Many parasites have evolved strategies to exploit host behavior such that it benefits parasite transmission. Ophiocordyceps manipulations of carpenter ant behavior represent an evident example. Manipulated ants are coerced to ascend vegetation and clamp down their mandibles in a stereotypical "death-grip" bite. The fungus then kills the ant, sprouts a stalk and releases infective spores. Research has focused on this ultimate manipulation, leaving the subtler behavioral changes pre-biting largely unexplored. Field and transcriptome data found that the host circadian clocks, olfaction, and communication may be disrupted, suggesting that the fungus is affecting ant foraging activity and effectivity. To test these hypotheses, we investigated if the foraging behavior of Camponotus floridanus ants is notably affected during early-stage Ophiocordyceps infection. Specifically, we use a maze to quantify foraging patterns and trail optimization. Moreover, by comparing infected individuals to healthy ants and those infected with non-manipulating Beauveria bassiana, we aimed to distinguish between non-manipulator and manipulator-specific changes. We found that Ophiocordyceps-infected ants become arrhythmic in their activity patterns, are less likely to participate in effective foraging efforts and are less able to communicate to their nestmates when optimizing to a food source. We hypothesize that these changed behaviors in Ophiocordyceps-infected ants are adaptive to fungal disease progression since they reduce chances of aggressive interference by nestmates. This study informs future work on parasitic strategies in underlying host manipulation, parasite-host interactions, and the behavioral ecology of infectious diseases in general.
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De Bekker, Charissa
Master of Science (M.S.)
College of Sciences
Length of Campus-only Access
Masters Thesis (Campus-only Access)
Trinh, Thienthanh, "Getting Lost: The Fungal Hijacking of Ant Foraging Behavior in Space and Time" (2020). Electronic Theses and Dissertations, 2020-. 305.