Earthworms use odor cues to locate and feed on microorganisms in soil

Lara Zirbes, Mark Mescher, Véronique Vrancken, Jean Paul Wathelet, François J. Verheggen, Philippe Thonart, Eric Haubruge

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Abstract

Earthworms are key components of temperate soil ecosystems but key aspects of their ecology remain unexamined. Here we elucidate the role of olfactory cues in earthworm attraction to food sources and document specific chemical cues that attract Eisenia fetida to the soil fungi Geotrichum candidum. Fungi and other microorganisms are major sources of volatile emissions in soil ecosystems as well as primary food sources for earthworms, suggesting the likelihood that earthworms might profitably use olfactory cues to guide foraging behavior. Moreover, previous studies have documented earthworm movement toward microbial food sources. But, the specific olfactory cues responsible for earthworm attraction have not previously been identified. Using olfactometer assays combined with chemical analyses (GC-MS), we documented the attraction of E. fetida individuals to filtrate derived from G. candidum colonies and to two individual compounds tested in isolation: ethyl pentanoate and ethyl hexanoate. Attraction at a distance was observed when barriers prevented the worms from reaching the target stimuli, confirming the role of volatile cues. These findings enhance our understanding of the mechanisms underlying key trophic interactions in soil ecosystems and have potential implications for the extraction and collection of earthworms in vermiculture and other applied activities.

Original languageEnglish (US)
Article numbere21927
JournalPloS one
Volume6
Issue number7
DOIs
StatePublished - Jul 26 2011

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All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

Cite this

Zirbes, L., Mescher, M., Vrancken, V., Wathelet, J. P., Verheggen, F. J., Thonart, P., & Haubruge, E. (2011). Earthworms use odor cues to locate and feed on microorganisms in soil. PloS one, 6(7), [e21927]. https://doi.org/10.1371/journal.pone.0021927