Speaker
Description
Spiroplasma is a gram-positive, cell wall-less, motile bacteria found in plants and animals. In Drosophila, these maternally inheritable bacteria were first found in neotropical willistoni-group samples in the 1960s with low prevalence as a sex-ratio disorder agent. Unfortunately, these strains were lost before being studied by molecular methods. Later, Spiroplasma has been found in different Drosophila species showing various phenotypes ranging from male-killing (MK) to protection against pathogens. Still, far too little attention has been paid to Spiroplasma in neotropical Drosophila to understand long-term interactions with Spiroplasma in their hosts and associations with other symbionts. Here, we investigate both the prevalence of Spiroplasma in neotropical Drosophila populations and further their phenotypic consequences for the hosts. Firstly, we managed to detect asymptomatic Spriroplasma infections that seem almost fixed in natural populations together and without Wolbachia indicating the early introduction of symbionts in the common ancestor. This systemic Spiroplasma infection belongs to the poulsonii clade and the detection by standard PCR is limited by temperature, i.e., infection only appears when flies are exposed to elevated temperatures and thereby express partial MK phenotype. Secondly, we found previously uncovered sex-ratio disorder strains at low prevalence in D. paulistorum hosts in combination with Wolbachia. Our unexpected findings of Spiroplasma in neotropical Drosophila hosts will open a new understanding of their long-term coexistence and dynamics over evolutionary dimensions.
