Intra-Individual Coexistence of a Wolbachia Strain Required for Host Oogenesis With Two Strains Inducing Cytoplasmic Incompatibility in the Wasp Asobara Tabida

Abstract

Abstract. Cytoplasmically inherited symbiotic Wolbachia bacteria are known to induce a diversity of phenotypes on their numerous arthropod hosts including cytoplasmic incompatibility, male-killing, thelytokous parthenogenesis, and feminization. In the wasp Asobara tabida (Braconidae), in which all individuals harbor three genotypic Wolbachia strains (wAtab1, wAtab2 and wAtab3), the presence of Wolbachia is required for insect oogenesis. To elucidate the phenotype of each Wolbachia strain on host reproduction, especially on oogenesis, we established lines of A. tabida harboring different combinations of these three bacterial strains. We found that wAtab3 is essential for wasp oogenesis, whereas the two other strains, wAtab1 and wAtab2, seem incapable to act on this function. Furthermore, interline crosses showed that strains wAtab1 and wAtab2 induce partial (about 78%) cytoplasmic incompatibility of the female mortality type. These results support the idea that bacterial genotype is a major factor determining the phenotype induced by Wolbachia on A. tabida hosts. We discuss the implications of these findings for current hypotheses regarding the evolutionary mechanisms by which females of A. tabida have become dependent on Wolbachia for oogenesis.

Wolbachia Symbiosis in Arthropods

“…It is however only one of the three that is obligatory for successful oogenesis. The other two Wolbachia types are able to induce CI [119]. Not only is this system remarkably similar to that seen with Sxl in Drosophila [113], it is also similar to effects seen with Wolbachia infections in filarial nematodes [120].…”

Influence of Wolbachia on host gene expression in an obligatory symbiosis

“…A. tabida is naturally infected by three strains of the intracellular bacterium Wolbachia ( w Atab1, w Atab2 and w Atab3): w Atab1 and w Atab2 induce cytoplasmic incompatibility, and only w Atab3 is required for oogenesis completion [6,25]. …”

“…In this study, we used the NA strain and a Pi-derived strain (Pi3). Pi3 was obtained by moderate antibiotic treatment, and contains only the obligatory Wolbachia strain w Atab3 [25]. The lines are stable, and have been maintained by regular sib-matings without antibiotic treatment for about 100 generations.…”

SNP calling from RNA-seq data without a reference genome: identification, quantification, differential analysis and impact on the protein sequence

“…A. tabida is naturally infected by three strains of Wolbachia , among which one (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$w$\end{document}Atab3) is necessary for oogenesis completion (32,33). However, when Wolbachia are removed by antibiotic treatment, the degree of oogenetic defect exhibits genetic variation within populations (34).…”