Nematode parasite reduces the fight or flight reaction in its host

Felicia Ebot-Ojong, a junior from the University of Georgia, worked with Dr. Andy Davis to study the effect of nematode parasites on the fight-or-flight reaction of infected beetles.

Abstract:  Parasites cause a range of unfavorable effects on host fitness, including reducing available energy. This could be detrimental in situations where the host needs to escape a harmful situation (in a “fight-or-flight” situation), though this is rarely studied in parasitology research. The bess beetle (Odontotaenius disjunctus) inhabits forests in the eastern United States and is host to a naturally-occurring nematode parasite (Chondronema passali), which can be extremely abundant within hosts. The goal of this project was to evaluate the how nematode infection affects the fight-or-flight responses of the beetles under simulated predator attack. A total of 150 beetles were collected locally and stored individually in plastic containers for 3 weeks. Each week, we assessed and video-recorded behavioral reactions to a series of “pokes and prods”, then scored level of the reactions in the videos. We assessed the number of vocalizations during attack, plus levels of physical resistance using a scoring system (Fig. 2). Beetles were later dissected and their level of nematode infection and gender was recorded. We found that beetles with nematode infections tended to have reduced fight-or-flight reactions to the predator attack compared to unparasitized individuals. The level of nematode infection had no effect on the amount of vocalization made by each individual during an attack. These results show that nematode infection has an energetic cost during situations where the host needs to respond quickly.

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