Indian Journal of Entomology Online published Ref. No. e23024 DoI. No.: 10.55446/IJE.2023.1024 EFFICACY OF METARHIZIUM RILEYI AGAINST FALL ARMY WORM SPODOPTERA FRUGIPERDA IN MAIZE SACHIN KHAIRNAR, CHARUDATTA CHAUDHARI*, SAKHARAM AGHAV, CHIDANAND PATIL AND VIVEK SHINDE Department of Agricultural Entomology, Mahatma Phule Krishi Vidyapeeth, Rahuri 413722, Maharashtra, India *Email: charudatta.abs@gmail.com (corresponding author): ORCID ID 0000-0002-5619-8162 ABSTRACT In this study, Metarhizium rileyi formulation was applied using four methods and their efficacy evaluated at different concentrations against the fall army worm Spodoptera frugiperda (J E Smith) in maize. The treatment of dusting of M. rileyi 1.15 % WP @ 2.5 kg/ ha followed by spraying of M. rileyi 1.15 % WP @ 5 g/ l was found superior. It was also observed that sole spraying and dusting treatment were comparatively less effective than dusting followed by spraying. Dusting of M. rileyi 1.15 % WP @ 2.5 kg/ ha followed by spraying of M. rileyi 1.15 % WP @ 5 g/ l gave the maximum cost benefit (ICBR of 8.70) and grain yield (61.09 q/ ha). Key words: Spodoptera frugiperda, Metarhizium rileyi, whorl application, dusting, spraying, Bacillus thuringiensis, azadirachtin, maize, plant damage, cost benefits, yield, ICBR Maize is grown on 90.27 million ha in India with an output of 25.50 mt of which 9.26 million ha is in Maharashtra, with a production of 1.77 mt (Anonymous, 2020). About 141 insect species have been identified as pests of maize in India (Kumar, 2015). Amongst these, the fall army worm Spodoptera frugiperda (J E Smith) (Noctuidae) is a devastating invasive pest (Bajracharya et al., 2019). It is a polyphagous insect pest that feeds on > 353 plant species and maize is the most preferred host. It has achieved a status of major pest of maize in a very short time after its invasion. Entomopathogenic fungi are found on variety of insects from different habitat and their association was found in fresh water, soil and air places (Hajek and Leger, 1994). Unlike insect pathogenic bacteria and viruses, fungus have the ability to pierce insect host cuticle, infiltrate by releasing proteolytic enzymes and allowing them to cause epizootics in favourable climatic conditions. Such fungi have already been found on S. frugiperda in Karnataka, India (Sharanabasappa et al., 2018a & b). Insecticides are frequently employed by farmers to control the fall armyworm in maize (Deshmukh et al., 2020). But biopesticides including entomopathogenic fungi like Metarhizium rileyi are best alternatives. Their efficacy against the fall armyworm has been investigated earlier work but there is a need to work on the application method. The present study evaluates some application methods of Metarhizium (Nomuraea) rileyi against fall armyworm in maize. MATERIALS AND METHODS Field experiments were conducted at the AICRP on Maize, Pulses Improvement Project, MPKV, Rahuri during kharif 2020. There were seven treatments viz., spraying of M. rileyi 1.15% WP @ 5 g/l-T 1 , dusting of M. rileyi 1.15 % WP @ 2.5 kg/ ha -T 2 , dusting of M. rileyi 1.15% WP @ 2.5 kg/ ha followed by spraying of M. rileyi 1.15 % WP @ 5 g/ l –T 3 , spraying M. rileyi 1.15 % WP @ 5 g/ l followed by dusting of M. rileyi1.15 % WP @ 2.5 kg/ha -T 4 , spraying of B. thuringiensis @ 2 ml/ l- T 5 and azadirachtin 1500 ppm @ 5 ml/ l -T 6 and untreated check- T 7 . The experiment was set up in a randomized block design with three replications and an untreated control. Rajarshri variety was sown on July 28, 2020 in a plot measuring 5 x 3 m with plant spacing 75 x 20 cm. At 20 and 35 days after sowing, biopesticides were applied twice an interval of 15 days. Infested and healthy plants were recorded from each plot one day before and, seven and fifteen days after treatment, and % infestation was calculated (Mallapur et al., 2018a). The % infestation data were subjected to arc sin transformation before statistical analysis (Gomez and Gomez, 1984). The grain yield/ plot (kg) was recorded and converted to q/ ha, and incremental cost-benefit ratio (ICBR) was determined (Ojha et al., 2019).