Floral biology, pollinators and reproductive success of Abutilon grandifolium in urban green spaces of Ciudad Autónoma de Buenos Aires

Abstract

Abstract Urban green spaces have gained importance in view of growing urbanization; however, limited research exists on the interactions of native plants with the local fauna, particularly comparing protected natural areas vs. recreated ones. To contribute to filling this gap, the floral biology and pollination of Abutilon grandifolium (Malvaceae) were studied in an Ecological Reserve and in a square where the local environment was recreated with native plants, both located in Ciudad Autónoma de Buenos Aires, Argentina. A. grandifolium was self-compatible. The flowers presented typical characteristics of biotic pollination (ornamented pollen, conspicuous perianth and rewards), particularly melittophily (diurnal anthesis, nectar, yellow-orange coloration, UV spectrum reward guides and pleasant odour). At both sites, the most frequent visitors were Apis mellifera and halictid bees, collecting nectar or pollen. While visits from the former were predominantly illegitimate, those from the latter were mostly legitimate. Occasional visitors included the bees Xylocopa sp. and Bombus pauloensis, syrphid flies, plus rarely, beetles. In specimens of all the bees, great amounts of A. grandifolium pollen was found in positions compatible with an effective transfer to the stigmas, therefore, all of them would be pollinators (when they access legitimately). The flies and the beetles would be mainly pollen and nectar thieves. In general, the identity, frequency and activity of the floral visitors coincided in the two sites, being species richness even greater in the square; therefore, the conditions that allow A. grandifolium to reproduce by xenogamy would be recreated in the square, thus maintaining its genetic variability.