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

Abstract

In a rain forest at the foot of Mt. Kinabalu, Borneo, we observed the food habits of Aenictus laeviceps and A. gracilis and surveyed the effects of A. laeviceps on the general ant community. We collected totals of 2,360 and 6,268 prey units, respectively, from seven A. laeviceps and six 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%) in A. laeviceps and Technomymex (52.1%), Paratrechina (22.4%), and Crematogaster (11.9%) in 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 total wet weight of prey ants, brood constituted 88.7% in A. laeviceps and only 68.7% in A. gracilis. This was probably because workers of A. gracilis were quicker in behavior 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 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.

Food supplementation alters caste allocation in a natural population of Pheidole flavens , a dimorphic leaf-litter dwelling ant

“…In this tropical climate, ants are not challenged by surviving winter, but are temporally restricted from foraging on a daily scale depending upon humidity (Levings, 1983;Kaspari, 1993). The lifespan of tropical leaf litter ant colonies are likely to be much shorter than temperate ants, as a result of frequent army ant predation, flooding, and patchy resources (Wilson, 1959;Kaspari, 1996 b;Hirosawa et al, 2000) For these reasons, a four-month food supplementation can strongly impact the environment of these short-lived leaf litter ants competing with dozens of similar species in a patchy environment. Gordon (1996) argued that the first experimental case of adaptive caste ratios in P. pallidula (Passera et al, 1996) was found in an unusual member of the cosmopolitan genus with a diverse variety of life histories.…”

Ant-nest distribution in a remnant of tropical rainforest in southeastern Brazil

“…Army ants of the subfamilies Ecitoninae (Neotropics), Dorylinae (Africa), and Aenictinae (Southeast Asia) can also cause frequent disturbance among forest floor ant communities (Hirosawa et al, 2000). These predatory ants make large foraging trails, that have great impact on the fauna (Sudd and Franks, 1987).…”

The reproductive cycle of thelytokous colonies of Cerapachys biroi Forel (Formicidae, Cerapachyinae)

“…We could not determine whether the three larvae whose head width was 0.184 mm were large 1 st instar or small 2 nd instar larvae. The 8 th day seemed to be a transition day, with 24 larvae ( , 1983;Otis et al, 1986;Hirosawa et al, 2000;Weissflog et al, 2000) were studied. Their nomadic phase (NP) is characterised by raids triggered to feed developing larvae.…”