Understanding how predators impact keystone species, like ants, is very important for our understanding of ecology because of ants' importance in shaping community dynamics and ecosystem functions. In this thesis I present research investigating the role of the ant-specialized spider Anasaitis canosa in influencing the foraging behavior of four ant species (Formica pallidefulva, Odontomachus ruginodis, Pheidole obscurithorax & Solenopsis invicta). Collectively, these four species use foraging strategies exhibited by most ants. I conducted two experiments to quantify the impacts of spider predation on ant prey. The first used forty colonies of four ant species to investigate how A. canosa changed foraging behavior at both the individual and colony level. The second used 27 lab-reared S. invicta colonies to see if there was any evidence for innate predatory avoidance in foragers and if predatory avoidance was influenced by learning. A field study observed the density and prey choices of A. canosa in 3 sites within the UCF arboretum. In sum, no consistent change in foraging occurred in the presence of A. canosa, over time scales sufficient to detect colony-level impacts and thus colonies as a whole appear to be risk insensitive. Naïve colonies had more ants beginning foraging before a single ant would return in their first trial compared to the second trial. This suggests forager learning occurs as foragers respond to the perception of a predator, and that S. invicta can reduce individual risk through increasing forager numbers. A. canosa predation rates and density were calculated and based on these estimates an approximate impact upon a colony was made. Most importantly, 13 foragers/m2 inside each foraging cohort can be expected to have prior experience with the spider.
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Master of Science (M.S.)
College of Sciences
Length of Campus-only Access
Masters Thesis (Open Access)
Schadegg, Philip, "Fear and Loathing in the Super Organism: Foraging Strategy Doesn't Change Forager Response in a Landscape of Fear." (2019). Electronic Theses and Dissertations, 2004-2019. 6704.