• Sequencing of 18S and ITS2-28S rRNA gene fragments from Bactrocera dorsalis samples from the Philippines was employed to assess their suitability for species diagnostics.
  • 18S and 28S rRNA sequences showed high similarity with other insect species in NCBI, while ITS2 displayed hits specific to B. dorsalis.
  • ITS2 demonstrates sufficient species-level nucleotide variation for molecular diagnostics of B. dorsalis.
Fruit flies belonging to the Bactrocera dorsalis species complex pose a significant threat to mangoes and other crops in the Philippines and worldwide. Identifying cryptic species within this complex is challenging, particularly when relying solely on morphological analysis. In this study, we sequenced two fragments of the nuclear 18S and ITS2-28S rRNA genes from specimens of B. dorsalis Hendel collected in the Philippines to assess their applicability for species diagnostics. Subsequent sequencing and analysis revealed that the 18S and 28S rRNA gene fragments matched B. dorsalis sequences in NCBI but also displayed high similarity with other Bactrocera and insect species. On the other hand, sequences of the ITS2 segment showed hits specific to B. dorsalis. Further analysis of the 18S rRNA gene in fruit flies collected from various sources and host plants in the country suggests conserved sequences among Bactrocera samples, irrespective of collection site and host plant species. In conclusion, our findings suggest that, among the tested nuclear DNA fragments, only the ITS2 demonstrates sufficient species-level nucleotide variation for effective use as a molecular diagnostic marker for B. dorsalis identification.
We wish to thank the people and organizations that provided or assisted in the collection of fruit fly-infested fruits: Perlita Farrales and family (Zambales), Adel Rapadas of Rapadas Farm (Quezon), Darlon Lantican (Oriental Mindoro), Bureau of Plant Industry – Guimaras National Crop Research, Development and Production Support Center (BPI-GNCRDPSC) (Guimaras), Gil Cortaga (Cebu), and Winifredo Sison (Cotabato). The authors also wish to thank Raquel Javier, Kristine Joy de Castro, Alvin Borja, and Cris Urriza for their assistance in the insect mass rearing and laboratory works; Dr. Fe Dela Cueva and the Plant Pathology Laboratory of the Institute of Plant Breeding, UPLB for their support and provision of research facilities; and the Department of Science and Technology-Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (DOST-PCAARRD) for continued support.
Vahid Mahdavi
The authors have declared that no conflict of interests exist.
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