Effects of land‐use changes on ecosystem services: decrease in ant predation in human‐dominated landscapes in central Brazil

Abstract

Anthropogenic disturbances often affect the abundance and diversity of ants (Hymenoptera: Formicidae) but relatively few studies have explored the implications of such changes on the ecosystem services mediated by these insects. Here, we evaluated how the transformation of Cerrado savanna habitats into crop plantations affects the abundance, diversity, and the predatory activity of ants. A survey of the ant faunas foraging above‐ and belowground was performed in six crop and six non‐crop (i.e., native vegetation) sites. Above‐ and belowground rates of ant predation were estimated at these same sites using mealworms, Tenebrio molitor L. (Coleoptera: Tenebrionidae), as baits, simulating crop herbivores. Belowground predation rates were significantly greater in the non‐crop sites, despite the lack of difference in overall abundance and species richness of ants foraging belowground between the crop vs. non‐crop sites. In contrast, we did not detect any significant difference in aboveground predation rates between crop vs. non‐crop sites even though there were significantly more species of ants foraging aboveground in the non‐crop sites. Army ants (subfamily Dorylinae) were the main predatory species belowground, and their abundance was significantly greater in non‐crop sites. In contrast, the main predators aboveground were omnivore ants of the genera Pheidole and Solenopsis, which had similar abundances in the crop and non‐crop sites. Overall, our results indicate that transformation of native Cerrado habitats into crop plantations reduces the abundance of some important predatory species, notably those that forage belowground, and this may negatively affect the potential for ants to provide pest control services in agroecosystems.

Fire ants: What do rural and urban areas show us about occurrence, diversity, and ancestral state reconstruction?

“…In the state of São Paulo (southeastern Brazil) the species is associated with the Cerrado patches ( Fowler et al, 1990 ), with expansion of territory to areas under Atlantic Forest dominance ( Martins et al, 2014 ; Souza et al., 2014 ). In addition to agriculture ( Pacheco et al, 2013 , 2017 ), urban growth contributes greatly to the expansion of the foraging territory of the populations of S. invicta , increasing its range of distribution ( Plowes et al, 2007 ). Our study areas include a region with accelerated urban growth ( Lima and Magaña Rueda, 2018 ) and, at the same time, many conserved remnants of the Atlantic ( Torres et al, 2019 ).…”

Effects of Habitat Conversion on Ant Functional Groups: A Global Review

“…The neutral response of cold-climate specialists to conversion in the tropical region may not reliable as there were only two observations from a single study, for this group. Generalist ants did not respond to habitat conversion, probably because of this group's ability to use different sites for nesting and food sources (i.e., broad ecological niche), permitting their occurrence in native habitats (Kone et al, 2012;Pacheco et al, 2017;Saad et al, 2017) as well as in anthropogenic land uses (Kone et al, 2012;Assis et al, 2018), with survival and even dominance in homogeneous and simplified environments (García-Martínez et al, 2015;Assis et al, 2018). In the tropical region, habitat conversion did not affect subordinate Camponotini even though this group is usually associated with complex and shaded habitats (Parui et al, 2015), suggesting a broader flexibility to their occurrence in this region.…”

Native ants help to spread an invasive African grass in the Cerrado

“…Mycocepurus is among the most common ants in Cerrado (Vasconcelos et al, 2008), and may occur even in croplands (Pacheco et al, 2017). Distances of seed removal (from 15 to 120 cm) are compatible to foraging distances of M. goeldii (129 ± 98 cm, Leal & Oliveira, 2000).…”