PHYLOGEOGRAPHY AND RECENT EMERGENCE OF THE OLD WORLD SCREWWORM FLY, Chrysomya bezziana, BASED ON MITOCHONDRIAL AND NUCLEAR GENE SEQUENCES

P. D. READY¹, J. M. TESTA¹, A. H. WARDHANA^1,2, M. AL-IZZI^3*, M. KHALAJ⁴ and M. J. R. HALL¹

^{1) Department of Entomology, Natural History Museum, London, U.K., 2) Department of Parasitology, Indonesian Research Centre for Veterinary Science (Balai Besar Penelitian Veteriner), Bogor, Indonesia., 3) Entomology Department, Iraqi Atomic Energy Commission, Ministry of Science and Technology, Baghdad, Iraq and 4) Veterinary Organization of the Islamic Republic of Iran, Tehnran, Iran.}

A previous study had identified an African and an Asian race of the Old World screwworm fly, Chrysomya bezziana Villeneuve (Diptera: Calliphoridae), based on the 3'terminal 279 basepairs (bp) of the mitochondrial cytochrome b gene. The current study improved the phylogeographic resolution of cytochrome b for this species by characterizing more of the gene (the 3'terminal 715 bp) and by sampling more geographical populations, including Oman, Iran, Hong Kong and the Indonesian Islands of Sulawesi and East Sumba. Strong support was found for recognizing an African race, but not for a monophyletic Asian race. The cladistic and genealogical relationships among the Asian populations were complex. There was sufficient ge- netic homogeneity throughout separate regions (mainland Asia and each Indonesian island) to suggest that there are no reproductive barriers within each region that might necessitate the production of more than one strain for control by the sterile insect technique (SIT). Primers were designed for the amplification by polymerase chain reaction of two nuclear loci, the highly conserved elongation factor-1alpha gene and the less conserved white gene, and the preliminary results indicated that these genes showed the same pattern of small-scale regional variation as cytochrome b. The cytochrome b haplotypes are useful markers for identifying the geographical origins of any emerging infestations of the species: the absence of Indonesian and African haplotypes in the Middle East demonstrates that the large-scale transport of livestock is not spreading Old World screwworm.

Gambar 1. Chrysomya bezziana, penyebab myiasis pada manusia dan hewan