Interactions between gall midges and fungi
Four different species of gall midge (Asphondylia) each form a different gall type on the plants Sarcocornia quinqueflora (Beaded Glasswort) andSclerostegia arbuscula. Larvae of the gall midge live in a chamber within the gall. Herbarium specimens of both plant species from the 1870s have galls, and thus the gall midge–host plant interaction is not a recent phenomenon.
When fresh galls are sectioned and stained, a fungal layer lining the larval chamber is observed. The fungal layer appears the same morphologically in different galls. However, it is unclear if there is more than one species of fungus within a gall or if a given fungus occurs in more than one gall type.
In 2007, galls were collected at three different sites around Port Phillip Bay, Victoria. Preliminary results from DNA analysis of fungi from these galls suggested that the fungus from the larval chamber in galls on Sarcocornia quinqueflora was a species of the ascomycete Botryosphaeria. However, in galls collected from two of the same sites a year later there were up to four different fungi in the one larval chamber.
Examination of galls from two new species of Tecticornia from Western Australia in 2009 resulted in the discovery of two new species of gall midges. Unfortunately, no fungal material was able to be cultured and nor was DNA isolated from these collections.
We plan to examine collections of galls formed by different gall midge species from a broad geographic range to:
- determine the diversity of fungi and gall midges present in galls on different species of glassworts
- examine biogeographic and co-evolution patterns of glassworts, gall midges and fungi
- determine whether or not the gall midge larvae are mycophagous.
- Teresa Lebel (Royal Botanic Gardens Melbourne)
- Anneke Veenstra (Deakin University)
- Kelly Shepherd (Western Australian Herbarium)
Veenstra-Quah, A.A., Milne, J. and Kolesik, P. (2007). Taxonomy and biology of two new species of gall midge (Diptera: Cecidomyiidae) infesting Sarcocornia quinqueflora (Chenopodiaceae) in Australian salt marshes. Australian Journal of Entomology 46, 198–206.