Ahmed, Muhammad ZaheerudinLi, Shao-JianXue, XiaYin, Xiang-JieRen, Shun-XiangJiggins, Francis M.Greeff, Jacobus MareeQiu, Bao-Li2015-03-242015-03-242015-02Ahmed MZ, Li S-J, Xue X, Yin X-J, Ren Shun-Xiang, Jiggins FM, et al. (2015) The Intracellular Bacterium Wolbachia Uses Parasitoid Wasps as Phoretic Vectors for Efficient Horizontal Transmission. PLoS Pathog 11(2): e1004672 doi:10.1371/journal.ppat.10046721553-7366 (print)1553-7374 (online)10.1371/journal.ppat.1004672http://hdl.handle.net/2263/44138Facultative bacterial endosymbionts are associated with many arthropods and are primarily transmitted vertically from mother to offspring. However, phylogenetic affiliations suggest that horizontal transmission must also occur. Such horizontal transfer can have important biological and agricultural consequences when endosymbionts increase host fitness. So far horizontal transmission is considered rare and has been difficult to document. Here, we use fluorescence in situ hybridization (FISH) and multi locus sequence typing (MLST) to reveal a potentially common pathway of horizontal transmission of endosymbionts via parasitoids of insects. We illustrate that the mouthparts and ovipositors of an aphelinid parasitoid become contaminated with Wolbachia when this wasp feeds on or probes Wolbachia-infected Bemisia tabaci AsiaII7, and non-lethal probing of uninfected B. tabaci AsiaII7 nymphs by parasitoids carrying Wolbachia resulted in newly and stably infected B. tabaci matrilines. After they were exposed to infected whitefly, the parasitoids were able to transmit Wolbachia efficiently for the following 48 h. Whitefly infected with Wolbachia by parasitoids had increased survival and reduced development times. Overall, our study provides evidence for the horizontal transmission of Wolbachia between insect hosts by parasitic wasps, and the enhanced survival and reproductive abilities of insect hosts may adversely affect biological control programs.en© 2015 Ahmed et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Parasitoid waspsPhoretic vectorsFluorescence in situ hybridization (FISH)Multi locus sequence typing (MLST)Horizontal transmissionEndosymbiontsWolbachiaVector-borne transmissionArticle