Wolbachia are the most successful maternally transmitted bacteria and inhabit the cells of about half of all arthropod species. Wolbachia induce reproductive manipulations in its arthropod host to spread within species, but its interspecific spread remains poorly understood. Our understanding of how intra- and interspecific transmission feedback with Wolbachia evolution and arthropod ecology also remains severely limited. With this proposal, I will address these caveats in our understanding of the drivers of the Wolbachia pandemic using a system that is highly amenable to complementary genomic and ecological work. This novel system consists of sympatric phytophagous Bryobia spider mite species infected with a great diversity of Wolbachia that manipulate each species into a parthenogenetic mode of reproduction. Using a multidisciplinary approach, I will disentangle the frequency, mechanisms, and modulating biotic factors that allow these diverse Wolbachia to infect Bryobia spider mites across species boundaries. I will explore by comparative genomics how distinct modes of transmission feedback with Wolbachia genome evolution and will shed light on the genetic architecture of Wolbachia-induced parthenogenesis. Finally, I will address how abiotic factors such as day length and temperature determine Wolbachia spread and explain the Wolbachia diversity observed in Bryobia spider mite herbivores in nature.