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Experimental evaluation of herbivory on live plant seedlings by the earthworm Lumbricus terrestris L. in the presence and absence of soil surface litter.

Kirchberger J, Eisenhauer N, Weisser WW, Türke M - PLoS ONE (2015)

Bottom Line: Lumbricus terrestris preferred to consume legume litter over litter of the other plant functional groups.Pulling live plants into earthworm burrows might induce microbial decomposition of leaves to make them suitable for later consumption.Herbivory on plants beyond the initial seedling stage may only play a minor role in earthworm nutrition and has limited potential to influence plant growth.

View Article: PubMed Central - PubMed

Affiliation: Terrestrial Ecology Research Group, Department of Ecology and Ecosystem Management, Technische Universität München, Hans-Carl-von-Carlowitz-Platz 2, D-85354 Freising, Germany.

ABSTRACT

Background: Recent studies suggested that the earthworm Lumbricus terrestris might act as a seedling predator by ingesting emerging seedlings, and individuals were observed damaging fresh leaves of various plant species in the field. To evaluate the significance of herbivore behavior of L. terrestris for plant and earthworm performance we exposed 23- to 33-days-old seedlings of six plant species to earthworms in two microcosm experiments. Plants belonged to the three functional groups grasses, non-leguminous herbs, and legumes. Leaf damage, leaf mortality, the number of leaves as well as mortality and growth of seedlings were followed over a period of up to 26 days. In a subset of replicates 0.1 g of soil surface litter of each of the six plant species was provided and consumption was estimated regularly to determine potential feeding preferences of earthworms.

Results: There was no difference in seedling growth, the number of live seedlings and dead leaves between treatments with or without worms. Fresh leaves were damaged eight times during the experiment, most likely by L. terrestris, with two direct observations of earthworms tearing off leaf parts. Another nine leaves were partly pulled into earthworm burrows. Lumbricus terrestris preferred to consume legume litter over litter of the other plant functional groups. Earthworms that consumed litter lost less weight than individuals that were provided with soil and live plants only, indicating that live plants are not a suitable substitute for litter in earthworm nutrition.

Conclusion: Our results demonstrate that L. terrestris damages live plants; however, this behavior occurs only rarely. Pulling live plants into earthworm burrows might induce microbial decomposition of leaves to make them suitable for later consumption. Herbivory on plants beyond the initial seedling stage may only play a minor role in earthworm nutrition and has limited potential to influence plant growth.

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Number of missing leaves in microcosms with and without earthworms.Comparison of the number of missing leaves in (A) microcosms with and without L. terrestris averaged over species and (B) among the six different plant species. Results are given as mean ± SE.
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pone.0123465.g003: Number of missing leaves in microcosms with and without earthworms.Comparison of the number of missing leaves in (A) microcosms with and without L. terrestris averaged over species and (B) among the six different plant species. Results are given as mean ± SE.

Mentions: The number of leaves per seedling and plant height did not differ significantly between treatments at the start of the experiment (S1 Statistics, S1.1 and S1.2). Results of an ANOVA comparing the number of leaves per seedling among treatments are shown in Table 1. The change in the number of leaves during the experiment in microcosms with (11.85 ± 1.31 mean ± SE per plant, taken all plant species together) and without L. terrestris (10.92 ± 0.92) did not differ significantly (Fig 2; Table 1; S1 Statistics, S1.3), but there was a significant interaction between the earthworm treatment and plant species (Fig 3; Table 1). For interpretation of the significant interaction, the number of leaves at the end of the experiment, after 26 days, are shown for earthworm treatments and controls in S1 Fig. There was also a significant interaction between the earthworm treatment and plant functional groups if replicates with dead earthworms were included (S1 Statistics, S1.3.2; p = 0.0161).


Experimental evaluation of herbivory on live plant seedlings by the earthworm Lumbricus terrestris L. in the presence and absence of soil surface litter.

Kirchberger J, Eisenhauer N, Weisser WW, Türke M - PLoS ONE (2015)

Number of missing leaves in microcosms with and without earthworms.Comparison of the number of missing leaves in (A) microcosms with and without L. terrestris averaged over species and (B) among the six different plant species. Results are given as mean ± SE.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401770&req=5

pone.0123465.g003: Number of missing leaves in microcosms with and without earthworms.Comparison of the number of missing leaves in (A) microcosms with and without L. terrestris averaged over species and (B) among the six different plant species. Results are given as mean ± SE.
Mentions: The number of leaves per seedling and plant height did not differ significantly between treatments at the start of the experiment (S1 Statistics, S1.1 and S1.2). Results of an ANOVA comparing the number of leaves per seedling among treatments are shown in Table 1. The change in the number of leaves during the experiment in microcosms with (11.85 ± 1.31 mean ± SE per plant, taken all plant species together) and without L. terrestris (10.92 ± 0.92) did not differ significantly (Fig 2; Table 1; S1 Statistics, S1.3), but there was a significant interaction between the earthworm treatment and plant species (Fig 3; Table 1). For interpretation of the significant interaction, the number of leaves at the end of the experiment, after 26 days, are shown for earthworm treatments and controls in S1 Fig. There was also a significant interaction between the earthworm treatment and plant functional groups if replicates with dead earthworms were included (S1 Statistics, S1.3.2; p = 0.0161).

Bottom Line: Lumbricus terrestris preferred to consume legume litter over litter of the other plant functional groups.Pulling live plants into earthworm burrows might induce microbial decomposition of leaves to make them suitable for later consumption.Herbivory on plants beyond the initial seedling stage may only play a minor role in earthworm nutrition and has limited potential to influence plant growth.

View Article: PubMed Central - PubMed

Affiliation: Terrestrial Ecology Research Group, Department of Ecology and Ecosystem Management, Technische Universität München, Hans-Carl-von-Carlowitz-Platz 2, D-85354 Freising, Germany.

ABSTRACT

Background: Recent studies suggested that the earthworm Lumbricus terrestris might act as a seedling predator by ingesting emerging seedlings, and individuals were observed damaging fresh leaves of various plant species in the field. To evaluate the significance of herbivore behavior of L. terrestris for plant and earthworm performance we exposed 23- to 33-days-old seedlings of six plant species to earthworms in two microcosm experiments. Plants belonged to the three functional groups grasses, non-leguminous herbs, and legumes. Leaf damage, leaf mortality, the number of leaves as well as mortality and growth of seedlings were followed over a period of up to 26 days. In a subset of replicates 0.1 g of soil surface litter of each of the six plant species was provided and consumption was estimated regularly to determine potential feeding preferences of earthworms.

Results: There was no difference in seedling growth, the number of live seedlings and dead leaves between treatments with or without worms. Fresh leaves were damaged eight times during the experiment, most likely by L. terrestris, with two direct observations of earthworms tearing off leaf parts. Another nine leaves were partly pulled into earthworm burrows. Lumbricus terrestris preferred to consume legume litter over litter of the other plant functional groups. Earthworms that consumed litter lost less weight than individuals that were provided with soil and live plants only, indicating that live plants are not a suitable substitute for litter in earthworm nutrition.

Conclusion: Our results demonstrate that L. terrestris damages live plants; however, this behavior occurs only rarely. Pulling live plants into earthworm burrows might induce microbial decomposition of leaves to make them suitable for later consumption. Herbivory on plants beyond the initial seedling stage may only play a minor role in earthworm nutrition and has limited potential to influence plant growth.

Show MeSH
Related in: MedlinePlus