Quadrastichus erythrinae
(Erythrina gall wasp)

Preferred Common Name

• Erythrina gall wasp

International Common Names

• English: erythrina gall wasp (EGW)

• Domain: Eukaryota
•     Kingdom: Metazoa
•         Phylum: Arthropoda
•             Subphylum: Uniramia
•                 Class: Insecta
•                     Order: Hymenoptera
•                         Family: Eulophidae
•                             Genus: Quadrastichus
•                                 Species: Quadrastichus erythrinae

Female: Length 1.45–1.6 mm. Dark brown with yellow markings. Head yellow, except gena posteriorly brown. Antenna pale brown except scape posteriorly pale. Pronotum dark brown. The mid lobe of mesoscutum with a ‘‘V’’ shaped or inverted triangular dark brown area from anterior margin, the remainder yellow. Scapula yellow. Scutellum, axilla and dorsellum brown to light brown. Propodeum dark brown. Gaster brown. Fore and hind coxae brown. Mid coxa almost pale. Femora mostly brown to light brown. Specimens from Mauritius are generally darker than those from Singapore. Oviposter sheath not protruding, short in dorsal view (Kim Delvare and La Salle 2004).
Male. Length 1.0–1.15 mm. Pale coloration white to pale yellow as opposed to yellow in female. Head and antenna pale. Pronotum dark brown (but in lateral view, only upper half dark brown; lower half yellow to white). Scutellum and dorsellum pale brown. Axilla pale. Propodeum dark brown. Gaster in anterior half pale; remainder dark brown. Legs all pale. Antenna with 4 funicular segments; without the whorl of setae; F1 distinctly shorter than the other segments and slightly transverse; about 1.4 wider than long. Ventral plaque extending 0.4– 0.5 length of scape and placed in apical half. Gaster shorter than female. Genitalia elongate, with digitus about 0.4 length of the long, exserted aedagus (Kim Delvare and La Salle 2004).

Introduction pathways to new locations
Ship: Boats carrying fallen infested leaves raise the risk of spreading Erythrina gall wasp (Quadrastichus erythrinae) (SPC 2006).

Local dispersal methods
Hikers' clothes/boots:Quadrastichus erythrinae may be transported on many items, including clothing and flowers (SPC 2006).
Wind dispersed:Quadrastichus erythrinae may be spread via the wind (SPC 2006).

Like other gall-forming eulophid wasps, the Erythrina gall wasp inserts its eggs inside young leaf and stem tissue. The wasp larvae, which develop within plant tissue, induce the formation of galls in the leaflets and petioles. As the infestation progresses, leaves curl and appear deformed while petioles and shoots become swollen. After feeding is complete, larvae pupate within the leaf and stem tissue. After pupation within the galls, adult wasps emerge after cutting exit holes through to the outside. Heavily galled leaves and stems result in a loss of growth and vigour. Severe infestations can cause defoliation and death of trees (Yang et al. 2004; Heu et al. 2006).

The Erythrina gall wasp infests Erythrina spp. of which there are approximately 110 mostly in tropical regions around the world. (Kim et al. 2004). Erythrina spp. are also known as coral trees and have a variety of functions in different locations. In Taiwan they are highly associated with farming and fishing activities (Yang et al. 2004). As indicated by its Latin name "erythros" meaning red, its obvious red flowers have been used as a sign of the arrival of spring and as a working calendar by tribal peoples (Yang et al. 2004). Specifically, the blooming of its showy red flowers serves as a signal to the coastal people to begin their ceremonies for catching flying fish, and for the Puyama people to plant sweet potatoes (Yang et al. 2004).

In Hawaii the Erythrina gall wasp infests coral trees, Erythrina variegata, E. crista-galli and the native E. sandwicensis (Heu et al. 2006). E. sandwicensis, known as the wiliwili tree, is endemic to Hawaii and a “keystone species in Hawaii's lowland dry forest, one of the most endangered ecosystems in the world.” For a closer look at the threat posed by the Erythrina gall wasp to the native Hawaii wiliwili, please see Wiliwili on Maui: threatened by the Erythrina gall wasp . Control of the spread of Erythrina gall wasp in Hawaii was predicted to cost over $1 million in 2008 (Brannon, 2007).

• Reduced native biodiversity

• Parasitism (incl. parasitoid)

Aliens-L 24-Jan-2006 JohnMauremootoo (CABI-Africa) Erythrina Gall Wasp in Mauritius

B. Napompeth, 2006. RE: [pestnet] Erythrina gall wasp - American Samoa. (Email posting).

Brannon, J. (2007, March 23). Dying trees cost $1M a year. The Honolulu Advertiser [online – accessed 07/01/2009]. http://the.honoluluadvertiser.com/article/2007/Mar/23/ln/FP703230359.html

Erythrina Gall Wasp (Quadrastichus erythinae), in American Samoa. 2006. Pest Alert (ISSN 1727 8473). Plant Protection Service, Secretariat of the Pacific Community.

Gates, M. & Delvare, G. (2008). A new species of Eurytoma (Hymenoptera: Eurytomidae) attacking Quadrastichus spp. (Hymenoptera: Eulophidae) galling Erythrina spp. (Fabaceae), with a summary of African Eurytoma biology and species checklist. Zootaxa 1751: 1–24.

Hawaiian Ecosystems at Risk Project (HEAR), 2006. Species Info Quadrastichus erythrinae (Eulophidae) http://www.hear.org/species/quadrastichus_erythrinae/

Heu, R.A., Tsuda, D.M., Nagamine, W.T., Yalemar, J.A. and Suh, T.H. 2006. Erythrina Gall Wasp Quadrastichus erythrinae Kim (Hymenoptera: Eulophidae), New Pest Advisory. Department of Agriculture: Manoa (Hawaii). http://www.hawaiiag.org/hdoa/npa/npa05-03-EGW.pdf

Hurley, T. 2005. Tiny wasp may kill off native trees, Hawaii Advertiser.

I. Buldawoo, 2006. [Aliens-L] Re Erythrina Gall Wasp in Mauritius. (Email posting).

Kami, P. (2008). Re Pestnet, 1 Dec. (Email posting).

Kaya, T. (2007, June 18). Wasp swap: A relief for wiliwili? The Maui News [online – accessed 06/01/2009]. http://www.mauinews.com/page/content.detail/id/31519.html

Kim, I., Delvare, G. and La Salle, J. 2004. A new Species of Quadrastichus (Hymenoptera: Euphidae): A Gall-Inducing Pest on Erythrina (Fabaceae), J. HYM. RES. 13(2): 243-249.

Kranz, B. (2008). Pestnet, 21 Jan (Email posting)

Lal, S. N. (2008). Pestnet, 29 Nov (Email posting)

Li, H.-M. et al. (2006). Potential global range expansion of a new invasive species, the erythrina gall wasp, Quadrastichus erythrinae Kim (insecta: Hymenoptera: Eulophidae). Raffles Bulletin of Zoology 54 (2): pp. 229-234.

Liebregts, W. (2008). [Personal communication – Pestnet, 28 Nov]

Medeiros, A. (2008). [Personal communication – Pestnet, 28 Nov]

Messing, R. H. et al. (2008). Using host plant relationships to help determine origins of the invasive Erythrina gall wasp, Quadrastichus erythrinae Kim (Hymenoptera: Eulophidae). Biological Invasions. pp. 1-9 [article in press].

Mille, C. (2008). Pestnet, 28 Nov (Email posting)

Oishi, D. (2008). Pestnet, 29 Nov (Email posting)

Rubinoff, Daniel; Brenden S. Holland; Alexandra Shibata; Russell H. Messing, and Mark G. Wright, 2010. Rapid Invasion Despite Lack of Genetic Variation in the Erythrina Gall Wasp (Quadrastichus erythrinae Kim). Pacific Science (2010), vol. 64, no. 1:23–31

Secretariat of the Pacific Community (SPC) Pest Focus - February 2006 Erythrina gall wasp (Quadrastichus erythrinae)

Tanji, E. (2008, November 29). Insects being released to attack gall wasps. The Maui News [online – accessed 06/01/2009]. http://www.mauinews.com/page/content.detail/id/511802.html

Thomas, P. (2005). Wiliwili on Maui: threatened by the Erythrina gall wasp [online - accessed 07/01/2009] http://www.hear.org/issues/wiliwilionmaui/

Uechi, Nami., Takumi Uesato and Junichi Yukawa., 2007. Detection of an invasive gall-inducing pest, Quadrastichus erythrinae (Hymenoptera: Eulophidae), causing damage to Erythrina variegata L. (Fabaceae) in Okinawa Prefecture, Japan Entomological Science (2007) 10, 209–212

Walker, K. 2007. Erythrina gall wasp (Quadrastichus erythrinae) Pest and Diseases Image Library. http://www.padil.gov.au/viewPestDiagnosticImages.aspx?id=989

Wiley, J. & Skelley, P. (2006). Erythrina Gall Wasp, Quadrastichus erythrinae Kim, in Florida [online – accessed 06/01/2008]. http://www.doacs.state.fl.us/pi/enpp/ento/gallwasp.html

Xu, T. et al. (2008). Efficacy of systemic insecticides on the gall wasp Quadrastichus erythrinae in wiliwili trees (Erythrina spp.). Pest Management Science 65(2): pp. 163 - 169. http://www3.interscience.wiley.com/cgi-bin/fulltext/121428027/PDFSTART

Yang, M., Tung, G., La Salle, J. and Wu, M. 2004. Outbreak of erythrina gall wasp (Hymenoptera: Eulophidae) on Erythrina spp. (Fabaceae) in Taiwan.