Complete mitochondrial genomes of two blattid cockroaches, Periplaneta australasiae and Neostylopyga rhombifolia, and phylogenetic relationships within the Blattaria.

Jinnan Ma,Bisong Yue,Zhenxin Fan,Chao Du,Chuang Zhou,Xiuyue Zhang,Yongmei Sheng,Xiu-Qing Li

doi:10.1371/journal.pone.0177162

Abstract

Complete mitochondrial genomes (mitogenomes) of two cockroach species, Periplaneta australasiae and Neostylopyga rhombifolia, 15,605 bp and 15,711 bp in length, respectively, were determined. As reported for other cockroach mitogenomes, the two mitogenomes possessed typical ancestral insect mitogenome gene composition and arrangement. Only several small intergenic spacers were found: one, which was common in all sequenced cockroach mitogenomes except for the genus Cryptocercus, was between tRNA-Ser (UCN) and ND1 and contained a 7bp highly conserved motif (WACTTAA). Three different types of short tandem repeats in the N. rhombifolia control region (CR) were observed. The homologous alignments of these tandem repeats with other six cockroach mitogenome CRs revealed a low similarity. Three conserved sequence blocks (CSB) were detected in both cockroach mitochondrial CRs. CSB1 was specific for blattinine mitogenomes and was highly conserved with 95% similarity, speculating that this block was a possible molecular synapomorphy for this subfamily. CSB3 located nearby downstream of CSB1 and has more variations within blattinine mitogenomes compared with CSB1. The CSB3 was capable of forming stable stem-loop structure with a small T-stretch in the loop portion. We assessed the influence of four datasets and two inference methods on topology within Orthopteroidea. All genes excluding the third codon positions of PCGs could generate more stable topology, and higher posterior probabilities than bootstrap values were presented at some branch nodes. The phylogenetic analysis with different datasets and analytical methods supported the monophyly of Dictyoptera and supported strongly the proposal that Isoptera should be classified as a family (Termitidae) of the Blattaria. Specifically, Shelfordella lateralis was inserted in the clade Periplaneta. Considering the K2P genetic distance, morphological characters, and the phylogenetic trees, we suggested that S. lateralis should be placed in the genus Periplaneta.

Highlights

Cockroaches are a various insect of some 4,600 species and 460 genera are described [1]
The sizes of the P. australasiae and N. rhombifolia mitogenomes were within the range of other blattarian mitogenomes, with the lengths ranging from 14,996 bp (NC_006076.1) to 17,340 bp (NC_029224.1) (S1 Table)
The relative synonymous codon usage (RSCU) value of P. australasiae and N. rhombifolia mitogenomes was summarized in S2 Table

Summary

Introduction

Cockroaches are a various insect of some 4,600 species and 460 genera are described [1]. A relatively small number, considering the large number of species, of cockroaches are known as pests [2]. These pest cockroaches cause health problems, such as asthma and allergies, as well as economic costs for controlling them [3]. The cockroach (Insecta: Blattaria) Periplaneta australasiae and Neostylopyga rhombifolia belong to the subfamily Blattinae family Blattidae. They both are abundant and widely distributed urban pests [4]. There are approximately 324 species and 24 genera of Blattinae [6], as most of them lack of molecular data, the phylogenetic relationships among them are still contrasty [7]

Methods

Results

Conclusion