The abundance of ants (Hymenoptera: Formicidae) and their ecological roles as predators in Arabica coffee plantations with different densities of shade trees

Abstract

Shade-grown coffee, incorporated in an agroforestry system, is a common practice of coffee plantations in Aceh Tengah Regency, Aceh Province, Indonesia. Coffee is grown under the shade of a canopy of surrounding trees. Shade trees reduce excessive light and provide a home for various predatory animals, including predatory ants. Some growers plant a dense population of shade trees, while others plant less shade trees. A study to investigate the diversity of ants and their abundance in different densities of shade trees has been conducted from April until August 2023. Ants were sampled from coffee trees (arboreal ants) in two coffee plantations with dense populations of shade trees and two plantations with sparse shade trees. We found 13 ant species in both categories of plantations (combined). All ant species were found in sparsely shaded coffee plantations, and only five were recorded from densely shaded plantations. However, the abundance of ants was much higher in densely shaded plantations than in sparsely shaded plantations. The ant genera Technomyrmex and Componatus were the dominant ants found in sparsely shaded plantations, while the dominant ants in densely shaded plantations were the genera Componatus and Crematogaster. These ants are known as general predators and potentially are predators of coffee berry borer (CBB), a significant pest in the area. This research has shown how different densities of shade trees in coffee plantations affected the ant fauna, which could be used as a basis for ant conservation to increase their ecosystem service as predators.