Gallwasp Taxonomy
Gallwasps are members of the insect order Hymenoptera, and part of a major subgroup (the Cynipoidea) in which most species are parasites (strictly, parasitoids) of other insects. The groups closest to gallwasps (e.g. members of the families Figitidae, Eucoilidae, Charipidae and Anacharitidae) all attack insect larvae, suggesting that this was also the life history of the ancestors of gallwasps.
All gallwasps can only feed on gall tissue, and either induce their own galls or develop as inquilines (if you like, herbivorous parasites) within the galls induced by other gallwasps. Evolutionary work by Fredrik Ronquist and his students strongly suggests that the first gallwasps induced galls on herbaceous plants (rather than woody shrubs or trees), and subsequently diverged into six recognised tribes (Ronquist and Liljeblad 2001). The numbers of species in these tribes keep changing, and very approximate numbers are given in brackets:
The Aylacini (ca. 180 species) are rag-bag group whose lifecycles and gall traits are thought to be closest to the gallwasp ancestral states. They gave rise to two main evolutionary lineages. One consists of four tribes whose members all gall woody rosaceous plants: the Diplolepidini (rose gallwasps, ca. 63 species), the Pediaspidini (galling Sycamore, 2 species), the Eschatocerini (galling Acacia and Prosopis, 3 species) and the Cynipini (oak gall wasps, ca. 900-1000 species). A second lineage gave rise to the tribe Synergini (ca. 173 species), whose members are all inquiline inhabitants of the galls of other gallwasps. Though able to induce the development of nutritive plant tissues within other cynipid galls, they are probably unable to induce their own galls.
Some examples of galls induced by herb and rose gallwasps are shown in the images below. A selection of oak galls can be seen here.
Above and Left: Examples of Aylacine Herb galls (all pictures Gyuri Csóka) ABOVE LEFT: Diastrophus rubi, a common gall on Rubus brambles. ABOVE: Liposthenes glechomae. Fact: These galls are known as Cat's testicles in Hungarian. LEFT: Panteliella fedtschenkoi. The galls of this species are hidden within the stems of Phlomis.
Examples of Rose gallwasp galls (all pictures Gyuri Csóka) LEFT: Diplolepis spinosissimae RIGHT: D. rosae, the common bedeguar or 'robin's pincushion'.
