Investigating Strength of Cytoplasmic Incompatibility and Rate of Maternal Transmission in Zaprionus tsacasi by Infection of Wolbachia wZts

Animals associate with diverse microbes that affect their health and fitness. Many insects and other species host microbes termed endosymbionts inside their cells. Among all endosymbionts, Wolbachia bacteria are the most common, occurring in about half of all insect species. Wolbachia are maternally transmitted – similar to our own mitochondria – and many variants have evolved the capacity to affect host reproduction to favor their transmission across host generations. This includes variants that cause cytoplasmic incompatibility (CI) that kills embryos without Wolbachia fertilized by males with Wolbachia. Here, I assess the strength of CI and rates of maternal transmission of a newly discovered Wolbachia (wZts) found in Zaprionus tsacasi flies sampled from west Africa. wZts is the closest known relative of model virus-blocking wMel Wolbachia first discovered in Drosophila melanogaster flies. wMel causes weak CI that depends on male age in D. melanogaster, but causes strong CI when transinfected into Aedes aegypti mosquitoes that transmit human diseases in the tropics. Once initially established in Ae. aegypti, CI assists with maintaining wMel at high frequencies, where it blocks dengue transmission. I demonstrate that like wMel in D. melanogaster, wZts causes CI that declines with male age—I also demonstrate that Z. tsacasi transmits wZts to ~67% of its male offspring. I discuss my results in the context of existing data and future work that will provide insight into leveraging this tropical variant for improving Wolbachia biocontrol of human diseases in the tropics.