Seed cleaning behavior by tropical ants and its anti-fungal effect

Abstract

In tropical forests, ants frequently consume fruit pulp around seeds of vertebrate-dispersed plants, which protects the seeds from infection by fungus and pathogens. Seed cleaning behavior by omnivorous ants was observed in the secondary forests of Bogor botanical garden in West Java. Fruit pulp around the seeds of the rambutan Nephelium lappaceum was completely removed by Pheidole plagiaria, Anoplolepis gracilipes, and other ants. When seed cleaners were excluded, however, many seeds were attacked by fungus and died. Seeds that were cleaned by hand, but not by ants, were similarly attacked. Field experiments on seed cleaning by P. plagiaria revealed that the anti-fungal effect was not merely caused by removal of fruit pulp, and that seed cleaning reduced the development of spores and hypha of fungi. We suggest that the workers apply anti-fungal substances to the fruit pulp and seed surface.