Semester

Spring

Date of Graduation

2024

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Wildlife and Fisheries Resources

Committee Chair

Christopher Lituma

Committee Member

Danielle Martin

Committee Member

James Kotcon

Committee Member

Scott Stoleson

Abstract

Beech leaf disease (BLD) is an emerging forest pathogen primarily affecting American beech (Fagus grandifolia, Ehrh.) in North America and has been attributed to tree mortality of sapling sized trees within five to seven years of infection. Symptoms typically occur in regenerating American beech thickets sprouting from roots of trees killed by beech bark disease. Scientists first observed BLD in Ohio in 2012 and currently has spread to 15 states in the USA and one Canadian province. The nematode Litylenchus crenatae subsp. mccannii (Lcm) is highly associated with BLD symptoms, interveinal chlorosis and defoliation of leaves, and is currently recognized as the major causal agent of BLD (Carta et al. 2020). Methods of dispersal are still being examined. Animal vectors could be responsible for the spread of Lcm and thus BLD. This was the first survey investigating birds as possible dispersal vectors of Lcm through endozoochory and ectozoochory. From 2021 to 2023 we collected 219 fecal, feather, and ectoparasite samples from 156 birds in infected BLD areas in Ohio and Pennsylvania. We kept birds in cages, fed them Lcm nematodes and collected fecal matter to determine if we could observe Lcm via endozoochory. We collected ectoparasite and feather samples to determine if Lcm nematodes could be observed via ectozoochory. We used PCR and microscopy to determine the presence of Lcm. Results confirmed presence in 21 samples from six avian species: tufted titmouse [Baeolophus bicolor], black-capped chickadee [Poecile atricapillus], white-breasted nuthatch [Sitta carolinensis], dark-eyed junco [Junco hyemalis], American goldfinch [Spinus tristis], and downy woodpecker [Dryobates pubescens]. We detected Lcm DNA from both endozoochory and endozoochory samples suggesting birds could act as vectors of Lcm. This study successfully used existing and novel methodologies to detect nematode DNA in avian biological samples. These methods can be adopted for future BLD research as well as animal vector and forest pathogen studies. If birds are dispersal vectors of BLD state, federal, or local agencies could create predictive models and implement preventative management to protect uninfected American beech stands.

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