Infections with the MicrobeCardiniumin the Dolichopodidae and Other Empidoidea

Abstract

Maternally transmitted reproductive parasites such as Wolbachia and Cardinium can drastically reshape reproduction in their hosts. Beyond skewing sex ratios towards females, these microbes can also cause cytoplasmic incompatibility. Wolbachia probably infects two thirds of insects, but far less is known about the occurrence or action of other bacteria with potentially similar effects. In contrast with the two more widespread reproductive parasites, Wolbachia and Spiroplasma, far less is known of infections with Cardinium (Bacteroidetes) and possible consequences in the Diptera. Here, in an extensive survey, 244 dipteran species from 67 genera belonging to the Dolichopodidae, Empididae, and Hybotidae were assessed for the presence of the microbe Cardinium. Although 130 of the species screened tested positive (ca. 53%), the presence of Cardinium could only be confirmed in 10 species (ca. 4%) based on analysis of sequences. Numerous additional sequences were found to be assignable to known or unknown Bacteroidetes.Considering the known issues concerning specificity of Cardinium primers and the phylogenetic uncertainties surrounding this microbe, the actual prevalence of this symbiont is worthy of further scrutiny. Potential directions for future research on Cardinium-host interactions in Diptera and in general are discussed.

Are sex ratio distorting endosymbionts responsible for mating system variation among dance flies (Diptera: Empidinae)?

“…We also did not test for all known symbiont taxa (e.g. Flavobacteria species [ 49 ] and Cardinium [ 50 ]) and instead limited our study to a subset of the sex ratio distorting symbionts. It therefore remains possible that other sex ratio distorting symbionts may infect these dance fly species.…”

A screen for bacterial endosymbionts in the model organisms Tribolium castaneum, T. confusum, Callosobruchus maculatus, and related species

“…70 species; Martin et al ., ), and the Dolichopodidae and other Empidoidea (ca. 240 species; Martin et al ., ,b). Although Wolbachia infected flies more commonly, infections with Spiroplasma , Rickettsia , and Cardinium were also found (Martin et al ., , ,b).…”

“…240 species; Martin et al ., ,b). Although Wolbachia infected flies more commonly, infections with Spiroplasma , Rickettsia , and Cardinium were also found (Martin et al ., , ,b). There is extensive evidence for both Wolbachia and Spiroplasma causing differences in host reproduction, including in Diptera (Duron et al ., ).…”

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

“…Populations infected with Cardinium originated only from subtropical regions and harbored either medium or low prevalence infections. Previously, 244 species of flies belonging to the Empidoidea (Order: Diptera), which consists of four families such as the long-legged flies (Family: Dolichopodidae) and the dance flies (Family: Hybotidae), were found to contain Cardinium infections in only ten species, with an incidence rate of 4% [28]. A similar study in various arthropods did not identify any Cardinium sequences in the seven families of Diptera studied [33] while laboratory populations of various Bactrocera species were also free of Cardinium infections [95].…”

“…Apart from Wolbachia, additional reproductive symbionts from distantly related bacterial genera have been recently brought to light, such as Arsenophonus, Cardinium and Spiroplasma. Strains belonging to the genus Cardinium, a member of the phylum Cytophaga-Flavobacterium-Bacteroides (CFB), exhibit the same broad range of reproductive alterations with Wolbachia [23][24][25][26][27][28][29], with the exception of male-killing which has not been identified yet [1,17,28]. 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].…”