Interactions between Fungus‐Growing Ants (Attini), Fruits and Seeds in Cerrado Vegetation in Southeast Brazil¹

Abstract

ABSTRACT We surveyed the material collected for fungus culturing by attine ants in the cerrado vegetation of southeast Brazil. Six genera of the so‐called lower attines ( Cyphomyrmex, Mycetarotes, Mycocepurus, Myrmicocrypta, Sericomyrmex and Trachymyrmex ) collect a wide variety of plant material as fungal substrate. Plant diaspores of nonmyrmecochorous species comprise a large portion of the items brought to the nest, especially in the rainy season. Removal experiments using fruits of selected plant species revealed that attine ants (including the leaf‐cutters Atta and Acromyrmex ) not only actively clean the seeds (remove fruit pulp), but also carry them up to 12 m in the cerrado. Germination tests showed that removal of fruit pulp by attine ants increases germination rate in Ocotea pulchella (Lauraceae), Prunus sellowii (Rosaceae), Ouratea spectabilis (Ochnaceae), Rapanea umbellata (Myrsinaceae) and Psychotria stachyoides (Rubiaceae). For P. stachyoides , however, ants had no effect on germination if seeds had already passed the digestive tract of birds. Aril removal by attines also increases germination success of Copaifera langsdorffii (Leguminosae) and Virola sebifera (Myristicaceae) seeds. The results indicate that attine‐fruit/seed interactions are particularly conspicuous in the cerrado, suggesting that fungus‐growing ants may play a relevant role in fruit/seed biology in this vegetation type. Potential ant‐derived benefits to diaspores of nonmyrmecochorous plants in the cerrado would include secondary seed dispersion and/or increased germination success by ant‐handled seeds.