Rickettsia bacteria are found in many animals, and are sometimes spread by blood-feeding insects. But the bacteria can be found in herbivorous insects too — because, it turns out, they can be transferred between insects via plants.

Einat Zchori-Fein at the Agricultural Research Organization in Ramat-Yishay, Israel, and her colleagues found that whiteflies (Bemisia tabaci) lacking the bacteria that were kept in isolation on the same leaf as those carrying Rickettsia acquired the bacteria within days. The team also show that the bacteria are present in the leaves of plants such as cotton and basil, where they survive in the phloem cells that carry nutrients, apparently without harming the plant.

The authors suggest that plants may also mediate the transmission of other bacteria that reside within insects.

Proc. R. Soc. B 10.1098/rspb.2011.2095 (2011)