Food habits of Aenictus army ants and their effects on the ant community in a rain forest of Borneo.

摘要

In a rain forest at the foot of Mount Kinabalu, Borneo, the food habits of Aenictus laeviceps and A. gracilis were observed and the effects of A. laeviceps on the general ant community were surveyed. Totals of 2360 and 6268 prey units were collected, respectively, from 7 A. laeviceps and 6 A. gracilis colonies; ants constituted 99.9% of all prey units. Dominant prey genera were Camponotus (48.2% in wet weight), Pseudolasius (20.8%) and Polyrhachis (15.2%) for A. laeviceps and Technomyrmex (52.1%),Paratrechina (22.4%) and Crematogaster (11.9%) for A. gracilis. A. laeviceps primarily hunted larger ground ants with small- or medium-sized colonies; in contrast, A. gracilis frequently foraged on smaller arboreal ants with larger colonies. Of the totalwet weight of prey ants, brood constituted 88.7% in A. laeviceps and 68.7% in A. gracilis. This was probably because workers of A. gracilis were quicker in behaviour and hunted adult workers more frequently than A. laeviceps. While 98.5% of the prey units were transported by single workers of A. gracilis, 71.5% were carried by up to 20 A. laeviceps workers. The numbers of ant colonies and species were significantly smaller in A. laeviceps-raided quadrats than in controls. This was mostly due to the escape of ants that nested under litter and had relatively larger colonies. Large colonies usually influence the foundation and establishment of incipient small colonies.