Parasitism
The process of parasitism is defined as the interaction between two living organisms where an organism diverts host’s resources (i.e., food and shelter) for its own growth, reproduction and survival with no rewards for the hosts. This process involves a specific recognition between parasite and its host, together with cell wall-degrading enzymes that allow the parasite to penetrate the host’s cell wall. Parasites are costly for their host while they increase their own fitness, often living in their hosts for an extended period, and their activity can sometimes result in pathogenicity. In this context, we consider parasitism of plant pest and pathogens by soil organisms. Microscopic organisms such as viruses, fungi, bacteria, protozoa and nematodes contribute to this process, but also bigger animals such as parasitoids wasps.
Parasitism is only considered under the Disease and Pest Management function. Through parasitism of plant pest and pathogens, soil organisms are able to decrease inoculum density of these detrimental organisms and control the damages they might cause to plants. Parasitism of plant pathogens and pests is a widely distributed phenomenon. Some secondary metabolites produced by microorganisms during parasitism can also activate induced resistance in the plants.
Parasitism can be estimated by measuring soil organism parasitic activity with in lab-based laboratory assays for assessing parasitism for example by nematodes[1] and by fungi[2]. Bioassays can also carried out in plants[3]. Other methods rely on the molecular detection of parasite with metabarcoding[4].
[1] Spence et al. 2008. Host-finding and invasion by entomopathogenic and plant-parasitic nematodes: Evaluating the ability of laboratory bioassays to predict field results. The Journal of Nematology 40: 93–98.
[2] Ginè et al. 2016. Characterization of Soil Suppressiveness to Root-Knot Nematodes in Organic Horticulture in Plastic Greenhouse. Frontiers in Plant Science 7.
[3] Manzanilla-Lopez et al. 2009. Pochonia chlamydosporia: Advances and Challenges to Improve Its Performance as a Biological Control Agent of Sedentary Endo-parasitic Nematodes. The Journal of Nematology 45: 1–7.
[4] Furlong et al. 2015. Knowing your enemies: Integrating molecular and ecological methods to assess the impact of arthropod predators on crop pests. Insect Science 22: 6–19.