Mitogenomics of Chinch Bugs from China and Implications for Its Coevolutionary Relationship with Grasses

Blissidae (the Chinch bug) is a group with high species richness in Lygaeoidea, but there are only a few descriptions of mitochondrial genomes available. We obtained mitogenomes from 10 species of eight genera from Blissidae through second-generation sequencing technology. The length of the mitochondrial genome (excluding the control region) is between 14643 and 14385 bp; the content of AT is between 74.1% and 77.9%. The sequence of the evolution rate of protein coding genes was as follows: ND5 > ATP8 > ND6 > ND2 > ND4 > ND4L > ND1 > ATP6 > ND3 > COIII > COII > CYTB > COI. The mitogenomic structure of Blissidae is highly conservative. Gene rearrangement is only found in Pirkimeru japonicus (PiGXBS1), which is formed as the duplication of tRNA-H. The intergenic spacer between ND4 and tRNA-H, which form an obvious stem-and-loop structure, was found in all samples in this study. The phylogenetic trees generated by BI and ML indicated that Blissidae can be divided into three major clades: Clade A (only included Macropes); Clade B ((Pirkimerus + Bochrus) + Iphicrates); and Clade C ((Ischnodemus + Capodemus) + (Cavelerius + Dimorphopterus)). The divergence within the Blissidae began at about 56 Ma. At the genus level, the divergence was concentrated at 30−51 Ma, slightly later than the diversification of Poaceae. The consistency of divergence time between Blissidae and Poaceae might hint at the coevolutionary relationship between them, but further molecular and biological evidence is still needed to prove it.