Banana plantations are treated with herbicides, nematocides, fungicides, and insecticides to control weeds, nematodes, fungal pathogens, and insect pests. The impact of these pesticides on the organisms within plantations, however, is largely unknown. Because they are integral to terrestrial ecosystems, ants have been widely used as biological indicators in invertebrate biodiversity assessments and studies of habitat rehabilitation. Hence, to evaluate the effects of pesticides on banana plantation invertebrates, ants were surveyed in six conventional plantations treated with the pesticides described above and in two low-input plantations that received reduced applications of herbicides, nematocides, and insecticides. To put banana into perspective relative to other tropical monocultures, ants in banana were also compared with those in four other crops: citrus (Citrus sinensis L. Osbeck), heart of palm (Bactris gasipaes Kunth), macadamia (Macadamia integrifolia Maiden and Betche), and Gmelina arborea (L.) Roxb. A total of 23,364 ants comprising 107 species, 48 genera, and 6 subfamilies was collected at the 12 study sites. Species richness was highest in the other crops, being lower in both low-input and conventional banana, which did not differ significantly. Ant species richness correlated with the richness of parasitoids collected concurrently from the same sites, but differences among low-input banana, conventional banana, and the other four monocultures were more pronounced for parasitoids. Species richness in conventional banana, low input banana, and the four other crops was independent of species origin (native or exotic), habitat preference, nest type, diet, or ant functional groups sensu Andersen.