Within-colony size variation of foragers and pollen load capacity in the stingless bee Melipona quadrifasciata anthidioides Lepeletier (Apidae, Hymenoptera)

Within-nest worker size variation in the eusocial stingless bees is a contingent phe nomenon of unknown adaptive value We assume that the magnitude of variation represents a compromise between a minimum population of foragers and foraging efficiency at colony level. In Melipona quadrifasciata, worker size was found to vary according to colony conditions, and the pollen carrying efficiency of an individual was related to its size. On average, the foragers from a weak colony are smaller and are able to carry greater amounts of pollen per unity of body weight ('load capacity') than the larger foragers from a strong colony. The allometric variation of the corbicula (the pollen carrying structure in the hind tibia) contributes to the observed decrease in pollen load capacity with increased body size. By higher pollen intake per worker, the colonies with smaller bees could increasing the rate of brood production and colony population recovery after population crashes. (C) Inra/DIB/AGIB/Elsevier, Paris.