Horizontal transmission of the insect symbiont Rickettsia is plant-mediated

Ayelet Caspi-Fluger, Moshe Inbar, Netta Mozes-Daube, Nurit Katzir, Vitaly Portnoy, Eduard Belausov, Martha S. Hunter, Einat Zchori-Fein

Research output: Contribution to journalArticlepeer-review


Bacteria in the genus Rickettsia, best known as vertebrate pathogens vectored by blood-feeding arthropods, can also be found in phytophagous insects. The presence of closely related bacterial symbionts in evolutionarily distant arthropod hosts presupposes a means of horizontal transmission, but no mechanism for this transmission has been described. Using a combination of experiments with live insects, molecular analyses and microscopy, we found that Rickettsia were transferred from an insect host (the whitefly Bemisia tabaci) to a plant, moved inside the phloem, and could be acquired by other whiteflies. In one experiment, Rickettsia was transferred from the whitefly host to leaves of cotton, basil and black nightshade, where the bacteria were restricted to the phloem cells of the plant. In another experiment, Rickettsia-free adult whiteflies, physically segregated but sharing a cotton leaf with Rickettsia-plus individuals, acquired the Rickettsia at a high rate. Plants can serve as a reservoir for horizontal transmission of Rickettsia, a mechanism which may explain the occurrence of phylogenetically similar symbionts among unrelated phytophagous insect species. This plant-mediated transmission route may also exist in other insect-symbiont systems and, since symbionts may play a critical role in the ecology and evolution of their hosts, serve as an immediate and powerful tool for accelerated evolution.

Original languageEnglish
Pages (from-to)1791-1796
Number of pages6
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1734
StatePublished - 7 May 2012


  • Aleyrodidae
  • Bacteriocyte
  • Bemisia tabaci
  • Horizontal transfer
  • Whiteflies

ASJC Scopus subject areas

  • General Agricultural and Biological Sciences
  • General Environmental Science
  • General Biochemistry, Genetics and Molecular Biology
  • General Immunology and Microbiology


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