Invasive ants affect spatial distribution pattern and diversity of arboreal ant communities in fruit plantations, in Tarakan Island, Borneo

Abstract

Human activities influence ant community structure. In tropical areas, the habitat characteristics of crop plantations frequently shape the structure of arboreal ant communities. The present study investigated the spatial distribution of arboreal ants dwelling in durian Durio zibethinus and citrus Citrus amblycarpa plantations in the Tarakan Island, North Kalimantan. Specifically, it was investigated whether ant communities are dominated by native or invasive species; and if ant arboreal mosaics occur. This study included two sites (A and C) comprising durian and citrus plantations and one site B with only citrus plantations. Ant workers dwelling on crop trees were collected by branch beating, and subsequently identified and counted. Across all sites, a total of 64,360 workers, from 22 ant species, were collected from 59 durian and 63 citrus trees. In site A, the invasive species Tapinoma melanocephalum and the native species Oecophylla smaragdina were numerically dominant. A null model analysis of species co-occurrence revealed that species segregation existed in this site. Conversely, in sites B and C the invasive species T. melanocephalum and Technomyrmex albipes were dominant, and native arboreal ants almost co-occurred with the two species. Moreover, the number of T. melanocephalum and T. albipes workers was negatively correlated with the species diversity index of arboreal ants. However, the number of O. smaragdina workers showed no significant correlation. The results suggest that the invasion and domination of non-native species dissasemble spatial structures and reduce the species diversity in arboreal ant communities. The community structures of arboreal ants in fruit plantations were varied, depending on the fruit species and the properties of dominant ants.