Genetic Differentiation of Lucilia cuprina and Lucilia sericata Using cox1 and 28S rRNA Genes: Phylogenetic Insights and First Report of L. cuprina in Northwest Africa

Lucilia cuprina Wiedemann and Lucilia sericata Meigen (Diptera: Calliphoridae) are blowflies that may cause cutaneous myiasis in sheep, among other wild and domestic animals, leading to major economic losses in the sheep industry. The mitochondrial cytochrome c oxidase subunit 1 (cox1) gene has been considered ineffective for species identification when used alone. Some Lucilia (Phaenicia) cuprina exhibit mitochondrial DNA haplotypes that closely resemble those of Lucilia sericata, suggesting a paraphyletic relationship between L. cuprina and L. sericata. To address this, we examined both the nuclear 28S rRNA gene and the mitochondrial cox1 gene to differentiate between L. cuprina and L. sericata using new DNA data from Northwest Africa. This study provides the first evidence of L. cuprina in Northwest Africa.

Adult flies were captured from Tipaza Province, North Algeria (36°33'11.254"N, 1°48'5.749" E). We sequenced both the cox1 and 28S genes and constructed phylogenetic trees using the maximum likelihood method with 1000 bootstrap replicates. The sequencing generated approximately 675 base pairs (bp) for cox1 and 633 bp for 28S. All sequences were identified using BLASTn and deposited in GenBank (accession numbers PP918012- PP918014, PP922527- PP922529, PP922531- PP9225333, and PP916230- PP916232). No intraspecific differences were observed among the sequences. The 28S analysis confirmed the monophyly of the two species, while the cox1 analysis revealed that L. cuprina is divided into two distinct clades, paraphyletic with respect to L. sericata. The 28S sequences clustered together without showing any consistent geographic patterns.

Despite the paraphyletic relationship between L. sericata and the two forms of L. cuprina, mitochondrial DNA appears useful in distinguishing these species. However, the subspecies L. cuprina cuprina (Wiedemann) and L. cuprina dorsalis Robineau-Desvoidy cannot be differentiated using the 28S and cox1 genes, nor can their differences be inferred based on geographic location, particularly in areas where both subspecies coexist.