Assistant Professor University of Minnesota Saint Paul, Minnesota
Bacteria in the genus Wolbachia have evolved numerous strategies to manipulate arthropod sex and reproduction, including converting would-be males to females. One form of this reproductive parasitism, so-called “parthenogenesis-induction”, can be found in some Wolbachia strains infecting arthropods with haplodiploid sex-determination. This male-to-female switch and subsequent transition to completely asexual reproduction is highly advantageous for Wolbachia as a maternally transmitted microbe. Despite the discovery of Wolbachia-mediated asexual reproduction more than 30 years ago, the underlying genetic mechanisms have since remained elusive. We used a suite of genomic, computational, and molecular tools to identify and characterize two Wolbachia proteins that we predict mediate the transition to asexuality in two parasitoid wasp species: Trichogramma pretiosum and Leptopilina clavipes. Our data support a model whereby these proteins (1) cause a specific mitotic disruption in haploid embryos to restore diploidy, and, (2) interact with the sex determination cascade to override the male-destined patterning normally present in haploid embryos. The transition in reproductive mode has vast consequences for the evolutionary dynamics of the insect, and our data indicate this is made possible by a novel mechanism of bacterial-host interaction.