~ 167 ~  Journal of Entomology and Zoology Studies 2016; 4(3): 167-169 E-ISSN: 2320-7078 P-ISSN: 2349-6800 JEZS 2016; 4(3): 167-169 © 2016 JEZS Received: 16-03-2016 Accepted: 17-04-2016 Somar Hazarika PhD. Scholar, Department of Entomology, College of Agriculture, Assam Agricultural University, Jorhat-785013, Assam, India Pulin Patgiri Principal Scientist, Department of Entomology, College of Agriculture, Assam Agricultural University, Jorhat-785013, Assam, India Pranab Dutta Scientist, Department of Plant Pathology, College of Agriculture, Assam Agricultural University, Jorhat-785013, Assam, India Shimantini Borkataki PhD. Scholar, Department of Entomology, College of Agriculture, Assam Agricultural University, Jorhat-785013, Assam, India Karishma Das Junior Research Fellow, Department of Entomology, College of Agriculture, Assam Agricultural University, Jorhat- 785013, Assam, India Correspondence Somar Hazarika PhD. Scholar, Department of Entomology, College of Agriculture, Assam Agricultural University, Jorhat-785013, Assam, India Efficacy of local isolate of Nomuraea rileyi (Farlow) Sampson against Helicoverpa armigera (Hubner) Somar Hazarika, Pulin Patgiri, Pranab Dutta, Shimantini Borkataki, Karishma Das Abstract A laboratory experiment was conducted to determine the efficacy of local isolate of entomopathogenic fungi Nomuraea rileyi (Farlow) Sampson against Helicoverpa armigera Hubner. The present investigation was carried out at Mycological Research Section, Department of Plant Pathology, Assam Agricultural University, Jorhat, Assam, India during the period 2013-2014. Different spore concentrations were adjusted and comparison was made with Malathion 50EC @ 1.5ml/l. Observations on larval mortality of 4 th instars H. armigera were recorded at an interval of 24hrs upto 10 days of post treatment. The results revealed that N. rileyi was highly virulent and infected the larvae in a dose dependent manner. At the highest concentration of 1 × 10 9 spores/ml, 17.40 % of the larvae were killed in 4 days and subsequently observed to be 85.92% at 10 days after treatment. At the next lower dose (1 × 10 8 ) total mortality was recorded to be 78.89%. The conidial concentration at 1 × 10 7 , 1 × 10 6 and 1× 10 4 conidia per ml caused 71.85%, 68.15% and 39.25% mortality respectively, with a minimum mortality of 25.14% at 1 × 10 2 concentration. The LC50 value of N. rileyi tested on 4 th instar larvae of H. armigera was found to be 2 × 10 4 conidia/ml at 10 days. Thus, field studies on combine application of the N. rileyi along with the selective pesticides will be a useful strategy for integrated pest management of H. armigera. Keywords: Efficacy, Helicoverpa armigera, Nomuraea rileyi 1. Introduction Helicoverpa armigera Hubner (Noctuidae; Lepidoptera) is a major pest that attacks a range of different vegetable crops and causes serious economic damage and yield loss. It is a polyphagous insect-pest and considered as an important insect-pest in different geographical regions. The major characteristics which contribute to H. armigera a pest status includes polyphagy, high mobility, high fecundity and a facultative diapauses that makes it particularly well adapted to different agro-ecosystems [1] . Management tactics for H. armigera relies heavily on insecticides and the extensive use of chemical pesticides resulted in insecticides resistance. The role of fungal pathogens as natural enemies for vegetable insect pests has been explored and many isolates have been identified [2] . N. rileyi (Farlow) Sampson is one of the naturally occurring potent entomopathogen pathogenic to a majority of the noctuids. Earlier, the natural occurrence of N. rileyi on Spodoptera litura Fabricius (Lepidoptera: Noctuidae) have been documented from Assam [3] and in most localities where it occurs, it affects the insect pest complex. Hence, the present study was initiated to test the efficacy of local isolate of N. rileyi against H. armigera under laboratory condition. 2. Materials and Method The present investigation was carried out at Mycological Research Section, Department of Plant Pathology, Assam Agricultural University, Jorhat, Assam, India during the period 2013-2014. 2.1 Culture of Helicoverpa armigera H. armigera cultures were established from a primary colony obtained from the Department of Agricultural Biotechnology, AAU, Jorhat, Assam. The culture of H. armigera was maintained in the laboratory on chickpea flour based semi synthetic diet [4] at a temperature of 27±1°C and 60±10 per cent relative humidity. The neonate larvae were fed individually on an artificial diet and healthy 4 th instars were used for the experiment.