four monoterpenes, alone and in combination, to mountain pine beetles, dendroctonus ponderosae, in the context of the beetles' individual body traits. chemical structures of tested monoterpene hydrocarbo ...	2017	28258318
breeding matters: natal experience influences population state-dependent host acceptance by an eruptive insect herbivore.	eruptive forest insects are highly influential agents of change in forest ecosystems, and their effects have increased with recent climate change. state-dependent life histories contribute significantly to the population dynamics of eruptive forest insect herbivores; however, the proximate mechanisms by which these species shift between states is poorly understood. laboratory bioassays were conducted using the mountain pine beetle (dendroctonus ponderosae) to determine the effect of maternal hos ...	2017	28207862
genetic and genomic evidence of niche partitioning and adaptive radiation in mountain pine beetle fungal symbionts.	bark beetles form multipartite symbiotic associations with blue stain fungi (ophiostomatales, ascomycota). these fungal symbionts play an important role during the beetle's life cycle by providing nutritional supplementation, overcoming tree defences and modifying host tissues to favour brood development. the maintenance of stable multipartite symbioses with seemingly less competitive symbionts in similar habitats is of fundamental interest to ecology and evolution. we tested the hypothesis that ...	2017	28231417