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

Zirbes L, Mescher M, Vrancken V, Wathelet JP, Verheggen FJ, Thonart P, Haubruge E - PLoS ONE (2011)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Functional and Evolutionary Entomology, Gembloux Agro-Bio Tech, University of Liege, Gembloux, Belgium. Lara.Zirbes@ulg.ac.be

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.

Show MeSH
Experimental set-up.(a) Dual-box earthworm sampling device, (b) four-arm olfactometer (A = central chamber, B = (identical) arms), (c) vertical olfactometer.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3140477&req=5

pone-0021927-g001: Experimental set-up.(a) Dual-box earthworm sampling device, (b) four-arm olfactometer (A = central chamber, B = (identical) arms), (c) vertical olfactometer.

Mentions: A PVC box (Box #1: 56 cm×36 cm×8 cm) was filled with moist compost (76% humidity content; obtained by drying a 25 g sample of moist compost at 105°C for 48 h), and 200 earthworms (100 matures and 100 immatures) were placed randomly within it. A second box (Box #2: 37 cm×26 cm×9 cm) was placed on top of Box 1 (Fig. 1). Box 2 had 5 slots (30 cm long×0.5 cm wide) in its bottom and was also filled with moist compost (prepared as above) Filtrate (275 ml) from the G. candidum culture was then poured evenly across the surface of Box 2. Pairs of control boxes were similarly placed but received tap water instead of the fungal filtrate. After 120 h, the number of earthworms in each box was determined. Six repetitions were conducted with the G. candidum filtrate and three for the controls.


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

Zirbes L, Mescher M, Vrancken V, Wathelet JP, Verheggen FJ, Thonart P, Haubruge E - PLoS ONE (2011)

Experimental set-up.(a) Dual-box earthworm sampling device, (b) four-arm olfactometer (A = central chamber, B = (identical) arms), (c) vertical olfactometer.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3140477&req=5

pone-0021927-g001: Experimental set-up.(a) Dual-box earthworm sampling device, (b) four-arm olfactometer (A = central chamber, B = (identical) arms), (c) vertical olfactometer.
Mentions: A PVC box (Box #1: 56 cm×36 cm×8 cm) was filled with moist compost (76% humidity content; obtained by drying a 25 g sample of moist compost at 105°C for 48 h), and 200 earthworms (100 matures and 100 immatures) were placed randomly within it. A second box (Box #2: 37 cm×26 cm×9 cm) was placed on top of Box 1 (Fig. 1). Box 2 had 5 slots (30 cm long×0.5 cm wide) in its bottom and was also filled with moist compost (prepared as above) Filtrate (275 ml) from the G. candidum culture was then poured evenly across the surface of Box 2. Pairs of control boxes were similarly placed but received tap water instead of the fungal filtrate. After 120 h, the number of earthworms in each box was determined. Six repetitions were conducted with the G. candidum filtrate and three for the controls.

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Functional and Evolutionary Entomology, Gembloux Agro-Bio Tech, University of Liege, Gembloux, Belgium. Lara.Zirbes@ulg.ac.be

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.

Show MeSH