Mass raiding army ants fascinated biologists ever since naturalists such as Bates and Darwin wrote about their behavior. Despite this profound human interest and the ecological importance of army ants as top arthropod predators in tropical forests, basic aspects of their biology still remain unknown. With up to 20 sympatric army ant species, certain tropical regions show high local army ant diversity and abundance. We asked how so many top arthropod predators can co-exist? We tackled this question by conducting a large-scale dietary survey of 11 army ant species in one Costa Rican location, i.e. La Selva Biological Station. We identified prey items morphologically, if possible, and via DNA barcoding in difficult cases (e.g., prey larvae). We were thus able construct a high-resolution species-level predation network. Army ant prey nearly exclusively consisted of other ants with 129 ant species being detected among prey. This is roughly 1/4th of all known ant species in this particular area. Most importantly, ecological network analyses revealed a high degree of dietary specialization in army ants, which was accompanied by differentiated prey niches between species. In summary, our results help to explain the coexistence of many army ant species in certain tropical regions. – Philipp Hönle, Technische Universität Darmstadt
Molecular Ecology Spotlight 