First report on floral morphology, pollen release dynamics and behavioral biology of Xylocopa (Neoxylocopa) frontalis (Olivier, 1789) in Crotalaria juncea L. (Leguminosae, Papilionoideae)

Abstract

Pollination is a clear example of an ecosystem service that provides benefits to people. Over 87.5% of the world flowering plants have been estimated to be pollinated by animals, and about one-third of global food volume produced depends on them. Our goals were to characterize for the first-time details about a) floral morphology, b) pollen release dynamics, c) behavioral biology in Xylocopa (Neoxylocopa) frontalis(Olivier, 1789) bees and their influence on the reproduction of green manure Crotalaria juncea L. We used male and female floral reproductive structures for scanning electron microscope. We collected all pollen grains of different anther morphologies. The pollen viability was obtained by acetic carmine dye test at 2%. We used four controlled tests (spontaneous self-pollination, a single, two and three visits – n = 30 floral buds to all) to evaluate pollen limitation in the crop. Keel blossom morphology in C. juncea allowed their opening and exposing the reproductive structures during X. frontalisforaging. There was statistical difference in the number of pollen grains between anther morphologies, as well as pollen viability. The rates of fruit and seed set were significantly higher as the number of visits by X. frontalisincreased. Seed abortions occurred mainly in the basal position (n = 93), followed by the median (n = 58) and apical (n = 53). We concluded that pollinators can be useful for agricultural crops increasing fruit and seed production. Information about X. frontalis contribution to pollination will be useful to greenhouse and outdoor growers.