Journal of Advanced Laboratory Research in Biology E-ISSN: 0976-7614 Volume 10, Issue 1, January 2019 PP 16-22 https:/ / e-journal.sospublication.co.in *Corresponding Author: Nada F. Hemeda 0000-0002-1570-7944. Received: 13 December 2018 E-mail: nfh00@fayoum.edu.eg. Accepted: 26 September 2018 Phone No.: 00201283987080. Research Article Evaluation of biological Control potential for different Trichoderma strains against Root-Knot Nematode Meloidogyne javanica Nada F. Hemeda 1, * and El Deeb M.A. 2 1 Department of Genetics, Faculty of Agriculture, Fayoum University, Fayuom, Egypt. 2 Department of Plant Protection, Faculty of Agriculture, Fayoum University, Fayuom, Egypt. Abstract: Twenty strains of four Trichoderma species (Trichoderma harzianum, Trichoderma viride, Trichoderma koningii and Trichoderma asperellum) were evaluated for its potential to control the root-knot nematode Meloidogyne javanica. Culture filtrates from Trichoderma strains were tested in 24-well tissue culture plates for effects on Meloidogyne javanica. Chitwood egg hatch and mobility of hatched second-stage juveniles (J2) were evaluated, all the twenty Trichoderma strains showed the ability to colonize M. javanica separated eggs and second- stage juveniles (J2) in sterile in vitro assays. T. asperellum possess the strongest egg-parasitic ability and very effective against 2nd stage larvae of M. javanica. In this investigation, randomly amplified polymorphic DNA (RAPD) markers was used to estimate the genetic variations between four strains of Trichoderma asperellum (KC898190, KC898191, KC898192 and KC898193) which were previously isolated from the rhizospheres of different plants growing in Fayoum Governorate, Egypt as a new strain of T. asperellum in Egypt. RAPD assay using 6 random primers identified T. asperellum strains with 5 specific unique markers. Keywords: Trichoderma spp., Biocontrol agent, Meloidogyne and RAPD marker. 1. Introduction The free-living soil fungus Trichoderma spp. is a potential biological control agent of plant-parasitic nematodes [1,2]. Biocontrol of the root-knot nematodes (Meloidogyne spp.) by different species of Trichoderma has been reported by several studies [3,4,5,6,7,8, 9,10,11]. Although Trichoderma species are sometimes found associated with Meloidogyne spp. in field soils and can penetrate their eggs and adult females, their successful deployment as a biocontrol agent against nematodes may depend on a thorough understanding of this fungus. Compatibility between the fungal isolate, host cultivar and soil substrate may, therefore, play an important role in the proliferation and persistence of Trichoderma spp. in soil. It is important that biocontrol strains are able to compete and persist in the environment, rapidly colonize and efficiently proliferate on newly formed roots [12] and provide continued benefits over the duration of annual crops [13]. Several articles have been published on Trichoderma spp. against Meloidogyne spp. with good results [6,7,14,15]. However, some important factors that are required for proper evaluation were sometimes neglected, especially the parasitic potential of the fungus in relation to its inoculum densities. To fully evaluate the potential of a biological control agent, a dose-response relationship between the concentration of the applied antagonist and the reduction of plant damage needs to be established. However, the inoculum density of the antagonist is difficult to determine in the kind and amount necessary for optimal activities. Different studies on antagonist dose–plant disease response relationships in biological control systems have been reported [16,17]. Some studies on the effects of different inoculum densities of Trichoderma against Meloidogyne spp. have demonstrated an increase in their efficacy at increasing inoculum density but up to certain levels [14,15]. The purpose of this study was to evaluate the effects of four Trichoderma species (Trichoderma harzianum, Trichoderma viride, Trichoderma koningii,