Microbial links and element flows in nested detrital food-webs

Pokarzhevskii, A. D.; Straalen, Nico M. van; Zaboev, D.P.; Zaitsev, Andrei S.

doi:10.1078/0031-4056-00185

Cited by 50 publications

(40 citation statements)

References 40 publications

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“…Overall, these studies confirm our conclusion that endogeic earthworms are not primarily limited by the amount of microbial N in soil, but the ability of earthworms to mobilize N from microbial biomass is controlled by C availability. This also indicates that endogeic earthworms use different resources to cover their carbon and nitrogen demands, as was earlier suggested for detrital food-webs (Pokarzhevskii et al 2003).…”

Section: Earthworm Growthmentioning

confidence: 80%

Carbon availability controls the growth of detritivores (Lumbricidae) and their effect on nitrogen mineralization

2004

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Activity of soil decomposer microorganisms is generally limited by carbon availability, but factors controlling saprophagous soil animals remain largely unknown. In contrast to microorganisms, animals are unable to exploit mineral nutrient pools. Therefore, it has been suggested that soil animals, and earthworms in particular, are limited by the availability of nitrogen. In contrast to this view, a strong increase in density and biomass of endogeic earthworms in response to labile organic carbon addition has been documented in field experiments. The hypothesis that the growth of endogeic earthworms is primarily limited by carbon availability was tested in a laboratory experiment lasting for 10 weeks. In addition, it was investigated whether the effects of earthworms on microbial activity and nutrient mineralization depend on the availability of carbon resources. We manipulated food availability to the endogeic earthworm species Octolasion tyrtaeum by using two soils with different organic matter content, providing access to different amounts of soil, and adding labile organic carbon (glucose) enriched in (13)C. Glucose addition strongly increased the growth of O. tyrtaeum. From 8 to 17% of the total C in earthworm tissue was assimilated from the glucose added. Soil microbial biomass was not strongly affected by the addition of glucose, though basal respiration was significantly increased and up to 50% of the carbon added as glucose was incorporated into soil organic matter. The impact of earthworms on the mineralization and leaching of nitrogen depended on C availability. As expected, in C-limited soil, the presence of earthworms strongly increased nitrogen leaching. However, when C availability was increased by the addition of glucose, this pattern was reversed, i.e. the presence of O. tyrtaeum decreased nitrogen leaching and its availability to soil microflora. We conclude that irrespective of the total carbon content of soils, O. tyrtaeum was primarily limited by carbon, and that increased carbon availability allowed earthworms to be more effective in mobilizing N. The presence of earthworms increases C limitation of soil microorganisms, due to increased availability of N and P in earthworm casts or a direct depletion of easily available carbon resources by earthworms.

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Section: Earthworm Growthmentioning

confidence: 80%

Carbon availability controls the growth of detritivores (Lumbricidae) and their effect on nitrogen mineralization

2004

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“…They can prey on other woodlice from the same species or from different species, especially during social interactions [40]. The probability to be eaten by congenerics or conspecifics increases for individuals that are weak, for example being injured or in the middle of a molting period [41]. Another advantage of using terrestrial isopods is their relatively long lifespan (a few years) that allows the monitoring of the infection status in the same individuals for months after the initial infection.…”

Section: Introductionmentioning

confidence: 99%

Cannibalism and Predation as Paths for Horizontal Passage of Wolbachia between Terrestrial Isopods

et al. 2013

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The alpha-proteobacteria Wolbachia are the most widespread endosymbionts in arthropods and nematodes. Mainly maternally inherited, these so-called sex parasites have selected several strategies that increase their vertical dispersion in host populations. However, the lack of congruence between the Wolbachia and their host phylogenies suggests frequent horizontal transfers. One way that could be used for horizontal Wolbachia transfers between individuals is predation. The aim of this study was to test whether horizontal passage of Wolbachia is possible when an uninfected terrestrial isopod eats an infected one. After having eaten Armadillidium vulgare harbouring Wolbachia, the predator-recipients (the two woodlice A. vulgare and Porcellio dilatatus dilatatus) that were initially Wolbachia-free were tested positive for the presence of Wolbachia both by quantitative PCR and Fluorescence in situ Hybridization (FISH). Even if the titers were low compared to vertically infected individuals, this constitutes the first demonstration of Wolbachia occurrence in various organs of an initially uninfected host after eating an infected one.

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“…However, Adl and Gupta [1] suggest this is not necessarily correct and Adl [3] suggested, from the literature, that insect larvae, earthworms and nematodes were probably the main consumers of protozoa, but this remains untested. It is also probable that there are nested compartments within the soil food web [42] and that feeding preferences reflect opportunity as well as predilection.…”

Section: Introductionmentioning

confidence: 99%

Protozoan Pulses Unveil Their Pivotal Position Within the Soil Food Web

et al. 2011

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Protozoa are one of the most abundant groups of bacterivores within the soil and are responsible for mineralisation of bacterial biomass, having a large impact on C and N cycling. Little is known of their contribution to soil nutrient transfers or the identity of their consumers. Here, for the first time indigenous flagellates and ciliates, enriched to 83 atom% for (13)C and 10 atom% for (15)N, were introduced to soil cores from two different land managements, grassland and woodland with the same soil type, to trace the flow of protozoan C and N through the soil food web. Nematodes, Collembola, earthworms and insect larvae obtained the greatest amounts of C and N of protozoan origin, either through direct consumption or uptake of biomass post-cell death. Our results show that changes in management, affect the functioning of the soil food web and the utilisation of protozoa as a food source.

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Microbial links and element flows in nested detrital food-webs

Cited by 50 publications

References 40 publications

Carbon availability controls the growth of detritivores (Lumbricidae) and their effect on nitrogen mineralization

Carbon availability controls the growth of detritivores (Lumbricidae) and their effect on nitrogen mineralization

Cannibalism and Predation as Paths for Horizontal Passage of Wolbachia between Terrestrial Isopods

Protozoan Pulses Unveil Their Pivotal Position Within the Soil Food Web

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