Original Article

Heredity (2004) 93, 78–84, advance online publication 12 May 2004; doi:10.1038/sj.hdy.6800482

Evidence for a new feminizing Wolbachia strain in the isopod Armadillidium vulgare: evolutionary implications

R Cordaux1,3, A Michel-Salzat1,4, M Frelon-Raimond1, T Rigaud2 and D Bouchon1

  1. 1Laboratoire de Génétique et Biologie des Populations de Crustacés, UMR CNRS 6556, Université de Poitiers, 40 Avenue du Recteur Pineau, F-86022 Poitiers Cedex, France
  2. 2Equipe Ecologie Evolutive, UMR 5561 BioGéosciences, Université de Bourgogne, 6 Boulevard Gabriel, 21000 Dijon, France

Correspondence: D Bouchon, Laboratoire de Génétique et Biologie des Populations de Crustacés, UMR CNRS 6556, Université de Poitiers, 40 Avenue du Recteur Pineau, F-86022 Poitiers Cedex, France. E-mail: didier.bouchon@univ-poitiers.fr

3Current address: Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.

4Current address: Department of Entomology, University of Illinois, Urbana-Champaign, USA.

Received 8 April 2003; Accepted 10 October 2003; Published online 12 May 2004.

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Abstract

Wolbachia are intracellular maternally inherited alpha-Proteobacteria infecting a wide range of arthropods. In the common pill bug Armadillidium vulgare, the known Wolbachia strain is responsible for feminization of genetic males. We have investigated Wolbachia diversity in 20 populations of A. vulgare from west and east Europe, north Africa and north America. A new Wolbachia strain (wVulM) was identified through the variability of the wsp gene, distantly related to that previously known (wVulC) in this host species. No individual with multiple infections was detected. Inoculation experiments indicated that the new wVulM bacterial strain also induces feminization in A. vulgare. However, the wVulC strain showed a higher transmission rate than the wVulM strain and was the most geographically widespread Wolbachia in A. vulgare populations. Mitochondrial 16SrDNA gene sequencing was conducted in Wolbachia-infected individuals, revealing the occurrence of four host lineages. The comparison of bacterial strains and their respective host mitochondrial phylogenies failed to show concordance, indicating horizontal transmission of the Wolbachia strains within populations of A. vulgare.

Keywords:

Wolbachia, Armadillidium vulgare, feminization, horizontal transmission