Ecologia da polinização e biologia floral de Heteropterys pteropetala A. Juss. (Malpighiaceae) em um Cerrado mineiro

Abstract

Ecological interactions occur between species that share the same environment within a given time frame and are important for maintaining biodiversity and ecosystem stability. Among the various ecological interactions, we highlight pollination, which is fundamental for the reproduction of plant species. Bees are the main pollen vectors in the world, especially in the Cerrado. The aim of the present study, therefore, was to investigate floral biology, reproductive ecology and floral visitors dynamics in a common species of the Malpighiaceae family, and the consequences for their reproduction. In order to do this, we investigated Heteropterys pteropetala, a shrub species from Brazilian Savannah. Our results showed that H. pteropetala has similar floral morphology to other species of the family, except for two stamen verticils with different heights, a new information for the genera. A second new information is the distinct amount of pollen grains found in each anther height, what is a new information for the family. The flower has its structures modified over up to three days, influencing the visitation by insects. The pollen/ovule ratio and pollen viability were, respectively, 6105.96 and 88.9%, indicating that the reproductive system of the species is xenogamic. Reproductive tests showed high fruit formation by natural pollination, the selfincompatibility index (0.24) suggests that the species is self-incompatible and the value reproductive efficacy (1.31) suggests that the area’s pollinators are efficient. The species of pollinating bees belong to the Centridini and Tapinotaspidini tribes, considered specialists in the collection of floral oil. Meliponini bees were considered pollen looters along with flies. Ants, wasps and spiders were considered predators. The main florivores were coleoptera and hemiptera, which can reduce the attractiveness of flowers by damaging their parts and negatively influence pollinator attraction, leading to a decrease in fruiting. We conclude that H. pteropetala presents typical floral morphology of the Malpighiaceae family, except in the two levels of height of the anthers, is dependent on cross-pollination for fruiting and is an important species for studies of ecological interactions due to the diversity in the floral visitor guild.