Review article ENTOMOPATHOGENIC NEMATODES : A HIDDEN ENEMY OF INSECT PESTS R. K. Patidar 1 *, Ksh. Sumita 1 , M. M. Kumawat 1 , M. Pathak 2 , Siddhartha Singh 1 , R. C. Shakywar 1 and Hem Singh Yadav 3 1 College of Horticulture and Forestry, Central Agricultural University, Pasighat - 791 102, India. 2 KVK East Siang, College of Horticulture and Forestry, Central Agricultural University, Pasighat -791 102, India. 3 College of Agriculture, SVPUA & T, Modipuram - 250 115, Meerut, India. *e-mail: raghubirpatidar@gmail.com (Revised 22 April 2017; Accepted 11 June 2017) ABSTRACT : Entomopathogenic nematodes (EPN’s) are attractive, organic alternatives for controlling a wide range of insect pests and they are utilized in classical, conservation and augmentative biological control programs. The history of entomopathogenic nematology is briefly reviewed. In general, EPN’s are soil borne and generally gets mutually associated with a bacterium which is responsible for pesticidal actions and its life cycle of consist of five developmental stages. The two most studied species of EPN’s are Steinernematidae and Heterorhabditidae families which has mutualistic association with bacteria of genus Xenorhabdus and Photorhabdus, respectively. The virulence mechanisms of the symbiotic bacteria were depending upon antibiotic properties, phase variants and impeding host defense responses. In the laboratory use and small scale field experiments, in vivo production of EPNs appears to be the appropriate method. In vitro technology is used when large scale production is needed at reasonable quality and cost. The efficacy of EPNs can be enhanced through proper production technology, storage mechanism, application technology etc. The scientific community, academician and industrialist are interest to development of new bio-insecticides, which are environmentally friendly. The concerns for the environment and human health and to reducing the risks connected with chemicals, the present review article focused on importance of EPN’s in insect pests management, its life cycle, virulence mechanism, mass production technology, commercial product and storage, application technology, guideline for field application and its ccompatibility with insecticide and fertilizers are briefly reviewed. Key words : Biological control, entomopathogenic nematode, Heterorhabditis, nematode storage, Photorhabdus, Steinernema, Xenorhabdus and synergism. INTRODUCTION The term entomopathogenic nematode (EPN) refers to those nematodes, which parasitize and killed the insect hosts. EPN generally belongs to Steinernematidae and Heterorhabditidae. Worldwide, over 80 species of EPN have been identified, out of which 23 nematode families are described and 11 commercialized (Kaya and Koppenhofer, 1999). The different species of EPNs differs in the choice of insects they attack, ecological needs and stability in commercial products (Gaugler, 1999). Although, there are large numbers of nematodes associated with insects, so far only nine families exhibit the biological control potential against insects. Families like Allantonematidae, Parasitylenchidae, Iotonchiidae, Tetradonematidae, Sphaerulariidae, Mermithidae, Phaenopsitylenchidae , Steinernematidae and Heterorhabditidae have the ability to killed insects. Out of these families, Steinernematidae and Heterorhabditidae have received greater attention due to their attractive attributes as effective biological control agents (Kaya and Gaugler, 1993; Grewal et al, 2005a; Koppenhofer, 2007). The first EPN was described by Steiner as Aplectana kraussei (now Steinernema kraussei) in 1923 (Poinar and Grewal, 2012). Dutky and Hough (1955) isolated the DD-136 strain of an undescribed Steinernematid from codling moth larvae in Eastern North America, from where the serious studies on the pathogenicity and life history of EPN began. According to Grewal et al (2001) eighty three species of EPN have been described worldwide. Out of which, 64 species of Steinernema, 8 species of Heterorhabditis and 1 species of Neosteinernema have been reported. Among the indigenous nematode isolates from India, two have been described as new species viz., H. indica (Poinar et al, 1992) and S. thermophilum (Ganguly and Singh, 2000, 2003) from Tamil Nadu and New Delhi, respectively. Families of Steinernematidae and Heterorhabditidae are fatal to soil insects and have a symbiotic relationship with bacterium Xenorhabdus and Photorhabdus, respectively (Poinar, 1990; Kaya and Gaugler, 1993). The J. Exp. Zool. India Vol. 20, Supplement 1, pp. 1275-1289, 2017 www.connectjournals.com/jez ISSN 0972-0030