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Bromeliads as habitats for cacao pollinators

In a new paper, we report the presence of cacao pollinators in bromeliad plants and identify factors that influence their abundances.

Bromeliads are common plants in the Neotropics. Being epiphytic, they are often incorrectly considered as parasites and removed from agroforestry systems. However, their water-filled leaf axils provide habitats for a diverse group of aquatic organisms, potentially including cacao pollinating dipterans which could be beneficial to local farmers. Thus far, it is unclear how frequently and abundantly potential pollinators occur in bromeliads in cacao plantations. Therefore, we investigated the aquatic fauna in different types of bromeliads in Nicaraguan cacao agroforestry systems. Our main goal was to study the impact of bromeliad morphology and vertical position on aquatic biodiversity with particular attention for larvae of presumed cacao pollinators. Aquatic biodiversity was higher in larger bromeliads and in bromeliads positioned closer to the ground. Particularly invertebrates without flying life stages were deficient in elevated bromeliads suggesting dispersal limitation. Potential cacao pollinators occurred in 66% of the bromeliads and were most abundant in bromeliads with larger tanks that were located higher in the canopy rather than on the plantation floor. We conclude that larvae of cacao pollinators can be common and relatively abundant inhabitants of tank bromeliads in cacao trees, and it is likely that preserving these habitats could boost local pollinator abundances.

The paper is out now in Hydrobiologia

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Bromeliads growing on the branches of a cacao tree in Nicaragua (photo: Bram Vanschoenwinkel)