Selectivity in individual foragers: Size and mass constraints on food choice in Dinoponera quadriceps

Ants use individual decision-making criteria that allow for choice among different foraging strategies according to prey characteristics. Some ant species do not vary their foraging strategy despite the probable ability to discriminate among prey. Here, our aim was to examine whether ants that forage individually, discriminate prey size, weight, and volume. We conducted laboratory experiments with Dinoponera quadriceps (Kempf 1971) workers in which we manipulated food items to observe differentiation in the ants among these parameters. D. quadriceps foragers discriminated food based on size and weight, preferring smaller, lighter items. A 50% increase in item weight significantly reduced collection frequency, indicating that weight is a critical discriminant factor. In contrast, a twofold increase in item volume, while maintaining constant weight, had no significant effect on the foraging rate. The preference for light loads and the fragmentation strategy suggest an optimization to maximize the number of successful foraging trips per unit of time, rather than maximizing payload per trip, which is consistent with a solitary foraging strategy.