Phylogenetically distant intracellular symbionts in termites

Area of Science:

• Microbiology
• Evolutionary Biology
• Entomology

Background:

• Cockroaches harbor intracellular bacteria in specialized mycetocytes.
• These symbionts are believed to originate from a common ancestor of cockroaches and termites.
• Mycetocyte bacteria have only been observed in the termite Mastotermes darwiniensis, suggesting loss in other lineages.

Purpose of the Study:

• To investigate the distribution and identity of intracellular bacteria in termites beyond Mastotermes darwiniensis.
• To determine the phylogenetic relationship between non-mycetocyte bacteria in termites and known mycetocyte symbionts.

Main Methods:

• Electron microscopy was used to examine intracellular bacteria in nine termite species.
• 16S rRNA gene sequence analysis was performed to identify bacterial groups.
• Polymerase Chain Reaction (PCR) assays with specific primers were employed for confirmation.

Main Results:

• Non-mycetocyte intracellular bacteria were found to be widespread across the examined termite species.
• Sequence analysis revealed these bacteria belong to the Wolbachia group (alpha-2 subclass of proteobacteria).
• The identified termite Wolbachia are phylogenetically distinct from the Blattabacterium group found in cockroaches and M. darwiniensis.

Conclusions:

• Intracellular bacteria, specifically Wolbachia, are prevalent in a diverse range of termite species.
• These findings indicate a separate evolutionary trajectory for intracellular bacteria in termites compared to cockroaches.
• The study highlights the potential for diverse bacterial endosymbionts within insect taxa.