Ant Interactions with Aroid Infructescences (Araceae) Used as Temporary Nesting Sites, Cohabiting with a Complex...

Ants are abundant and diverse in the tropics, nesting in different forest layers and utilizing a wide range of nesting sites, from specialized to opportunistic. To describe the floral interactions of endophagous insects in the Los Tuxtlas Biosphere Reserve (Mexico), samples of Araceae infructescences were collected during an annual cycle at different altitudes. Ten species of Araceae belonging to the genera Dieffenbachia (1), Philodendron (5), Syngonium (3) and Xanthosoma (1) were investigated. A total of 334 infructescences were sampled, of which only 5.1% were found to be infested by ants. However, they also harboured a diverse community of endophagous insects coexisting with the ants, including 22 other families of Diptera, Coleoptera, Hemiptera, Lepidoptera and Hymenoptera. We recovered 1030 specimens of the family Formicidae, belonging to eight ant species as follows: Neoponera carinulata (Roger), N. crenata (Roger); Pheidole nebulosa Wilson, P. punctatissima Mayr, P. dossena Wilson, Solenopsis picea Emery, Tapinoma ramulorum Emery and Tapinoma sp. In terms of spatial distribution, ants were represented in the bottom layer (< 500 m) with four species accounting only for 6.7% of the abundance, whereas six ant species were recorded in the upper layer (> 500 m), representing 93.3% of the specimens. Our results provide evidence that ants use aroid infructescences as nesting sites. The ant colony structure was highly variable, suggesting that aroids may be used by ants to establish colonies, as temporary polydomous colonies, and to gather prey as a food resource. Most of the ant species found are predators or omnivores and may benefit from the diverse endophagous insects that feed in these structures, as well as from their waste products. The overall low colonization rates of aroid structures may be due to their temporary availability in the environment prior to dehiscence.