Interaction between bees and the flowers of Clethra scabra Person in the Araucaria Forest in Rio Grande do Sul State, Brazil

Clethra scabra is a plant native to the Araucaria Forest of the Rio Grande do Sul State and provides food resources to flower visitors, however, it is threatened with extinction, and little is known about this interaction. We aimed to characterize the floral biology of C. scabra and identify its potential pollinators. The study was conducted in a 250 ha fragment of predominately Mixed Ombrophilous Forest in Cambará do Sul, RS. The number of flowers in inflorescences, the anthesis stages, the frequency of flower visitors and their behavior was recorded. The flowers of C. scabra are grouped in panicle-type inflorescences measuring between seven and 27 cm in length. The mean number of flowers/inflorescence was 64. Three phases were characterized and, in all of them, the presence of nectar was registered. Stingless bees (Apidae: Meliponini) are the potential pollinators of C. scabra, representing 80 % of the flower visitors. The important interaction between Meliponini and C. scabra in areas of Araucaria Forest in Campos de Cima da Serra in Rio Grande do Sul, observed in this study, provides a knowledge base for the conservation of these species, development of strategies for the sustainable management of biodiversity in the region, especially for endangered species such as Melipona and C. scabra.