Ficus deltoidea and its associated fig wasps in Peninsular Malaysia

The interaction of fig trees (Ficus) and their fig wasp pollinators (Agaonidae) is an obligate mutualism where the fig trees need the pollinators in order to reproduce while
the pollinators require the figs as their brood sites. Ficus deltoidea is a common dioecious fig tree in Malaysian oil palm plantations and may contribute figs and other
resources for birds and other animals that would otherwise not be able to survive in the plantations. F. deltoidea is a true epiphyte – a growth form that is very rare in Ficus.
It has numerous named varieties and the taxonomic and biological status of these varieties is unclear, as is the extent to which different varieties support different
Blastophaga pollinators. A period of 18 months practical study was carried out in Malaysian oil palm plantations and the F. deltoidea germplasm collection in Universiti
Sultan Zainal Abidin. F. deltoidea was found to be one of ten fig tree species in oil palm plantations in Peninsular Malaysia, but the only true epiphyte. The figs of different
varieties of F. deltoidea showed a high degree of variation in terms of flower numbers, tepal numbers and size of the figs. Male and female F. deltoidea var. angustifolia
produced new leaves and figs all year around. There was no existence of nonpollinating fig wasps in this species. A Blastophaga sp. foundress can enter several figs to lay their eggs and pollinate, but many figs on female plants were not entered and many figs aborted. The pollinators liked to enter figs on their natal male plants if the figs were available. Experiments found pollinators preferred to enter figs of their own variety. The high specificity of the pollinators suggests that many varieties might
be distinct species. The limited dispersal of Blastophaga sp. helps them to reproduce but results in the pollinator shortage that is prominent in the female figs. The pollinator can be said to be ahead of the trees. Greater understanding of how they interact may help explain how the mutualism can persist. This is important because the mutualism between F. deltoidea and its pollinators can increase biodiversity in oil palm plantations. This study can also increase our understanding of coevolution between
plants and insects.