Present address: Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA.
Defensive endosymbionts: a cryptic trophic level in community ecology
Article first published online: 13 DEC 2010
© 2010 Blackwell Publishing Ltd/CNRS
Volume 14, Issue 2, pages 150–155, February 2011
How to Cite
Jaenike, J. and Brekke, T. D. (2011), Defensive endosymbionts: a cryptic trophic level in community ecology. Ecology Letters, 14: 150–155. doi: 10.1111/j.1461-0248.2010.01564.x
- Issue published online: 24 JAN 2011
- Article first published online: 13 DEC 2010
- Editor, Jacob Koella Manuscript received 24 September 2010 First decision made 31 October 2010 Manuscript accepted 4 November 2010
- Drosophila neotestacea;
- host-parasite dynamics;
- trophic cascades
Ecology Letters (2011) 14: 150–155
Maternally transmitted endosymbionts are widespread among insects, but how they are maintained within host populations is largely unknown. Recent discoveries show that some endosymbionts protect their hosts from pathogens or parasites. Spiroplasma, an endosymbiont of Drosophila neotestacea, protects female hosts from the sterilizing effects of parasitism by the nematode Howardula aoronymphium. Here, we show that Spiroplasma spreads rapidly within experimental populations of D. neotestacea subject to Howardula parasitism, but is neither strongly favored nor selected against in the absence of Howardula. In a reciprocal experiment, Howardula declined steadily to extinction in populations of Spiroplasma-infected flies, whereas in populations of uninfected flies, the prevalence of Howardula parasitism increased to c. 100%. Thus, Spiroplasma and Howardula exhibit effectively consumer-resource trophic dynamics. The recent spread of Spiroplasma in natural populations of D. neotestacea coincides with a decline in the prevalence of Howardula parasitism in the wild.