Quadrastichus erythrinae Kim

Unusual growths caused on leaves and young shoots of coral trees (Erythrina spp.) alerts to the presence of Erythrina gall wasp (Quadrastichus erythrinae) a gall-forming eulophid wasp, that measures a mere 1.5mm and may be spread easily via infected leaves from infected Erythrina specimens. A newly described species Q. erythrinae is believed to be native to Africa. It is now a serious pest of Erythrina trees in the tropics

and sub-tropics; it was first collected in Florida on coral trees

Erythrina variegata, it is now reported in Miami and Hawaii, also known from Singapore, Mauritius and Reunion. Taiwan, Hong Kong, China, India, Thailand, Philippines, American Samoa, Guam and in the Amami Islands and Okinawa in Japan Erythrina spp. have a variety of functions in different locations.

In Taiwan they are highly associated with farming and fishing

activities. 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. Specifically, the blooming of its showy red flowers signal to the coastal people to begin their ceremonies for catching flying fish, and for another

people (the Puyama people) to plant sweet potatoes (Yang et al. 2004). The Erythrina gall wasp infests E. variegata, E. crista-galli and the

native E. sandwicensis in Hawaii (Heu et al. 2006). E. sandwicensi,

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.

Photo credit: Kim & Forest Starr

Short-term control options are limited. The application of a systemic insecticide appears to have been partly effective in protecting highly valued individual trees in Hawaii. The Hawaii Department of Agriculture released a biocontrol agent, the parasite Eurytoma erythrinae to control the Erythrina gall wasp in 2008.

References:

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

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