Flower visitors of Aechmea nudicaulis (Bromeliaceae): species richness, visitation frequency, and interactions in different habitats of southern Brazil

The present study aimed to record all flower visitors of Aechmea nudicaulis (Bromeliaceae) and their foraging behavior as well as their role in animal–plant and animal–animal relationships, and to assess temporal pattern of visitation on flowers. In order to estimate the influence of habitat on species richness and abundance, we compared the diversity and visitation frequency of flower visitors to Ae. nudicaulis in three different habitat types – secondary forest, low and high vegetation restinga – in Paraná and Santa Catarina. We recorded 40 taxa of flower visitors. The secondary forest sites showed highest, the restinga habitats lowest species richness and visitation frequency. Main visitor groups were birds, bees and butterflies. The species spectrum differed considerably among habitats and similarity was lowest between the two secondary forests in Paraná and Santa Catarina. We recorded mainly hummingbirds (54.6% of all visits) as flower visitors in Paraná, whereas flowers in Santa Catarina were dominated by bees (44.5–59.7% of all visits). The temporal pattern of visits was similar at all sites; visits occurred mainly in the morning hours. However, there was no significant correlation between number of visits and hour of day. In contrast to the expectation that Ae. nudicaulis flowers, due to their morphology, attract mainly hummingbirds, they were visited by a much wider spectrum of animal species, mainly insects and arachnids, varying according to habitat. Our findings answer the question of what attracts animals to the inflorescences and elucidate the nature of some of the manifold interactions between Ae. nudicaulis and its associated flower visitors.