Extensive research conducted so far suggests that the physiological functionality of myrmecophilous Acacia and Pseudomyrmex ants have evolved through a coevolutionay process. This is one of the most recognized myrmecophilous interactions present in the Neotropics. In our system of A. cornigera and the ant P. ferrugineus and P. gracilis, we first reported a neighborhood effect in the colonization of plants by both ant species, a higher proportion of colonization and larger host plants colonized by P. ferrugineus. However, which is the function of P. gracilis, in classic terms of anti-herbivory, were the two ant species Pseudomyrmex equally efficient in defending their Acacias? A first level of observation is based on an index of herbivory per plant. We also used simulated herbivory and found that P. ferrugineus is more efficient, when present on plants less damage is caused by herbivores, and ants were recruited faster in the presence of a potential herbivore. LARS et al. (2008) suggested that the coexistence of both species and especially the persistence of P. gracilis on a similar system whit Acacia hindsii is because they have fast-growing, low-density colonies, suggesting reproductive winged forms as an r - strategy. However, these authors are not including chemical stimuli, only visual or physical stimuli, so which other mechanisms promote the interaction of P. gracilis with Acacia cornigera. We will find out in the next part (part III).
Acacia cornigera; Pseudomyrmex gracilis; Pseudomyrmex ferrugineus; Herbivory; Defensive celerity