Wolbachia–induced parthenogenesis in a genus of phytophagous mites

Abstract

The vertically transmitted endosymbiotic bacterium Wolbachia modifies host reproduction in several ways in order to enhance its own spread. One such modification results in the induction of parthenogenesis, where males, which are unable to transmit Wolbachia, are not produced. Interestingly, parthenogenesis-inducing Wolbachia have only been found within haplodiploid insects and it is not known whether this exclusivity is the result of functional constraints of Wolbachia. Here we find a unique pattern of Wolbachia infection that is associated with parthenogenesis in six species within the phytophagous mite genus Bryobia. Through antibiotic treatment we show that, in two species, Bryobia praetiosa and an unidentified species, the Wolbachia infection is strictly associated with parthenogenesis. Microsatellite loci show the mechanism of parthenogenesis to be functionally apomictic and not gamete duplication, with progeny identical to their infected mother. Crossing experiments within B. praetiosa showed no evidence of sexual reproduction. These results are discussed with reference to the distribution of parthenogenesis-inducing Wolbachia and the diversification of the Bryobia genus.