Understanding Ophiocordyceps, The Zombie Ant Fungus: A Case Study In Host Behavioral Manipulation
Open Access
- Author:
- Fowler, Benjamin Dylan
- Area of Honors:
- Immunology and Infectious Disease
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Dr. David Peter Hughes, Thesis Supervisor
Dr. Pamela A. Hankey-Giblin, Thesis Honors Advisor - Keywords:
- Fungi
behavioral manipulation
parasite
host-parasite
transmission
infectious disease
ant
Ophiocordyceps
zombie ant - Abstract:
- Millions of years of evolution have led many pathogens to develop unique strategies to maximize their transmission. Behavioral manipulation is one of these strategies and has captured wide audiences with the idea of zombie-like mind control. Ophiocordyceps is a genus of fungal parasites that infect insects, leading to the zombie-ant phenomenon, in which an infected ant leaves its home colony, climbs onto foliage above the forest floor, and subsequently dies. The species complex O. unilateralis even causes infected ants to bite into the plant’s flesh prior to death. Previous work has shown that this manipulation is essential for successful maturation of the fungus, but studies have not evaluated the role this manipulation may play in transmission of the fungus to susceptible host ants. Chapter 2 of this thesis introduces a novel strategy to evaluate the transmission potential of a particular species of the zombie-ant fungus, O. camponoti-atricipis. Experiments using spore-clocks and gravitational grids indicated that the fungus tightly concentrates infectious ascospore release during the early morning hours with a clear peak between 0500 and 0600 hours and that the release of spores is focused downwards by gravitropic growth. Chapter 3 of this thesis covers efforts to use phylogenetic analyses to assess the host specificity of O. unilateralis sensu lato. Together, these studies of transmission and host selectivity provide insights into the evolution of both behavioral manipulation and host specificity that help understand and model potential zoonotic diseases of humans.