Plant-parasitic nematodes cause significant damage to a broad range of agricultural crops throughout the world. For decades, the control of phytonematodes has relied heavily on chemical nematicides. Recently, the use of chemical nematicide has been restricted due to their toxic effect towards the physical environment. So an environment friendly alternative for nematodes control is increasingly important. As the natural enemies of nematodes, nematophagous microorganisms offer a promising approach to control the nematode pests (Tian et al., 2007). Most of the microorganism released or secrets some metabolites which are toxin, antibiotic or inhibitory to phytonematodes and some have stimulatory effect. They act synergistically on nematode through direct suppression of nematodes, promoting plant growth, and facilitating the rhizosphere colonization. Some of the rhizobacterial species like Bacillus subtillis, Pseudomonas florescence produces hydrolytic enzyme such as protease, lipase, and cellulase which reduce the egg hatching, recognition and penetration (Siddiqui et al., 2005). Avermectin MK-936 is an antibiotic produced by Streptomyces avermitilus found to kill infective juvenile and inhibit egg hatching. Mycoparasitic fungi and other egg and female parasitizing fungi also parasitize nematode egg and larva through extracellular enzymes, producing toxin and other metabolites (Li et al., 2015). Researches on agents that work against phytonematode do not have detrimental impact on environment. Therefore increased understanding of the microbial secretion of the various mechanisms of beneficial microorganism could potentially enhance their value as effective biocontrol agent.
