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

Simple SummaryThe fall armyworm,Spodoptera frugiperda, is an economically important pest that has caused extensive damage to many crops all around the world over the past decade. Due to the advantages of being bioactive, biodegradable, and ecologically safe, thymol, one of the principal ingredients identified in essential oils, has exhibited its potential in pest control. However, the effects and toxicological mechanisms of thymol onS. frugiperdaare still unclear. In this study, we evaluated the bioactivity of thymol on the larvae ofS. frugiperda. RNA-Seq was performed to explain the preliminary toxicological mechanisms of thymol on larvae by the identification and functional enrichment analyses of differentially expressed genes (DEGs). Overall, our findings indicate that thymol also exhibits the potential for the control ofS. frugiperda.The global migratory pest,Spodoptera frugiperda, 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 onS. frugiperdais still undetermined. This study examined the growth inhibition and mortality induction inS. frugiperdalarvae after thymol exposure. The detrimental effects of 2.0 and 4.0 mg/g thymol treatments on the growth and development ofS. frugiperdawere also examined. RNA-Seq was used to investigate the probable toxicological mechanism of thymol onS. frugiperda, 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 controllingS. frugiperdaand lay the groundwork for understanding the molecular toxicological mechanisms of thymol on larvae.