Masters Theses
Date of Award
5-2025
Degree Type
Thesis
Degree Name
Master of Science
Major
Entomology and Plant Pathology
Major Professor
Denita Hadziabdic-Guerry
Committee Members
Denita Hadziabdic-Guerry, Dewayne Shoemaker, Bonnie H. Ownley
Abstract
Theobroma cacao L. (Malvaceae) is the main source of chocolate and cocoa related products. Around 60 countries in the pantropical region are involved in cacao production, and it is the main source of livelihood for approximately 60 million people. The cacao industry faces significant challenges from various pests and diseases that threaten the livelihood of subsistence farmers, who produce 90% of the world’s cacao. The first chapter investigates the impact of key cacao diseases, particularly in the Caribbean and Central America, focusing on their biological and environmental implications. The most prevalent pathogens discussed included Peronophythora, Moniliophthora, and Ceratocystis species, along with their economic consequences on global cacao markets. Chapter two explores the endophytic species associated with Criollo varieties. Putatively diseased leaf samples were collected from Criollo trees found at the Belize Foundation for Research and Environmental Education (BFREE) during two growing seasons (wet and dry). The Criollo sampled from the private protected area were part of a sub spontaneous population that were likely cultivated by early human civilization such as the Mayas. The culture dependent approach was used to get axenic fungal cultures. Mycelia from the cultures were used for DNA extraction and amplification, targeting the ITS region. Sequences were trimmed using the SangeranalyseR package in the R software, taxonomy were assigned using the UNITEver10 database. The sequences were also clustered into 97% similarity and the genera were matched to their primary lifestyle using FungalTraits. Ascomycota was the only fungal phylum identified in the dry season samples. In contrast, Ascomycota was the dominant phyla in the wet season however there was slightly more diversity, with Basidiomycota and Mucoromycota also being detected albeit in lower percentage. The findings provide baseline information for the important pathogenic species associated with criollo cacao and the need for integrated disease management and genetic improvement programs in securing the future of cacao cultivation in the face of ongoing challenges.
Recommended Citation
Ash, Lenardo, "A Survey of Fungal Communities Harbored in Leaves of Agroforestry and Wild Criollo Cacao (Theobroma cacao L.) in Southern Belize. " Master's Thesis, University of Tennessee, 2025.
https://trace.tennessee.edu/utk_gradthes/13869