An agent-based model to investigate the roles of attractive and repellent pheromones in ant decision making during foraging

Abstract

Pharaoh's ants organise their foraging system using three types of trail pheromone. All previous foraging models based on specific ant foraging systems have assumed that only a single attractive pheromone is used. Here we present an agent-based model based on trail choice at a trail bifurcation within the foraging trail network of a Pharaoh's ant colony which includes both attractive (positive) and repellent (negative) trail pheromones. Experiments have previously shown that Pharaoh's ants use both types of pheromone. We investigate how the repellent pheromone affects trail choice and foraging success in our simulated foraging system. We find that both the repellent and attractive pheromones have a role in trail choice, and that the repellent pheromone prevents random fluctuations which could otherwise lead to a positive feedback loop causing the colony to concentrate its foraging on the unrewarding trail. An emergent feature of the model is a high level of variability in the level of repellent pheromone on the unrewarding branch. This is caused by the repellent pheromone exerting negative feedback on its own A c c e p t e d m a n u s c r i p t 2 deposition. We also investigate the dynamic situation where the location of the food is changed after foraging trails are established. We find that the repellent pheromone has a key role in enabling the colony to refocus the foraging effort to the new location. Our results show that having a repellent pheromone is adaptive, as it increases the robustness and flexibility of the colony's overall foraging response.

A context-dependent alarm signal in the antTemnothorax rugatulus

“…The nature of this signal has not been determined, but it may be the same as the alarm pheromone that we have identified in T. rugatulus. In both cases, unlike other reported negative pheromones (Giurfa and Núñez, 1992;Robinson et al, 2005;Robinson et al, 2008;Stout et al, 1998), the signal does not actually repel ants from entering a marked nest, but instead reduces the colony's probability of moving to the nest (Stroeymeyt et al, 2014; T.S. and B.H., personal observation).…”

“…Many species rely on positive feedback from mass recruitment to concentrate foraging forces on the best available food source (Hölldobler and Wilson, 2009;Seeley, 1995;Sumpter, 2010). In a few species, evidence suggests that scouts apply repellent pheromones to deter nestmates from foraging in areas of low-quality food (Giurfa and Núñez, 1992;Robinson et al, 2005;Robinson et al, 2008;Stout et al, 1998). Theoretical models predict that such repellent signals can prevent the strong positive feedback of mass recruitment from locking a colony into a suboptimal choice (Giurfa and Núñez, 1992;Robinson et al, 2005;Robinson et al, 2008;Stout et al, 1998).…”

Agent-based Models as Fictive Instantiations of Ecological Processes

“…Robinson et al (2008) constructed a simulation model based on experiments conducted on Pharaoh's ant, Monomorium pharaonis. Figure 1A shows the state changes in the modeled antagent behavior depending on environmental context.…”

Response to a change in the target nest during ant relocation

“…In addition, their movement to the new nest will be more gradual as the entire colony marches on chemical trails from their old nest. The pheromones used along these trails are complex mixtures, giving information regarding direction and strength; the trail may also include short-lived repellants (Hölldobler and Wilson, 1990;Robinson et al, 2008). Aspects of relocation, including the manner of decision making has been studied in Temnothorax species.…”