Diurnal anthophilous fauna in Brazilian Chaco vegetation: phenology and interaction with flora

Abstract

Phenology is the basis for understanding the life cycle of plants or animals throughout the year. Thus, we surveyed diurnal anthophilous fauna on plant species in the Brazilian Chaco to determine (1) groups of floral visitors and occurrence; (2) richness and abundance of fauna in relation to flowering flora and meteorological variables; (3) groups of visitors that pollinate or thieving flora; (4) distribution of herbaceous and woody strata throughout the year of flowering; (5) variation in flowering as a whole community, in the context of abiotic factors; and (6) the predominant plant families and species. We sampled eight groups of floral visitors, totalling 105 sampled species and 644 specimens. The flies and bees were the richest groups, with bees forming the most abundant group. The phenology of the fauna and flora was not clustered and exhibited a continuous and bimodal flowering. The abundance and richness of floral visitors were positively related to the quantity of plant species and flowering, as well as rainfall. Herbaceous and woody strata are important for the maintenance of anthophilous fauna throughout the year. Plant species with the highest abundance and the longest flowering period presented the highest richness and/or abundance of floral visitors. The percentage of pollination was higher than that of resource theft. Bees and flies were the main groups of pollinators, whereas flies were the main thieves. The present survey is only a starting point for future studies on the networks of interactions between plants and their floral visitors in the Brazilian Chaco.