Using spatial genetics to characterize spruce budworm dispersal
The spruce budworm (SBW; Choristoneura fumiferana) is a lepidopteran forest pest that devastates huge areas of spruce and fir forest during its periodic outbreaks. SBW outbreak dynamics are shaped by the complex interactions among climate, forest structure, communities of natural enemies, and dispersal. Despite the significance of movement to the spatial dynamics of SBW outbreaks, little is known about SBW dispersal, how it varies with spatial context and over course of an outbreak, and how it affects spatial synchrony in outbreak dynamics. This research applies tools and methods from spatial population genetics to characterize genetic connectivity among outbreak patches in the current outbreak in eastern north America. Using this information on genetic connectivity, and how it varies within and among years, we will infer patterns of gene flow and dispersal and how it varies as a function of intervening land-cover (isolation by resistance) and local environmental conditions (isolation by environment). Concurrently, we are developing dispersal models using predicted phenology (BioSIM) and demographic data collected from pheromone traps (adult males). Together, this work will increase our knowledge of how SBW movement varies in different forest and landscape contexts and will be used to improve simulation models that predict insect population dynamics and forecast future outbreak risk. This work will also address the important question of the potential efficacy of currently proposed early intervention strategies.
Check out our photo gallery illustrating our sampling network and developing results.
Students: Jeremy Larroque, Simon Legault
Collaborators: Rob Johns (CFS, AFC)
SBW larva hanging by a thread. Photo: Olivier Pontbriand-Paré
Spatial genetic structure is influenced by ecological context. Genetic structure in cyclic and irruptive populations will depend on the timing of data collection (peak or trough), context-dependent dispersal in the species, as well as the amplitude and frequency of population oscillations. See James et al (2014). for more details.