Tabebuia lepidota: effect of nectar robbing by hummingbirds and bumblebees

Abstract

Nectar robbing occurs when some floral visitors pierce the corolla of the flowers to take the nectar. It has positive effect when it facilitates the robbed species reproduction, negative when it impedes it, and neuter when it doesn't influence it. Although this phenomenon has been documented in Cuban plants, its effect in their reproductive success is still ignored. The flowers of Tabebuia lepidota present evidences of nectar robbing, by bumblebees and hummingbirds. The main objective of this investigation was to determine, in a locality, the frequency of nectar robbing of Tabebuia lepidota by each robber species, and the effect of the robbery in the reproductive success of the species. For this there were counted, in a xeromorphic thorny thicket in the ridge of Pelo Malo, Villa Clara (Cuba), the robbed and non-robbed flowers of 50 plants, and there were marked 30 flowers robbed only by hummingbirds, 30 robbed only by bumblebees and 30 without robbing evidences to evaluate the fructification. The individuals of T. lepidota presented high nectar robbing frequency, which could be due to the high production of nectar of the species, in relation to its floral neighborhood, and its capacity to resynthesize. The hummingbirds robbed more than the bumblebees, which was possibly related to the energetic requirements and the visitation rates of the robber species. T. lepidota produced similar quantities of fruits from robbed flowers that from non-robbed flowers. It was concluded that nectar robbing has neutral effect in the reproductive success of T. lepidota.