Modelling the interactions of soil microbes and nematodes

Abstract

Six different soil food webs, assembled from a bacterium, a bacterial-feeding nematode, a fungus and a fungal-feeding nematode, were established in replicated laboratory microcosms. Glucose was supplied as the sole carbon source for the microbes. Biomasses of the organisms and the concentration of dissolved organic carbon (DOC) were measured ten times during 20 weeks. A discrete dynamic model based on the material flow between system components was fitted to the experimental data. Bacterial-based food chains were largely inactive in the absence of fungi, but mutual facilitation was observed in the systems with both fungus and bacterium. The population dynamics of a fungal-feeding nematode was adequately described by the models, but the model failed to describe DOC dynamics. The quality of fungal biomass appeared to be a key parameter in the system. Model performance was improved by letting fungal parameters vary with time and food web structure. Because fungal dynamics could not be explained by a trophic-dynamic model with rigid parameters, it is suggested that non-trophic effects of fungal-feeding nematodes on fungi may be more important in microcosms.

Does Plant Identity Affect the Dispersal of Resistomes Above and Below Ground?

“…Interestingly, Candidatus Xiphinematobacter , a known endosymbiont of the plant-parasitic nematode group, Xiphinema americanum , , was dominant in nematode samples planted with A. fistulosum . Perhaps bacterial communities, even resistomes, have a potential transfer pathway through a complex trophic delivery via the plant–bacteria–nematode food chain . Although our aim was to focus on the effect of surface microbes, endophytic bacteria cannot be completely left out due to inevitable wounds of leaves.…”

“…Perhaps bacterial communities, even resistomes, have a potential transfer pathway through a complex trophic delivery via the plant−bacteria−nematode food chain. 62 Although our aim was to focus on the effect of surface microbes, endophytic bacteria cannot be completely left out due to inevitable wounds of leaves. Soil and plant bacterial communities are selectively introduced into nematodes, forming the core bacterial taxa.…”

Effects of banana wilt disease on soil nematode community structure and diversity

“…Decreased abundance of bacterivores was associated with increased abundance of FOC which in turn strongly inhibited the abundance of soil beneficial bacteria in disease areas (Neher, 2005;Quénéhervé, 2008). Nieminen (2009) observed that soil beneficial bacteria provided available food resources for nematodes of Cephalobidae and Rhabditidae reproduced themselves. However, the mean abundance of fungivores was 40.2% higher in the disease area than in the control area.…”