Reduced damage and epiphyll cover of leaves ofKorthalsiarattans that hostCamponotusants in the rain forest of Malaysian Borneo

Abstract

Abstract:Many species of palm produce chambers called domatia that are used by ants as nesting spaces. However, the ecological nature of this association is not well understood, and the information on palm–ant interactions is primarily anecdotal. Here, we conducted a field study in the secondary forest of the Danum Valley Conservation Area, Malaysian Borneo, on 41 individuals of the rattan Korthalsia furtadoana. All studied plants showed signs of a past or present partnership with domatia-nesting ants, as indicated by entry holes in domatia. In 14 plants, our physical disturbance of a stem provoked the appearance of patrolling ants of Camponotus sp. We compared the leaf conditions of rattans with and without patrolling ants, testing whether the presence of ants is linked to improved leaf health. The leaflets of plants with patrolling ants were significantly less physically damaged and less covered by epiphylls. On average, 19% of the leaflets of plants with patrolling ants were damaged (52% in plants without patrolling ants), and the epiphyll cover of their leaflets was 0.2 on our scale of 0–4 (1.3 in plants without patrolling ants). Our results suggest that this poorly studied plant–ant association has a mutualistic character. It seems that the ants take advantage of the nesting space created by the plant partner, while the plants gain protection for their photosynthetic apparatus against herbivores and epiphylls.

Rattan litter-collecting structures attract nest-building and defending ants

“…In relation to these, the ocrea in Korthalsia was the most studied adaptation. 15,16,18,19,24 The ocrea in Calamus was also found to be colonized by ants. 21 Rickson & Rickson 22 reported spine whorls associated with Camponotus.…”

“…Korthalsia furtadoana experience less leaf damage when their ocreas where colonized by patrolling ants. 19 Unlike rattan Korthalsia possessing ocreas that could serve as domatia for ant colonies, the rattans D. lewisiana and C. castaneus do not directly provide shelter for ants. However, the litter that they collect may also encourage ants to build nests and protect the plant.…”

“…33 The leaves of K. furtadoana were covered with fewer epiphylls when patrolling ants were present. 19 Indirect interactions also existed among rattans, ants, and Cerataphis (Homoptera). Cerataphis is a rattan pest which sucks the sap from the rattan plant.…”

“…In the tropical rain forests of Southeast Asia, Korthalsia is a common rattan genus associated with ants. 2,15,18,19 Other rattan taxa with similar relationships include Calamus sp. and Daemonorops sp.…”

“…18 K. furtadoana enjoys healthier leaves if colonized by certain ant species. 19 In addition to Korthalsia, Daemonorops verticillaris, has overlapping spine structures that provide cavities for ants. In return, the ants help the rattan absorb nutrients and water at higher efficiency.…”