Mitochondrial phylogenomics provides insights into the taxonomy and phylogeny of fleas

Abstract

Background Fleas (Insecta: Siphonaptera) are obligatory hematophagous ectoparasites of humans and animals and serve as vectors of many disease-causing agents. Despite past and current research efforts on fleas due to their medical and veterinary importance, correct identification and robust phylogenetic analysis of these ectoparasites have often proved challenging. Methods We decoded the complete mitochondrial (mt) genome of the human flea Pulex irritans and nearly complete mt genome of the dog flea Ctenocephalides canis, and subsequently used this information to reconstruct the phylogeny of fleas among Endopterygota insects. Results The complete mt genome of P. irritans was 20,337 bp, whereas the clearly sequenced coding region of the C. canis mt genome was 15,609 bp. Both mt genomes were found to contain 37 genes, including 13 protein-coding genes, 22 transfer RNA genes and two ribosomal RNA genes. The coding region of the C. canis mt genome was only 93.5% identical to that of the cat flea C. felis, unequivocally confirming that they are distinct species. Our phylogenomic analyses of the mt genomes showed a sister relationship between the order Siphonaptera and orders Diptera + Mecoptera + Megaloptera + Neuroptera and positively support the hypothesis that the fleas in the order Siphonaptera are monophyletic. Conclusions Our results demonstrate that the mt genomes of P. irritans and C. canis are different. The phylogenetic tree shows that fleas are monophyletic and strongly support an order-level objective. These mt genomes provide novel molecular markers for studying the taxonomy and phylogeny of fleas in the future.

Metagenomics of culture isolates and insect tissue illuminate the evolution ofWolbachia,RickettsiaandBartonellasymbionts inCtenocephalidesspp. fleas

“…No information available regarding the sequencing technology used for the smaller C. felis assembly (MK941844) is available, but it was likely produced by a short-read method. For the single published C. canis mitogenomic assembly, the authors reported that the AT-loop region was incomplete, so the short control region is an artefact [90]. However, we achieved full resolution of the long control region in C. orientis , as some of the raw Nanopore reads spanned its entirety.…”

“…S10a). We compared this assembly to the C. felis EL2017-DRISC mitogenome and a partial assembly of the C. canis mitogenome from China [90], which lacks most of the AT-rich control region (Fig. 11a).…”

Metagenomics of culture isolates and insect tissue illuminate the evolution of Wolbachia, Rickettsia and Bartonella symbionts in Ctenocephalides spp. fleas

“…No information available regarding the sequencing technology used for the smaller C. felis assembly (MK941844) is available, but it was probably produced by a short-read method. For the single published C. canis mitogenomic assembly, the authors reported that the AT-loop region was incomplete, so the short control region is an artefact [102]. However, we achieved full resolution of the long control region in C. orientis , as some of the raw nanopore reads spanned its entirety.…”

“…S10a). We compared this assembly to the C. felis EL2017-DRISC mitogenome and a partial assembly of the C. canis mitogenome from China [102], which lacks most of the AT-rich control region (). The three mitogenomes were highly similar to each other, with an extended control region apparent in C. orientis compared with C. felis EL2017-DRISC.…”

“…S10a). We compared this assembly to the C. felis EL2017-DRISC mitogenome and a partial assembly of the C. canis mitogenome from China [102], which lacks most of the AT-rich control region (Fig. 10a).…”