The fig wasps form a heterogenous group of microhymenopterans showing convergent evolution in response to adaptations for life in their unique habitat—the interior of the syconia of the differentFicus species. Sexual dimorphism is very common among the various tribes of the chalcidoid families constituting the fig wasps. This is in response to the different types of functions that the female and the male sexes are called upon to perform in their specialized habitat. The unisexual variations commonly met with in the male sex and rarely in the female sex, in the cleptoparasitic tribes belonging to theTorymidae and thePteromalidae may be attributed to competitive feeding on a limited provision of food—a trophic factor. In the homeomorphic sexes of the subfamilyEpichrysomallinae (Pteromalidae) copulation takes place outside on the top of the syconia. The importance of making observations on the biology including mating behaviour of the dimorphic (apterous and alate) males in the subfamilySycophaginae (Torymidae) for the proper study of the systematics of this group is stressed.
The true fig wasps which are the fig pollinators (Agaonidae) are generally highly host specific, i.e. only one species of these pollinators is associated with a given species ofFicus. TheFicus species and its wasp pollinator are in intimate symbiotic relationship. There has been co-evolution of theFicus species with its specific wasp pollinator. The females of these pollinator wasps often possess pollen storing structures as well as the behavioural attributes for the active collection of pollen from the stamens of the ripe fig and for the active dispersal of pollen on to the stigmas of the ovaries of flowers of tender figs into which these females penetrate for oviposition.
The ecological niche of theFicus syconia is virtually identical to that of many plant galls and as such attract many species of gall-inhabitingEurytominae (FamilyEurytomidae). SuchEurytominae include a variety of genera, with numerous species both of phytophagous and entomophagous habits.
The modern systematics of the fig wasps is based on the above aspects of their functional morphology, biology, convergent evolution, sex-limited variations, sex-limited dimorphism, host specificity, behavioural attributes, etc. A conspectus of the modern classification of the figChalcidoidea is presented.