Endophytic Entomopathogenic Fungi: A Potential Tool for Biological Control of Fall Armyworm in Maize

Abstract

Aims: To evaluate the lethal and sublethal effects of maize-derived fungal endophytes on Spodoptera frugiperda and assess their potential as sustainable biological control agents based on larval survival, feeding performance, growth, and developmental parameters. Study Design: Laboratory-based experimental study conducted in a completely randomized design. Place and Duration of Study: Maize Research Center, Agricultural Research Institute (ARI), Rajendranagar, Hyderabad, Telangana, India, during 2024-2025 under controlled laboratory conditions. Methodology: Fungal endophytes were isolated from maize stem samples collected across Telangana using a modified surface sterilization protocol. Bioefficacy was evaluated through leaf bioassays using second-instar larvae of S. frugiperda. Each treatment consisted of three replications with 10 larvae per replication (n = 30). Parameters recorded included larval mortality, relative growth rate (RGR), efficiency of conversion of ingested food (ECI), feeding deterrence index (FDI), larval and pupal developmental periods, pupation, and adult emergence. Biochemical characterization of isolates was carried out for plant growth-promoting traits. Molecular identification of the most effective isolate was performed using ITS rDNA sequencing. Results: Marked differences were observed among fungal isolates. ESF-8 recorded the highest larval mortality (61.40 ± 0.57%), lowest RGR (0.152 ± 0.001), lowest ECI (12.04 ± 0.51%), and highest feeding deterrence (38.94 ± 2.80%). It also prolonged larval (17.13 ± 1.18 days) and pupal periods (8.60 ± 0.49 days), and reduced pupation (55.56 ± 7.59%) and adult emergence (57.86 ± 3.24%). Biochemical analysis revealed high indole-3-acetic acid production (13.19 µg ml⁻¹) along with multiple growth-promoting traits. ITS sequencing identified ESF-8 as Talaromyces verruculosus (GenBank Accession No. PV876225). Conclusion: Maize-associated fungal endophytes, particularly T. verruculosus, demonstrated strong potential for incorporation into sustainable fall armyworm management programs, warranting further validation under field conditions.