Mtgenomes of Culex tritaeniorhynchus and Cx. pipiens pallens with Emphasis on Comparitive Mtgenome Analysis of Culex Species (Diptera: Culicidae)

The characteristics and evolution of mitochondrial genomes (mtgenome) in the genus Culex has little been known. Culex tritaeniorhynchus and Cx. pipiens pallens are the major vectors of the Japanese encephalitis virus and Wuchereria bancrofti, the causative agent of filariasis. This study aims to sequence the mtgenomes of these two species and make basic understanding of the characteristics of mtgenomes in the genus Culex.

In this study, we sequenced and annotated the mtgenomes of Cx. tritaeniorhynchus and Cx. p. pallens, and performed a comparative analysis including four known mtgenomes of species in the subgenus Culex (Culex). Based on concatenated protein-coding gene sequences, the evolutionary connections of Cx. tritaeniorhynchus, Cx. p. pallens, and four known Culex mtgenome sequences were reconstructed. Culex tritaeniorhynchus and Cx. p. pallens mtgenomes are 14,844 bp and 15,617 bp long, both consists of 13 PCGs, 22 tRNAs, 2 rRNAs and 1 CR (not sequenced for Cx. tritaeniorhynchus). Analysis of phylogenetic data showed that the mtgenome of Cx. tritaeniorhynchus was significantly separated from the remaining five mtgenomes of Culex spp. Culex p. pipiens, Cx. p. pallens and Cx. p. quinquefasciatus formed a monophyletic clade with Cx. p. quinquefasciatus linked in the middle of the clade, and Cx. p. pallens should have the same taxonomic level as Culex p. pipiens and Cx. p. quinquefasciatus.

Cx. tritaeniorhynchus and Cx. p. pallens mtgenomes have the same gene makeup and order as two other Culex species. Culex p. pallens of the Pipiens complex should be classified at the same level as Culex p. pipiens and Cx. p. quinquefasciatus. We enhanced the Culex mtgenome data and established a foundation for future Culex mtgenome sequencing and analysis.