Abstract

The red palm weevil, Rhynchophorus ferrugineus (Olivier), is among the most destructive invasive pests of date palms worldwide. In this study, mitochondrial cytochrome c oxidase subunit I (COI) and nuclear internal transcribed spacer (ITS) markers were analyzed in parallel to comparatively assess genetic diversity and haplotype variation in R. ferrugineus populations from Qassim Province, Saudi Arabia. Sequencing success rates reached 96.5% and 93.0% for COI and ITS, respectively. COI sequences exhibited very low nucleotide divergence among Qassim specimens (0.0–0.0077), indicating a highly conserved mitochondrial background and close phylogenetic similarity (p-distance = 0.0–0.0078) with an Egyptian reference haplotype (GU581319) and the reference R. ferrugineus mitochondrion (KT428893). In contrast, ITS analyses revealed substantially greater nuclear variation, identifying multiple haplotype groups with divergence levels of 10–19%. Haplotype diversity was higher in ITS (Hd = 0.876 ± 0.041) than in COI (Hd = 0.663 ± 0.068), while nucleotide diversity in ITS (π = 0.0387 ± 0.0013) was 36.9-fold greater than in COI (π = 0.00105 ± 0.00025; Z = 27.66, p < 0.001). Phylogenetic reconstruction showed greater population structuring in ITS than in COI. Integrated mitochondrial and nuclear markers improve genetic resolution and species identification in R. ferrugineus.

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