Synchrotron X-ray micro-computed tomography as a tool for in situ elucidation of insect bacteriomes

• The bacteriomes of the leafhopper Orosius albicinctus were studied.
• The bacteriome was mushroom-like with a cap and stem and consisting of two different tissues.
• The primary symbiotic bacteria, Sulcia muelleri was found in the cap of the organ.
• X-ray micro-computed tomography allowed the 3D reconstruction of the bacteriome.

Obligate bacterial endosymbionts are common, influential associates of arthropods, and are often found in specific organs termed bacteriomes. Three dimensional images of bacteriomes of the leafhopper Orosius albicinctus (Hemiptera: Cicadellidae) were reconstructed from synchrotron-based X-ray micro-computed tomography (CT). Results show that bilateral bacteriomes are located between the first and second abdominal tergites, are mushroom-shaped and consist two different types of tissue. Fluorescence in situ hybridization reveals that the primary bacterial symbiont Sulcia muelleri is in the ‘cap’ part of the of organ. The technique allows a noninvasive, in situ, means of visualizing bacteriomes and will facilitate understanding their form and function.