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Layers of Symbiosis - Visualizing the Termite Hindgut Microbial Community
Published on: May 28, 2007
Defensive endosymbionts: a cryptic trophic level in community ecology
John Jaenike1, Thomas D Brekke
1Department of Biology, University of Rochester, Rochester, NY 14627, USA. joja@mail.rochester.edu
Ecology Letters
|December 16, 2010
Summary
Spiroplasma endosymbionts protect Drosophila flies from parasitic nematodes. In experimental fly populations, Spiroplasma spread rapidly when nematodes were present, leading to nematode extinction and protecting the fly hosts.
Area of Science:
- Insect microbiology
- Evolutionary ecology
- Symbiotic relationships
Background:
- Maternally transmitted endosymbionts are common in insects, yet their population dynamics remain poorly understood.
- Some endosymbionts offer protection against pathogens and parasites, influencing host survival and reproduction.
Purpose of the Study:
- To investigate the population dynamics of Spiroplasma, an endosymbiont of Drosophila neotestacea, in relation to its host and a parasitic nematode, Howardula aoronymphium.
- To determine the selective pressures on Spiroplasma in the presence and absence of nematode parasitism.
Main Methods:
- Experimental manipulation of Spiroplasma-infected and uninfected Drosophila neotestacea populations under controlled conditions.
- Monitoring the prevalence and spread of Spiroplasma and Howardula parasitism over time in these populations.
- Reciprocal experiments to assess the impact of Spiroplasma infection on nematode survival and vice versa.
Main Results:
- Spiroplasma rapidly spread in D. neotestacea populations exposed to Howardula parasitism.
- In the absence of Howardula, Spiroplasma showed no strong selective advantage or disadvantage.
- Howardula parasitism declined to extinction in Spiroplasma-infected fly populations.
- In uninfected fly populations, Howardula parasitism reached nearly 100% prevalence.
- Observed a correlation between the recent spread of Spiroplasma and a decline in wild Howardula prevalence.
Conclusions:
- Spiroplasma and Howardula exhibit consumer-resource dynamics, with Spiroplasma acting as a key factor in regulating nematode populations.
- The presence of Spiroplasma provides a significant advantage to Drosophila hosts by suppressing nematode parasitism.
- Findings suggest that endosymbiont-mediated protection can influence the population dynamics of both hosts and their parasites in natural ecosystems.
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