Buffa, L. M., P. Jaureguiberry, and M. A. Delfino. 2009. Exudate-gathering ants (Hymenoptera: Formicidae) at three different liquid food rewards. Acta Zoológica Mexicana (n. s.), 25(3): 515-526. ABSTRACT. Extrafloral nectaries (EFNs) and hemipteran honeydew are liquid food rewards (FRs) that encourage ant visitation in many plant families in a wide variety of habitats. In this study we explored the diversity, distribution and interactions of exudate-gathering ants at three different liquid food rewards: nectar from EFNs on Croton sarcopetalus and honeydew from the aphids Aphis spiraecola and Dysaphis foeniculus on Eupatorium hookerianum (Asteraceae) and Foeniculum vulgare (Apiaceae) respectively. For each FR we measured ant diversity and performed quantitative and qualitative comparisons among ants associated with the FRs. In addition, a linear regression was performed to test for possible associations between aphid and ant abundances in the case of honeydew FRs. Eight out of the 23 ant species found fed on both nectar from EFNs and honeydew from aphids, four of which fed at all FRs. Two ant species visited both aphid species and 13 were found exclusively at either one of the FRs. Brachymyrmex brevicornis was the most abundant ant species and Pheidole sp.2 had the greatest occurrence. Both ant species diversity and richness were higher at EFNs of C. sarcopetalus. Regressions showed positive significant association between ants and aphids abundances both on E. hookerianum and F. vulgare. We can conclude that the three liquid food rewards compared here showed modest similarity in their ant fauna. Furthermore, there was selectiveness of ants towards EFNs of C. sarcopetalus, which might be due to food source attributes rather than co-evolutionary factors.