The highly rearranged mitochondrial genomes of three economically important scale insects and the mitochondrial phylogeny of Coccoidea (Hemiptera: Sternorrhyncha)

Abstract

The mitochondrial genomes (mitogenomes) of scale insects are less known in comparison to other insects, which hinders the phylogenetic and evolutionary studies of Coccoidea and higher taxa. Herein, the complete mitogenomes of <i>Unaspis yanonensis</i>, <i>Planococcus citri</i> and <i>Ceroplastes rubens</i> were sequenced for Coccoidea. The 15,220-bp long mitogenome of <i>U. yanonensis</i> contained the typical set of 37 genes including 13 PCGs, 22 tRNA genes and two rRNA genes; the 15,549-bp long mitogenome of <i>P. citri</i> lacked the tRNA gene <i>trnV</i>; the 15,387-bp long mitogenome of <i>C. rubens</i> exhibited several shortened PCGs and lacked five tRNA genes. The mitochondrial gene arrangement of the three mitogenomes was different from other scale insects and <i>Drosophila yakuba</i>. Most PCGs used standard ATN (ATA, ATT, ATC and ATG) start codons and complete TAN (TAA or TAG) termination codons. The <i>ND4L</i> had the highest evolutionary rate but <i>COX1</i> and <i>CYTB</i> were the lowest. Most tRNA genes had cloverleaf secondary structures, whereas the reduction of dihydrouridine (DHU) arms and T<i>ψ</i>C arms were detected. Tandem repeats, stem-loop (SL) structures and poly-[TA]n stretch were found in the control regions (CRs) of the three mitogenomes. The phylogenetic analyses using Bayesian inference (BI) and maximum likelihood methods (ML) showed identical results, both supporting the inner relationship of Coccoidea as Coccidae + (Pseudococcidae + Diaspididae).