Floral visitors of the Opuntia monacantha (Cactaceae) in sandbank of the Florianópolis, SC, Brazil.
Flowers of Opuntia spp. (Cactaceae) may have close mutualistic relations with their visitors. Opuntia monacantha (Willd.) Haw. is a cactus from the Atlantic coastal area in Brazil and its flower morphology is related to a melittophilous floral syndrome. This study was developed in the years of 2005 and 2006 on the restinga vegetation in Florianópolis, SC, Brazil. The central goal of this study was to survey the floral visitors, determine the potential pollinators and to investigate the occurrence of oligolectic bees associated with O. monacantha flowers. The flowers are visited by a few species of insects, such as bees, beetles and ants. Female bees of Cephalocolletes isabelae Urban, 1995 (Colletidae) were abundant and frequent and touched many times the stigma of the flowers and collected, in most visits, only pollen, indicating the possibility of being a oligolectic species, specialized in O. monacantha flower rewards.