Social animals are predicted to increase dominance of a resource by foraging in groups. Group foraging strategies may be particularly important for the eusocial stingless bees (Hymenoptera, Apidae, Meliponini), tropical pollinators that experience high levels of competition for floral resources. We tested the role of group foraging in attaining dominance using six Brazilian stingless bee species that span a broad range of foraging strategies, colony sizes, body sizes, and aggression levels. Simulating mass-flowering trees with an array of artificial “flowers”, we compared species’ dominance and visitation under unrestricted foraging conditions and with removal of group-foraging species. For each species we calculated numerical dominance (local abundance), behavioral dominance (a colony’s ability to control feeders), displacement success (individuals’ ability to win fights) and attack probability. We hypothesized that removal would increase feeding opportunities for all species, with solitary foragers benefiting manly after removal of all group-foraging species.
Results/Conclusions
Species that recruit large numbers of nestmates — Scaptotrigona aff. depilis, Trigona hyalinata, T. spinipes — dominated both numerically and behaviorally. They also had high displacement success and attack probability. Removal of group foragers increased feeding opportunities for the solitary foragers: Frieseomelitta varia, Melipona quadrifasciata, Nannotrigona testaceicornis. Individual body size, which is also hypothesized to predict dominance, did not correlate with dominance. Our results show that group foraging, in conjunction with large colony sizes and aggressive behavior, enables stingless bee colonies to improve dominance of rich resources. Because bee foraging patterns determine plant pollination success, understanding the forces that shape these patterns in the natural context of diverse, interacting communities is crucial to ensuring pollination of both crops and natural areas in the face of current pollinator declines.
