AUTHOR=Liu Yuan , He Zi-Qi , Wen Qin , Peng Jing , Zhou Yu-Tong , Mandour Nasser , McKenzie Cindy L. , Ahmed Muhammad Z. , Qiu Bao-Li TITLE=Parasitoid-mediated horizontal transmission of Rickettsia between whiteflies JOURNAL=Frontiers in Cellular and Infection Microbiology VOLUME=Volume 12 - 2022 YEAR=2023 URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2022.1077494 DOI=10.3389/fcimb.2022.1077494 ISSN=2235-2988 ABSTRACT=Intracellular bacterial endosymbionts of arthropods are mainly transmitted vertically from mother to offspring, but phylogenetically distant insect hosts often harbor identical endosymbionts, indicating that horizontal transmission from one species to another occurs in nature. Here we investigated the parasitoid Encarsia formosa- mediated horizontal transmission of the endosymbiont, Rickettsia between different populations of whitefly Bemisia tabaci MEAM1. Rickettsia was successfully transmitted from the positive MEAM1 nymphs (R+) into E. formosa and retained at least for 48 h in E. formosa adults. FISH visualization results revealed that the ovipositors, mouthparts and digestive tract of parasitoid adults get contaminated with Rickettsia. Randomly occurred non-lethal probing of Rickettisia negaive (R-) MEAM1 nymphs by these Rickettsia-carrying E. formosa resulted in newly infected MEAM1nymphs, and the vertical transmission of Rickettsia within the recipient feamles can be remained at least up to F3 generation. Further phylogenetic analyses revealed that Rickettsia had high fidelity during the horizontal transmission in whiteflies and parasitoids. Our findings may help to explain why Rickettsia bacteria are so abundant in arthropods, and suggest that in some insect species that shared same parasitoids, Rickettsia may be maintained in populations by horizontal transmission.