Insecticidal Activity of Entomopathogenic Fungi against the Immature Stages of 𝐹𝑎𝑙𝑙 𝐴𝑟𝑚𝑦𝑤𝑜𝑟𝑚

This study investigated the potential of five entomopathogenic fungal isolates for controlling the Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), known as fall armyworm (FAW), a devastating agricultural pest. The findings demonstrate a remarkable impact on the mortality rate of eggs, neonates, and larvae, highlighting their potential as eco-friendly biocontrol agents. Beauveria bassiana exhibited the most potent effect, significantly reducing hatchability to 40.9, 73.3, and 87.8% at 1 × 106, 1 × 107, and 1 × 108 spores/mL, respectively, followed by Metarhizium anisopliae M4 (31.5%, 51.4%, and 77.6%). In addition, both B. bassiana and M. anisopliae M4 has the highest neonatal mortality of 58.9 and 45.5% at 1 × 108 spores/mL, respectively. B. bassiana and M. anisopliae M4 caused cumulative mortality, including 92.4 and 82.2% mortality of eggs and neonates, respectively, at 1 × 108 spores/mL. Similarly, B. bassiana and M. anisopliae M4 caused the highest second instar larvae mortality by 44.9 and 35.7%, respectively. However, no significant effect was found on pupal formation. Furthermore, compared with the control treatment, both B. bassiana and M. anisopliae M4 significantly reduced relative consumption rate and conversion of ingested food.