Insect pollination in temperate sedges? A case study in Rhynchospora alba (Cyperaceae)

Abstract

Sedges (Cyperaceae) are commonly pollinated by wind, but some transitions from wind to insect pollination have been reported in tropical sedges. Despite being a temperate sedge, the pollination strategy of Rhynchospora alba may partly depend on insects, as suggested by its white-colored inflorescences. Here we quantify the contribution of insects to the reproductive fitness of R. alba as an exploration of the success of entomophily in temperate sedges. Honeybees and hoverflies seem to be the primary visitors of R. alba in the study site, and pollen of R. alba was recovered from the mouthparts and legs of the insects. Treatments excluding insects led to a lower reproductive fitness (regarding fruit weight and fruit viability) than those not excluding them. Therefore, insects seem to contribute significantly to the pollination of R. alba despite moderate morphological adaptation. We highlight the role of entomophily as an overlooked reproductive mechanism in cold-temperate sedges.

Keywords:

• Anemophily
• entomophily
• fitness traits
• reproductive biology
• tetrazolium test

Acknowledgements

The authors thank Sonia Acosta, Giovanni E. Rodríguez, Marina Mellado, and Bernardo García for their support during field campaigns; Inés Álvarez, Pablo Vargas, Modesto Luceño and Rocío Pérez Barrales for their advice, encouragement and critical help with some material supplies; Yurena Arjona for help with preparation of the TZ test; the microscopy service of the Real Jardín Botánico de Madrid (CSIC), and especially Yolanda Ruiz, for technical assistance with SEM. This study has been performed without additional external funding.

Disclosure statement

No potential conflict of interest is reported by the authors.