Trichogramma pretiosum whole-genome transcriptome and bisulfite sequencing.

Wolbachia are maternally transmitted intracellular symbiotic bacteria that induce a range of pathogenic and fitness-enhancing effects on insect and nematode hosts. In the tiny parasitoid wasps of the genus Trichogramma, Wolbachia exploits the haplodiploid sex determination system of the wasp host to make female offspring, thus increasing Wolbachia transmission. Wolbachia induces parthenogenesis by converting haploid, unfertilized eggs (which would normally develop into males) to diploid eggs that then develop into females. Over time, infected Trichogramma can become dependent on their resident Wolbachia for the production of female offspring. The genetic basis of this so-called gamete duplication and subsequent conversion to asexual reproduction is unknown. An interesting hypothesis posited by studies in other insects is host epigenome reprogramming by Wolbachia. Our study represents the first steps towards identifying the genetics basis of symbiont-mediated asexuality in this sytem.