In vitro assessment of ten strains of nematophagous fungi to control Meloidogyne exigua, Meloidogyne incognita and Radopholus similis

Abstract

The search of alternative strategies to the use of nematicides to control plant parasitic nematodes is a major issue today. On this matter there has been a growing interest in the effectiveness of biological control using nematophagous fungi.  Therefore, the objective of this research was to determine the predatory capacity of several fungal strains were isolated from soil from plantations located in the Región Huetar Norte. To reach this goal, laboratory experiments were established to evaluate the in vitro mortality of individuals of Radopholus similis, Meloidogyne incognita and M. exigua, in the presence of each one of these fungal strains. According to the criteria, Hypocrea virens and Penicillium janthinellum strains had no predatory activity against the nematode species tested. Monacrosporium megalosporum, Trichoderma spirale and T. asperellum 2 strains showed nematicide activity against R. similis and M. exigua. Meanwhile, Gliocadium roseum and Fusarium oxysporum showed predatory activity against R. similis, only. Furthermore, T. asperellum and Gongronella butleri, showed potential for controlling M. exigua. None of the strains had the capability to control M. incognita. Moreover, P. lilacinus and F. oxysporum showed the capability to parasitize the eggs of both Meloidogyne species tested. In the same way, the eggs of M. incognita were parasitized by T. asperellum and T. spirale, and 56% of the eggs of M. exigua were parasitized by M. megalosporum. These results should be confirmed by field tests. It is also important, to study the secondary metabolites produced by these fungi, evaluate the possibility of genetic improvement and study the mechanisms involved in their nematode predatory capacity.