UCLA

Foragers often face difficult landscapes in terms of encountering previously unexplored areas or areas where risk is present along paths to food. Cooperatively foraging groups work both to find food and thereafter efficiently exploit or retrieve it and therefore may need to adapt their search strategies in complex environments in order to attain these goals. Previous work has focused on the simultaneous appearance of food and risk. Further, little research has been done to describe whether or not individual foragers mark their paths as they explore their environment and if they do, how this information affects subsequent foragers as they encounter the marks. Here, I examine the path choice by Argentine ants (Linepithema humile) in novel and complex environments. In Chapter 1, I tested if solitary exploring workers leave behind marks as theyexplore novel areas and if this affects the direction subsequent individuals travel. The resulting pattern does not significantly differ from random choice, as workers are neither more nor less likely to choose the path taken by a previous ant. The time between decisions also does not predict the path chosen. This suggests that L. humile is more expansive in initially distributing its workers across novel ground. In Chapter 2, I examined whether colonies learn and respond to negative features of their environments and how this affects their path choice over time. L. humile workers respond differently depending on the type of risk present where they patrol/defend more in the presence of live competitors but decrease foraging in response to just a chemical cue.