Growth Inhibition, Mortality Induction, Adverse Impacts of Development, and Underlying Molecular Mechanisms of Thymol Against Spodoptera frugiperda

The global migratory pest, <i>Spodoptera frugiperda</i>, has garnered widespread attention due to the serious damage it inflicts on agricultural productivity, particularly in maize. Thymol is a phytochemical that exhibits functional diversification in plant defense, encompassing antibacterial activities and insect pest management. However, the impact of thymol on <i>S. frugiperda</i> is still undetermined. This study examined the growth inhibition and mortality induction in <i>S. frugiperda</i> larvae after thymol exposure. The detrimental effects of 2.0 and 4.0 mg/g thymol treatments on the growth and development of <i>S. frugiperda</i> were also examined. RNA-Seq was used to investigate the probable toxicological mechanism of thymol on <i>S. frugiperda</i>, resulting in the identification of 1754 and 1022 DEGs impacted by 2.0 and 4.0 mg/g thymol treatments, respectively. The DEGs associated with chitin metabolism and cuticle synthesis, hormone biosynthesis, and protein and fat digestion were subjected to additional analysis. Our findings demonstrate the efficacy of thymol in controlling <i>S. frugiperda</i> and lay the groundwork for understanding the molecular toxicological mechanisms of thymol on larvae.