Land‐use change in the Amazon decreases ant diversity but increases ant‐mediated predation

Food production in Amazonian traditional societies often occurs through shifting cultivation that uses few pesticides and relies on ecosystem services provided by natural enemies. However, these sustainable agricultural practices are being threatened by increasing livestock and mechanised agriculture. This study aimed to evaluate the effects of the conversion from Amazon Forest to anthropogenic land uses (shifting cultivation and pasture) on α‐ and β‐diversity, functional groups, and ant‐mediated predation. Three types of habitats were sampled: forest (eight sites), shifting cultivation (five sites) and pasture (seven sites). The ant assembly of each site was sampled using pitfall traps in the epigeic and hypogeic strata. Beetle larvae were used to evaluate the predation function. Negative effects on epigeic ants and functional groups were found to be greater in sites where anthropogenic land use was more intensive (pasture) than in those where it was less intensive (shifting cultivation). Furthermore, this change increased the predation of insects in shifting cultivation and pasture compared to that in forest. This increase in insect predation was due to high activity of Ectatomma brunneum Smith, 1858, an environmental indicator for shifting cultivation and pasture. The increase in the number of predations in shifting cultivation and pasture may be beneficial from the perspective of biological pest control. However, this relationship needs to be better understood because the high presence and predatory activity of Ectatomma brunneum in these environments may be one mechanism by which α‐ and β‐diversity decrease through antagonistic interactions and dominance. We found that conversion of the Amazon Forest to shifting cultivation and pasture decreased α‐ and β‐diversity of ants, mainly in pastures. The conversion from Amazon Forest to shifting cultivation and pasture decreases the functional group of predatory ants but increases insect predation. Ectatomma brunneum Smith, 1858, an environmental indicator for shifting cultivation and pasture, was the dominant predator in these anthropogenic land uses, and may be beneficial from the perspective of biological pest control.