Negative Effects of Azteca Ants on the Distribution of the Termite Neocapritermes braziliensis in Central Amazonia

Termites play important roles in tropical ecosystem functioning, and their evolutionary success has been linked to their defense mechanisms. However, microhabitat overlap with potential aggressors may constrain their distribution and thus, their environmental impacts on an ecological timescale. We investigated a possible negative effect of abundant generalist ants (Azteca sp.) on the termite Neocapritermes braziliensis. Both taxa frequently build their nests attached to trees. We determined the densities of their active nests in 10 plots (250 x 10 m) systematically distributed over 5 km(2) in central Amazonia, Brazil, and recorded their co-occurrence in individual trees. Using generalized nonlinear modeling in a Bayesian framework, we found good support for a negative effect of Azteca's nest density on N. braziliensis'. This effect conformed to a power law, and accounted for more than half of the variation in the termite's nest density (r(2) = 0.56). Additionally, of all counted N. braziliensis mounds, only 1.08 percent was attached to trees also hosting Azteca. Such patterns may have arisen due to N braziliensis' inability to establish new nests within Azteca territories, or predation by ants on established colonies of the termite. We suggest that even non-strictly termitophagous ant species may have important impacts on termite populations and, consequently, on their roles in nutrient cycling and ecosystem engineering.