High visitation rate of oil bees may increase pollination efficiency of Couepia uiti in Pantanal wetland

Abstract

Pollen transfer to the stigma is the primary mechanism of sexual reproduction in plants. Among bee species that act as pollen vectors and pollinators, attributes such as floral visitation rate, synchrony with the receptive phase of the flower, compatibility between flower shape and foraging behavior, and morphological traits are often used to infer pollination efficiency. Herein, we evaluate visitation frequency and behavior of bee species on Couepia uiti (Chrysobalanaceae) flowers in the southern Pantanal, Brazil. Additionally, after experimental manipulation of flower visitation and by accompanying pollen tube growth in the pistil after one single visit to the flowers, we were able to pinpoint the roles of Centris spilopoda and Apis mellifera on the pollination of C. uiti. Centris spilopoda was the most important pollinator of C. uiti in the study area. In fact, we found that this oil bee might enhance plant reproductive success by almost 40% after a single visit. In addition to its high abundance, the efficiency of C. spilopoda as pollinator may be explained by its tight synchrony with pollen liberation and stigmatic receptivity of flowers of C. uiti.