Pollinating and non-pollinating fig wasps (Hymenoptera: Chalcidoidea) from Ficus elastica, the living root bridge tree of Meghalaya in northeast India

Abstract

The Indian rubber fig tree Ficus elastica Roxb. ex Hornem. Moraceae is the constituent of the iconic living root bridges (LRBs) in Meghalaya, India, and is characterized by a highly specific mutualism between the fig and its pollinating agaonid fig wasp, in which the wasps breed within fig inflorescences. F. elastica is restricted to south and southeast Asia in its distribution. We identified the pollinating fig wasp as Platyscapa clavigera (Mayr 1885) which was first described from F. elastica in Bogor in 1885 and from Singapore in 2017. This is the first record of the pollinator (family Agaonidae) from F. elastica in Meghalaya, northeast India, in the westernmost portion of the fig’s range. We also discovered and identified in F. elastica, a non-pollinating fig wasp of the genus Micranisa which appears close to Micranisa ralianga Mathew and Balakrishnan 1981 (Pteromalidae). This fig wasp has not been earlier reported anywhere from the closed urn-shaped inflorescences (i.e. syconia) of F. elastica and was only described from the syconia of Ficus altissima Blume in 1981 from Meghalaya. Notes on the morphology of both fig wasps are provided and illustrated. The phenology and developmental cycle of F. elastica syconia are documented. Evidence of passive pollination was confirmed in F. elastica which sheds light on the evolution of character traits in figs and their wasps