In vitro evaluation of metabolites of Trichoderma spp. against second stage juveniles of Meloidogyne incognita.

Trichoderma harzianum and T. viride are beneficial fungi, found in nearly all soils and other diverse habitats and are potential biological control agents, known to influence a number of pathogens including nematodes. The biological control ability of Trichoderma spp seems to be due to multiple factors, as they had the ability to produce a variety of extracellular lytic enzymes and the production of many secondary metabolites. The metabolites of both Trichoderma harzianum and T. viride were extracted with acetone, benzene, methanol, and ethyl acetate using soxhlet extractor. The different concentrations (1000, 500, 250 & 125 ppm) of all these extracts were tested separately against J₂ of Meloidogyne incognita in vitro by immersion bioassay method. Observations on mortality were recorded after 24, 48 and 72 hrs of exposure. Based on the mortality data, LC₅₀ values were calculated by probit analysis and LC₅₀ values of all these extracts were compared with that of standard nematicide (triazophos). The ethyl acetate extract of both the fungal bio-agents were found most effective, while the extracts of T. harzianum was found better to that of T. viride irrespective of the solvents used. Methanol was found as the second best solvent whereas acetone and benzene were the least efficient.