Ficus rosulata photographed by Jean-Yves Rasplus at Lambir Hills on 6 August 2004. Note the distinctive prominent bracts around the ostiole.
The ecology of Ficus rosulata has been extensively researched at Lambir Hills by Rhett Harrison. See Ficus cereicarpa: Lambir Hills, Sarawak and the text and link at the bottom of this article.
RHETT HARRISON’S ECOLOGY STUDY OF FICUS ROSULATA AT LAMBIR HILLS
(Note that in Berg (2005) Ficus rosulata is called Ficus schwarzii. Berg changed the name. in 2010. See Ficus schwarzii is now Ficus rosulata, Berg (2010)
In Borneo around two thirds of fig species are dioecious with separate male and female trees. Male fig fruits act as brood chambers for pollinating fig wasps whilst female fig fruits only produce seeds. Ficus rosulata is a dioecious fig.
Rhett Harrison studied the breeding ecology of an isolated colony of 27 individual Ficus rosulata fig trees at Lambir Hills over four years 1994-1998. 16 of the study trees were male and 11 female. Both sexes fruited continuously with a breeding cycle of around 85 days and an average of 4 crops a year. Crops were synchronised on each tree but there was no synchrony between individual trees.
Male fruiting trees were visited by four species of fig wasps, one pollinating wasp and 3 non-pollinating parasite wasps. The male trees were also visited by two species of ants which fed on the wasps. When the ants were excluded from the male figs, the figs were heavily attacked by the parasite wasps and aborted. The fig trees attracted ants by producing ant food from nectaries on the surface of the fig fruits. The nectaries only produced nectar during periods when fig wasps were present.
A severe drought starting in 1998 caused all the fig trees in the study to stop producing fig fruit and the result was the complete extinction of the fig wasp colony.
See Harrison’s original article here; Harrison (2013) Fig-Ant plant interactions
See also Ficus rosulata, Crocker Range, Sabah