Floral scent and pollinator interactions of three species in Isabela Island (Galapagos)

ABSTRACT

The study focused on examining the chemical composition of floral scents and the insect visitors of three species of Asteraceae endemic to the Galapagos archipelago: Scalesia affinis, Darwiniothamnus lancifolius, and Darwiniothamnus tenuifolius. These species inhabit different zones, with S. affinis found in dry areas and the Darwiniothamnus species in humid areas. Each species displayed a distinct scent and pollinator profile. Scalesia affinis emits a floral scent dominated by the monoterpene α-pinene, and its primary pollinators, nearly exclusive to the species, are the female carpenter bees Xylocopa darwini (Hymenoptera). Darwiothamnus lancifolius and D. tenuifolius exhibited a complex mixture of floral aroma compounds. Both species were characterized by a significant presence of sesquiterpenes, particularly aristolene. In D. tenuifolius, benzaldehyde and indole were also abundant. This aromatic profile appears to attract dipterans, the predominant group of pollinators in elevated and humid regions. This study is the first to investigate the chemical composition of floral scents in plants from the Galapagos Islands and their relationship with entomophily.

KEYWORDS:

• Aroma chemical profile
• Scalesia
• Darwiniothamnus
• Asteraceae
• pollinators

Acknowledgments

The authors thank the Universidad de Técnica de Manabí for financial support from the project ‘La vegetación de la isla Isabela. Fitosociología y Ecología’ which was performed with assistance in logistics and fieldwork from Leonardo García responsible of Ecosistemas (UTO) in Isabela and Lic. Galo Quesada, responsible of Proceso de Investigación Aplicada de la Dirección del Galapagos National Park (DPNG). Our thanks also go to the park rangers for their company and help in fieldwork. Special thanks to: M.T. García (SCT/UIB) for their analytic technical assistance and L. Cortés and E. Llorens-Bobadilla for your valuable comments of the manuscript and linguistic assistance. We express our appreciation to three anonymous reviewers for their thorough and valuable feedback.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

J.M.M and L.C.G. were involved in gathering samples in the field, while P.F. and H.B. conducted data analysis and manuscript writing. L.Ll., who originated the concept, actively participated in all stages of the project.

Additional information

Funding

The work was supported by the Project: La vegetación de la isla Isabela. Fitosociología y Ecología (Universidad de Técnica de Manabí) .