Pollination ecology of the Neotropical gesneriad Gloxinia perennis: chemical composition and temporal fluctuation of floral perfume.

Although common among orchids, pollination by perfume-gathering male euglossine bees is quite rare in other Neotropical families. In Gesneriaceae, for example, it is reported in two genera only, Drymonia and Gloxinia. Flowers of G. perennis are known to emit perfume, thereby attracting male euglossine bees as pollinators. However, detailed reports on the pollination ecology, as well as on chemistry of floral perfume of individuals in natural populations, are still missing. In this study, we report on the pollination ecology of G. perennis, focusing on the ecological significance of its floral perfume. In natural populations in Peru, we documented the floral biology and breeding system of G. perennis, as well as its interaction with flower visitors. We also characterised the chemical composition of floral perfume, as well as its timing of emission. Gloxinia perennis is self-compatible and natural pollination success is high. Spontaneous self-pollination occurs as a 'just in case strategy' when pollinators are scarce. Perfume-collecting males of Eulaema cingulata and El. meriana were identified as pollinators. The perfume bouquet of G. perennis consists of 16 compounds. (E)-Carvone epoxide (41%) and limonene (23%) are the major constituents. Perfume emission is higher at 09:00 h, matching the activity peak of Eulaema pollinators. Flowers of G. perennis have evolved a mixed strategy to ensure pollination (i.e. self- and cross-pollination), but cross-pollination is favoured. The size and behaviour of Eulaema males enables only these bees to successfully cross-pollinate G. perennis. Furthermore, G. perennis floral perfume traits (i.e. chemistry and timing of emission) have evolved to optimise the attraction of these bees.