A host of hardships: How a long-lived parasite affects its host's fitness.

Monday, October 7, 2019 - 4:10pm
Event Type: 

Dr. Amy Worthington, Creighton University, Department of Biology

Co-sponsored by EEB / EEOB.

Abstract. Parasites often manipulate their host’s behavior and physiology to their benefit, which can have significant and detrimental impacts on the host’s fitness. For example, parasites may actively suppress their host’s immune response to avoid detection, yet an unfortunate consequence of immune suppression could prevent the host from surviving a secondary infection – prematurely killing host and parasite alike. Additionally, parasites may divert host use of resources away from reproduction, as doing so likely increase the energetic resources available for the parasite’s own growth and development. From the host’s perspective, surviving infection is imperative, yet so too is the ability to produce viable offspring, and any negative effects that parasites have on either survival or reproduction will drastically limit host fitness. The horsehair worm is a long-lived parasite that infects arthropods, including the sand field cricket Gryllus firmus. Interestingly, infection by and emergence of the parasite does not immediately kill its host, yet may drastically reduce or even prevent reproduction. In my lab, we investigate how the horsehair worm, Paragordius varius, avoids immune detection without making its host vulnerable to secondary infections, and examines whether host investment into energetically expensive processes are negatively affected, specifically focusing on the growth of somatic and reproductive structures. Finally, we examine the ability of infected males to invest in the energetically expensive courtship behaviors required to attract a female (i.e. calling), and quantify whether infection negatively affects female mate preference. Our work provides further insight into the complex manipulative physiological and behavioral mechanisms that define many parasite-host relationships, while taking into account a unique life-history from the perspectives of both host and parasite.