The mitochondrial genome of Binodoxys acalephae (Hymenoptera: Braconidae) with unique gene rearrangement and phylogenetic implications.

Background: Species in the subfamily Aphidiinae from the Braconidae of Hymenoptera are endoparasitic wasps that exclusively utilize aphids as hosts. Some Aphidiinae species are widely used as biological agents. However, there were only one species with determined complete mitochondrial genome from this subfamily.

Methods And Results: In this study, we sequenced and annotated the mitochondrial genome (mitogenome) of Binodoxys acalephae, which was 15,116 bp in size and contained 37 genes. The start codon of 13 protein-coding genes was ATN, and the complete stop codon TAA and TAG was widely assigned to 11 protein-coding genes. The lrRNA contains 43 stem-loop structures, and srRNA contains 25 stem-loop structures. Translocation and inversion of tRNA genes was found to be dominant in B. acalephae. In contrast to Aphidius gifuensis from the same subfamily Aphidiinae, inverted tRNA was translocated to the gene cluster between tRNA and COX2, and the control region between tRNA and tRNA was deleted in the mitogenome of B. acalephae. Within Braconidae, gene clusters tRNA-tRNA-tRNA and CR-tRNA-tRNA-tRNA were hotspots for gene rearrangement. Phylogenetic analysis showed that both Bayesian and maximum-likelihood methods recovered the monophyly of Aphidiinae and suggested that Aphidiinae formed sister clades with the remaining subfamilies. The phylogenetic analyses of nine subfamilies supported the monophyly of Cyclostomes and Noncyclostomes in Braconidae.

Conclusion: The arrangement of mitochondrial genes and the phylogenetic relationships among nine Braconidae subfamilies were constructed better to understand the diversity and evolution of Aphidiinae mitogenomes.