Produção de voláteis em Passiflora Pohlii (Passifloraceae) e relações com abelhas crepusculares Ptiloglossa (Colletidae): abordagens morfológicas e químicas

Abstract

The primary aim of this work is to investigate the volatile compounds that mediate the specialized crepuscular pollination between Ptiloglossa and Passiflora pohlii, and to determine their production sites. This interaction is characterized by a remarkable chemical overlap between the olfactory profiles of the bee and the flower, as well as by the exclusivity of the mutualism, where P. pohlii relies on Ptiloglossa as its only effective pollinator. Thus, our work is structured around two main axes: Floral Fragrance Characterization: The first chapter aims to identify the chemical composition of the volatiles of P. pohlii, determine their emission rhythm, and anatomically locate the odor-producing structures. We found that the filaments of the outer corona were the source of the intense citrus aroma, as proven through chemical, morphological, and ultrastructural analyses of these structures. The emission of volatiles, dominated by monoterpenes (97%), peaked at dawn, coinciding with the foraging time of the bees described in the literature, and decreased drastically (90%) a few hours later a decline correlated with the degradation of cellular organelles. It is concluded that P. pohlii possesses a highly coordinated system of structural, chemical, and temporal characteristics, which strongly suggests an adaptation to selectively attract its crepuscular pollinators within a restricted time window. Bee Fragrance Characterization: The second chapter analyzes the volatile compounds emitted by the Ptiloglossa bees themselves, comparing males and females and identifying the gland responsible for production. The results demonstrated that the mandibular gland is the source of the bees' characteristic citrus odor, which is predominantly composed of monoterpenes, such as geraniol and geranial. A clear sexual dimorphism was documented: the gland morphology is rounded (bean-shaped) in females and trilobed in males. These results support the hypothesis that these compounds would function as pheromones, for which future bioassays will be needed to confirm it. Together, the two chapters reveal a remarkable chemical and ecological parallel: both the plant and its specialized pollinator emit profiles dominated by citrus-scented monoterpenes, synchronized with the crepuscular activity window, suggesting a mutually adjusted and highly specialized pollination system.