chapter  5
24 Pages

Stammerula and Other Symbiotic Bacteria within the Fruit Flies Inhabiting Asteraceae Flowerheads

Introduction ..............................................................................................................90 The Subfamily Tephritinae ....................................................................................... 91 The Discovery of Symbiotic Bacteria in the Subfamily Tephritinae and in Other Tephritid Flies ................................................................................................ 91 The Esophageal Bulb in Tephritinae and in the Other Tephritid Flies .....................92 Midgut Bacterial Symbiosis in the Tephritinae Subfamily ......................................97 Mechanism of Vertical Transmission of the Symbiont ............................................98 Detection of Symbionts in Tephritinae Flies .......................................................... 100

Laboratory Handling of the Flies ...................................................................... 100 Rearing under Microbiologically Controlled Conditions ................................. 101 Insect Dissection ............................................................................................... 103 Attempts to Culture Ex Situ Symbionts of Tephritinae Have Failed So Far ..... 103 SpeciŒcity of the Bacterial Nucleotide Sequence ............................................. 104 Can Bacterial SpeciŒcity Become a Tool to Detect Groups of Sibling Species? ............................................................................................................. 104

Phylogenetic Position of the Symbiotic Bacteria ................................................... 104 Proposal of “Candidatus Stammerula tephritidis” ................................................. 107 Rates of Evolution .................................................................................................. 107 Considerations around the Symbiosis .................................................................... 108 Conclusions and Perspectives ................................................................................ 108 Acknowledgments .................................................................................................. 109 References .............................................................................................................. 109

The many instances of associations between insects and microorganisms observed in nature have long since stimulated the curiosity of scientists. In the past, such studies mostly relied upon microscopy to deŒne the morphohistological features of symbiotic organs and describe the bacteria hosted within. Indeed, many insect-microbe associations were covered in Buchner’s renowned treatise (Buchner 1965). However, as most of the prokaryotic microsymbionts are not culturable ex situ, their characterization and taxonomical placement has had to wait until the advent of biomolecular techniques that have enabled 16S rRNA-based taxonomy via gene ampliŒcation and sequencing.