Stay or grow? Linking temperature regimes to maladaptive mountain pine beetle development

PROJECT TEAM

Bennett Wardman, MSc

Dr. Allan Carroll, PhD

What are the limits of adaptive mountain pine beetle development?

Mountain pine beetle (Dendroctonus poderosae Hopkins Coleoptera: Scolytinae; MPB) is a native disturbance agent of Pinus species across its historic range, capable of landscape level disturbance in its epidemic state. Appropriate climatic conditions are needed in conjunction with suitable hosts for beetle populations to build. While climate change may benefit beetle winter survival, increases in summer temperatures may lead to pupation within the same growing season as host colonization, which could result in reduced population synchrony and cold tolerance. Given that no predictive models account for both the drawbacks of warm summers and the facultative diapause of MPB in its Canadian range, we sought to determine the thermal conditions that lead to maladaptive development (pupation before overwintering) using 3 British Columbian MPB populations grown in the field across an elevational gradient, with the goal of furthering our understanding of MPBs’ thermal range in the context of climate change.

“Trees can’t move, but temperature fluctuates through time. To proactively manage mountain pine beetle outbreaks, we need to know where mountain pine beetles optimal thermal habitat is, and where it is going in the future”

– Bennett Wardman

When and where will temperatures be suitable for mountain pine beetle?

MPB range has historically been limited by cold temperatures. However, the loss of synchrony and reduced cold tolerance of developmental stages past the late larval instars could limit or disrupt outbreaks with climate change. Using aerial overview survey data, we hope to determine whether excessive development has disrupted past outbreaks in MPBs’ historical Canadian range. If warm temperatures can alter outbreak dynamics, we will predict what areas will likely remain or become viable for the species in the context of climate change, to further our understanding of how MPB outbreak risk may change in the future.