Interactions between leaf-cutter ants and fungus garden: Effects of division of labor, age polyethism, and egg cannibalism

Abstract

Division of labor (DOL), age polyethism, and egg cannibalism all play roles in shaping colony-level population dynamics in social insect colonies. The ways in which these mechanisms interact with one another to shape population dynamics is not currently understood. In this study, we examine how these mechanisms influence population dynamics in colonies of fungus-gardening leaf-cutter ants by developing and studying two sets of models: (1) We study age polyethism contribution to the dynamics of this multi-species interaction model which incorporates mechanisms of DOL; (2) We explore effects of egg cannibalism in colony dynamics and understand how to model such social conflict behavior realistically using different functional responses. Our results suggest that: (a) Age polyethism is important to keep stable population dynamics. (b) Large maturation rate and mortality rate of inside workers induce colony death. (c) Small enough egg cannibalism rate benefits adult worker ant’s growth and (or) development, large proportion of ants performing a given task can promote colony survival, and too large egg cannibalism rate can lead to colony’s death. (d) Increasing energy invested on brood care and (or) the conversion rate between fungus and ants could induce oscillatory dynamics in models with cannibalism.