A Senior Capstone Experience by Nathaniel Braddock ’22

Submitted to the Department of Biology

Advised by Dr. Jennie Rinehimer

Contributor Biography: Nathaniel Braddock ’22 is a recent graduate who majored in Biology with a concentration in Ecology and Evolution and a minor in Art and Art History. He is an avid birdwatcher and lover of all plants. He hopes to take everything he has learned at Washington College into the world of public horticulture to create healthier, happier gardens that support native ecological communities.

Description: Some parasites modify host behavior to their own benefit. One such parasite is Ophiocordyceps unilateralis, an entomopathogenic fungus specializing in manipulating Camponotus ants. Infection causes muscle atrophy and novel behaviors such as full body tremors, phototaxis, and synchronized “death grip” biting, all of which help position the ant in ideal environmental conditions for fungal growth. At the morphological level, these changes are due to fungal invasion of the ant’s head and brain. Novel behaviors also seem to result from fungal proteins and secondary metabolites with putative neurological effects differentially secreted throughout the process of behavioral manipulation. This parasite-host system is so intricately coevolved that colonies do not seek to remove the parasite as they do with generalist pathogens. Understanding the mechanism behind O. unilateralis manipulation of Camponotus ants has impacts in ecological theory surrounding the “extended phenotype” as well as commercial impacts in the drug and cosmetics industries.

Read Nathaniel’s SCE below: