<p align="center"><strong>A review of prevalence and phylogeny of the bacterial symbiont <em>Cardinium</em> in mites (subclass: Acari)</strong></p>

Abstract

Many species of mites are of agricultural and veterinary importance to human. The bacterial symbiont Cardinium is assumed to be widespread and involved in manipulating its mite host's reproduction. We investigated Cardinium infections in phylogenetically diverse mite species based on published data. Cardinium was reported in 45 mite species, representing 3 orders and 14 families. Some Cardinium strains can influence their mite hosts' reproduction via two strategies: cytoplasmic incompatibility and feminization. The phylogeny of the examined mites was well resolved based on the 18S rRNA gene, whereas Cardinium phylogeny was not completely concordant with its associated host phylogeny, raising the possibility that horizontal transmission of Cardinium has occurred among species. In addition, Cardinium phylogeny was associated with the ecology of the hosts. Cardinium cooperating with other endosymbionts influences the ecology and evolution of its host.

Comparative Genomics of Wolbachia–Cardinium Dual Endosymbiosis in a Plant-Parasitic Nematode

“…In theory, obligate mutualism could lead to 100% prevalence, but this is not known in Cardinium . Instead, high prevalence may be a sign of strong reproductive parasitism: CI and high Cardinium prevalence have been observed in spider mites ( Gotoh et al, 2007 ; Kopecky et al, 2013 ; Zhao et al, 2013 ; Zhang et al, 2016a ; Zhu et al, 2018 ) and Encarsia wasps ( Hunter et al, 2003 ; Zchori-Fein et al, 2004 ; Zchori-Fein and Perlman, 2004 ; Perlman et al, 2008 ; White et al, 2011 ; Gebiola et al, 2017 ; Mann et al, 2017 ).…”

“…Wolbachia pipientis (α-proteobacteria) and Cardinium hertigii (Bacteroidetes) (hereafter denoted Wolbachia and Cardinium ) are among the most widespread endosymbionts in animals, co-occurring extensively ( Gotoh et al, 2007 ; Nakamura et al, 2009 , 2012 ; White et al, 2011 , 2009 ; Ros et al, 2012 ; Zhao et al, 2013 ; Mee et al, 2015 ; Zhang et al, 2016a ; Nguyen et al, 2017 ; Zélé et al, 2018 ). Their effects on host biology make these endosymbionts a major focus in studies of biocontrol, especially for their independently acquired phenotype known as cytoplasmic incompatibility (CI), in which infected males mating with uninfected females fail to produce viable offspring, therein increasing the relative success of the maternally inherited endosymbionts.…”

Detection and characterization of bacterial endosymbionts in Southeast Asian tephritid fruit fly populations

“…On the other hand, members of Arsenophonus, of the Gammaproteobacteria, and Spiroplasma, wall-less bacteria belonging to the class Mollicutes, are known to induce male-killing phenotypes [1,17,[30][31][32]. The incidence rate of all three genera in insects was shown to vary between 4 and 14%, fairly lower than that of Wolbachia [1,[33][34][35][36][37][38][39], although higher occurrence was observed for Arsenophonus in aphids and ants, reaching up to 30 and 37.5% of species respectively [40,41] as well as for Cardinium in planthoppers (47.4% of species) [36]. In Cardinium and Spiroplasma-infected species a wide range of prevalence (15-85%) was observed while in the case of Arsenophonus, prevalence reached values above 75% with relatively few exceptions, such as the wasp Nasonia vitripennis with a 4% infection rate or various ant species that showed a broader range (14-66%) [1,38,40,42].…”

“…The remaining closely related Entomoplasmatales genera, Mycoplasma, Entomoplasma and Mesoplasma, form the separate Mycoides-Entomoplasmataceae clade [76]. Phylogenetic analyses for Cardinium are performed with the use of the 16S rRNA and gyrB genes but also with the amino acid sequence of Gyrase B (gyrB gene) [35,36,[78][79][80]. Cardinium strains can be separated into group A, which infect wasps, planthoppers, mites and other arthropods, group B, found in parasitic nematodes and group C in biting midges [36].…”

Wolbachia and Cardinium infection found in threatened unionid species: a new concern for conservation of freshwater mussels?

“…Infections of endosymbiotic microorganisms have been detected in many invertebrates, but they are most widespread in the arthropods, the largest of the Animal phyla on Earth, especially in terrestrial insects (Ma and Schwander 2017) and mites (Zhang et al 2016). The obvious question arises about their presence in molluscs, the second largest phylum among Animalia.…”