S14 - Session O1 - Modeling biological control of tomato root-knot nematode by predatory mites in the presence of an alternative prey

Authors: Thais Juliane Do Prado *, Yann Tricault, Larissa J. Rossini, Pedro L. M. Soares, Raphael de C. Castilho

Among plant-parasitic nematodes (PPN), the root-knot nematodes, Meloidogyne spp., are among the major pests, particularly in tomato cultivation, where they cause significant economic damage (a bout 20% yield losses per year ) . Several Mesostigmata mites are predators belonging to the top of the edaphic mesofauna food chain. Studies have recently evaluated the potential of these predatory mites (PM) as biological control agents of PPN. Additionally, this studies showed that supplementing the soil with non-parasitic free-living nematodes (FLN), as alternative prey for PM, may improve the biological control of PPN. This system represents an original case where the provision of alternative food could generate apparent competition between a pest nematode and a non-pest nematode in the feeding of the same PM. In this study, we present a population dynamic model that simulates direct and indirect interactions between the two nematodes species, Meloidogyne incognita (PPN) and Rabditella axei (FLN), their predator Protogammaselopsis zaheri (PM) and the tomato plant. We investigate whether apparent competition can improve pest control and limit damage and losses. We present a stage-structured model where the two preys (PPN, FLN) interact indirectly through the population dynamics of the PM. The model simulates the daily densities of PM and both nematode species at the scale of a tomato root system in greenhouse conditions, during the whole growing season. PPN loads are converted to root damage that add up to estimated losses. The model parameterization is based on PM life tables, experimental data and information from the literature. We explore the behavior of the model by varying the initial conditions of nematode densities (PPN load and FLN supply). Based on the simulation results, we discuss how apparent competition may contribute to a better strategy of PPN management in tomato greenhouses.