Biologists Laura Carolina Leal and Felipe Passos have performed a series of experiments to determine how plants with extrafloral nectaries interact with ants in Brazil's Northeast region—specifically, in the interior of Bahia State, where the semiarid Caatinga biome predominates.
source https://www.lifetechnology.com/blogs/life-technology-news-blog/ants-that-defend-plants-receive-sugar-and-protein