Development of Cytochrome Oxidase I Gene Specific Primers for Diagnosis of Melon Fly, <I>Zeugodacus cucurbitae</I> (Coquillett) (Diptera: Tephritidae) for Export Promotion

Abstract

The melon fly, Zeugodacus cucurbitae (Coquillett), is a quarantine pest species for many countries. Larvae of melon fly are intercepted by quarantine inspections, but their morphological similarity to other fruit fly species makes identification difficult and unreliable. Rapid, precise identification of immature fruit flies associated with imported/exported fresh produce is essential to ensure appropriate biosecurity decisions at quarantine barriers, or where commodities are inspected prior to export. Species-specific primers were designed by amplifying the cytochrome oxidase I (cox1) gene to identify Z. cucurbitae in its various life stages. The species - specific assay demonstrated high specificity, sensitivity and reliability for 11 species examined (Bactrocera carambolae, B. correcta, B. dorsalis, B. latifrons, B. umbrosa, Dacus longicornis, Zeugodacus apicalis, Z. caudatus, Z. cilifera, Z. cucurbitae and Z. tau). This study demonstrated the feasibility of using species - specific diagnostic tools (utilising 83 base pair sequences) for identifying fruit fly populations from all regions of Thailand. The primers were also validated on samples intercepted by plant inspections at Suvarnabhumi airport of agricultural products destined for exporting from Thailand. The primer pairs from this research are accurate, fast and efficient. Thus, they make it possible to detection of quarantine pests at early points in the production and export pathway. The present study is a model for developing diagnostic techniques for various pests which will in turn: promote trading partner confidence in Thai certification systems and enhance the diversity, quality and value of Thai agricultural products.