Diversity and ecology of insect herbivores associated with Cecropia (Cecropiaceae) in Costa Rica and their relationship with its Azteca (Hymenoptera: Formicidae) mutualists.

摘要

The mutualism between the Neotropical plant Cecropia (Cecropiaceae) and species of the ant Azteca has arguably received more attention than any other ant-plant system in the world. It is especially well known in regards to the ants' efficacy at reducing herbivory and encroaching vegetation. The details of the Cecropia-Azteca mutualism are, however, based principally on the interaction between Azteca and a few herbivores associated with juvenile plants. Little is known about the interaction between Azteca and herbivores on adult trees, and with few exceptions scant attention has been focused on the diversity and ecology of insect herbivores associated with Cecropia .; I surveyed the faunal diversity (richness and abundance) of five insect herbivore guilds (leaf-miners, leaf-chewers, gall-formers, stem-borers and petiole-borers) associated with seven species of Cecropiaceae (Cecropia insignis, C. obtusifolia, and C. polyphlebia; Coussapoa nymphaeifolia and C. villosa; Pourouma bicolor scobina and P. minor) in Costa Rica. I focused on Cecropia species in comparing the diversity of herbivores among species, as well as between juvenile and adult age classes within species, in regard to species turnover. I measured herbivore diversity and amount of herbivore damage on juvenile and adult Cecropia inhabited by Azteca colonies of different activity levels to see if they differed. Finally I recorded mortality levels (due primarily to predation and parasitism) for the leaf-mining guild on adult Cecropia insignis to see if they differed on trees inhabited by Azteca ants of different activity levels.; The herbivore fauna associated with the Cecropiaceae is diverse and exhibits high turnover among the species studied. For Cecropia, few species are shared between C. insignis and C. obtusifolia , and even fewer are shared between juvenile and adult conspecifics. Herbivore diversity and damage on juvenile Cecropia decreased rapidly with increasing Azteca activity, but did so more gradually on adult trees. Parasitism levels, but not predation, of leaf-miners were lower on trees inhabited by more active Azteca. This study is the first to measure the interaction between herbivores and Azteca on adult Cecropia, and it presents the first evidence that herbivores feeding on ant-plants can enjoy enemy free space by feeding in the presence of plant-ants.