Quadrastichus erythrinae Kim induces galls on coral trees (Erythrina spp.), which

became an aggressive invasive pest since year 2000. Its African origin was hypothesized but

remains supported only by indirect and limited evidence. In this study, molecular phylogeny

and DNA haplotype were used to determine the origin of the erythrina gall wasp Q.

erythrinae based on cytochrome oxidase I (COI) and internal transcribed spacer 2 (ITS2)

regions of taxa from Mauritius, Tanzania, Singapore, Taiwan, Thailand, India, Indonesia,

Philippines, China, Japan, Guam, and Hawaii. A total of 90 COI and 94 ITS2 sequences were

generated from five Quadrastichus species, including Q. erythrinae and four African

congeners. Three COI haplotypes and one ITS2 haplotype were detected from 66 taxa of Q.

erythrinae. Taxa from most localities were observed to have an identical COI haplotype

(haplotype a); the outliers with other haplotype compositions were the taxa from Indonesia

(haplotype a and c) and Tanzania (haplotype n). The moelecualr phylogeny suggested that

the Tanzanian taxa of Q. erythrinae is more primitive than the other taxa. This finding

supported the hypothesis that Q. erythrinae, which is an invasive pest in many countries and

regions, has an African origin.