Role of tardigrades in the suppressive service of a soil food web

In a previous study, soil suppressiveness to populations of the plant-parasitic nematode Meloidogyne incognita was correlated with abundance of omnivore and predatory nematodes. In the current study, performance of the regulatory function switched from nematodes to tardigrades when predatory nematodes disappeared due to predation pressure and/or unfavorable environmental conditions. Two tardigrade species, Macrobiotus richtersi and M. harmsworthi effectively suppressed nematode populations. While there were significant changes in the soil food web over time, the regulatory function was maintained. Under experimental conditions, M. richtersi consumed 61 nematodes per day, indicating that tardigrades may significantly reduce nematode biomass. The impact of tardigrades on soil food web dynamics and their relationships with nematodes are discussed.