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June 2003. This is the first report on PestNet of the outbreak of the Erythrina gall wasp in Asia and the Pacific. Singapore reported that in recent months, they have found galls on the leaves, stems, petioles and young shoots of the coral trees, Erythrina variegata and E glauca planted. Adult midge-like wasps/insects emerged from infested samples when incubated in the laboratory. There are two types of wasps: yellow colour and dark brown. The wasps are preliminary identified as belonging to Eulophidae.
Inside the leaf galls, there are one wasp per cell, while in the other swollen tissues of shoots, twigs and petioles, more than five wasps together with larvae, pupae and pre-imago stages were seen in the same nest tissues.
A member reported that the wasp is in the family Eulophidae (Chalcidoidea), and almost certainly in the subfamily Tetrastichinae. The Tetrastichinae is very interesting biologically, because it is a huge subfamily that attacks hosts in over 100 families and 10 orders of insects, as well as gall forming mites and nematodes, and spider eggs. Phytophagy (usually gall formation, but occasionally seed infestation) has arisen on several occasions.
A book chapter reviewing gall induction in the Chalcidoidea, has just been completed, but this did not find any references to gall inducers on Erythrina. So, if this has been published, it has not been in literature that would have been picked up by an abstracting service.
However, later it was said that a reference had been found. It is provided below, but there is a bit of
misinformation in this, particularly in assuming that eulophids never form galls. Also, although a few Eurytoma species do form galls, most do not and one should not assume that they are gall formers simply because they emerge from the galls.
Insects and Mites of Cultivated Plants in South Africa, by Annecke & Moran. 1982, Butterworth and Co. publishers. pp. 231-232.
Erythrina gall wasps — Eurytoma species. The green lumpy galls, each the size of the matchhead or somewhat larger, are usually common on the upper surface of leaves of Erythrinas or coral trees, and are familiar to many people in South Africa. Young and sometimes mature leaves become badly galled and distorted and it is surprising that despite their frequent and widespread occurrence, we do not know precisely what causes these galls. Five or more distinct species of small blackish chalcidoid wasps have been reared from these galls. Included are species of Eulophidae that may be expected to be parasitic or perhaps to live in some other association with the primary gall maker, which may be an unidentified species of Eurytoma, another chalcidoid wasp that has been reared from these galls. Species of Eurytoma, are often phytophagous and are sometimes known as seed chalcids but as far as we know eulophids feed on other insects in their immature stages and none produce galls on plants. The biology of the insects associated with Erythrina leaf galls would undoubtedly prove to be most interesting and would reward careful study.
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