Development of a Diagnostic Technique using Species-Specific Primers for the Guava Fruit Fly, Bactrocera correcta (Bezzi) (Diptera: Tephritidae)

Abstract

The guava fruit fly, Bactrocera correcta(Bezzi) causes major economic losses in fruit and vegetable crops in Thailand and many countries. It is also aquarantine pest of countries currently importing the fly’s host commodities from Thailand or are potential new markets. The morphological similarity between immature guava fruit fly and other fruit fly species makes visual identification difficult. Thus, methods for the rapid and accurate identification of immature fruit flies are needed to support quarantine officials at the border stations to make correct decisions when inspecting both importing or exporting commodities. In this study, we used molecular diagnostic methods based on cytochrome c oxidase subunit I (cox1) and species-specific markers to identify B. correcta. DNA barcode sequences obtained from 113 individuals of 11 fruit fly species were used. Based on these 650 bp barcode sequences, we successfully designed species-specific primers for identification of B. correcta in all life stages (egg, larva, pupa and adult).The size of the B. correcta specific fragment was 141 base pairs. The diagnostic protocol based on these primers elicited no cross-reactions with the other 10 tephritid species tested. A PCR product confirmed the specificity of the primers. The species-specific primers have greatly assisted plant quarantine of imported/exported fresh agricultural produce. The diagnostic protocol from this study can be used by pest diagnostic agencies and research organizations worldwide to develop tools for the rapid, accurate identification of invasive alien fruit fly species.