Orchid seed removal by ants in Neotropical ant-gardens

Most plants that inhabit in ant-gardens (AGs) are cultivated by ants. Some orchids occur in AGs, however, it is unknown if their seeds are dispersed by AG ants, because most of the orchid seeds are tiny and dispersed by wind. We performed in situ seed removal experiments, in which we simultaneously provided Azteca gnava ants with seeds of three AG orchid species and of another three AG epiphyte species (Bromeliaceae, Cactaceae and Gesneriaceae), as well as the non-AG orchid species Catasetum integerrimum. The seeds most removed were those of the bromeliad Aechmea tillandsioides and of the gesneriad Codonanthe uleana, while seeds of AG orchids Coryanthes picturata, Epidendrum flexuosum and Epidendrum pachyrachis were less removed. The non-AG orchid was not removed. Removal values were positively correlated with the frequency of the AG epiphytes in the AGs, and seeds of AG orchids were larger than those of non-AG orchids, which should favour the myrmecochory. Our data show that Azt. gnava ants discriminate and preferentially remove seeds of the AG epiphytes. We report for the first time the removal of AG orchid seeds by AG ants in Neotropical AGs. This article is protected by copyright. All rights reserved.