# Isolation, Identification, and Pathogenicity of Entomopathogenic Fungal Strains and Their Secondary Metabolites Against Spodoptera frugiperda (Lepidoptera: Noctuidae)

## TL;DR

This study isolates and tests entomopathogenic fungi and their metabolites for controlling the fall armyworm, showing promising larvicidal effects in the lab.

## Contribution

The study identifies new fungal isolates and evaluates their insecticidal potential against Spodoptera frugiperda using both conidial and metabolite treatments.

## Key findings

- Three entomopathogenic fungal isolates caused 60-84.44% mortality in S. frugiperda larvae at 14 days.
- Albifimbria verrucaria had the lowest LC50 and LT50, indicating high virulence.
- Fungal metabolites showed up to 50% larval mortality and elevated catalase activity in treated larvae.

## Abstract

The fall aِrmyworm, Spodoptera frugiperda (J.E. Smith), causes significant yield losses due to its high fecundity, broad host range, defoliation capability, and voracious larval feeding. Biological control using microorganisms has gained attention as a sustainable alternative to chemical pest management. Entomopathogenic fungi employ distinct modes of action and produce secondary metabolites with insecticidal properties. This study aimed to isolate and identify indigenous entomopathogenic fungal species and evaluate their pathogenicity against S. frugiperda. Three isolates belonging to the division Ascomycota were recovered from soil samples and identified as Botryotrichum domesticum isolate MP3H-5, Albifimbria verrucaria isolate E16, and Purpureocillium lilacinum isolate WARSO2 6 8. When applied at a concentration of 1 × 109 conidia mL⁻1, the fungal isolates induced significant cumulative mortality (60 to 84.44%) in S. frugiperda larvae at 14 days post-treatment. Albifimbria verrucaria was the most virulent, exhibiting the lowest LC50 (2 × 107 conidia mL⁻1) and LT50 (0.46 days). At a lower concentration of 1 × 107 conidia mL⁻1, the P. lilacinum isolate caused the highest pupal mortality (80%) at 7 days post-treatment. Crude fungal metabolites also demonstrated larvicidal activity, resulting in cumulative mortality rates of up to 50%. Furthermore, larvae treated with the entomopathogenic fungi showed elevated catalase activity. The high toxicity observed is likely associated with fungal secondary metabolites, which were characterized using GC-MS analysis. Under laboratory conditions, the tested entomopathogenic fungal isolates demonstrated strong potential as microbial agents for the control of S. frugiperda. However, further field-based validation is necessary to confirm their efficacy.

The online version contains supplementary material available at 10.1007/s13744-026-01360-3.