CARBON DIOXIDE AND ETHYLENE EFFECTS IN THE CO‐ORDINATION BETWEEN THE POLLINATOR BLASTOPHAGA QUADRATICEPS AND THE SYCONIUM IN FICUS RELIGIOSA

Abstract

The multilateral inter‐relationships between figs and their pollinators contain ecophysiological elements in addition to morphological and behavioural co‐adaptations. The changes in the internal atmosphere of the ripening fig have a decisive effect on the activity of males and females of the pollinating wasp. During the early stages of the male phase of Ficus religiosa, the internal atmosphere of the fig consists of about 10% CO2, 10% O2 and some ethylene. The males of the pollinator, Blastopliaga quadraticeps, carry out their usual activities in perforating the walls of the galls and in fertilizing the females under these conditions while at the same time the females are inactivated. After perforation of the syconia wall by the males, the atmosphere within the fig becomes equilibrated with the external atmosphere. As a result, male wasps are inhibited, whereas the females become active, leave their galls, load pollen pockets with pollen and emerge from the fig. The differential response of male and female wasps to the changes in the composition of the internal atmosphere within the fig ensures the completion of the developmental cycle of both the pollinator and the fig. Differences in the behaviour of wasp pollinators of different Ficus spp. under normal conditions are regarded as adaptations to diversely composed internal atmospheres within male‐phase figs of the respective species. Copyright © 1973, Wiley Blackwell. All rights reserved