Biosystematics and biogeography of oriental Chalcidoidea (Hymenoptera) associated with plant galls

Chalcidoid wasps have exquisite life histories and diverse host relationships. They are believed to have originated in the upper Jurassic period. Among the chalcidoids it is not always easy to separate the obligatory gall inhabitants and those which have a discrete association with the galls. The following three categories of chalcidoids are treated in the present article (i) gall inducers (ii) gall inquilines and (iii) parasitoids attacking the gall inducers and gall inquilines. Gall-inducing chalcidoids mostly belong to Agaonidae, Eulophidae, Eurytomidae, Pteromalidae, Tanaostigmatidae, and Torymidae. The families of Chalcidoidea associated with plant galls in widely varying degrees of dependence are Aphelinidae, Encyrtidae, Trichogrammatidae, Eupelmidae, Mymaridae, Ormyridae, and Chalcididae. Several hypotheses explain the phylogeny of Chalcidoidea. Morphological features tend to support the monophyletic origin of Chalcidoidea. However, no hypothesis is acceptable totally to a chalcidologist, since a comprehensive knowledge on the distribution of the character states throughout the superfamily is lacking. Gall induction arose more then once in the six families referred above. The biogeography of gall-associated Chalcidoidea is related to the distribution of their respective host plants. The Oriental chalcidoids are not isolated from the nearby Asiatic and Middle-eastern countries. Even the Palearctic and Ethiopian elements are quite frequently met with in the Oriental region.