Mitochondrial genome and morphological variability of Bactrocera oleae (Diptera: Tephritidae) from an organic olive orchard in Southern Spain

Background The olive fruit fly, Bactrocera oleae , is the most damaging pest of olive production. This study aimed to characterize the intraspecific morphological variability and assemble the complete mitochondrial genome of a population from an organic olive orchard in Órgiva (Granada, southern Spain), a region showing high biodiversity and habitat heterogeneity. Methods A total of 140 adults emerging from naturally infested olives were examined for morphological variation (thoracic pigmentation, abdominal banding, abdomen shape, body size, and ovipositor morphology). Morphometric analyses were performed to identify distinct groups. Longevity and fecundity were assessed on two olive varieties (Picual and Picholine). The complete mitochondrial genome, reflecting the local population of this biotope, was assembled using Oxford Nanopore sequencing from a pooled subset of 40 individuals selected among the 140 adults. Results Marked morphological variation was observed. Morphometric analyses revealed six distinct groups, primarily separated by body size and ovipositor traits, with significant differences in longevity (25–32 days) and fecundity (36–52% on Picual; 32–49% on Picholine). A complete circular mitogenome of 15,810 bp was assembled (GenBank accession number: PZ179621). The Órgiva haplotype differed from the Italian reference by 21 nucleotide substitutions, including 11 non-synonymous changes in ND and COX genes, and clustered within the Mediterranean clade in phylogenetic analyses. Conclusions This study provides a high-quality consensus mitochondrial genome and a comprehensive baseline of morphological and fitness variation of B.oleae from a traditional organic olive orchard, offering valuable resources for comparative studies, haplotype tracking, population monitoring, and research on phenotypic plasticity in Mediterranean organic olive systems