Nectar foraging by stingless bees in Costa Rica:: botanical and climatological influences on sugar concentration of nectar collected by Melipona

Nectar foraging by two species of stingless bees, Melipona beecheii and Melipona fasciata, was studied in Costa Rica. In the humid forest environment M. beecheii collected more concentrated nectar than M. fasciata. Pollen analysis showed that their nectar sources overlapped considerably and that M. beecheii collected richer nectar than M. fasciata even from the same plant species. Thus, the botanic origin of the nectar explained only part of the differences. There was no difference in the sugar concentration of the nectar collected by the two species at a dry tropical site where M. fasciata was introduced and M. beecheii occurs naturally. In the dry habitat, both species collected more concentrated nectar than at the humid site. Foraging behaviour of the bees is suggested as the basis for resource partitioning in humid forests. (C) Inra/DIB/AGIB/Elsevier, Paris.