Polinização e insetos visitantes florais associados à pitaia

Abstract

To produce pitaya, it is essential that pollination occur, either artificially or by pollinating agents. In this study, we evaluated manual pollination compared to natural pollination, pollen viability, and stigma receptivity in white-fleshed pitaya. An experiment was conducted with a randomized block design consisting of four treatments: T1: manual self-pollination; T2: nocturnal open pollination; T3: diurnal open pollination; and T4: manual cross-pollination. The experiment had four replicates, with two plants per replicate (two flowers per plant), totaling 16 flowers per treatment. The analyzed variables were fruit weight, length, diameter, titratable acidity, pH, soluble solids, and SS/TA ratio; the germination percentage of pollen grains; and the receptivity of stigmas. Artificial pollination (cross or self-pollination) of white-pulped pitaya is viable, resulting in larger fruits compared to natural pollination. During the entire period of floral opening, the pitaya flower remains with the receptive stigma able to receive the pollen, however, the highest percentage of pollen germination occurs at 07:00 p.m. Besides, was to evaluated the community of flower-visiting insects in red dragon fruit (S. undatus) outside its geographic area of origin. Fifteen seven-year-old H. undatus plants were randomly selected. For each of the plants, the flowers that opened on a given night were surveyed for the collection of floral visitors. Insect collection was performed in two periods (daytime and nighttime), which correspond to the time of anthesis for dragon fruit flowers, over two years of production. The following variables were evaluated: number of visits (counted as the number of times an insects touched a flower stigma) and visiting species. From the data on the number of insect visits and their identification, analyzes of abundance (number of visiting insects), richness (number of species) and diversity (relation between the number of insects and the number of species) were performed. The bee Apis mellifera can be considered as a potential pollinator of white-fleshed pitaya in regions with a subtropical climate. During the flowering of the pitaya, a much greater abundance of insects was found during the daytime.The plant attracts a diversity of floral visitors who collect food resources from the flowers. The conditions of high temperature and low precipitation and relative humidity in 2020 allowed greater visitation of insects in flowers.