About

Professor Brian Aukema is a Professor of Forest Entomology who moved his lab to the University of Minnesota in 2010 after working as a research scientist with the Canadian Forest Service at the University of Northern British Columbia. He holds degrees from the University of Wisconsin-Madison in forest entomology (MS, PhD) and biometry (environmental statistics, MS). In recognition of his work, he was awarded a University McKnight Land-Grant Professorship in 2011. His research and academic career are rooted in forest entomology, with a strong foundation in environmental statistics. As a transplanted Canadian, he humorously notes that his favorite type of stick is a hockey stick.

Research topics

• Biology
• Ecology
• Demography
• Engineering
• Zoology
• Computer Science
• Programming language
• Aerospace engineering
• Environmental resource management
• Horticulture
• Aeronautics
• Environmental science
• Geography
• Geology
• Climatology
• Engineering ethics
• Simulation

Selected publications

• Tree defenses, host choice, and reproductive success of a native bark beetle under novel outbreak conditions

  Ecological Applications · 2026-01-01

  articleOpen accessSenior author

  Bark beetles of the genus Dendroctonus are some of the most important disturbance agents in North American forests, having colonized conifers for millions of years. The selection pressure posed by tree-killing bark beetles pushed trees to develop an arsenal of defensive strategies to which beetles have adapted in their turn. Recent surges in bark beetle-related tree mortality have highlighted the potential of novel climatic and landscape conditions to push tightly calibrated relationships beyond historical norms. One such example is an unprecedented outbreak of the native eastern larch beetle (ELB), Dendroctonus simplex LeConte (Coleoptera: Curculionidae; Scolytinae), that has killed eastern larch (tamarack), Larix laricina (Du Roi) K. Koch, trees across more than 460,000 ha of forest in the Great Lakes Region since 2001. The ability of a bark beetle to attack healthy trees is dependent on sufficient local beetle numbers to overwhelm host defenses and a behavioral switch to target those trees that are avoided at lower population levels. ELB was not previously considered an aggressive tree colonizer, but extended growing seasons have contributed to recent eruptions in local populations of the species. We combined a dendrochronological analysis of tree cores with observational data collected from 2011 to 2013 in Beltrami Island State Forest, Minnesota, to understand tree defensive capacity and beetle outbreak dynamics in this understudied system. We found that preformed defenses visible in tamarack xylem were limited and did not determine host preference of ELB during our study. Beetles colonized the largest trees with the thickest phloem regardless of defensive capacity. Preformed resin defenses measured in tree phloem were correlated with reduced beetle reproductive success but were unrelated to resin metrics from tree xylem. With this work, the interaction between ELB and tamarack serves as a model to explore how climate change may alter species associations within native forest systems and the management challenges associated with underestimating historically benign pests.

  PublisherDOI

• Fungal and Bacterial Communities of the Red Turpentine Beetle (Dendroctonus valens LeConte) in the Great Lakes Region, USA

  Forests · 2025-10-19 · 1 citations

  articleOpen access

  Fungi and bacteria associated with bark beetles can facilitate successful tree colonization, and, in some cases, these fungi act as pathogens of trees. The red turpentine beetle (RTB, Dendroctonus valens) is a bark beetle native to North America that colonizes stressed pines, rarely killing healthy trees. The fungal communities associated with RTB adults, larval galleries, and control tree phloem from red pine (Pinus resinosa) and white pine (P. strobus) forests in the Great Lakes region of the United States were characterized using both culture-independent and culture-dependent methods. Similarly, the bacterial communities associated with RTB adults in the same region were characterized using a culture-independent method. There were significant differences between the adult beetle fungal communities and the tree-based fungal communities. Culture-independent sequencing of RTB adults showed high abundances of the fungal order Filobasidiales (red pine: 28.71% relative abundance, white pine: 6.91% relative abundance), as well as the bacterial orders Enterobacterales (red pine: 53.72%, white pine: 22.15%) and Pseudomonadales (red pine: 15.86%, white pine: 12.91%). In contrast, we isolated high amounts of fungi in the orders Pleosporales (red pine: 21.79%, white pine: 15.90%) and Eurotiales (red pine: 15.38%, white pine: 16.51%) from the adult beetles by culturing. Culture-independent sequencing of beetle galleries yielded high abundances of fungi in the orders Helotiales (red pine: 22.23%, white pine: 23.21%), whereas culture-based isolation from the same galleries yielded high amounts of Eurotiales (red pine: 17.91%, white pine: 17.91%), Hypocreales (red pine: 16.42%, white pine: 16.42%), and Ophiostomatales (red pine: 23.39%, white pine: 23.39%). This contrasts with the culture-independent method, where, likely due to limitations in the sequencing method, the Ophiostomatales accounted for only around 2% of the fungi from RTB galleries in both pine species. We observed a high species-level diversity of Ophiostomatales associated with RTB, isolating 14 species from the Great Lakes region. Leptographium terebrantis, a species that has been described in association with RTB throughout the United States, was the most common species (e.g., >35% of the Ophiostomatales relative abundance in red pine environments and >14% of the Ophiostomatales relative abundance in the white pine environment). This study enhances our understanding of RTB-associated fungi and bacteria in the beetle’s native range at both the community and species levels.

  PublisherOA PDFDOI

• Behavioral responses of eastern larch beetle (Coleoptera: Curculionidae: Scolytinae) to pheromone components and selected host-produced compounds in the Great Lakes region

  Environmental Entomology · 2025-01-26

  articleSenior author

  The eastern larch beetle, Dendroctonus simplex LeConte, is a North American species of bark beetle that shares the distribution of its host, Larix laricina (Du Roi) K. Koch. A recent outbreak in the Great Lakes region has prompted renewed interest in the chemical ecology of eastern larch beetle and its natural enemies. Here, we describe field assays elucidating these insects' flight responses to host resin odors and pheromone components in Minnesota and laboratory olfactometer assays illustrating walking responses by eastern larch beetle to pheromone components produced by female beetles. In field trials, the addition of host monoterpenes ∆-3-carene and α-pinene to seudenol lures increased trap captures of eastern larch beetles. Similarly, α-pinene increased captures of Thanasimus spp. predators in seudenol-baited funnel traps. Frontalin release rates between 0.014-3.3 mg/day did not significantly alter catches of eastern larch beetles with seudenol alone, however, still higher concentrations of frontalin (24 mg/day) decreased catches. In contrast, increasing frontalin release rates increased attraction of Thanasimus spp. to seudenol. In a laboratory olfactometer assay, a combination of frontalin and seudenol released at rates comparable to those of a solitary, mining female arrested walking male eastern larch beetles whereas either compound alone did not. Insights into the eastern larch beetle's chemical ecology will improve understanding of cues in host and mate location that may be exploited for management.

  PublisherDOI

• Population phase-dependent niche requirements may limit outbreaks of the range-expanding mountain pine beetle in the western boreal forest

  Forest Ecology and Management · 2025-09-22 · 1 citations

  articleOpen access

  Climate warming has exacerbated hyperepidemics by irruptive species in habitats outside their historic range. However, range expansion during epidemics may not result in long-term persistence or proliferation in novel habitats if requirements of sub-outbreak (endemic) populations differ from those of epidemic populations. Mountain pine beetle ( Dendroctonus ponderosae ), an irruptive bark beetle in western North American lodgepole pine forests, recently breached the Rocky Mountain geoclimatic barrier and expanded into evolutionarily naïve lodgepole pine and jack pine forests. We examined its potential to naturalize in newly invaded habitats by quantifying biotic interactions with trees known to predispose hosts to endemic beetle populations in 16 stands along a transect from the native range to eastern edge of the invasion front. The density of trees susceptible to endemic mountain pine beetle was 3 × greater in native and naïve lodgepole pine than in jack pine. The quality of the endemic niche in novel habitats for D. ponderosae , especially in jack pine, was further constrained by greater competition with other subcortical species. In newly invaded jack pine forests, 50 % of defensively compromised trees were co-occupied by woodboring beetle species versus 20 % in naïve lodgepole and < 1 % in historical lodgepole pine forests, and when woodborers were present, 17 × , 6 × , and 0.25 × more phloem was consumed, respectively. Thus, the niche available to endemic D. ponderosae in western boreal jack pine forests appears to be constrained by both lower resource availability and higher competition, suggesting recurrent outbreaks originating there are unlikely. In contrast, novel lodgepole pine habitats appear suitable for endemic populations, and may generate outbreaks during favorable conditions. • Niche requirements distinct for endemic and epidemic mountain pine beetles. • Persistence in novel habitats requires an available endemic niche. • Endemic niche assessed in native lodgepole and newly invaded jack pine habitats. • Endemic niche in jack pine constrained by low resources and high competition.

  PublisherDOI

• Pheromone Composition of the Eastern Larch Beetle Dendroctonus simplex Leconte (Coleoptera: Curculionidae): Quantitative Analyses and Olfactory Responses

  Journal of Chemical Ecology · 2025-02-01 · 1 citations

  article
  PublisherDOI

• Survival of elongate hemlock scale (Hemiptera: Diaspididae) with prolonged cold exposure: overwintering mortality risk across North America

  Environmental Entomology · 2025-08-26 · 1 citations

  article

  Elongate hemlock scale, Fiorinia externa Ferris (Hemiptera: Diaspididae), is an invasive pest of eastern hemlock, Tsuga canadensis, and other Pinaceae such as Fraser fir, Abies fraseri. Cut Fraser firs (ie for Christmas trees and other holiday greenery) with F. externa have been intercepted in US states beyond where the insect is known to be established and, in some cases, where exposure to freezing temperatures might be prolonged. This study measures the effect of constant low temperatures (3, -10, or -20 °C) on survival of overwintering F. externa females from eastern hemlock in Michigan and from eastern hemlock and Fraser fir in North Carolina. Survival was determined with biochemical viability testing, which assesses the presence of metabolically active cells, and changes in survivorship through time were quantified with Kaplan-Meier methods and beta regression. Collection date and host occasionally affected survival rate but not in a consistent pattern. Survival rates generally decreased as temperature decreased. At 3 °C, F. externa maintained high survival (>75%). At -10 °C, survival was projected to fall to 50% within 22 to 92 d and 10% by 45 to 195 d. At -20 °C, survival typically declined to 50% by 1 to 27 d and 10% by 6 to 52 d. We used survival durations at -20 °C to map how often F. externa might experience 50 or 90% mortality from prolonged cold exposure. Temperatures in recent winters have not been below -20 °C for long enough to stop F. externa from spreading throughout the ranges of eastern hemlock or other hosts in Canada and the continental United States.

  PublisherDOI

• Population Phase-Dependent Niche Requirements May Limit Outbreaks of the Invasive Mountain Pine Beetle in the Western Boreal Forest

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• Population Phase-Dependent Niche Requirements May Limit Outbreaks of the Invasive Mountain Pine Beetle in the Western Boreal Forest

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• Eastern larch beetle (Dendroctonus simplex LeConte) as a potential threat to western (Larix occidentalis Nutt.) and subalpine larches (Larix lyalli Parl.)

  Frontiers in Forests and Global Change · 2024-11-19

  articleOpen accessSenior author

  Eastern larch beetle Dendroctonus simplex LeConte has been outbreaking for the past two decades in the Great Lakes region of North America, impacting approximately 400,000 hectares of eastern larch Larix laricina (tamarack) forest in Minnesota, United States, alone. Range expansions of some Dendroctonus species driven by climate change have occurred across North America as rising temperatures increase climatically suitable habitats across latitudes and elevations. The range of eastern larch beetle is currently sympatric to that of its host, eastern larch, but the insect could, in theory, eventually access ranges of other species of Larix native to North America. We compared host suitability of two potential novel hosts, western larch ( Larix occidentalis Nutt.) and subalpine larch ( Larix lyalli Parl.) against the beetle’s native host, eastern larch, using a reproductive success experiment conducted in cut bolts of all three species. We measured fertility, maternal gallery length, and offspring size and lipid content as metrics of reproductive success. We found beetles could reproduce in both novel Larix species, with subalpine larch having high levels of success compared to the beetle’s native host, eastern larch. These findings suggest that subalpine larch may be at risk should a range expansion of eastern larch beetle occur.

  PublisherOA PDFDOI

• The <i>Polydrusus</i> weevils (Coleoptera: Curculionidae) of the United States of America and Canada: identification and insights into the ecology of two nonnative species in hazel (<i>Corylus</i> spp.)

  The Canadian Entomologist · 2024-01-01

  articleOpen accessSenior author

  Abstract Seven species of Polydrusus Germar weevils (Coleoptera: Curculionidae) occur in the United States of America and Canada, three of which are introduced from Europe, are polyphagous, and may be displacing native weevil fauna in select areas of North America. We review host plant information for these species and provide distributional maps for each. We also present results on the seasonal phenology and sex ratios of two nonnative species, Polydrusus impressifrons (Gyllenhal) and Polydrusus formosus (Mayer), recorded in 2020 and 2021 in two orchards of hybrid hazelnuts (Betulaceae) in Minnesota, United States of America. These two species may present an episodic threat to the burgeoning hybrid hazelnut industry due to their ability to damage buds, foliage, and roots of hardwoods. We found that adults of these two species began emerging in late May of each year and remained present until mid-July. We found higher numbers of P. formosus than of P. impressifrons on hazel plants. Sex ratios of both species were generally between 50–60% male. We supply a compendium of species descriptions that (1) distinguishes between native and nonnative species and (2) identifies the sex of nonnative species. This research contributes to work on the ecology of Polydrusus , conservation of native species, and the management of tree crops.

  PublisherOA PDFDOI

Frequent coauthors

• Kenneth F. Raffa

  University of Wisconsin–Madison

  83 shared

• Jun Zhu

  University of Wisconsin–Madison

  36 shared

• Jesper Møller

  32 shared

• Jakob Gulddahl Rasmussen

  Aalborg University

  32 shared

• Allan L. Carroll

  University of British Columbia

  23 shared

• Robert C. Venette

  Northern Research Station

  22 shared

• Fraser R. McKee

  Alberta Ministry of Agriculture and Forestry

  17 shared

• B. Staffan Lindgren

  17 shared

Labs

• The Aukema LabPI

Education

• PhD in Forest Entomology

  University of Wisconsin

  2003

• MS in Biometry (Environmental Statistics)

  University of Wisconsin

  2003

• MS in Forest Entomology

  University of Wisconsin

  1999