Difference in leaf herbivory between two plant-ant taxa associating with a myrmecophytic species, Macaranga lamellata

Abstract

Macaranga lamellata (Euphorbiaceae) is a myrmecophytic species that is protected against herbivorous insects by two plant-ant taxa, Colobopsis macarangae (Formicinae) and Crematogaster spp. (Myrmicinae). Although a single M. lamellata tree houses one plant-ant colony of either of the two taxa, both coexist in a population of M. lamellata in a Bornean rainforest. To elucidate the extent of herbivory damage upon M. lamellata trees associated with Colobopsis relative to trees associated with Crematogaster, we counted the number of leaf galls and measured the leaf loss area chewed by leaf-chewing insects on M. lamellata in the forest. The occurrence of gall midges was not significantly different between the trees associated with the two plant-ants, while the degree of leaf-chewing herbivory was significantly higher on Crematogaster-associated trees than Colobopsis-associated trees. The data gathered on chewing traces observed on Crematogaster-associated trees indicated that most herbivory damage was caused by a phasmid species. These results suggest that the herbivory pressures and occurrences of different herbivore species differ between Crematogaster-associated and Colobopsis-associated trees within a population of M. lamellata.