Assigning Phenologically Asynchronous Moths to Source Populations Using Individual Genotypes.

Area of Science:

• Forest entomology
• Population genetics
• Insect ecology

Background:

• Spruce budworm (Choristoneura fumiferana; SBW) outbreaks cause significant boreal forest damage.
• Understanding the drivers of spatial synchrony in SBW outbreaks is crucial for effective management.
• The role of long-distance dispersal in synchronizing SBW outbreaks remains poorly understood.

Purpose of the Study:

• To investigate the contribution of long-distance dispersal to spruce budworm outbreak synchrony.
• To differentiate between resident and migrant SBW moths using genetic markers.
• To assign migrant moths to their likely source populations to characterize regional dispersal patterns.

Main Methods:

• Genotyping-by-Sequencing (GBS) was used to analyze genetic diversity and structure in SBW larvae and moths.
• A machine learning approach was employed to assign putative migrant moths to source populations.
• Phenologically separated moth groups were sampled across a single flight season.

Main Results:

• Two spatially overlapping genetic clusters were identified within the SBW population.
• Subtle but significant genetic differences were observed between resident SBW larvae and migrant moths.
• Findings support the hypothesis that long-distance dispersal plays a role in SBW outbreak dynamics and synchrony.

Conclusions:

• Long-distance dispersal is a contributing factor to the spatial synchrony of spruce budworm outbreaks.
• Genetic analysis successfully distinguished between resident and migrant moth populations.
• Management strategies, like the Early Intervention Strategy (EIS), should incorporate dispersal dynamics for improved efficacy.