Morcegos nectarivoros e a polinização de pitayas (Selenicereus spp. Cactaceae) na caatinga

Abstract

Pollination is an ecosystem service of regulation, provision, and culture, responsible for producing fruits, seeds, and several other essential resources for humanity. Therefore, it is a service of great importance to the global economy. In recent years, economic interest in the dragon fruit species (Selenicereus spp.) has gained prominence due to its commercial value. Dragon fruits have floral features similar to those of native cacti pollinated by bats in the Caatinga, Brazilian semiarid region. Therefore, the present study aimed to evaluate the role of bats as effective pollinators of pitaya species in the Caatinga and whether bat diversity is influenced by the landscape. Natural pollination (control), manual pollination, and self-pollination (spontaneous and manual) treatments were performed on pitaya flowers. To assess pollination efficiency, the developed fruits were weighed and the number of seeds estimated. To test the efficiency of nocturnal and diurnal pollination, the flowers were exposed at different times. Finally, to assess the influence of the landscape on chiropteran diversity, mist nets were installed in two distinct locations (preserved vs. deforested) to identify species richness and abundance in the regions. The results indicate that the heaviest fruits were produced by manual cross-pollination in the species S. undatus and S. monacanthus, while S. costaricensis produced larger fruits through manual self-pollination. Furthermore, the number of seeds showed a positive correlation with increased fruit weight. Comparing pollination across different periods indicated that nocturnal pollination produces heavier fruits than diurnal pollination. Bat diversity was higher in the preserved area. Therefore, pitaya plantations become more efficient when formed by more than one pitaya species, producing better-developed fruits. Pollination efficiency can be observed by the number of seeds in the fruit, directly influencing fruit size and weight. Bats are the most efficient pollinators of dragon fruits, although bees can also pollinate these species. Finally, the level of landscape conservation influences bat diversity and, consequently, the pollination services realized by these animals.