Effects of the tropical endogeic earthworm Pontoscolex corethrurus on the horizontal dispersal of soil nematodes

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Raharijaona, Sariaka | Blanchart, Eric | Razafindrakoto, Malalatiana | Rafolisy, Tovonarivo | Trap, Jean

Edité par CCSD ; Elsevier -

International audience. Free-living nematodes are key organisms that greatly enhance plant growth and nutrient uptake. In contrast, plant-parasitic nematodes are considered a major pest group in agriculture. The effect of nematodes, either positive or negative, on plant productivity depends on their ability to disperse in soils. Understanding the dispersal process of nematodes is therefore crucial but is still poorly documented. The aim of this study was to examine the effects of the endogeic tropical earthworm Pontoscolex corethrurus on the horizontal dispersal of nematodes in Ferralsols in Madagascar. A microcosm experiment was conducted under controlled laboratory conditions. Two factors modulating dispersion were studied: (i) the earthworm density with three modalities (without, five or ten individuals) and (ii) the duration of the experiment with two modalities (four and eight weeks). The results showed that P. corethrurus favored the horizontal dispersal of nematodes. This is mainly a dispersal mechanism through the earthworm casts that they deposit in the soil or on the soil surface during their movements. The total abundance of dispersed nematodes increased with the earthworm density and the duration of the experiment. Cephalobidae dominated the trophic structure of the dispersed nematodes, similar to the original populations. However, the original populations had a higher taxonomic diversity than the dispersed nematode communities. These results indicate that P. corethrurus, through dispersion, influences the spatial and temporal distribution, abundance and structure of nematode communities in the soil.

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