Chemical study of the flowers of the orchid Oncidium baueri Lindley and their visiting bees Trigona spinipes Fabricius

Abstract Oncidium baueri Lindley is a South American orchid characterized by the production of numerous yellow-brown flowers, arranged in inflorescences that reach up to four meters long. Herein, the chemical study of the flowers led to the identification of compounds present in the floral oil, such as long chain acids and methyl esters, including the first report of the occurrence of rare compound byrsonic acid in orchids in the free form. In addition to this, steroids and the flavonoid glycosides acacetin-7- O -rutinoside, pectolinarin, oncibauerins A and B were identified in large amounts. Finally, the flower-insect visit by Trigona spinipes Fabricius bees was also studied. Video analyses of the process revealed that the bees spend a long time collecting material from the flower labellum callus. The chemical analyses of bees and flowers showed the presence of palmitic acid and stearic acid in both samples, leading to suspicious about the attraction of bees by flowers oils as floral rewards.