Fitness costs of symbiont switching using entomopathogenic nematodes as a model

John G. McMullen, Brittany F. Peterson, Steven Forst, Heidi Goodrich Blair, S. Patricia Stock

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Background: Steinernematid nematodes form obligate symbioses with bacteria from the genus Xenorhabdus. Together Steinernema nematodes and their bacterial symbionts successfully infect, kill, utilize, and exit their insect hosts. During this process the nematodes and bacteria disassociate requiring them to re-associate before emerging from the host. This interaction can be complicated when two different nematodes co-infect an insect host. Results: Non-cognate nematode-bacteria pairings result in reductions for multiple measures of success, including total progeny production and virulence. Additionally, nematode infective juveniles carry fewer bacterial cells when colonized by a non-cognate symbiont. Finally, we show that Steinernema nematodes can distinguish heterospecific and some conspecific non-cognate symbionts in behavioral choice assays. Conclusions: Steinernema-Xenorhabdus symbioses are tightly governed by partner recognition and fidelity. Association with non-cognates resulted in decreased fitness, virulence, and bacterial carriage of the nematode-bacterial pairings. Entomopathogenic nematodes and their bacterial symbionts are a useful, tractable, and reliable model for testing hypotheses regarding the evolution, maintenance, persistence, and fate of mutualisms.

Original languageEnglish (US)
Article number100
JournalBMC Evolutionary Biology
Issue number1
StatePublished - Apr 17 2017


  • Entomopathogenic nematodes
  • Mutualism
  • Partner choice
  • Symbiosis

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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