Role of bacterial endosymbionts in asexual reproduction of two bark lice species, Echmepteryx hageni and Peripsocus subfasciatus (Psocoptera)

We have previously investigated the genetic structure of two bark lice species, Echmepteryx hageni and Peripsocus subfasciatus. Each of these species is predominantly asexual, but also has isolated sexual populations. However, asexual reproduction can arise through several different mechanisms, which may have different genetic consequences. In order to understand the evolution of reproductive mode of the two species, it is first necessary to determine the mechanistic origin of asexuality in each. A common basis of asexual reproduction in insects is infection by a parthenogenesis-inducing bacterial endosymbiont, Wolbachia, Rickettsia, and Cardinium being the most well-known. Reciprocal best BLAST searches of EST databases of each species found evidence for Wolbachia infection in E. hageni, but no evidence of an endosymbiont infection in P. subfasciatus. This pattern of infection was confirmed via PCR screening. Evidence for the role of Wolbachia as parthenogenesis-inducing rather than parthenogenesis-associated will be strengthened by consistently recovering Wolbachia from asexual E. hageni and not from sexuals. This study is the first investigation of parthenogenesis-inducing endosymbionts in bark lice with both sexual and asexual forms.