The root-knot nematode, Meloidogyne spp., is an endoparasite that infects plants' root system and causes yield losses in several important crops. Meloidogyne is one of the most devastating pests, so searching for effective biological agents is needed to mitigate its damage. In this study, the predatory activity of Arthrobotrys oligosporus Fresen strain C-2197, obtained from a tropical dry forest of Ecuador, was evaluated as a biocontrol alternative for root-knot caused by Meloidogyne spp. Our results showed that A. oligosporus C-2197 has predatory activity against juvenile nematodes, 72.31%, and 79% efficacy, for in vitro and greenhouse conditions. Besides, the studied strain showed growth-promoting activity, increasing leaf and root area of inoculated plants. Growth promoting activity was also observed in field tests. The present study validates the potential use of A. oligosporus as a biocontrol of Meloidogyne spp. in tomato production systems under greenhouse. It also presents useful information on the use of different cultivation media and substrates for massive A. oligosporus spore concentrates.

Nematophagous fungi (NF) are a group of diverse fungal genera that benefit plants. The aim of this review is to increase comprehension about the importance of nematophagous fungi and their role in phosphorus solubilization to favor its uptake in agricultural ecosystems. They use different mechanisms, such as acidification in the medium, organic acids production, and the secretion of enzymes and metabolites that promote the bioavailability of phosphorus for plants. This study summarizes the processes of solubilization, in addition to the mechanisms of action and use of NF on crops, evidencing the need to include innovative alternatives for the implementation of microbial resources in management plans. In addition, it provides information to help understand the effect of NF to make phosphorus available for plants, showing how these biological means promote phosphorus uptake, thus improving productivity and yield.

Mecanismos de captura, colonización y alimentación empleados por parásitos y predadores de nematodos. Los organismos del suelo tienen un papel fundamental en la estructura y ciclo de nutrientes en los ecosistemas; especialmente los nematodos que son abundantes y funcionalmente diversos. Debido a que algunos taxones de nematodos causan enfermedades a las plantas, la mayoría de los estudios tienen un enfoque agrícola, por tanto, es de relevancia ecológica conocer los diferentes grupos de organismos de suelo que los consumen o parasitan. El propósito de esta revisión es discutir sobre los mecanismos de captura, colonización o alimentación que ejercen los enemigos naturales de los nematodos, especialmente los predadores y parásitos, tales como bacterias, hongos, nematodos, microartrópodos y tardígrados. Algunas bacterias que se encuentran en la rizosfera sintetizan moléculas tóxicas que matan a los nematodos mientras que los hongos nematófagos pueden ser predadores, endoparásitos, parásitos de huevos, productores de toxinas y presentar dispositivos especiales para la captura de sus presas. Además, los nematodos predadores presentan tres mecanismos de alimentación: las especies del orden Mononchida cortan a sus presas o las consumen enteras, las del orden Diplogasterida cortan y succionan los contenidos y finalmente las de los ordenes Dorylaimida y Aphelenchida emplean un estilete para perforar y succionar. En el caso de los microartrópodos, los colémbolos emplean sus maxilares y los ácaros sus quelíceros para agarrar, triturar y masticar, mientras que los tardígrados pueden devorar nematodos enteros. Conocer las estrategias de los parásitos y predadores de nematodos complementa la investigación en patógenos de importancia agrícola y contribuye a la comprensión de la complejidad de las redes tróficas del suelo.

Nematophagous fungi can feed on nematodes under nutrient-poor conditions. They live in the soil and their study is important because of their possible use in the biocontrol of phytoparasitic nematodes. These fungi can be cultivated in the laboratory using different media and substrates, making them potential agents for agricultural use in tropical environments. The objective was to review recent scientific advances in the ecological interactions of nematophagous fungi and their prey, with emphasis on their use as biological controllers. Given the importance of their interactions in the soil, diversity, abundance, dispersal, and colonization of different types of habitats, these fungal microorganisms can be specialists or generalists in the predation of nematode populations in their various stages (egg, juvenile or adult). The different scientific advances and applications of predatory fungi in some tropical crops in Latin American countries are also briefly described. After these explorations, it is possible to conclude that the integrated application of microorganisms in the soil could improve the production of some cultivars by efficiently reducing nematode populations. In addition, it could improve the structure of soil trophic interactions, with environmentally benign treatments that reduce the use of chemical pesticides.