Soil nematode genera that predict specific types of disturbance

Nematode community indices would be more cost-effective and interpretable if ambiguous genera were removed and indices reduced to only genera with known sensitivity or response to specific types of disturbance. The objective of the present study was to perform a methodical multivariate analysis of existing datasets of high quality and enumerate the genera that respond universally consistent to a specific type of disturbance, treatment, or management worldwide. We collected 20 sources of original data from land used for agricultural purposes, whether cropland, livestock grazing or fruit orchard with manipulated treatments in cultivation, inorganic or organic fertilization or contaminated by heavy metals. Canonical correspondence analysis was performed to determine the effect of disturbance type on the composition of soil nematode communities. Genera that performed consistently in a single direction and across at least two seasons were identified. Briefly, cultivation reduced abundances of Diphtherophora, Prismatolaimus and Tylenchorhynchus. Application of synthetic chemical fertilizers reduced numbers of Plectus. Application of organic fertilizers resulted in increased numbers of Cruznema, Mesorhabditus, Mesodorylaimus and Nygolaimus. No genera met the criteria for responding positively to either cultivation or inorganic fertilization or negatively to organic fertilization. The source of nutrients apparently affected nematode communities differently. Selected nematode genera were correlated positively with the heavy metals Cd, Cu and Zn, while nematode genera correlated negatively with Cr and Se. These genera need to be verified by independent data to confirm that they respond predictably and consistently to these specific types of disturbance. Once verified, this subset of genera will improve interpretation of index values and can be the initial targets for developing molecular probes that can be made accessible to non-specialists.