Leaf-cutting ants (Atta mexicana) as facilitators of arthropods through waste dumps in a neotropical city of Mexico.

Waste dumps of leafcutter ants have been considered nutrient and plant hotspots, but their effect on arthropod diversity has not been tested, particularly in an urban environment at local and landscape scale. We hypothesized that Atta mexicana would be a facilitating species since their waste dumps are habitats for a high diversity of adult and immature arthropod stages due to their high content of organic material. Three microsites were selected for the collection of arthropods: within the waste dump, on the surface of the waste dump, and at a distance of ~ 3 m in the surrounding soil without the presence of a nest (control). We also analyzed whether the environmental conditions (temperature, humidity, and vegetation cover) influence arthropod richness and abundance in the waste dumps at a local and landscape scale. The results supported our hypothesis: there was a higher richness of arthropod families and a higher abundance of adults and immatures within the waste dumps of 24 nests. Also, at the landscape scale, the presence of tree cover favored a higher richness of the families found within and on waste dumps. Our results demonstrate that A . mexicana is a facilitatator species, since at the local scale, waste dumps provide habitat and refuge from depredators, food source, and sites of oviposition, but arthropods depend on vegetation cover at larger spatial scales. The presence of A . mexicana , is key in maintenance of biodiversity reservoirs, highlighting thus the potential role of this species in ecosystem services in urban areas.