Impacto de machos de abelhas oligoléticas na polinização de Calibrachoa elegans (Solanaceae)

Abstract

We studied the association between Calibrachoa elegans (Miers) (Solanaceae) and Hexantheda missionica (Oglobin 1948) (Colletidae, Neopasiphaeinae) in Campo Rupestre of Minas Gerais, a highly specialized interaction between a plant and an oligolectic bee. The performance of male oligolectic bees as pollinators is poorly understood. Therefore, this work aims to investigate the role played by males of the bee H. missionica as pollinators of its host plant. We ask: What are the types of floral visits by males and in which they touch the stigma and can transfer pollen? What is the impact of stamen and style cutting behavior on dormitory flowers on the fruit and seed set of C. elegans? Our results show that male bees can enter the flowers of C. elegans to drink nectar in 16% of cases, during inspection flights in search for females. After visits, they leave the flowers containing pollen grains adhered to their body. When entering another flower to drink nectar, they can contact its stigma and, thus, transfer pollen grains and promote pollination. Therefore, although males of H. missionica are not as efficient pollinators as females, whose pollination rate in a single visit is 40% and 93%, respectively, they also pollinate C. elegans. To take shelter inside the flower, the bee cuts the stamens and the style with their jaws. This behavior induces the senescence of flowers. Males that cut flowers on the first day of anthesis can impact them negatively, since the pollen tube has not yet reached the ovary in less than 24 hours. However, only 33% of the males preferred flowers from the first day of anthesis, which indicates a low negative impact on flowers of C. elegans.