The first complete mitochondrial genome characterization and phylogenetic analysis of a potential biocontrol agent,...

Species of Trissolcus Ashmead (Hymenoptera: Scelionidae) are minute egg parasitoids of economic importance in biological control. Trissolcus elasmuchae (Watanabe) parasitizes several stink bugs, including Niphe elongata (Dallas) (Hemiptera: Pentatomidae), a serious pest in East Asia and the Oriental Region. Mitochondrial genomic data for Indian scelionids remain unavailable, limiting evolutionary and phylogenetic insights.

The complete mitochondrial genome of T. elasmuchae was sequenced and annotated. The circular genome is 16,290 bp long and contains 13 protein-coding genes (PCGs), 22 tRNAs, two rRNAs, and two putative control regions. It exhibits strong A + T bias (84.5%), with positive AT skew (+ 0.0470) and negative GC skew (- 0.2392). All PCGs use standard ATN start codons and predominantly terminate with TAA. Codon usage is biased toward Leu, Ile, Phe, and Met. Most tRNAs show typical cloverleaf structures except trnS1 and trnR. Five conserved ancestral gene blocks were identified. Platygastrinae retains more ancestral gene order features than Scelionidae, which shows derived rearrangements. The cox1 gene was most conserved, whereas nad6 was most variable. Selection analyses indicated strong purifying selection across 11 PCGs and positive selection on two. Phylogenetic analyses supported the monophyly of Telenominae and Platygastrinae and the paraphyly of Scelioninae.

The high A + T content, strong purifying selection on cox1, and conserved gene rearrangements, including ancestral gene blocks and hotspot regions, underscore key evolutionary patterns within Scelionidae. These findings advance our understanding of mitogenome evolution and functional genomics in Platygastroidea and provide a foundation for future phylogenomic and comparative studies.