Koichi Kurumatani, Electronical Laboratory (ETL), Amagasaki, Hyogo, Japan
Email: kurumatani@etl.go.jp
In previous study, we proposed a model for foraging behavior of an ant
colony composed of many ants who behave to collect foods from food
sites to a nest. Their behavior was modeled as follows: At first, an
ant walks randomly in search of food and recruit pheromone. If it
finds food, it carries food straight to the nest laying recruit
pheromone. The pheromone evaporates soon, and gradually diffuses. If
a searching ant perceive the pheromone, it is recruited to the food
site. As a result of an interaction among micro-scale behaviors of
many ants, macro-scale foraging behavior of a colony is organized. We
performed simulation of above model, and observed a competition
process of recruitment among food sites, which results in
over-concentrated recruitment to a single site. Then, we made a
desensitization assumption, as "when an ant perceives
over-concentrated recruitment around itself, it becomes desensitized
to recruited pheromone for a while", so that some of ants might be
desensitized to circumvent such unwanted over-concentration. In this
presentation, we set the desensitization rule as "when an ant misses
food at food sites, it gets desensitized", to improve foraging
efficiency. We performed further simulations, and observed that the
system organizes different recruitment pattern and selects appropriate
foraging strategy according to rate of food supply. When food supply
is sufficient, concentrated recruitment to a single site is organized,
and when food supply is not sufficient, stable distributed recruitment
to several sites is organized. Mechanism of changing the foraging
strategies could be explained.