Antagonistic interactions of fig trees and psitacid birds

Abstract

Plants of the genus Ficus supply frugivorous animals with food throughout periods of scarcity of fruits from other species, and therefore are considered key-resources to the functioning of tropical forests. Only females of Agaonidae wasps pollinate Ficus flowers and those utilize the ovaries of pollinated flowers to oviposit their eggs and develop offspring. Thus, the offspring of pollinating wasps play the male role and fruit (achenes) play the female role in the plant. The present work aimed to evaluate frugivory rates of Pyrrhura leucotis (Psittacidae) on a F. cyclophylla tree within the Linhares Forest Reserve (Espírito Santo State), Brazil. We evaluated frugivory rates obtained with a group of approximately 20 individuals of P. leucotis throughout July, 1996. Results have shown that P. leucotis keeps an antagonistic relationship with the studied Ficus species. Frugivory rates on figs reached 100% prior to maturation and, consequently, the offspring of pollinating wasps did not have the chance to disperse. Parakeets broke achenes and ate their content. A low germination rate of 24% was found in achenes that escaped predation and fell down below canopy. Pollinating wasps that emerged off cut fragments below canopies did not convey pollen on their bodies and did not play the role of pollen vectors anyway. Thus, P. leucotis brought a negative impact over the female and male functions of the plant. By considering that impacts on reproductive functions of Ficus might hinder the dynamics of tropical forests and interfere with the maintenance of the mutualistic relationship between Ficus and fig wasps, special attention should be given to similar studies that might be carried out with other species.