Leaf‐cutting ant abundance and distribution under different agricultural practices in grassland biome

Abstract

Leaf-cutting ants (LCA) frequently show positive associations with human disturbance in forest biome, explained by habitat opening and increase of pioneer vegetation. However, little is known about LCA response in grassland biome. Agriculture and commercial forestry typically introduce closed habitats and displace pioneer vegetation when occurring in grasslands. The aim of this study was to assess the response of LCA to different land use types developed in a grassland biome. 2 Semi-natural grassland remnants, soybean crops, cattle pastures and young and mature eucalypt plantations were sampled in Entre Ríos, Argentina. LCA nest abundance and occurrence of workers was obtained by hand sampling and baited pitfall traps. 3 LCA nest abundance significantly decreased in most land use types when compared with the grassland sites. All habitat types were characterized by the presence of different LCA species, which showed different associations with temperature, vegetation and soil structure. 4 Our results suggest that LCA response to human disturbance depends on the biome where it occurs; contrary to what was observed in forests, the LCA assemblage was negatively associated to human disturbance in grasslands. The response of the whole assemblage masked different responses of LCA species, possibly indicating differences in their ecological niche.

Landscape configuration modulates the presence of leaf-cutting ants in eucalypt plantations

“…Although no differences were found in the number of LCA nests between the studied land uses or in the different sampled interfaces, the interface constituted between young Eucalyptus plantations and semi-natural remnants was the one that seems to present the highest average density of LCA nests. This trend could reflect what has been reported in other works carried out within Argentina for this same genus 26 , 27 . In addition, studies carried out on changes in the nest density of the genus Atta in the Cerrado (Brazil), have shown similar patterns along a gradient of the different types of forests 28 .…”

“…Few studies have contemplated how land use gradients affect the density of LCA nests per unit area. Ribero et al 27 used a similar approach to evaluate the effects of landscape components on LCA abundance and obtained similar results, with no differences in the abundance of LCA nests in mature and young eucalypt plantations It´s important to note that LCA nests are generally controlled with pesticides (such as, chlorpyrifos or sulfuramides) during the early stages of development of eucalypt plantations 10 , but not in the mature stage. Thus, other local regulation mechanisms, such as decreased understory vegetation cover, increased ground litter cover, and lower and more stable temperatures 11 , all of which are associated with mature plantations, can be linked with changes in LCA abundance and be more relevant than the cover of plantations.…”

Landscape configuration modulates the presence of leaf-cutting ants in eucalypt plantations

“…Although no differences were found in the number of LCA nests between land uses or in the different sampled interfaces, the interface constituted between young Eucalyptus plantations and semi-natural remnants was the one that showed the highest average density of LCA nests. This trend reinforces what has been reported in other works carried out within Argentina for this same genus (Barrera et al 2015;Ribero et al 2021). In addition, studies carried out on changes in the nest density of the Atta genus in the Cerrado (Brazil), have shown similar patterns along a gradient of the different types of forests (Costa and Vieira-Neto 2016).…”

Passive restoration of subtropical grasslands leads to incomplete recovery of ant communities in early successional stages

“…Dorymyrmex is a highly thermophilic genus characteristic of open habitats reportedly associated with crop fields (Pacheco et al, 2013) and abandoned agriculture (Dalle Laste et al, 2019). Acromyrmex, as well as other leaf-cutting ants, has been frequently associated with disturbed habitats, especially in forest environments (Leal et al, 2014), but see Ribero et al (2021). Overall, ant biological and ecological traits seem to explain their distinct prevalence among environments, and if local ant species were better known, a quantitative functional diversity viewpoint could be employed to demonstrate that.…”