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Updated: Aug 17, 2026
Systemic Bacterial Infection and Immune Defense Phenotypes in Drosophila Melanogaster
Published on: May 13, 2015
Male-killing Spiroplasma naturally infecting Drosophila melanogaster
H Montenegro1, V N Solferini, L B Klaczko
1Departamento Genética e Evolução, Instituto de Biologia, Universidade Estadual de Campinas, SP, Brazil. h.montenegro@gmail.com
Abstract:
Elucidation of the mechanism of action of selfish genetic elements is difficult outside species with well-defined genetics. Male-killing, the phenomenon whereby inherited bacteria kill male hosts during embryogenesis, is thus uncharacterized in mechanistic terms despite being common and important in insects. We characterized the prevalence, identity and source of the male-killing infection recently discovered in Drosophila melanogaster in Brazil. Male-killing was found to be present in 2.3% of flies from Recife, Brazil, and was uniquely associated with the presence of Spiroplasma infection. The identity of sequences across part of the 16S and across the 16S-23S ITS region indicated that the male-killing infection of D. melanogaster was very closely related to S. poulsonii, the source of the male-killing infection in willistoni group flies also found in South America. The sequences of two further protein-coding genes indicated the D. melanogaster infection to be most closely related to that found in D. nebulosa, from the willistoni group. Our data suggest that the establishment of D. melanogaster in South America was associated with the movement of male-killing bacteria between species.
Insights
A newly discovered male-killing Spiroplasma infection in Drosophila melanogaster flies in Brazil was identified. This selfish genetic element is closely related to bacteria found in other fly species, suggesting inter-species transmission.
Area of Science:
- Microbiology
- Genetics
- Evolutionary Biology
Background:
- Male-killing bacteria are selfish genetic elements that kill male hosts during embryogenesis.
- The mechanistic basis of male-killing remains poorly understood, especially in insects lacking well-defined genetic systems.
- This phenomenon is common and ecologically significant in insect populations.
Purpose of the Study:
- To characterize the prevalence, identity, and origin of a recently identified male-killing Spiroplasma infection in Drosophila melanogaster in Brazil.
- To investigate the evolutionary relationship of this Spiroplasma strain with known male-killing agents in other Drosophila species.
- To explore the potential for inter-species transmission of male-killing bacteria.
Main Methods:
- Prevalence assessment of male-killing in Drosophila melanogaster populations in Recife, Brazil.
- Molecular identification of the Spiroplasma infection using 16S rRNA and 16S-23S Internal Transcribed Spacer (ITS) region sequencing.
- Phylogenetic analysis based on sequences of two additional protein-coding genes.
Main Results:
- Male-killing was detected in 2.3% of Drosophila melanogaster flies sampled in Recife, Brazil.
- The infection was exclusively associated with Spiroplasma, identified as closely related to Spiroplasma poulsonii.
- Phylogenetic analyses indicated the Spiroplasma strain is most closely related to those found in Drosophila nebulosa and other willistoni group flies.
Conclusions:
- The male-killing Spiroplasma infection in Brazilian Drosophila melanogaster is closely related to strains found in other South American flies.
- The findings suggest that the establishment of Drosophila melanogaster in South America was linked to the movement of male-killing bacteria between fly species.
- This study provides insights into the transmission dynamics and evolutionary history of selfish genetic elements in insects.
