Comparative Foraging Behavior of Six Stingless Bee Species Exploiting a Standardized Resource

We report on differences in foraging and recruitment patterns among 6 stingless bee species simultaneously exploiting a large grid of baits in a tract of tropical dry forest in Costa Rica. Comparative data for the species were obtained on the following parameters of foraging: time to initial bait discovery, rate of discovery of additional baits, rate of worker recruitment, time till attainment of approximate steady—state number of workers and visited baits, frequency of number of workers per bait, degree of site constancy of foraging within and between days, and responses to presence of intraspecific and interspecific rivals at baits. All species had unique aspects to their foraging, which reflected whether the species mark food sources and lay trails with pheromones, the degree to which workers forage solitarily, and their use of aggression. The behavior of Trigona fuscipennis, the pheromone—using group forager, was particularly distinctive. It found baits the most slowly, was the most site constant, and excluded all other bees from its baits. We hypothesize that in group foragers, extreme localization of workers and resultant slowness of discovery of new food sources represent a trade—off for the advantages of group defense of good sources. Other responses to rival bees included bullying tactics by lone, marauding workers of the large, facultative recruiter, Trigona silverstriana, and persistent, opportunistic insinuation by small, solitary foraging species. Spatial segregation of foraging location between the species increased over time on each day of the experiment, especially among interspecifically aggressive species. The observed diversity of tempo and mode of foraging reinforces the hypothesis that coexistence among these apparently food—limited social bees does not result from the simple partitioning of food resources by size or taxon, but from rather subtle partitioning based upon diversity in the timing, persistence, renewal rate, and spatial dispersion of their limited food resourves.