Eastern Spruce Budworm In The Great Lakes Region: Forest Regeneration, Natural Enemies, And Dispersal. Rootes, J. M. Ph.D. Thesis, University of Minnesota, December, 2025. ![Eastern Spruce Budworm In The Great Lakes Region: Forest Regeneration, Natural Enemies, And Dispersal [link]](https://bibbase.org/img/filetypes/link.svg "link")
Paper abstract bibtex The eastern spruce budworm (Choristoneura fumiferana Clemens), (Lepidoptera: Tortricidae), is native to northeastern North America and feeds primarily on balsam fir (Abies balsamea (L.) Mill) and white spruce (Picea glauca (Moench) Voss). Outbreaking populations have been mapped annually in Minnesota since 1954. This dissertation examines forest regeneration in areas of northeastern Minnesota and on Isle Royale 15 years following outbreaks of spruce budworm, the natural enemy communities in both locations, and examines the potential connectedness of regional populations in Minnesota and Wisconsin by looking for evidence of dispersal over a flight season using adult trap catches and meteorological modeling. On Isle Royale, trees suffered higher mortality and negative alterations to their growth compared to similar forests in Minnesota. Those results suggest a positive correlation between moose density and adverse effects on forest regeneration in areas recovering from an outbreak of spruce budworm and support the use of wolves as predators of moose on the island to restore ecological function. Late instar larvae and pupae of spruce budworm were sampled from current outbreaks in these same locations in 2023 and 2024. Though the diversity of the parasitoid community was similar between the two locations, Isle Royale demonstrated higher rates of parasitism (18.8% to 33.7%) than Minnesota (10.3% to 17.1%), suggesting that natural enemies in both locations are capable of assisting with mediation of outbreaking spruce budworm populations. Fluctuations in populations of spruce budworm are likely related not only to natural enemy populations but dispersal of adult spruce budworms. To assess dispersal, I evaluated ten areas in northeastern Minnesota and northern Wisconsin in summer 2024 using automatic trapping methods and meteorological modeling. I found that sub-populations of spruce budworm were highly synchronized and that trap captures were predicted by captures in neighboring sites, precipitation, temperature, wind speed, and landscape composition (i.e., percent of a putative trajectory over forest or open water). Outbreaks of spruce budworm are multi-faceted, impacted by factors such as natural enemies and regional-wide dispersal, and can result in cascading effects on forest regeneration and composition.
@phdthesis{rootes_eastern_2025,
type = {Doctor of {Philosophy}},
title = {Eastern {Spruce} {Budworm} {In} {The} {Great} {Lakes} {Region}: {Forest} {Regeneration}, {Natural} {Enemies}, {And} {Dispersal}},
shorttitle = {Eastern {Spruce} {Budworm} {In} {The} {Great} {Lakes} {Region}},
url = {https://hdl.handle.net/11299/279274},
abstract = {The eastern spruce budworm (Choristoneura fumiferana Clemens), (Lepidoptera: Tortricidae), is native to northeastern North America and feeds primarily on balsam fir (Abies balsamea (L.) Mill) and white spruce (Picea glauca (Moench) Voss). Outbreaking populations have been mapped annually in Minnesota since 1954. This dissertation examines forest regeneration in areas of northeastern Minnesota and on Isle Royale 15 years following outbreaks of spruce budworm, the natural enemy communities in both locations, and examines the potential connectedness of regional populations in Minnesota and Wisconsin by looking for evidence of dispersal over a flight season using adult trap catches and meteorological modeling. On Isle Royale, trees suffered higher mortality and negative alterations to their growth compared to similar forests in Minnesota. Those results suggest a positive correlation between moose density and adverse effects on forest regeneration in areas recovering from an outbreak of spruce budworm and support the use of wolves as predators of moose on the island to restore ecological function. Late instar larvae and pupae of spruce budworm were sampled from current outbreaks in these same locations in 2023 and 2024. Though the diversity of the parasitoid community was similar between the two locations, Isle Royale demonstrated higher rates of parasitism (18.8\% to 33.7\%) than Minnesota (10.3\% to 17.1\%), suggesting that natural enemies in both locations are capable of assisting with mediation of outbreaking spruce budworm populations. Fluctuations in populations of spruce budworm are likely related not only to natural enemy populations but dispersal of adult spruce budworms. To assess dispersal, I evaluated ten areas in northeastern Minnesota and northern Wisconsin in summer 2024 using automatic trapping methods and meteorological modeling. I found that sub-populations of spruce budworm were highly synchronized and that trap captures were predicted by captures in neighboring sites, precipitation, temperature, wind speed, and landscape composition (i.e., percent of a putative trajectory over forest or open water). Outbreaks of spruce budworm are multi-faceted, impacted by factors such as natural enemies and regional-wide dispersal, and can result in cascading effects on forest regeneration and composition.},
language = {en},
urldate = {2026-06-01},
school = {University of Minnesota},
author = {Rootes, Jessica Michelle},
month = dec,
year = {2025},
keywords = {NALCMS},
}
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This dissertation examines forest regeneration in areas of northeastern Minnesota and on Isle Royale 15 years following outbreaks of spruce budworm, the natural enemy communities in both locations, and examines the potential connectedness of regional populations in Minnesota and Wisconsin by looking for evidence of dispersal over a flight season using adult trap catches and meteorological modeling. On Isle Royale, trees suffered higher mortality and negative alterations to their growth compared to similar forests in Minnesota. Those results suggest a positive correlation between moose density and adverse effects on forest regeneration in areas recovering from an outbreak of spruce budworm and support the use of wolves as predators of moose on the island to restore ecological function. Late instar larvae and pupae of spruce budworm were sampled from current outbreaks in these same locations in 2023 and 2024. Though the diversity of the parasitoid community was similar between the two locations, Isle Royale demonstrated higher rates of parasitism (18.8% to 33.7%) than Minnesota (10.3% to 17.1%), suggesting that natural enemies in both locations are capable of assisting with mediation of outbreaking spruce budworm populations. Fluctuations in populations of spruce budworm are likely related not only to natural enemy populations but dispersal of adult spruce budworms. To assess dispersal, I evaluated ten areas in northeastern Minnesota and northern Wisconsin in summer 2024 using automatic trapping methods and meteorological modeling. I found that sub-populations of spruce budworm were highly synchronized and that trap captures were predicted by captures in neighboring sites, precipitation, temperature, wind speed, and landscape composition (i.e., percent of a putative trajectory over forest or open water). 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