Population structure and associated larval host variation of the forest tent caterpillar, Malacosoma disstria

• Author / Creator

  Snape, Kyle L

• The forest tent caterpillar, Malacosoma disstria (M. disstria) Hübner, is a major forest defoliator with regional differences in host association across its range, but the factors shaping its population structure are poorly understood. In eastern Canada, M. disstria primarily feeds on maple (Acer saccharum) or aspen (Populus tremuloides), and earlier studies have documented functional differences between populations on different larval hosts. However, it is not known whether these populations differ genetically. Clarification of the link between host races, genetic variation and geographic distribution can help to inform our understanding of M. disstria population dynamics. I collected 130 M. disstria larvae from eastern Canada, Alberta and Saskatchewan to characterize their population genetic structure, using a reduced representation library to genotype 9,284 SNPs (single nucleotide polymorphisms) across their genome. I found no meaningful genetic differences between M. disstria sampled on different larval hosts. However, I did detect regional genetic variation between populations sampled from different ecozones within eastern Canada. On a broader geographic scale, I also found strong divergence between eastern and central populations. Mitochondrial sequences (new and previously published) loosely supported this east-west division. M. disstria population structure therefore appears to be shaped by geography and regional forest structure, rather than larval host.

• Subjects / Keywords

  • SNP
  • COI
  • Population
  • Malacosoma

• Graduation date

  Fall 2020

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-g90e-p211

• License

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