Entomopathogenic fungus - arthropod host interactions along environmental gradients

Frederik Christiaan DE WINT

Disertační práce

Entomopathogen-mediated negative density dependence as a driver of arthropod diversity along elevational gradients

Abstract:

This thesis explores the diversity, ecology, and biogeography of entomopathogenic fungi (EPF) and their interactions with arthropod hosts, emphasizing their roles in natural ecosystems and under changing environmental conditions. Chapter 1 presents a comprehensive literature review of EPF-arthropod interactions in the Anthropocene, highlighting the ecological importance of EPF, their evolutionary adaptations such as host behavior manipulation, and their potential as environmentally sustainable biocontrol agents. This chapter also addresses how global change, including climate shifts and species invasions, may disrupt EPF-host dynamics. Chapter 2 shifts focus to a field-based inventory of ant diversity in the cloud forests of Cusuco National Park, Honduras. By combining new data with prior records, the study expands the known ant species count from 121 to 162, presents several national first records, and provides a practical identification key to ant genera in Honduras. This foundational work will inform future biodiversity assessments in one of the world's most irreplaceable protected areas. Chapter 3 introduces EntomoFun, an open-access global database centralizing 1,791 documented EPF-host associations drawn from literature and herbarium sources. Here we reveal major gaps in our understanding of EPF distributions, particularly in tropical Africa and Southeast Asia, and highlight host preferences across fungal families. The database is designed to support ecological research, conservation, and the development of biocontrol applications. Chapter 4 investigates entomopathogenic fungus (EPF)-host communities across natural environments. We studied these communities along an elevational gradient in the primary forests of Mt. Kinabalu, Sabah, Borneo. Infected arthropods were collected using a standardized framework, with measurements of multiple environmental factors. EPF, host arthropods, and substrate plants were identified using morphological and molecular methods. We assessed cadaver abundance and height across host groups and fungal orders, and constructed three-level interaction networks (EPF-arthropod-plant) to evaluate taxon richness and network structure (specialization, robustness, and modularity). Cadaver abundance varied with elevation and host group but not fungal order. Cadaver height was unaffected by elevation, but showed patterns in models that included multiple environmental variables. Species richness of EPF and associated plants, as well as network modularity, changed with elevation, but arthropod richness, specialization, and robustness did not. However, robustness changed in relation to environmental variables. These patterns reflect the importance of a multilayered forest structure, which buffers EPF microclimate and likely influences host availability. Our findings offer insights relevant to climate change, habitat loss, and agricultural impacts.

Abstract:

This thesis explores the diversity, ecology, and biogeography of entomopathogenic fungi (EPF) and their interactions with arthropod hosts, emphasizing their roles in natural ecosystems and under changing environmental conditions. Chapter 1 presents a comprehensive literature review of EPF-arthropod interactions in the Anthropocene, highlighting the ecological importance of EPF, their evolutionary adaptations such as host behavior manipulation, and their potential as environmentally sustainable biocontrol agents. This chapter also addresses how global change, including climate shifts and species invasions, may disrupt EPF-host dynamics. Chapter 2 shifts focus to a field-based inventory of ant diversity in the cloud forests of Cusuco National Park, Honduras. By combining new data with prior records, the study expands the known ant species count from 121 to 162, presents several national first records, and provides a practical identification key to ant genera in Honduras. This foundational work will inform future biodiversity assessments in one of the world's most irreplaceable protected areas. Chapter 3 introduces EntomoFun, an open-access global database centralizing 1,791 documented EPF-host associations drawn from literature and herbarium sources. Here we reveal major gaps in our understanding of EPF distributions, particularly in tropical Africa and Southeast Asia, and highlight host preferences across fungal families. The database is designed to support ecological research, conservation, and the development of biocontrol applications. Chapter 4 investigates entomopathogenic fungus (EPF)-host communities across natural environments. We studied these communities along an elevational gradient in the primary forests of Mt. Kinabalu, Sabah, Borneo. Infected arthropods were collected using a standardized framework, with measurements of multiple environmental factors. EPF, host arthropods, and substrate plants were identified using morphological and molecular methods. We assessed cadaver abundance and height across host groups and fungal orders, and constructed three-level interaction networks (EPF-arthropod-plant) to evaluate taxon richness and network structure (specialization, robustness, and modularity). Cadaver abundance varied with elevation and host group but not fungal order. Cadaver height was unaffected by elevation, but showed patterns in models that included multiple environmental variables. Species richness of EPF and associated plants, as well as network modularity, changed with elevation, but arthropod richness, specialization, and robustness did not. However, robustness changed in relation to environmental variables. These patterns reflect the importance of a multilayered forest structure, which buffers EPF microclimate and likely influences host availability. Our findings offer insights relevant to climate change, habitat loss, and agricultural impacts.

Keywords

Fungal pathogens, host interaction, arthropod association, spatial gradients, elevational gradients, latitudinal gradients, anthropogenic pathogen disturbance

Jazyk práce: angličtina

Datum vytvoření / odevzdání či podání práce: 4. 12. 2025

Obhajoba závěrečné práce

• Vedoucí: Tom Maurice Fayle, Ph.D.

JIHOČESKÁ UNIVERZITA V ČESKÝCH BUDĚJOVICÍCH

Přírodovědecká fakulta

Doktorský studijní program / obor:
Entomology / Entomology